99ssleeper

iTrader: (98)

Im in the middle of rebuilding the trans with new 1-2 and 3-4 synchros. I have pressed the new synchros on, put the gears on, and set the mainshaft back into the input shaft assy.

When I actuate the 1-2 syncho it's super smotth and easy to go in and out of gear. The 3-4 is not...it's very hard to engage and disengage. It seems like the keys are not retracting.

How hard is the 3-4 syncro supposed to be??

Mine will engage ok but is damn near impossible to disengage.

85MikeTPI

iTrader: (9)

Did you put in billet keys? Replace the springs? Lubricate the keys with ATF assembly lube or at least ATF? How are you trying to engage 3-4, by hand on the slider, or with a punch slid into the shift rail?

If you're sure the 4th gear blocker ring was properly aligned with the synchro keys when you set the mainshaft inplace, it may just be the alignment of everything without the case and guide pins installed. I find that setting the shift rail in the proper fork arm, and moving the slider by gripping it directly, it's not so hard to move..

99ssleeper

iTrader: (98)

No billet keys. Here's wat I did...

I lubed the 3-4 synchro assy before I put it out. I took it out of the bag, put ATF on it, and pressed it on the mainshaft. Then proceeded to install the 2nd gear, syncho, and first gear. Then i set the entire assy onto the input shaft. Everything was aligned properly.

I tried to actuate the 3-4 by hand, no shift rails, and it was very difficult to move. I tried to actuate the 1-2 and it was smooth as silk.

So I took the 3-4 synchro back off, disassembled it, inspected, cleaned, and reassembled properly with new oem keys and springs. Reinstalled the synchro.

Better but still difficult. Now it seems to engage the gears decent, but disengaging is very difficult if it does at all.

thesource

iTrader: (60)

Did you get the slider lined up properly on the hub?

99ssleeper

iTrader: (98)

yes, the slider detents are lined up as well as the scribed marks on the hub and slider.

i dont know what else it could be.

85MikeTPI

iTrader: (9)

Since I guess the synchro was torn up, were the engagement teeth of 3 & 4 also checked? If they have burrs on them, it can hinder engagement until they are clearanced or cleaned.

Did you notice/check if the slider moved on the hub easily when it wasn't installed on the mainshaft?

99ssleeper

iTrader: (98)

yep, checked all the engagement teeth, they look good. the slider will actually engage 3rd easier than 4th. but once its in either gear its very hard to get it to disengage.

i did check the hub and slider when it was disassembled and there were a couple small burrs which i cleaned with a small fine sanding disc on the dremel. all slid well until it was reassembled and installed.

it really seems to be an issue with the keys. i know the springs are very tight. im going to remove it again, check it and re install it if all looks good.

if this is normal, no wonder the 3-4 fork and pads break.

85MikeTPI

iTrader: (9)

This would have me triple-check that you aligned the 3 notches in the 4th blocker-ring, with the 3 keys. If not, the keys are not free to sink down and allow the slider to engage.

I assume you're putting in a steel 3-4 fork also...

99ssleeper

iTrader: (98)

When I set the mainshaft into the input shaft, I rotated it slowly until the keys dropped into the notches...otherwise, as you know, the mainshaft wont spin easily or sit as straight as it should.

No...I didnt buy a steel fork because I dont beat on the car or go racing. Im past those days LOL..and I'm 27 so thats a little scary. But after seeing your hard it is to engage 3 and 4, I'm thinking I may as well drop $50 on it.

99ssleeper

iTrader: (98)

Figured it out. After I disassembled it the first time, I reassembled it wrong. The hub had a line scribed on each side and I lined up the wrong side. The correct scribe mark was very small and could barely be seen...the one on the wrong side was more obvious but wrong. Once the hub was flipped it actuates much smoother. The wierd thing is, the keys were properly lined up with the recesses in the slider with either mark.

Thanks for the help. Came down to a dumb mistake.

raven154

iTrader: (14)

I have a brand new steel 3-4 fork i'll sell you if you want it.

99ssleeper

iTrader: (98)

Too late, trans is already back together and sealed. Thank for the offer though.