915 5th gear issue during rebuild

[HawaiiScott]

Hi all,

I'm just wrapping up a rebuild of my engine (3.2L) and transmission (915). Everything has been going great thanks to all the forums and articles! Until now...

I have just torqued the pinion and input shaft nuts and put the 5th/revers slider, shift rod and fork on. It is EXTREMELY difficult to engage 5th gear, while reverse is no problem. At first I thought it was just the new synchro so I removed the fork and rod and it slides into fifth with normal amount of force as all the other gears with new synchros. So I try again with the fork and rod installed and still very difficult. The detent is in the proper place and functioning as should. I removed the shift fork and rod and inspected the case bore and didn't see anything abnormal. So I put the rod in the bore without the fork and I find that it is very very difficult to push the rod down into the 5th gear position. Did some cleaning and reassembled everything and its still very difficult to get into 5th. I can push the slider with both hands and engage 5th with some force but I cannot remove it without prying it back with a piece of wood. I did this a bunch of times and it really didn't get easier.

So I'm thinking there is something wrong in the bore???? I can shift 1st - 4th with the shift rod no problem but it is very difficult to engage 5th with the shift rod and almost impossible to pull it out. Anybody got any thoughts on this?

[john walker's workshop]

The bore can get dented a bit if there were chunks flying around from 1st or 2nd syncro bits coming loose. Inspect the top of that bore from inside the center housing for a dent. BTDT.

[HawaiiScott]

John, that's exactly what happened and why I needed a rebuild. 1st gear completely destroyed itself and the synchro and brake band were all over inside the transmission. Assuming the bore got a detent, what can I do about it? I'm really hoping to not have to remove the nuts and intermediate housing...

[gled49]

I have a 15mm reamer that I’ve used to clean up the shift rail bore. The detents and inter lock pins can be left in place and intermediate housing can be left in place. A little clean up after, but not very much.

[HawaiiScott]

Originally Posted by gled49

I have a 15mm reamer that I’ve used to clean up the shift rail bore. The detents and inter lock pins can be left in place and intermediate housing can be left in place. A little clean up after, but not very much.

Thanks for the suggestion! I think that is my next course of action.

[john walker's workshop]

Grease the reamer to capture the chips.

[HawaiiScott]

Finally got the bore reamed out and it worked perfect. Thanks again for the tips!