View Full Version : T-5 transmission in 1/3 scale

03-28-2011, 08:58 AM
Over the last number of years my winter machining generally involved designing and building I.C. engines, in miniature of course. This year I decided on something a little different, a T-5 transmission to go with my 302 V-8 engine.
My son had one in his garage so the first thing was to clean it up, dismantle it and make drawings. With all the sketches and dimensions taken I made up a set of Autocad drawings for all the parts.
As with all miniaturization some parts needed to be modified for strength and simplicity. The full sized trans has helical gears and for the home machinist that wasn't a viable option so I designed the trans for spur gears. That involved making 3 different sized gear cutting hobs for non standard pitches. This was necessary to maintain approximate gear ratios and center spacing from the mainshaft to countershaft.
I started with a block of 6061 aluminum. All of the holes were put in first as it's easier to drill, bore and ream holes when you have support metal around the tool. The first couple of pictures show the starting block and some of the progressive machining steps to get to the finished case.

03-28-2011, 09:02 AM
As with any complex machining project, large or small, the most important part is fixturing or clamping. You can't get to a point where you still need to remove metal but have nowhere to grab onto the part. I started with the inside then moved to the outer sides leaving the last material on the bottom. That way I could clamp on the front and rear faces to cut the bottom.

03-28-2011, 09:05 AM
Very impressive. How about a couple of shots of the 302?


03-28-2011, 09:05 AM
The bottom involved cutting radii and curved shapes. Some could have probably been done on a rotary table but to change setups on the mill is time consuming so in most cases I just set up a step-off chart (sine and cosine) and do them by hand.

03-28-2011, 09:06 AM
The finished main case.

03-28-2011, 09:08 AM
Looking forward to seeing that completed, please post the images of that. Next project would be a scale Mustang to mount engine and tranny on.

03-28-2011, 09:11 AM
Oh! There has to be more!:eek:

03-28-2011, 09:13 AM
Very impressive. How about a couple of shots of the 302?


Not quite a year ago. Don't miss the video...it's worth a look!!


All I can say is WOW!
First a stellar engine project and now this.
Good to see someone is actually doing some machining here.:D
Reminder to get my ass in gear.;)

03-28-2011, 10:09 AM
inspirational work as always, thanks for sharing it

03-28-2011, 11:04 AM
The tailshaft housing posed a few more problems as there aren't a lot of flat surfaces to clamp to. I started out by drilling and reaming the shaft holes. Next I machined out the front cavity where the overdrive gears go.

03-28-2011, 11:11 AM
After finishing the front cavity I laid out the shifter box area to give me some visual references. It's hell when you think you're doing fine and then realized that you machined off something important.
After that I started cutting away the sides and bottom down to a certain point to where I could leave some clamping ears.

03-28-2011, 11:13 AM
The next 2 pics show the rough machining done on the bottom side. I know there's a trans case in there somewhere.

03-28-2011, 11:14 AM
Extremely impressive work, George!

At the risk of repeating others, thanks for sharing. The images were excellent at displaying your remarkable talent.


03-28-2011, 11:18 AM
Next up was starting all the radiusing and more profiling. As I stated earlier in most cases it's just easier to step off the radius. I have an Autocad program which simplifies the calculations. I draw the desired radius, offset the cutter radius and then give myself coordinate dimensions for the steps. This way I can calculate my stopping or tangency points without over cutting.

03-28-2011, 11:21 AM
The trans mount, ribbing, some holes and the speedometer drive boss were now put in.
You can see the 2 rectangular pieces of stock remaining on the top side of the case. These would get removed after all the heavy stock was cut off.

03-28-2011, 11:28 AM
With only moderate to light cuts to be made from here out I could clamp it lightly enough from the front face and the square I left on the end of the tailshaft. I had to cut the shift shaft housing area next. The housing is a conical taper that steps around other shapes. What I ended up doing was to step off a straight radius first, then I clamped the housing at the required cone angle and repeated the radius. It didn't give me a perfect cone but the bottom side of the shape would blend into a rib so it could be faked out when the finish hand work was started.

03-28-2011, 11:31 AM
At this point I no longer had surfaces to set up to for all the remaining angular and conical cuts that needed to be made so I had to make a fixture plate to bolt the front face of the housing to.

03-28-2011, 11:34 AM
I got all the rough machining done and just had to bolt the 2 pieces together to see what they looked like.

03-28-2011, 11:35 AM
At this point all the machining is complete.

03-28-2011, 11:43 AM
Now comes all the hand work. I start out by covering all the surfaces with a permanent marker. This makes it easier to see what's being removed with the burrs and stones. I use a Dremel grinder with a flex shaft for all this work. The burring is done first, cleaning out heavy spots and removing stock that was too difficult to cut with a ball mill. This process has to be done very carefully as the burrs can grab and skate along a surface cutting or marring unwanted areas.
With the burring done I use jeweler's and riffler files to work down the flat surfaces. Finished aluminum reflects every divot and irregularity so you have to try and smooth everything you can with a file. The stones get into small pockets and corners to smooth out what the burrs left behind.
These 2 shots show the burring, stoning and filing compete.

