Rebuilt Transmission Binding

TimG · 06-28-2008, 05:24 PM

I'm doing a trans rebuild right now and have run into a pretty big problem. I know most of you guys have never opened up, let alone rebuilt a transmission but I had the bright idea to do it.

Everything went well. All the parts fit together properly and within clearances. I clearanced the shims with the crush solder method and everything came out consistant and happy. My results were:

1. Front Diff - 1.43mm
2. Front/Center Output Shaft - 1.69mm
3. Center Diff Housing - 1.64mm
4. Intermediate Shaft - 1.22mm
5. Input Shaft - 1.33mm

Each shaft has it's own designated clearances or preloads so I simply added or subtracted the limits to the solder thickness' and came up with these shim sizes.

1. Front Diff - 1.38mm
2. Front/Center Output Shaft - 1.77mm
3. Center Diff Housing - 1.56mm
4. Intermediate Shaft - 1.30mm
5. Input Shaft - 1.33mm

I went to put the transmission together today and upon placing the first two cases together, I ran into a big problem. The tighter I tightened the bolts for the case, the harder the front/center output shaft gets to turn until it totally binds up and locks itself in the case.

Can someone who has experience with this type of thing give me some pointers as to where to look for my answers? I re-clearanced the transmission and came up with near identical results so I'm literally lost.

Update: I just re-shimmed the center/front output shaft and attempted to turn the shaft and it's locked with the crushed solder in there. Obviously the crushed solder is too thick. How can this be? I'm using 3mm plumbing solder, which is recommended for this rebuild.

->PrOjEcTGS<- · 07-20-2008, 12:01 PM

Anybody have any thoughts on this. I am in the process of rebuilding mine also and did the exact same thing. My shims that I ordered were a lot thicker than the old ones that were in there. Even on the center diff which I did not replace those bearings.

turboglenn · 07-20-2008, 02:46 PM

This is why i now pay for tranny work

It could be anything from what side the spacers were placed on, to how the gears/forks were placed and held while putting the transmission together. The only local guy i know who touches them just puts them back together with stock shims. I've seen him build a few trannies from 2 broken ones and they all worked great but still felt like "old transmissions" slightly grinding and what not.

Maybe call Jon at TRE, he's honestly very helpfull about things like that, or at least he is when I call.

I helped his dad find some vintage motorcycle parts once years ago when i first met jon on the phone, so maybe that helped *shrugs* But either way he's a great guy and easy to talk to. I'm sure he'd give ya some hints at least.

->PrOjEcTGS<- · 07-20-2008, 07:02 PM

There is no way to mess up the fork position since it is located with a roll pin.

The guy who put two transmissions together didn't use new parts he just used old parts from two trannies. Therefore the reason they still felt old.

I used all new hub/sliders, syncros, keys, springs, forks, 1st gear, shaft bearings.

It has to be something about the way we are measuring for the preload. Maybe there is a softer solder we should use to get the proper crush? If I put in the shims I bought with the calculated preload I can't turn my shafts. Yet, I put the old ones in and it turns great, shifts into every gear and I cannot move the shaft back/forth in/out.

sbiggi · 07-20-2008, 07:22 PM

I checked my preloads by measuring the endplay and adding shims as necessary.

TimG · 09-03-2008, 04:23 PM

FYI for those who run into this problem (I have had 2 PMs about it in the last 2 months). I tried 2.5mm ROSEN core solder and my results were different and now perfect. The trans shifts great with over 2000 miles on it now.