Flathead 39 style trans help

N

novaskilling

Member
Have a closed drive 39 style trans that I fully rebuilt all new bearings new synchros new detents etc. been driving it a year now and lately it’s giving me some issue. Sometimes when I go to shift into second from first it’s like I hit a wall and can’t get into second. If I release the clutch and press it in again usually it’ll go fine. Sometimes it does it going into reverse. Any suggestions or help please? Throw out and clutch/pressure plate were also done with the trans.
 
It could be soft aftermarket 7121 and 7111 bearings going bad. Ive opened up 3 transmissions this year with that problem. Try to find good used bearings. Put a file to them to check for hardness.
 
Low and reverse are on one fork and 2nd & high are on the other. I'd first check condition of the bottom tip of the shift lever and the condition of the pin in the tower that holds the ball part in place there. Wear in the little fork notches also could be a factor. The little pin could be loose in the tower housing so be careful not to let it fall out and down into the transmission.

As was mentioned, the three rollers for the joint between the input & main shaft and the counter shaft cluster gear have had a lot of problems with premature wear. The original Hyatt bearings were the best but getting rare now. I would check with Mac VanPelt about decent replacements. None are as good as the old Hyatt parts but there may be some that will last better than others.
 
You must log in or register to reply here.
Back
Top