03-28-2011, 11:51 AM
The final steps are to polish everything, not to a high finish but rather to smooth out the surfaces. I have several home made mandrels, .125 diameter rods that have been split to accept emery paper. I wind various grades of paper onto these rods using enough wraps to get the desired radius. I then tape them off to the shank of the mandrel and start cleaning everything up. As I stated earlier aluminum reflects everything so even though the emery is fine compared to the mounted stones care must be taken not to sit in one spot too long or a minute surface imperfection will appear. Here the two cases are finished and bolted together. The last picture shows a comparison of the small replica to the full sized piece.

I have the top cover machined and will post about it when I get a chance.

03-28-2011, 09:05 PM
Sheesh! That's impressive!

Just one question- this is going to be a 1/3 World Class T5, right???



03-28-2011, 09:50 PM
I can't quite get bearings small enough for the gear sets but that is what the original is. The shafts will ride on ball bearings and I bought spline shaft and spline bushings for the shift collars. The only thing I'm concerned about is if the mainshaft will have enough strength to try and start the engine with. I think I will make a test mainshaft first to see if it will work. Right now I use a .50 one way bearing in the flywheel to start the engine.

03-28-2011, 10:16 PM
You are a sick man sir. It's a disease I know well.

That reminds me of an incident that happened to me when I was very small. My father took me to my Uncle's office to show me his latest project. He was an architect and a fine model builder. In his office was the model for his latest project. I couldn't have been more than five years old but I recall being completely mystified as to how they would turn that perfect model into the full size building. Even then I grasped that it must be impossible to physically enlarge something but it still seemed like that was the intent.

Your model reminds me of that moment.

03-28-2011, 10:23 PM
What sort of bearings are you looking for and what size?

03-28-2011, 11:43 PM
Wow! Holy smokes ! Awesome! :eek:
Will all of the gears be functional?

gary hart
03-29-2011, 12:03 AM
Very nice, great, awesome and more. Thanks for sharing your talents.

Curious on your method used when contouring around something with changing depths. Do your write out list with the x,y & z moves you calculated out and then check them off after making every move?

That is a heck of a lot of math and moves without making a fatal mistake.

03-29-2011, 02:42 AM
Your skills are very impressive, But I envy your patience and dedication the most.

03-29-2011, 06:33 AM
Thanks everyone for the comments.
Evan, When I was designing the shift collars I had to find some commercially available spline shafting and spline bushings. I found some through SDPI. It would be a complete redesign of the shafts and gears at this point to put bearings in them but thanks for asking.
Gary, I draw an arc of the desired radius. I then offset that radius with the radius of the ball mill that I'm going to use to make the cut. This gives me the proper radius centerline to make the calculations to. I then break that arc up into enough divisions to give a relatively small cusps (ridges between cuts) and dimensions the centerpoints. It's kind of like a manual CNC job.
When I learned my trade (metal patternmaking) there were many times this technique had to be used so that's where I learned it. It does require concentration but I have a digital readout on my mill so it's not that hard.
This is my mill, shown without the readouts on it.

Bill Pace
03-29-2011, 08:41 AM
Geez, Mr Britnell --- you obviously have never paid attention to the loud out cry about those sorry, inaccurate, non-recentering, etc,etc "round column" blankety, blank mills --- HAH, damn good thing too...


You just keep right on turning out that awful looking work on that poor excuse for a mill;)

03-29-2011, 09:01 AM
Good God. I could have DRO's out the butt and I'd still manage to fudge that up in hurry. My mouth is hanging open here. That is just fantastic work sir!

03-29-2011, 09:03 AM
Beautiful work as usual George. Will you have it at the NAMES show in April?

George is another of those unassuming individuals who quietly make some of the most inspiring models. He is among the few who have been honored by the Craftsmanship Museum. More of his work can be seen in this link;


03-29-2011, 09:12 AM
Hi Bill,
I bought this mill new in 1978. They had just started to import them through Grizzly on the west coast and Enco. At that time buying a used Bridgeport or similar mill wasn't like it is today. Most of the shops used them and they weren't as cheap or prolific as they are today. There was no internet so no one knew what these mills were.
Starting out with just a milling attachment for my lathe I thought, man this is the big time, a real honest to goodness milling machine. Mine was the first generation and it's made quite heavy.
It does have drawbacks (round column) and inaccuracies (poor lead screws), fixed with digitals and some other minor annoyances but I have done 95% of my work with this mill. I have learned to work around the round column issue and hardly concern myself with it. I have the head trammed to .0015 in 8 inches and it stays there. Even after years of use it only has .011 backlash in Y and .014 in X. I built a high speed spindle adapter for it so I can use small end mills. I would like to move up to a knee mill but at my age I don't know how much extra use I would get out of it.

03-29-2011, 09:33 AM
You are quite sure about the bearings? I have a feeling you may have been looking for some like this. They are flanged with extremely low profile and are stainless steel. They can take a tremendous load for their size. I'm not sure that they are available as a stock item as they were probably custom made for the machines they were used in.


03-29-2011, 09:49 AM
Hi Evan,
Even the smallest bearings have a minute amount of play from the inner race to outer race. The gears in the full sized trans run on needle bearings for more support. I would think that in this small size some type of needle bearing should probably be used as well. I do have quite a few instrument bearing like you show but after trying to incorporate them with the splines and shift collars I found it easier to just go with plain bronze bearings.

03-29-2011, 11:55 AM
Nope... No way... You did not make that model... Not with a mill drill. I've been told too many times on this BBS: Can't be done with a junk round column mill.

