UncleMaz

Do I need to swap shift linkages and torque tubes to use an early gearbox in my 1985?

I have broken centering and reverse l.o.springs and need to drop my transaxle for servicing. While the trans is out and weighing my limited spring options, I am thinking about installing my G28/03 TA and installing it in my 1985. I realize this is counter-coventional, but I am very curious about driving my car with shorter gearing and testing my early transaxle in the process, as I have never tested it on a running car.

Thanks.

Jadz928

It might be a straight swap. I'm sure the really smart people here will chime in... I've never done that before.

IcemanG17

G28-03 and G28-11 are NOT a straight swap....

The transmission length is different and so the TT is different along with the shift rods as well.... I think the rear cross member might be different too...

My freshly rebuilt by Doc Brown G28-03 is GREAT....shifts excellent & I really like the lower rear end gear...plus it is the "closest" 928 box available.....all the others have slightly bigger gaps inbetween gears...

For example on my race 928 when I shift at redline, 6000 it never drops lower than 4400rpm.....always in the sweet spot of the engine!!!

Jadz928

And there you go! Thanks smart person.

Mark Anderson

Actually the transmission is not a different length. The difference is the input which is 5th gear. The relief for the clamping bolt is in a different location. Some people cheat and add a new relief to their torque tube shaft but I don't recommend it

UncleMaz

[QUOTE=mark anderson;10213574]Actually the transmission is not a different length. The difference is the input which is 5th gear. The relief for the clamping bolt is in a different location. Some people cheat and add a new relief to their torque tube shaft but I don't recommend it[/QUOTE

Thanks Mark. So, will swapping the TT and linkage work?

Mark Anderson

[quote=MJ928;10213794]You would need to do the rear cross member as well

UncleMaz

[quote=mark anderson;10214062]Perfect. Thank you.

Rob Edwards

Just for grins, here's a table of ring and pinion and gear info by transmission type. This is all based on PET, not reality, so take with a large grain of high quality German salt.





EDIT: Fixed R&P info 2-11-13

jpitman2

Surely the 2.75 final drive ratio should be 12:33 teeth? Or is the 2.73 wrong?
jp 83 Euro S AT 55k

Rob Edwards

Good catch, I edited the pic above to reflect 12:33. It is infact 2.75.

genikz

Michael, let me know if you need a hand. Maybe I can bring PorKens car up

UncleMaz

Thanks for all the replies

GlenL

I'm swapping to a G28/11 from the stock transmission in a 1980 Euro S.

I've attached two pictures. The dirty transmission is the current one and the clean transmission is stamped G28/11 on the bottom. I measured the cases and position of the motor mounts and the two cases are the same. Reading this thread, I went to look, again, at the input shaft and found that they are identically placed.

The pics are trying to show the location of the groove for the clamp bolt. Looks the same from that angle. When viewed from above, in the plane of the flange, the edge of the bolt groove aligns with the face of the flange. I could measure with a straightedge but the difference would be a lot less than the slop in the grooves on the torque tube.

The tranny should be a G28/05. I'll confirm that.

Vilhuer

Big difference is between 03 and 05. Easy way to identify 03 vs 05 is rear subframe. 03 uses same part as automatic gearbox cars. It has mounting points for '78 only gearbox shocks. 05 and later use casting which do not have them. Other easy way to identify 03 vs later setup is TT lenght. Tube used with 03 is 30mm longer than later version.

For 05 to 11 swap only needed parts are selector arms on top of TT and selector itself. Even 05 original parts work but movement is very short with stock selector.