View Full Version : Any ideas for freshening dog teeth on a gear?

07-09-2010, 10:01 AM
I am curious if anyone has every tried to freshen/sharpen dog teeth on a gear? It looks like it is doable to me and I would like to give it a try.

I am thinking indexing head or setup of some kind and a small grinding stone.

The dog teeth are the ones rounder over (most of you probably know this already)


07-09-2010, 12:27 PM
Going by the engagement marks on the flanks they don't look too bad to me. Are they not staying in engagement?

07-09-2010, 02:49 PM
The dog teeth are ok so tell us what is the problem that you want to recut them.

07-09-2010, 03:05 PM
Recutting will also alter the engagement of the syncro clutch cones..

07-09-2010, 03:22 PM
Nothing abnormal with those dogs.

If it is jumping out of gear, then it is likely the synchro ring.

07-09-2010, 07:50 PM
Jumping out of gear can also be caused by to much end play in the output shaft. That is why I want to know what is going on to cause him to want to recut the teeth which would not be a good idea.

07-09-2010, 09:52 PM
At high rpms the gear grinds when shifting fast. The synchros and slider are good but the rounded edges on the dog teeth aren't getting the bite they should and allowing the slider to skip across a few teeth before engaging. Every now and then I get rejected.

I don't think just sharpening the point would change the gear engagement much. I am willing to test out the idea just to know if it works or not. I am looking for some ideas on how you guys think would be the best way to go about doing this.

07-09-2010, 10:28 PM
Does ot go on a dirt bike? just guessing.

07-09-2010, 10:54 PM
From the looks of the cone surface, your syncro lining/taper is worn...

Did you measure gap between syncro ring and gear to determine if in spec???

Be sure you have minimal/recommended endplay on maingear shaft or bearings...

07-09-2010, 11:43 PM
I was thinking the same thing Bguns when I first saw the photo. The synchro ring has worn grooves in the taper and it appears to have a shoulder. Even though the brass ring may seem to fit right it is probably not stopping the gear as it should for the shift. Your probably going to have to replace that gear and the synchronizer ring at the least. Doing it half way will just have you pulling the tranny again and doing it right. The dog teeth is not the problem.

I am in the process of rebuilding my CJ3 trannny and transfer boxes and have the second and third synchro issue. In fact I am having to replace a LOT of the gears, shafts, bearings, etc. and I don't want to do it twice.

07-09-2010, 11:46 PM
I wouldn't touch those teeth either as they do not look bad enough to cause your problems. That's second gear isn't it?

In addition to what has already been mentioned by Carld and Bguns, I would also check for main shaft mis-alignment, shift linkage and shift fork wear or mis-alignment(bent forks or rods). Also are you using the recommended transmission lubricant.

A factory service manual is probably going to be you best ally, it won't hurt to know the exact specs for the transmission you are working on.
Could save you a few parts never mind having to RE & RE the trans again.

07-10-2010, 12:14 PM
Sorry I wasn't completely clear in the OP. That is just a reference picture, not an actual picture of the gear(s) I would be trying this on.

The gears I would be testing this idea out on are out of a B16A honda transmission. Mainly second and third gears. This car gets raced just about every weekend and sees high rpm shifts constantly. I will most likely replace the synchros because they are a little cheaper $211.00 for the set. I do have many honda factory manuals and I have rebuilt/fixed many trannys before.

The reason I want to try out sharpening the teeth not only to try and eliminate the high rpm grinds but because these gears are not cheap. Just one gear is $230-250. 1-2 hub and slider is $220. 3-4 hub and slider is $200.

I want to test out sharpening the teeth because if it does work and the engagement isn't effected much it could save me alot of money now and in the future.

07-10-2010, 01:18 PM
The Ford top loader 4 speed was not a tranny that would speed shift well and there were some after market synchro's that would improve the shift. There was also a field mod that I read about and tried and it did help some.

Maybe there is a mod for that tranny or an after market synchro that can speed shift easier.

07-10-2010, 05:28 PM
angled stand on the mill table, index off a tooth. cut one side rotate a tooth, go on around. run the table to the other side of the quill and do the other side of the teeth.

I've done the same by hand with diamond stones before, doesn't seem that they need extremely precise angles.

I always ran toploaders in my mustangs, along with an inline shifter (V-gate, slapper etc) power on, clutch free shifts ate a lot of synchros.
Had it rigged with solenoid shifting for a while, triggered by the shift light on the tach


07-10-2010, 08:50 PM
The upgrade for these transmissions is strait cut (dog) gears but are also very expensive. The honda manual transmission is great right from the factory with carbon coated synchros, steel shift forks, and strong gears. People use the stock transmissions in these cars up to 800hp. However the replacement parts are expensive and it is normally cheaper to buy another known good tranny rather then rebuild. If this method does work out to my liking it could save me, friends, and willing customers some money and possibly time.

Thanks for the tip! What kind of difference did you notice in shifting? What shape of stone did you use to get in between the teeth?