I have a RC Jet mill (Taiwan made), and though I cannot anywhere nearly equal your awesome skills, I still manage to turn out parts with it. I am really glad you posted a picture of your mill to the naysayers in cyber land.

My round column is no longer for sale (never was, but really not now!).

Thanks for sharing. Looking forward to more eye candy.

03-29-2011, 01:21 PM
Ima seeing it but still don't believe my eyes, that absolutely meets the "different" criteria and just very cool not to mention outstanding work on the model and drawings to boot yet.

Peter Neill
03-29-2011, 01:44 PM
Very, very, impressive work on this.
Well done indeed.


03-29-2011, 02:50 PM
I doubt I'd have the guts to do all that machning on one piece. The inevitable faux-pas would break my heart.

My hat is off to you, sir!

03-29-2011, 04:37 PM
Thanks everyone for the gracious comments. Along with the enjoyment I get from designing and building these things I really like sharing them with other machinists/gearheads.

03-29-2011, 04:53 PM
Very very impressive,, thaks for posting the great pics and info.

While going through these postings the thought crossed my mind as- geez now wonder what type of mill he,s using?

Very interesting!!!

03-29-2011, 05:42 PM
Absolutely beautiful job as always George. Many hours were spent standing on that concrete floor in front of your mill, that's for sure!:eek: You must have some VERY comfortable shoes.;)

Question: I read where you mentioned you took measurements and drew it up in CAD. I'm comfortable with doing that myself on what I previously thought were complex objects but my goodness; there are SO many intricate features on that tranny! All those flanges, holes, curves, ribs, radii, fillets....I cringe thinking how long it'd take for me to attempt something like that.

Did you by chance take some digital pics and do a bit of raster/vector conversion for some parts of the drawing? I used to do that on some of my model aircraft projects to trace an accurate outline into CAD and then fill in the construction details.

03-29-2011, 06:37 PM
in a word. awesome.:)

03-29-2011, 06:50 PM
I take plenty of digital pics for reference but the dimensions are taken by hand. My process is to clamp a straight edge or parallel to some flat surface on the part and then take measurements from there. In the case of a tapered surface I mark 2 spots along the taper then measure down to those spots, a little trig and I can calculate what the angle should be. As far as radii what I don't have in templates I make up out of card stock. For measuring the details on the side of the trans where I didn't have a flat surface to work from I clamp my parallel to the front face and then clamp a combination square to that parallel giving me a side reference plane. Once I have a handful of dimensions I can work the other features to them. Details like drilled and tapped holes I use threaded plugs in them with a center point, kind of like transfer plugs. As far as getting bolt patterns correct I put bolts into the holes, measure across the bolts in triangular patterns and then calculate the center distances. Time consuming but the only way I know to do it.
I made a compete set of plans for a 16hp. Russell traction engine. I went to Pennsylvania twice and in Ohio once with calipers, rulers, camera, a large set of home made wooden calipers, tape rulers, pencils and drawing pads. Everything was photographed from every conceivable angle with full shots taken from as far back as I could get. That way the distortion is reduced and I can blow up the pictures and compare a known feature to something else to establish a dimension. It took 2-1/2 years to compete the set of drawings.
I have done that with Case hay balers, saw mills, etc. etc.
Here's a picture of my 'wooden calipers' for measuring large diameters.

03-29-2011, 07:01 PM
I would think exact scaling would drive one almost insane, not to say that you are of course :D

Roughly, what level of scaling accuracy guide lines do you try to settle on ?


03-29-2011, 07:12 PM
On something this size I probably try to maintain .02 on non critical shapes but naturally shaft holes, etc. are held as close as I can, .002. My digitals only read to 3 places so I guess +-.001 is as close as I can get.

03-29-2011, 07:21 PM
I am barely qualified to even view your work, very humbling

Mad Scientist
03-29-2011, 08:50 PM
Wow absolutely amazing! :eek: You should be very proud of your accomplishment. Few would even consider tackling a project like that.

03-29-2011, 09:52 PM
Thanks George, detailing your methods on the various forums is much appreciated by many, many people.:)


03-30-2011, 07:16 PM
it is work like this that attracted me to this forum to begin with.
keep us posted on your work,as i am sure that you wont "stop" after this project either :D .


03-30-2011, 07:31 PM
Excellent as always George!

What's left for a challenge now? An Automatic?:)

03-30-2011, 09:56 PM
Looking at the first few pictures, I would of guessed you were using CNC!
Excellent work!

04-03-2011, 11:26 AM
I have the top cover machined. All that remains is to bench it out and tap a few holes. Yesterday I did the input shaft housing. It will also need the required hand finishing work.This will finish up the housing pieces and the rest will all be internal, gears, shafts, linkages etc. One of the trickiest parts will be the steel shifting gate that goes into the rectangular housing at the rear of the tailshaft. There is a block with a pin on the shift shaft which slides into the notches in this gate block. In the full sized trans it's probably a forging but for this it will require machining the gates on a curvature.

04-03-2011, 11:29 AM
One more pic of the inside of the top cover. Two with the cover installed on the trans and one of the input shaft housing.

John Stevenson
04-03-2011, 11:53 AM
Wondering aloud if it would be possible to blend the machining in with an airbrush style shot blaster ?

Very impressive work BTW.

