TR6 Transmission Question TR6 in TR4 ... will it work?

[mgedit]

Helping a friend with a TR4 rebuild transmission and a-type OD. We had several transmissions/ODs to select and the best was a combination from an early TR6. My question. The "spigot" on the front of the transmission on the TR4 extends beyond the front of the case; whereas, on the TR6 it is more or less flush with the front of the case. Will the TR6 transmission fit and function correctly? We don't want to go to this work and find out that the TR6 transmission and clutch combination don't work in the TR4. What is the purpose of the longer spigot on TR3/TR4 setup? Why shorter on the TR6? Input greatly appreciated. Cheers, Mike

 

[TR3driver]

No worries; I've been running a TR6 gearbox with the short input shaft for many years (in both TR3A and TR3) and it works just fine. It doesn't fully engage with the pilot bearing in the end of the crankshaft, but that doesn't seem to hurt anything. I changed the pilot bearing after perhaps 50,000 miles (since I was also changing the clutch & flywheel), but I couldn't find any wear to speak of in the one I removed.

Note that the front cover is also slightly shorter, because the TR4A-TR6 style clutch will hit the earlier cover. I've been told that using the later front cover with the earlier clutch is no problem, but I opted for the longer cover (then had to shorten it when I switched to the later clutch).

 

[mgedit]

Thanks Randall. I was pretty sure it would be OK, but it is nice to have reassurance. Cheers, Mike

 

[Marvin Gruber]

Done the same as Randall, it will work fine.

Marv

 

[TRDejaVu]

I believe that you also need to lengthen a couple of the attachment studs on the back of the engine to allow for the thicker TR6 bell-housing flange.