Transmission input shafts?

[jwtaylor]

Is it possible to use the input shaft from an early 4 speed to replace the input shaft on a '82/83 5 speed? The 5 speed input shat is scored where the seal sets.

I would like to rebuild the 5 speed so it can be reinstalled in place of the 4 speed, which has a bad 3rd gear synchro and bearings a getting a little loud also.

[Arne]

When you say "early 4 speed" I'm assuming you mean the Type A with external shift linkage as used in the US in '70 and '71 only. If that is correct, I'd say probably not, as the bearing and front mounting are different between those two types. You might be able to use one from a later 4 speed though.

[jwtaylor]

Thanks Arne! Yes, the 4 speed is a 'dog leg' Type A. Well I guess it's time to find another 5 speed then, or at least a newer 4 speed. Thanks again.

[preith]

Even if you had an input shaft from a later "b" 4 speed I would suggest against it. It would work from a fitment standpoint, but the gear counts on the 80-83 trans are different for the 1-2-3 gears. In other words the end result would be weird, unfavorable, ratios. I spent a great deal of time counting gears, hoping for something good, but unfortunately that's not the case. It would work wonderfully on the earlier 77-79 trans though as they use the same gearsets for 1-4.

Also, a fun tidbit of info. The input shaft is also 4th, but 4th really isn't a gear as when engaged, the input & output shafts are locked together forming a solid shaft straight through (1:1 ratio) and all the other gears are simply "freewheeling", along for the ride.

[Arne]

Good catch, Phillip. I hadn't thought about the tooth count being different. Shoot, if the count is different the teeth probably wouldn't mesh properly anyway.

[preith]

Good catch, Phillip. I hadn't thought about the tooth count being different. Shoot, if the count is different the teeth probably wouldn't mesh properly anyway.

That's true too, but I was under the assumption the input shaft would be installed with it's "mate" on the countershaft, this gear is removable. That being the case, it would install just fine but again, bad ratios.

Edited May 1, 2009 by preith

[Arne]

Still getting used to the thought of the gear on the end of the countershaft being removable. I was rather surprised to see that when I rebuilt my Type A. Used to working on British gearboxes up until then. Most of those have a one-piece countershaft (or layshaft in Brit-speak).

[jwtaylor]

I was told to check out 'Speedi-sleeve' over at zcar. It looks like it would work, but you would have to remove it to remove/replace the input bearing. Might give it a try if I can't find a good 5 speed around.

John