Center Differential problem?

[redX90]

I am chasing a problem with what I thought was a center differential issue. When backing up, cars (trans area) shakes violently. If backing and turning wheels at same time car really resists and shaking is worse. It turns out, the trans was held in by the top two bolts holding trans to engine and the right side mount to frame only. The bell housing is cracked in three places. I thought this might have something to do with the problem. Well I took the trans apart and checked the center differential and other things just to see what was up inside. Not even so much as a shaving; clean oil, no grit, pieces of anything. On inspecting the center diff I find that when I rotate it, shaft up and main body, clutch side flat on table, it does not turn smoothly as I would think it should. Instead, it kind of shudders or grumbles (best I can describe it with out sound file). If I lift up on shaft it turns a little smoother. Theres no visible damage to gears. It's the first time I've disected one of these so I'm not sure whats correct or not. Any input on this?

 

[pneumo]

That sounds like what mine does. I think it's normal, I don't see any way of fixing it since the side gears and spider gears have few large teeth. Just make sure you check the shims behind the side gears for wear and thickness, they have been known to cause trouble once you start launching hard.

 

[redX90]

Thanks for the reply. I took it over to Prostreet last night and they said it's probably got a cracked gear. I'm trying to get it apart (lack of proper tools) so I can see whats up.

 

[redX90]

Ok it wasn't such a big deal getting it apart after all. It is very clean inside, no shaving or anything. Gears also look fine. All shims are in place but there is a lot of place. Like 2 mm on the spiders to the case. Situation I'm having is I'm building a 90 GSX. The tranny I found was held in by top two bolts and the right mount to frame only. Car has this shaking issue when backing up and some other weird phenomena related to that. The bell housing is majorly cracked from this. That plus the 2700 lb rigid dsk clutch makes driving it interesting. So I pulled the tranny to check internals. Seems like it's all ok. New everything on intermediate and input shafts. No metal shavings anywhere. I have a feeling all problems were related to tranny twisting in reverse. I'm going to use all internmals from my 92 TSI to make one good one and go from there. I think I might just go ahead and have the CD welded to since if it's not bad now, it does tend to be the weakest link from what I've found. Someday I'll try to pick up a four spider diff when I've got the extra cash.