PDA

View Full Version : Torsion Bars



ecdperf
04-19-2006, 09:23 PM
I am investigating the feasability of machining some torsion bars for a streetrod project that I am doing. Does anyone have info about what material and sizing for spring rates. Any help would be appreciated.

steve
04-19-2006, 10:47 PM
i wouldn't re-invent the wheel on this one. go to a salvage yard, plenty of cars and trucks still use them. if you're building a rod you'll have plenty of better things to spend time on.

CCWKen
04-19-2006, 11:27 PM
Ditto what Steve says.

Baring self punishment.....Ummmmmm. What about spring steel? I hope you have access to heat treating facilities too.

George Barnes
04-20-2006, 10:58 AM
I haven't made any torsion bars but here is the formula for determining spring rates:

lbs. per inch = 2,200,000 x d(4) divided by L x l(2)

The number in parentheses are powers of that number (i.e. diameter to the fourth power)

Where L = bar effective length, d = bar diameter, and l = lever arm length.

http://img.photobucket.com/albums/v707/gbarnes/TorsionBarAssembly.jpg

From what I have been able to ascertain, the material of choice is either 4340 or 4130 and the heat treatment is to 35 on the Rockwell C scale.

The real fun is making a broach for the splines. It's not impossible, I've done that.

Hope this helps.

Guess I'm not doing this right...I suppose that I should be joining the others in telling you to just buy some parts. By all means, check out what is available off of the shelf, but if that does not prove satisfactory or if you just want a challenge...I say go for it!

I haven't ever figured out how you learn by NOT doing something. :)

ecdperf
04-20-2006, 01:25 PM
I'm not building a junkyard streetrod. Nor would the spring rates be correct. I was basically seeing if anyone had any differant info than I. Thanks anyway.

IOWOLF
04-20-2006, 01:37 PM
No one said you were, You asked for advice ,you got it and some suggestions.
some people are so Thin skinned. ;)

George Barnes
04-20-2006, 06:26 PM
ecdperf,

I don't know if the info that I presented is different than what you have or not. What info do you have?

CCWKen
04-20-2006, 07:41 PM
I think you answered his question completely George.

George Barnes
04-20-2006, 08:13 PM
ecdperf,

Here are some junkyard parts that make a pretty decent looking and great working front end. This used to be a pretty popular adaption back in the early days. It uses the front suspension parts from an XKE Jag along with some homebrew fabrication. The Jag uses a torsion bar for a springing medium. It is just inside the lower control arm pivot shaft on the right side in the photo. I don't remember the specs on the bar but would guess about a 3/4" diameter and an effective length of about 30". The lever arm is fairly long as it is length of the lower A arm.

http://img.photobucket.com/albums/v707/gbarnes/JagFrontEnd.jpg

One neat thing about the Jag bars is that the splines on one end are different than the other end. 25 and 26 splines if I remember correctly. That means that the ride height can be adjusted almost infinitely without an adjustable anchor. Just slip the bar out and rotate it however much you need.

This setup was on the front of a '32 Ford chassis.

IOWOLF
04-20-2006, 08:19 PM
They come in, ask a question, and when they don't like the answers they leave in a huff.
Same ole song, different tune.

;)

ecdperf
04-23-2006, 09:45 AM
IOWOLF, I thought that machinists were on this site not junkyard divers. I am not in a huff just that I am a experienced chassis builder of some 40 years experience and with high end cars I do not use junkyard parts.

IOWOLF
04-23-2006, 03:09 PM
There are both here, if you searched the threads you would know that.
You haven't answered Georges Question,yet.

With 40 years exp. why ask any thing here, It was not a machinist type question any way,IMO.

JRouche
04-23-2006, 05:33 PM
Hi George. Not that it matters much but my formulas show a constant of 1,178,000.... JRouche

JRouche
04-23-2006, 05:45 PM
"It was not a machinist type question any way,IMO"


Here, I'll add the word lathe in there, that should make it OT ;) :D :D JRouche

"M-5 TORSION PENDULUM AND LATHE"

http://www.lhup.edu/~dsimanek/scenario/labman1/torsion.htm

George Barnes
04-25-2006, 11:03 PM
JRouche,

The information that I have came from Paul Van Valkenburgh's book "Race Car Engineering and Mechanics". As to which one is correct, your guess is a good as mine. As you say, it doesn't much matter as I don't think that ecdperf isn't too interested in really learning anyway.