04-03-2011, 12:09 PM
Hi John,
I don't think it would be possible as the highs and lows would all receive the same blasting. It does work for small scratches though and also gives it a cast look. This type of finishing just requires hand work, burring stoning and filing.

04-03-2011, 04:36 PM
Great looking work! I hope your planning on attending the NAMES show again this year. I would really like to see it in person. Do you think it will be finished by then?

04-03-2011, 05:58 PM
Hi Jonathan,
I'll be there on Saturday only this year. I will have the trans with me but I doubt it will be finished. I have too many other projects going at the same time.

04-03-2011, 06:13 PM
I'm lost for words

How many hours so far ..

I would definitely bugger that up, if i tried to make it ..have a habit of turning the handles the wrong way..which i cant seem to get out of

any tips on not doing this appreciated ..as you seem to be the master .

all the best.markj

04-17-2011, 06:06 PM
Wow! I read the thread wondering how long it would take for the readers to determine this wasn't CNC work.

I've always wanted to talk to someone that did hard things on manual machines back in the pre-cnc days.

I sure hope I run into you at NAMES while you are explaining your techniques. Have you ever given a seminar in the meeting rooms on your techniques? If not, why not. You would have an audience hanging on your every word.

Thank you for sharing this,


04-17-2011, 09:12 PM
Wow all on a round collumn mill? Truely amazing work! I bet most people with high end CNC's would cringe at just coding a program to cut that.

04-17-2011, 09:41 PM
Hi Clutch,
I'll be at NAMES this year for Saturday only. I'll have at least 4 of my gas engines with me. With getting there early Saturday morning so I'm not sure how much space there will be so I'm limiting my display. I'll have the trans case with me as it's being made for my 302 engine which I'll be running.
Stop by and say Hi.
George D. Britnell

04-17-2011, 11:15 PM

This reminds me of "That statue of Venus was easy - you just take a hunk of marble and chisel away anything that doesn't look like a beautiful woman."

04-26-2011, 10:50 AM
I got some time to work on the trans between other projects so first up was to bench out the top cover and input shaft housing. As I was benching out the top cover I noticed that the front bulkead had an irregular shape to it. I turns out that I was breaking through because I had cut the inside shape too deep in one spot. To repair the part (too many hours to start over) I picked out a slitting saw of the proper diameter and width and slotted the thin area until I had a pocket deep enough to accept a small patch. I then turned up a disc and cut and fitted it to the pocket. I was able to lightly peen most of the areas before re-cutting and benching it so the only visible mark is a line across the top. I couldn't peen that area.

04-26-2011, 10:57 AM
With all the housings finished I started on the shafts and gears. When miniaturizing the trans I had to come up with gears that would be the approximate ratios of the full sized box and still maintain the correct center to center spacing between the mainshaft and countershaft. To do this I had to make up 3 different hobs, 36, 40 and 48 pitch. They're not that far apart to make a visible difference when looking at it. The cutters were made from W-1 drill rod. They required a separate lathe tool bit for each pitch. I have used involute cutters and home-made flycutters in the past but had never tried making a hob type cutter. The hardest part is maintaining an accurate spacing between teeth. Trying to plunge into drill rod with a blunt nosed cutter presents it's problems.

04-26-2011, 11:04 AM
The next photos show the countershaft mounted in my set-true chuck. The countershaft needed to be made in two pieces because the center two gears are too close together to cut. I chucked the part and indicated it concentrically and then set one of the center teeth on the cutter to the center axis of the shaft. When making the hobs it's better to cut extra teeth in case it wears you can shift up and down to a sharp tooth. When using this type cutter it puts the proper involute form on the gear as the adjacent teeth are being cut.

04-26-2011, 11:07 AM
Here's what the countershaft looks like. As I said it was made in two pieces then pressed and Loctited together.

04-26-2011, 11:13 AM
These are several pictures of the input shaft. The input gear and shift spline needed to be pressed onto the shaft as well as cutting the clutch spline on the end. For that I had to make another drill rod cutter. The last picture shows the gear mesh of two of the gears. When I made the input gear I cut extra stock to use as a checking gauge for the subsequent gears. The fit is quite good for home-made cutters.

04-26-2011, 11:16 AM
The last set of pictures show the bearings, mainshaft, and main and countershafts installed in the box. It's actually starting to look like a trans now.

04-26-2011, 11:32 AM
You didn't say how you avoid turning the handles the wrong way, when doing something as intricate as that ...I presume you have DRO on your mill ..so you can see immediate change on the reading no matter how small, when you turn the handle the wrong way.

I somehow cant see me getting all the way through all that machining ..all those stages, without making a screw up somewhere...how many parts did you trash and have to start again .

the above are compliments ..dont take it any other way

all the best.markj

04-26-2011, 11:43 AM
Yes I have a DRO. It's one of the Chinese scale types but it has worked good for me.
I haven't scrapped any parts yet. Like I said, I've made a few 'errors' but all were fixable. I guess if I was a purist whenever something wasn't 100% I would start over but as anal as my wife says I am I'm not that far along. When I learned my trade I was taught that if something was fixable it wasn't junk.
When doing many hundreds of steps on a project like this the hardest part is maintaining concentration, wife questions, telephone calls, where the hell did I set that tool, etc.

