T-18 Shift Forks

Has anyone ever tried to swap a T-18 aluminum shift forks into a T-18 that has cast iron forks? Sort of a long shot. The cast iron forks are in the close ratio version so I imagine the shift collars are larger in the granny gear version which I guess is when the aluminum ones were used.

 

Pretty sure the aluminum forks were used for the later transmission that shifts reverse over-and-down rather than over-and-up. My J20 uses the aluminum forks, and it was my understanding that all the earlier T18s used cast iron.

I will check the parts book later and see if the close-ratio and wide-ratio transmission forks are the same PN.

 

Ok, the wide-ratio and close-ratio T18s through 1978 use the same forks. These should be cast iron. Then the later transmissions with the different shift pattern are aluminum.

 

Yes, the aluminum shift forks were used on the late T-18's with reverse to the right and back. You can easily tell a late T-18 by the bulge on the left rear of the case and top. The earlier T-18's with reverse to the right and forward were cast steel/iron. Some had a plastic type coating, some did not. These are easily identified as the case has no bulge on the left rear, basically smooth. Gear ratio has no bearing on the type of forks the transmission used as both 4.02 and 6.32-1 first gear ratios were used with both styles of T-18.


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My cast iron (you are right they are cast steel) shift forks had a wear coating on them (looked like the were dipped in some liquid) that had, over the miles, worn through to the metal in the contact areas and was peeling away elsewhere. I removed the remaining coating and polished the surfaces. It shifts fine with no noticeable change in noise or feel. I must have 3 or 4 sets of the replaceable plastic tips for the aluminum forks (they are like a freebie item with a full rebuild kit, gasket kit, small part lower kit and top rebuild kit) but they do me no good. In any case, doing research while also looking for new cast steel forks make me believe they are probably a hold over from the T-19 (My T-18 top has T-19 on it).

If cast steel T-19 forks were not $150.00 each (drivetrainparts) and/or aluminum forks $100 each (ebay) I'd buy some just to see if they work since my floor pan is bolted in and I can have the top off the T-18 in 20 minutes. As far as aluminum ones go I'm betting that the change in reverse orientation (when the reverse shift fork moved from a case pivot to top hung) probably change top dimensions and the 1/2 3/4 forks are not interchangeable.

Again, thanks for the info...

 

T-19 top will NOT fit a T-18. Completely different top and will not bolt up. Are you sure you don't have a T-19? If you can post a pic of a top view I can tell you from the shape. The T-18 is a modernized version of the T-98 and early T-18's came with T-98 tops. While some parts are interchangeable between the two, the T-19 is in effect a completely different transmission with a synchronized first gear which the T-18 and T-98 did not have.


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I have postulated so many scenarios in my mind I have confuse myself. (not to mention you guys) My T-18 does not have T-19 on it (despite what I type previously) it is a hold over and has a T-98 top. I had been looking at T-19 parts and then in my aged mind T-98 became T-19. Sorry for the confusion.....