I wish that he had stuck around and shown some of his work as I have been fooling around with this stuff since 1959.

He might have had some interest in this design exercise as it is torsion bar based.

http://img.photobucket.com/albums/v707/gbarnes/FramePurple.jpg

On second thought, he probably wouldn't be interested as the design is for a lowly T-Bucket and he apparently only builds mega-buck stuff. At least the design does not use any junkyard parts. :)

CCWKen
04-26-2006, 12:42 AM
Geez Frank C., you don't have to get hyper because somebody suggests an off the shelf or existing part. Just trying to save you some work and/or cash. Whether it's not the right spring rate, we don't know since all you've done here is banter and insult everyone. A little explanation could have saved everyone a heartache.

You do nice work but your tools indicate you do a little dumpster-diving yourself. ;)

JRouche
04-26-2006, 01:37 AM
The information that I have came from Paul Van Valkenburgh's book "Race Car Engineering and Mechanics". As to which one is correct, your guess is a good as mine. As you say, it doesn't much matter as I don't think that ecdperf isn't too interested in really learning anyway.


Hey George. Yeah, that was the impression I got. Doesnt make sense. Go to a site, ask questions then bash the folks for giving answers.

My constant came from Fred Puhn's "how to make a car handle". Prolly simplistic to some but easy to comprehend for folks like myself :D

As for scrounging the auto dismantelers, I'm all over that, big time. Maybe not for springs due to the specific rates required and the fact that springs are a consumable, they do change in rate over use.

But heck, there are a whole lot of "quality auto manufactures" engineering designs sitting there for the taking. They have worked out the issues of stress, fatigue, wear, weight, size, cost and an endless list of factors. Nope, I'll never bash someone for using the recycling system.

Always use your best judgement when using used parts too. I always thought it bad voodoo to use a steering or braking component from a wreck where the driver died during or shortly after the crash :( But, what I don’t know wont hurt me, right :) JRouche

lugnut
04-26-2006, 02:21 AM
Some where in the archives of Street Rodder is a article on using a Chrysler front suspension, Valari or Dart that had torsion bar suspension. It was a cut, clip and weld procedure that was like using the Nova clip. No use trying to reinvent the wheel. Do some search on Google or old Street Rodder Mag.
Mel

ecdperf
04-26-2006, 12:25 PM
I have posted here years ago and once again I receive one decent answer and a completely unnecessay attitude from some of you. As I previously stated I am not in a huff only that I have better things to do than play name calling and games. I presume that a torsion bar begins like as a torsion bar and no one or machine creates it. Yes the cars I build are high dollar vehicles. I presune that that is also wrong to build high quality products. Thanks for the exercise in child's play and good bye.

J. Randall
04-26-2006, 11:21 PM
I would presume that a torsion bar starts as raw material and someone and some machinery creates it. I don't think it is just born a torsion bar. I think you might be the one with the attitude problem. James

bob308
04-26-2006, 11:59 PM
well now if you build high end cars do you build them for looks or to drive?
the front ends that were sugested were designed and tested at great expense. can you do that? you dont want to use used parts ok go to the dealer and buy new ones. still a lot cheaper then trying to carve out your own and then test them on someone's high end car.

George Barnes
04-27-2006, 01:50 AM
An exercise in childs play? HUH? If this was such an exercise, why the hell did he even bother to ask? While making torsion bars is not an impossible task for a well equipped small shop, I wouldn't exactly call it childs play. Maybe he would like to tackle making the broach for the end fittings? That might keep him busy for a few minutes.

http://img.photobucket.com/albums/v707/gbarnes/SplineBroach.jpg

I thought that I had tried to answer his question as honestly as I could and got not so much as a "thank you". Or even "I think you're full of crap", at least then I wouldn't think that I was even below the decency of a reply.

Gee, I'm sure glad that I went to the bother to post that drawing to my PhotoBucket account and spent the time to search out the formula for someone who is so appreciative. (Which one of these emoticons is for "He said facetiously"?)