04-26-2011, 12:14 PM
I was always told the difference between an apprentice and a master machinist is that the master knows how to fix his mistakes and I don't see any mistakes George:)

04-26-2011, 12:45 PM
Someone earlier used the term "awesome!" Ordinarily I hate to hear or read that word which is so overused by the teenage crowd, as to have become meaningless.
...but in this case it does truly apply, literally!!

Following this thread has been a real treat!

04-26-2011, 01:40 PM
"I chucked the part and indicated it concentrically and then set one of the center teeth on the cutter to the center axis of the shaft."

That, and the photo was what I've been looking for. Making gears, I never could get the involute cut properly on both sides of each gear tooth, and sometimes ended up making gears that looked more like wide saw blades.

Great work, gbritnell! While I was working, I had many of these 5-speed transmissions apart. Through the years I learned a great deal about them, and their strengths and weaknesses. Borg-Warner really knew what they were doing.

Most people don't know it, but Ford, GM, and Chrysler all used T-5 transmissions. Several high-performance Japanese brands did , too.

Borg-Warner made their cases, gearsets, and tailshaft housings all interchangeable, to fit the application. Last time I looked, GM alone had six different gearsets for the basic transmission case, and five different shift lever locations on the top cover and tailshaft housing. And.....no gaskets.

The last T-5 that I tangled with was the one my brother and I installed in his wife's 1931 Ford Model "A" Roadster pickup. It has a mild 8BA flathead V-8 in it, and originally had a Ford 9-bolt side cover, three-speed, out of a 1951 Ford sedan. We had to saw the lug off of the bottom of the tailshaft to make it fir. But, the driveshaft, and everything else fit well. My brother's wife had to make new floorboards and transmission tunnel for it, but it was worth it.
With 5 speeds and a 30% overdrive in fifth gear, the old flathead performed flawlessly (almost like the ratios were designed specifically for it)....Gas mileage went from a paltry 18mpg to 26mpg, and the car is much more comfortable on the freeway.

The T-5 is probably one of the best manual transmissions available, even bettering the smooth shifting Italian and British gearboxes by a large margin.

05-08-2011, 08:43 PM
I managed to get a little time in on the trans. I cut the remaining gears for the main case plus the overdrive gears that are located inside the tailshaft housing.
As I had mentioned earlier the gears were cut with homemade hobs mainly because of the irregular D.P. (36 and 40) The overdrive gears are 48 pitch for which there are commercially made cutters but I figured being as I was making the other hobs I might as well make that one also.
I started with the countershaft thinking that it would be easier to adjust the individual mainshaft gears than trying to recut the countershaft. After touching the cutter to the blank I went in the required depth (add+ded) and added .001 with the hope of not having to recut. To my surprise and pleasure each of the mainshaft gears and the overdrive gears fit perfectly. Well perfectly might be an overstatement but there was no binding and negligible backlash so for cutting with a homemade cutter I would class that as perfect.
The first several pictures show the gearsets in the main case. The only thing remaining is to cut the key slots in the spline bushings to lock them to the mainshaft.
The pictures of the overdrive gears show the shift collar in the disengaged and engaged positions. The shifting fork will straddle this collar.
The 2 remaining pictures show a closeup of the reverse idler gear. This is a 36 pitch gear. You can see how well the involute curve was formed on the teeth using the hob. The gear still needs to be deburred and cleaned up but I'm quite happy with the results.


05-08-2011, 08:45 PM
Overdrive gears

05-08-2011, 08:46 PM
36 D.P. gear cut with hob.

05-08-2011, 09:36 PM
Stop it George, you and your mill/drill are embarrassing the hell out of the rest of us.:D

Seriously though you could knock me over with a feather, very impressive work.
As I look at your work I keep having to remind myself that I'm looking at a 1/3 scale model and not the real thing!

Thanks for sharing your work with us, very inspirational indeed.

Bill Pace
05-08-2011, 10:19 PM
I had complemented your work earlier, but I have to give praise again!! and on a mill-drill!! Hah! I wonder if any of those "purists" proclaiming all the sorry attributes of a mill-drill (and others along that line) are even following this - probably too embarrassed.

Those gears are sooo nice, could you show a pic of one or two of your hobs, and maybe a few comments on your construction of them.

05-08-2011, 10:55 PM
Beautiful job, George. My one criticism is the gears in a full-sized T-5 are all helical pitch. But, I can hardly expect anybody without access to a five axis CNC mill to even begin to contemplate helical gears.

There was a time when all cars had straight-cut gears, and bevelled gears in their differentials. Characteristically, straight-cut, or spur gears tend to be noisy, and not quite as durable as a helical gearset mainly because the helical pitch carries a much wider tooth contact pattern, and the teeth overlap, making it much quieter.

Other than that, your 1/3 scale T-5 looks quite impressive....I'm pretty sure that I could never duplicate your work, myself. Kudos, George...

