rx7sportscar

My tranny was exhibiting the signs of a bad needle bearing that is located between the input and output shafts (the noise would be greatest in 1st gear, and progressively less in the higher gears).. I did a complete tranny rebuild, replacing all the bearings as I went along. I put the thing back together and unfortunately I still have the noise problem. I'm pretty sure I know why I have the noise, but I'm not sure how to fix it. I'm wondering if anyone else has this problem.

I believe the reason why I have this noise is because I have too large of a gap between the two shafts. You see, when you follow the FSM in the assembly process, towards the end you install the front tranny case/bell housing, and then you install the front input shaft bearing on the input shaft. You have to then install a snap ring on the shaft, and another one on the outside of the bearing (this snap ring then contacts the housing). When I pounded the bearing on the shaft, I first did the snap ring on the shaft. However, the input shaft moved too far back into the tranny to put on the outside snap ring. I had to build a simple tool to pull the shaft (along with the bearing) out about 0.050" so that I could install the outside snap ring. It is this 0.050" that I think is causing the needle bearing to rattle around between the two shafts.

I was very careful putting things together, and while this gap would disappear if the whole gear train was moved foreword relative to the main bearing housing assembly (by picking different selective washers that fit in front of the main bearing), there would be problems because then the shift forks would be ridding on one side of there clutch hub assemblies. I'm kind of stumped on this one, and I was wondering if anyone else has experienced this problem.

As background information, it was apparent that the tranny was rebuild before, so while it seems that I put it back together the way I found it, it was probably not put together correctly during the first rebuild.


Thanks for any advice

Mark

86 Sport Restoration Project

SureShot

How did the needle bearings & races look?
Can the input shaft bearing be flipped backwards or shimmed?
(I'm thinking it may not be exactly symmetrical)

rx7sportscar

The needle bearings and race looked fine for both the old one and the new one. I was actually quite dissappointed to find the old bearing in such good shape. The bearing is symmetrical as far as I can tell, and the S5 FSM is pretty good at noting things like that and there is no mention of it.