Well our friend Mr. ecdperf says that he has better things to do than participate. I do too! I need to get going on another batch of X-members for one of my customers who also builds some high quality cars. He might even recognize some of their names...Roadster Shop, Lobecks, Pete & Jakes, Heinzmans, Don's Hot Rods. IIRC Don has had a couple of Ridler Award winners and maybe some of my stuff was on them. Not sure but it's not a big deal. Those cars could probably be considered "high dollar" by most people.

http://img.photobucket.com/albums/v707/gbarnes/XMU-5.jpg

JRouche,
I have the Puhn book and had never noticed the formula...they hid it in amongst the drawing...right in plain sight. :)

Jaymo
04-27-2006, 09:44 PM
Perhaps he's never built a high end car, and is just trying to stroke his own ego?

He could buy control arms and torsion bars for Chrysler A bodies brand new from aftermarket suppliers.

davidfe
08-24-2006, 08:10 PM
JRouche,

The information that I have came from Paul Van Valkenburgh's book "Race Car Engineering and Mechanics". As to which one is correct, your guess is a good as mine. As you say, it doesn't much matter as I don't think that ecdperf isn't too interested in really learning anyway.

I wish that he had stuck around and shown some of his work as I have been fooling around with this stuff since 1959.

He might have had some interest in this design exercise as it is torsion bar based.

http://img.photobucket.com/albums/v707/gbarnes/FramePurple.jpg

On second thought, he probably wouldn't be interested as the design is for a lowly T-Bucket and he apparently only builds mega-buck stuff. At least the design does not use any junkyard parts. :)

George,

Do you recall where the purple frame jpg came from?

Very interesting looking to me. I'd like to read/ see a little more.

Thanks,

David Edwards

ASparky
08-24-2006, 09:54 PM
This is a home shop machinist forum last time I checked, It would seem that using junkyard parts is an appropriate answer. At the risk of cross :D promoting, the question may have been better posted at
http://www.practicalmachinist.com
which is more for manufacturing engineers, and might give the type of answer the questioner was looking for.

wierdscience
08-24-2006, 10:13 PM
Award winners and maybe some of my stuff was on them. Not sure but it's not a big deal. Those cars could probably be considered "high dollar" by most people.

http://img.photobucket.com/albums/v707/gbarnes/XMU-5.jpg




That is some mighty fine tube work there George.

Mcgyver
08-25-2006, 12:32 AM
yeah that was kinda a strange one, didn't really get the 'junk yard rod' thing, sort of like if you use a part from another car you're not worthy. still, following that thinking, please take lots of pics when you cast your own block and vulcanize the rubber hoses and tires :D

IOWOLF
08-25-2006, 06:50 AM
I was hopeing that thread wouldnt be brought up again,or him ever to come back,I don't think he has been either.

TGTool
08-25-2006, 11:08 AM
Poor guy missed a great hint and a major opportunity. You avoid being a junkyard builder by going right to the Jaguar dealership, having them pull out the parts book and point to the pieces you want to buy - NEW. They've got great new part prices on them (at least from a dealer's perspective) and he'll be able to brag for years about what it cost him to get those parts. Better yet, do a little research to see if Aston Martin or Rolls Royce used any torsion bar suspensions. I know for a fact that Maserati did on some of their models, so he could go that route. Of course Maserati bought parts from Jaguar, but the extra shipping, warehousing and having them touched by Italian parts men means they're now much better parts for his purposes.

One Wild and Greasy Guy

LarryinLV
08-25-2006, 12:09 PM
I don't think the OP has been paying much attention to the Hot Rod world of high end rides.

Several high end builders have used torsion bar suspension parts by turning the skin from off the shelf pieces making them appear custom.

Boyd's built their hand made Aluma-Dub-Tub using a staight front axle with a torsion bar behind the axle and machining the attaching parts. (this is the obligatory machining sentence)

Junk yard parts are abundant on high end hotrods in the steering boxes, brake master cylinders, rear ends, brake drums, steering columns, rack-and-pinion steering, and on and on, although now-days they buy them new..

Some high end shops do build their own parts like these, but they just copy the factory product in billet.

OK...I feel better now. Glad I didn't do that in all caps.

pcarpenter
08-25-2006, 12:56 PM
Seems to me that a wise chassis builder, machinist, or whatever knows that there is no value in making anything that costs you more to make than to buy...especially if what you end up with may be less than adequate. Someone here has a sig that reflects this well..."Why buy something for $3 when you can make it for $6" or something of the sort;)

Torsion bars are likely forgings. Could you forge your own, and then machine the tough SOB's when you are done? Yup....as an exercise in stupidity or so that you could say you did it.