05-09-2011, 06:37 AM
Thanks everyone for the comments. Saltmine,
When I first started on the project a fellow on another forum had come up with a way of making helical gears in the home shop. The problem was that every gear required it's own template to produce the helix so I quickly gave up that idea.
As it is I had to go with the different diametral pitches to maintain my shaft center spacing and approximate the gear ratios.
Bill, the cutters are made from W-1 drill rod. The hardest part of the job is making the lathe bit to cut the hob. It's critical that the tip of the cutter be exactly the width of the gash at the root diameter. These gears are 14-1/2 pressure angle. I calculated the width and then after grinding the side angles I slowly started grinding back the tip and measuring it with my mikes while looking at it with a magnifier. I would just hook the tip of the mikes on the tool to get a reading. I probably got within .001-.002 of what I needed.
Once the lathe tool was made and set up I would touch off the stock for the cutter and plunge in the proper depth (addendum+dedendum). The spacing for each tooth is equal to the spacing of the rack form of the gear's D.P.
With the teeth cut I put the cutter in my dividing head and fluted the cutter to form the relief for the teeth. Prior to hardening I carefully filed and stoned all the burrs from the tool blank. Once hardened I used a small flat diamond hone to touch up the front faces of the teeth to give them as sharp of an edge as possible.
Here's what the cutters look like.

05-09-2011, 06:47 AM
Next came the setup for cutting the gears. I put a setup bar in the dividing head and indicated it true to the mill's axis. In the case of the countershaft which you see in the pictures I then indicated the blank and adjusted the set-true chuck until it was running concentrically. For the individual gears on the mainshaft I used a mandrel to mount the gears on.
I then set my height gauge against the blank and moved up the radius of the stock. At this point you are asking why I'm using a surface gauge to set the cutter tooth height? It was just too hard to see the flat edge of the height gauge scriber against the tooth so I then set my surface gauge to the height gauge. This way I could use a magnifier and get the center of the scribe point almost perfectly in the center of the cutter tooth.

05-09-2011, 06:52 AM
The next two pictures show the first couple of passes with the cutter and then the finished gear. As I stated I go to the full depth of the tooth +.001. If I have a choice I would rather have a touch too much clearance than to have to reset the blank and try and take .001 or .002 more off of the gear.

05-09-2011, 07:12 AM
Excellent ..briliant job you are doing, great work !!!

Those hobs when bought, ready made, cost gazillions

How about a whole new thread on making the hobs ..will be much appreciated by all.

all the best.markj

05-09-2011, 07:33 AM
I had the opportunity to see and handle George's transmission at the NAMES show last weekend. The photos are excellent, but in person and up close it is even more impressive.

One question I have on the gear cutting is how do you advance the index head when cutting the gears? Do you go one whole tooth at a time or something less?

05-09-2011, 10:09 AM
WOW!! Holy Crap Thats Incredible WOW!!! Did I mention WOW !!!!!


05-09-2011, 10:35 AM
I think it is just a form tool with a profile equal to the equivalent rack. You make multiple passes with the form tool to create a number of facets approximating the involute curve.

Here's an example of the cutter to make the form tool and a pair of form tools on the left:



Excellent ..briliant job you are doing, great work !!!

Those hobs when bought, ready made, cost gazillions

How about a whole new thread on making the hobs ..will be much appreciated by all.

all the best.markj

05-09-2011, 12:21 PM
Hi Jim,
There were many people who stopped by to see the trans at the NAMES show. They had been following the build series and wanted to see it.
When you advance the dividing head you go to the next tooth or spacing. Because the flutes on the cutter above and below the centerline are angular to the blank they cut the involute curve onto the teeth. On a large diameter gear it's not as noticeable but on a gear with say 12-14 teeth you can really see the profile of the tooth. The picture that Phil posted is an excellent representation of the whole process, the lathe tool, the hobs and the finished gears.

05-09-2011, 12:43 PM
Thanks George, I wasn't sure you would get that good a profile by simple indexing.

I always stop by for a visit with you, but had to elbow my way through the crowd on Saturday.

07-11-2011, 10:24 AM
I would like to bring this thread to it's conclusion. Having finished the transmission this past week I am posting some final pictures. The pictures aren't quite as interesting as seeing all the gears and parts inside but it still is neat to look at the finished piece.
I chucked the trans up in the lathe, supported by a live center in the tailstock, and spun it at about 300 rpm to go through all the gears and make sure everything worked as it should. It seemed to work fine.
The first pictures show the completed trans with the floor shifter. This was copied from a Hurst shifter I had sitting on the shelf. It required some special machining to produce the hemispherical pieces that mount to the shift arm. These provide the rotational point for the lever. It's a ball type joint with a .093 pin through the center to keep it from rotating in the vertical axis.

07-11-2011, 10:31 AM
The final pictures are overall shots and a couple of closeups of the reverse and neutral switches. These were machined from steel with the plastic pieces machined from black Delrin.
I am in the process of designing the clutch and pressure plate to hook the trans to my 302 engine.
At the time the engine was built the crankshaft was made a little longer to accommodate the starting mechanism so it will need to be pulled out and modified to accept the trans, clutch and pressure plate.
I have the remainder of the yearly shows to go to so it won't get pulled down till winter.

07-11-2011, 10:34 AM
The big ugly slotted head screw on the side of the crankcase is the pivot bolt for the reverse/overdrive lever. I possibly have a fellow helping me out by burning a small torx drive slot into a new bolt so it matches the full sized case.

07-11-2011, 10:58 AM
George if I didn't know better, I would say that I'm looking at the real, full scale transmission.
Congratulations on completing this stage of the project. I only hope those lucky enough to see it in the flesh will fully appreciate the tremendous amount of thought and engineering you have invested into it.

This begs the question.
Now that you will soon have a complete and fully functional powertrain, are you perhaps entertaining the thought of taking it to another level?

07-11-2011, 02:24 PM
Thanks Willy,
I would eventually like to have the compete drive train, engine, clutch, trans, drive shaft and diff. all mounted in some type of frame. It just takes time.

