Having trouble after replacing broken center diff

[dsm5062]

I am having some trouble I broke my center diff in my 95 gsx then went to replace it with a good one out of a 92 trans I had sitting around. I replaced the broken spider gears with the good gears out of the 92 trans and reinstalled it following the procedure on the VFAQ site yet after reinstalling the diff and reassembling the trans it doesnt want to roll right it seems like it is rubbing/ binding slightly. I have just pushed it back and forth in the shop I havent driven it or filled it with fluid because redline shockproof is too expensive to waste, I just wanted to make sure it rolled. Does anyone have a clue what could be causing that rubbing/ binding?

 

[twicks69]

More than likely you didn't actually put in a 1992 diff. Pull it out and inspect the gear tooth profile to your 1995 housing. You likely have a 1990-early 1991 diff installed.

Tim Zimmer via Evo Phone

 

[dsm5062]

That is what I thought also so I pulled just the spider gears out of the spare supposed 92 trans and put them into my 95 diff housing then reassembled it would the spider gears themselves different or just the diff housing?

 

[twicks69]

Ahhhh, I read it closer this time. Did you properly reshim it and use new spider gear washers and upper/lower pinion gear shims? You checked the condition of the center diff housing inside wear areas, the center diff cover riding surface for the upper pinion gear oiling shim, the lower pinion gear shim and gear riding surface, the cross-shaft riding areas and the spider gear inside and backside wear areas for galling, damage, discoloration, etc? After you assembled the diff, did you rotate it both directions to get it shimmed properly? If it is binding up assembled and you know everything is good inside of it, then your upper or lower oiling shim needs to be swapped for a thinner one based upon where the gearset sits in the case and gear contact patch area evenness.

Tim Zimmer via Evo Phone

 

[dsm5062]

I think this may be part of the problem when my spider gears exploded they put a few gouges in the surface where the shims ride behind the spider gears and I tried to smooth the down with my die grinder the best I could. I think it may have taken out too much surface and given the gears excess play. Where can I get thicker shims to take up the play and how do I measure acceptable play?

Would I be better off welding the center diff since the shim surfaces were damaged? And what temp do I need to heat the assembly to before welding none of the write ups have that temp I could find, and what is the trick to keeping the bottom aligned when welding that gear?

 

[dsm5062]

Well I pulled everything apart and it seems the spider gears were binding slightly so I decided to just go ahead and weld the center diff so I dont have to worry about the spider gears breaking anyway.

 

[dsm5062]

I am now having trouble getting it into gear, I welded the center diff and put it back in and reassembled the transmission filled it with redline etc. and started it on the lift and went to run it through the gears to make sure it was working. It didnt want to go into gear at all at first, then after going into third and fourth a couple times and trying first a couple times it would go in and i was able to run it through the gears but it was whining really loudly as I got into each higher gear almost like a trans with straight cut gears and then after going through the gears it still didnt want to go into first or second gear right away it would take a few attempts. What would be causing this I put everything back together the same way it came apart, and its the same diff housing that was in the trans, and the bearing shims for the races are the same I didnt change them.

 

[GSXeclipsePSI]

I'm afraid I might run into this problem this week so anyone have any ideas?