Forget "junk yard" if you are too uppity to realize that it is a great place to get parts like this that are in good shape. Go buy new ones....but making such a critical part suggests to me that this chassis builder doesn't really want to know the right answer....which is that this is a big piece of spring steel that is machined....which means it is a real bear to do and perhaps not wise to make from scratch.

Do you make your own wheel bearings?

Paul

LastOldDog
08-25-2006, 04:26 PM
I am confused re this entire matter. I perceived the man's initial inquiry was directed to "How do I calculate the characteristics of torsion bars?" Then, armed with data such as George and JRouche presented, plus a Google, he would retire to the inter sanctum of his shop and develop suitable criteria to fit his unique requirements such as working envelope, static loading, travel, force vectors, materials, off the shelf components etc. His question seemed innocent enough to me.

I'm inclined to think his offensive response was directed not toward the tech data offered, but more toward "Go buy something at the junk yard" with no idea of suitability of purpose. What am I missing?

Lloyd

topct
08-25-2006, 05:07 PM
Why does this stupid subject rate five stars?

pcarpenter
08-25-2006, 06:59 PM
I think the stars thing relates to the *rate* of activity on the thread or something.

The reason the guy got the answers he did is because sometimes the information you really need is not the information you asked for;)

I wish the guy luck and hope his suspension is made from materials that will not break...no matter how he gets there. I realize the "I made every part no matter what the cost" factor sometimes has some appeal...but it should never interfere with safety. A broken torsion bar on an already low rod could be pretty catastrophic I would think. When one corner digs into the pavement suddenly, it would likely swap ends...maybe several times.

Paul

IOWOLF
08-25-2006, 07:03 PM
It's not 5 star anymore.

George Barnes
08-26-2006, 12:30 PM
The .jpg of the independent front end for a T-Bucket came from my computer.

A couple of years ago on the National T-Bucket Alliance website, there was a discussion about IFS for buckets and most of it was about using the popular Pinto style assembly. Personally, I don't care for the appearance of that. I got to thinking about how I would do it and started to drawing. This is the result.

http://img.photobucket.com/albums/v707/gbarnes/Drawing1.jpg

I tried to retain as much of the appearance of the traditional tube axle and hairpin radius rod look as possible. That is why the lower tie bar for the front of the torsion bar mounts has the "hot rod holes" motif. The torsion bar is hidden in the lower tube. The trailing links of the A-arms suggests the hairpins.

This unit has not ever been built and exists as 0's and 1's on my computer only. :)

If you desire further information, let me know.

Millman
08-26-2006, 01:03 PM
Sometimes you guys are really mean and to the point!.....I just LOVE that!!

davidfe
08-26-2006, 02:01 PM
The .jpg of the independent front end for a T-Bucket came from my computer.

A couple of years ago on the National T-Bucket Alliance website, there was a discussion about IFS for buckets and most of it was about using the popular Pinto style assembly. Personally, I don't care for the appearance of that. I got to thinking about how I would do it and started to drawing. This is the result.

http://img.photobucket.com/albums/v707/gbarnes/Drawing1.jpg

I tried to retain as much of the appearance of the traditional tube axle and hairpin radius rod look as possible. That is why the lower tie bar for the front of the torsion bar mounts has the "hot rod holes" motif. The torsion bar is hidden in the lower tube. The trailing links of the A-arms suggests the hairpins.

This unit has not ever been built and exists as 0's and 1's on my computer only. :)

If you desire further information, let me know.

George,

Thank your for replying to my question. It is a very nice idea and the drawing presents it well.

I am a total novice / klutz with the design / drawing part. I 'd like to know what software you used.

Thanks again for taking the time to answer my question.

David Edwards

Wirecutter
08-26-2006, 03:29 PM
FWIW, the on-topic content in this thread is interesting to me. I'm not a car builder, nor do I play one on TV, but on the pictured hotrod front ends, I like the cleaner look of torsion bar suspension. Nice drawings, too.

edit - question removed - answered by an archive search.

-Mark

George Barnes
08-26-2006, 05:01 PM
I use Inventor for the drawings.