Alistair Hosie
07-11-2011, 02:45 PM
I wish I had half your skills my friend ,even a quarter would do :D Alistair

07-11-2011, 09:12 PM
Great job George. Can't wait to see the next project.

07-12-2011, 11:47 AM
Wow, that's simply stunning George!

07-12-2011, 01:05 PM
Wow, I would love to see a photo of that mated to the 302. Now all you need is a 1/3 scale Fox Body for it. I only wish I had your talint I have ben a big Mustang fan for years that would look great sitting with my Mustang collection

07-12-2011, 02:23 PM
I have posted this before but here is the engine it will be bolted to.

John Stevenson
07-12-2011, 02:58 PM
That truly is a work of art, I can appreciate work like this far more than fancy art work and jewellery.

Works like this are constrained by size and design, art to me is pure abstract and can be anything the artist wants even if the finished job isn't what he envisaged.

07-12-2011, 03:31 PM
I have posted this before but here is the engine it will be bolted to.

Beauty! Can't wait to see the engine and transmission assembled!

07-13-2011, 12:26 AM
To call this work amazing would be an insult to you and your fine talent.

What you have done here, and the tools you have done it with will give us all something to strive towards.

I will never look at a chunk of aluminum and a piece of steel quite the same. You have created a miracle in metal. My hearty congratulations.

07-13-2011, 03:13 AM
I have posted this before but here is the engine it will be bolted to.

Any chance you have a vidio of this running I would love to here it run:)
Never mind I think I found it.

07-13-2011, 06:39 AM
This one's better.

07-13-2011, 07:02 AM
George is another of those very talented machinists who don't come on with a great deal of braggadocio, but quietly continue to create masterpiece after masterpiece and generously and patiently share their expertise with others. He has quite deservedly earned a spot in the Joe Martin Craftsmanship Museum;


George is also an accomplished artist;


Lew Hartswick
07-13-2011, 10:16 AM
George, In watching that engine run the thought occured to me,
Some things DON'T scale. Like the breakdown voltage of a spark
gap. :-) so how do you manage the distributor size and things like
the ign. wiring? (as an ex electronics engineer) :-)

07-13-2011, 11:29 AM
George, Are the plans for your engin and trany Avillablle. Or do you know of a place that sells raw castings for us less tallinted. :-)

07-13-2011, 12:45 PM
Hi Lew,
When I first got into multi-cylinder I.C. engines there weren't spark plugs and electronic ignitions available so you had to make your own plugs and miniature points, if you wanted to keep the distributor in scale. I used a 12 volt automotive coil with a couple of ceramic ballast resistors to drop the voltage. I used a 12 volt motorcycle battery for power. The plug wires were made from test probe lead wire. I never have had any leakage through the wires but I have had spark jump down the side of the plug on occasion, when the plug gets loaded up.
When I built the 302 I tried to keep the distributor to scale, somewhat, and the points were very small. The biggest problem was getting enough movement from the cam to open the point enough. The engine would run but not great. I played with many 'point' configurations until I got frustrated and quit. The engine sat in my display case for many years.
A lot of the model engines up until the late 80's had oversized distributors to accommodate bigger points etc.
When a few of the fellows developed miniature transistorized ignitions with Hall effect triggers I redesigned my distributor. The latest video is with the new ignition system. I can get an honest 7800 rpm out of the 302. I have a single magnet in the distributor with a timing disc with 8 windows in it. It turns the Hall sensor on and off to fire the ignition.
For the most part the ignition systems are quite dependable. They now have porcelain bodied spark plugs available, although quite expensive, high voltage wire and the aforementioned ignitions.
I took apart a full sized trans an made a complete set of drawings for it but I never did the 302. With copyright issues I didn't want to a problem. I guess I could have just drawn and sold them as 'engine drawings'.
Both the 302 and the T-5 are carved from solid aluminum. No casting were used.

07-24-2011, 06:23 AM
I have made a video of the transmission turning over and shifting through the gears. Not much to look at actually but it does show that everything is working like it should. Over the winter I will be making the clutch, pressure plate and clutch disc. The clutch is cable operated so provision for an attachment point will be needed.
I would like to thank everyone who commented on this build. It was greatly appreciated.

07-24-2011, 07:50 AM
you did a swell job of that

Even a normal transmission ..it's very hard not to grind the gears without using a clutch ..you seem to be able to change gear without it ..and a complete absence of any difficulty engaging gear or noise ..so you must have got it perfect..well done

all the best.markj

07-24-2011, 09:14 AM
Truly great work!!!!

07-24-2011, 12:30 PM
I would like to thank everyone who commented on this build. It was greatly appreciated.

George, I would think that it is us that should be thanking you. :)

Not only for sharing this well documented project, but also for the inspiration.
Especially for the guys that have a mill/drill and thought to themselves that they didn't have a machine capable of this caliber of work.
Once again, well done, and that's an understatement.

07-24-2011, 02:24 PM
my comment on the first page was 'its inspirational'.....lol little did I know what has coming. Tremendous workmanship, effort and scope of project and very well recorded and presented. I also really liked the vid of the engine running. Thanks George!

07-24-2011, 02:36 PM
Brilliant craftsmanship!

07-24-2011, 04:01 PM
Outstanding work

The work shown by yourself and Mr G Wilson raises the bar for all of us..

Its nice to see a thread that HSM can be proud of..


07-24-2011, 05:14 PM
you did a swell job of that

Even a normal transmission ..it's very hard not to grind the gears without using a clutch ..you seem to be able to change gear without it ..and a complete absence of any difficulty engaging gear or noise ..so you must have got it perfect..well done

all the best.markj

It helps when you don't have an output load on the gearbox, I do the same thing with my lathe feed gearbox, as long as the RPM's are low enough, and theres little or no load or momentium involved, you can just force the gears to mesh and they don't grind.. much :)

(Ie, Don't do it at high spindle rpms and high feed rates, and don't do it midcut)

Still, Awsome work. I wish I could buy mini 5 speed gearboxes like that... For less then the thousands of dollars its likey worth!

Jaakko Fagerlund
07-24-2011, 05:35 PM
I don't even start to look for my dictionary to find pretty enough words to describe your work mr Britnell, the work speaks for itself :)

I do have a question though: How did you make the internal splines to the gears?

07-24-2011, 07:46 PM
you did a swell job of that

Even a normal transmission ..it's very hard not to grind the gears without using a clutch ..you seem to be able to change gear without it ..and a complete absence of any difficulty engaging gear or noise ..so you must have got it perfect..well done

all the best.markj

I once drove my 89 5.0 mustang for 3 weaks without a clutch do to a broken clutch cable.:D The T5 is a great tranny. I haven't fount a manuel I couln't drive with out the clutch just need to know when and how to shift

07-24-2011, 09:15 PM
I went though 7 of those transmissions before the "world class" t-5 came out. Second gear was really weak. Mr. Britnell, you're work, both with metal, and pencil, is beautiful to behold, thank you for sharing it with us.

07-25-2011, 05:54 AM
I once drove my 89 5.0 mustang for 3 weaks without a clutch do to a broken clutch cable.:D The T5 is a great tranny. I haven't fount a manuel I couln't drive with out the clutch just need to know when and how to shift
yup, easy enough to do with a sincro box ..far as i can tell..Georges box does not have them.

all the best.markj

07-25-2011, 07:10 AM
Hi Markj,
I pondered 'briefly' the idea of building synchros for the trans. It would have become a huge project with no practical use other than to say I made them. This one works more along the lines of a motorcycle transmission where a sliding collar with teeth on it engages windows in the adjacent gear. On this one instead of the teeth engaging windows they slide into splines. I didn't take pictures of the final fitment of all the parts but what I did was to put a small tapered lead on the matching spline to help the shift collar engage.
In the old days, before synchros, when gear changing was done by actually 'shifting gears' a person would have to 'double clutch' the gear box. In other words when it became time to shift, the clutch would be disengaged, the gear selector would be pulled to neutral, the clutch would be reengaged, the engine revved slightly to match the next gear set's speed, the clutch disengaged again and the shift made to the next gear. It's actually more seamless than it sounds once a person got the hang of it.
Although there's no practical use for my transmission, I guess there's no practical use for miniatures in general, it was a challenge for me to make something mechanical, that operated and looked 'cool'.
Thanks for the comments,

07-25-2011, 09:21 AM
yup, easy enough to do with a sincro box ..far as i can tell..Georges box does not have them.

all the best.markj

Easy on a crash box too. I've had to do it a few times with broken clutch cables on my bikes.

07-25-2011, 10:40 AM
Easy on a crash box too. I've had to do it a few times with broken clutch cables on my bikes.

I've not seen a 'crash box' on a motorcycle. Even my 1929 Favor 350 has a constant mesh gearbox (a Birman lightweight badged as a 'Staub'). Gear head lathes are generally crash boxes.

07-25-2011, 11:42 AM
Ok not strictly 'crash' but certainly non-syncromesh plain dog engagement boxes. You're right, they are constant-mesh just without a syncro. You needn't be so precise at matching shaft speeds since there is a larger gap between the dogs but it's still required somewhat especially on bigger bikes.

Jaakko Fagerlund
07-25-2011, 10:44 PM
gbritnell, how did you make the internal splines?

07-26-2011, 07:10 AM
Hi Jaakko,
When I started the project I drew up the gears and shafts that I would need to make and also the splines that would work. I made up the cutters for the gears and I also made a spline broach.
The spline broach was about 1.5 inches (37mm) long. It had 6 rows of 10 teeth on it, each one stepping out about .006 (.15mm) Having never made a broach before I didn't realize the pressure it would take to force it through a piece of metal, and this one wasn't even up to the required diameter. It was just a test tool. It did cut the spline quite cleanly but realizing that making it the required diameter and number of teeth would require a hydraulic press to force it through.
There is a company in New York city that I have dealt with over the years. They sell all types of miniature gears and drive components. I went through their catalog and found a spline set, shaft and bushing stock, that I could design into my transmission. The spline stock came in 3 ft lengths (900mm) and the bushing material was about 1.5 long (37mm).
The spline stock is keyed and set screwed to the main shaft in the necessary positions. I turned the bushing stock into the shifting collars, one completely and one is pressed inside the reverse gear. The reverse gear is also used for the 1st-2nd shifting collar.
The first set of attached pictures show the overdrive gear set which is located in the tailshaft housing.

07-26-2011, 07:12 AM
The other splines can be seen inside the main housing with the other gear sets.