sbcrazy86

i was wondering if anyone knows if it i possible to put a newer manuel trans. in the older manuel trans spot. if so please reply. i am thinking about swapping because my trans is near the end. would it be more economical to repair trans or swap with a new trans from a newer car. thanks

Rich9928p

A transaxle swap from older to newer is possible, however you need to also change the torque tube. I leaned the hard way with my '79. I suggest a 1985 to 1989 transaxle (pre PSD). The synchros are better in those transaxles.

While you're there, you'll want to change the bearing body and bellow (shift linkage just in front of the transaxle). Keep your twin plate clutch. If you haven't changed anything in the clutch, at least change the throw-out bearing and pilot bearing.

Jim bailey - 928 International

Lance you would also need to switch the torque tube (different length) and I believe the rear suspension crossmember (different mounting hole location)plus shift linkage . Plus "late" model 5 speeds 1987-88 are becoming hard to find. We can have your transmission rebuilt for $1995. Give me a call !

sublimate

What about updating an '82 manual? Does it need a different TT and crossmember to go to the later model with better synchros? Or if I rebuild the tranny is it possible to retrofit the better synchros? How about adding LSD?

Peter F

I have done it on my -81S and it was a straight swap.
Here's a link with some pictures on it as well.

Manual gearbox swap



/Peter

Jim bailey - 928 International

the 78-79 and some early 1980s used the 03 trans if you look at our store you will see the different torque tube variations. But yes the late 1980-1995 interchange easily however there are differences in the shift linkage.

Vilhuer

In this case can't help it, I have to disagree with Jim. We have replaced G28.03 gearbox on relatives '78 Euro to G28.10 from '85 Euro S. '78 -> early '80 TT is longer but difference is only maybe an inch. Did have to modify TT center shaft a little as on later boxes clamp bolt groove is few mm towards the front compared to TT/gearbox mounting surface. Other than that, change was done without swapping any other parts except using G28.03 gearbox endplate on 28.10 because .10 had wrong (too new from digital dash car where ABS sensor is used) endplate (no place for speedo sender) installed when purchased. Endplate was mounted with studs on G28.03 when G28.10 has bolts.

Now car has been driven like this for few thousand miles without any side effects that can be directly attributed to difference in design. Car has odd tendency to use drive shaft rubber boots but this has probably more to do with sub standard quality of installed boots themselves than anything related to changed parts. There seems to be enough free movement in CV joints so that slight position change of gearbox output shafts doesn't matter. Simply can't see how box change could contribute to this as suspension arms normal up down movement creates larger angles to inner and outer boots than this front back change ever could.

Currently we have TT of said '78 and my '92 GTS side by side and plan to take measurements and pictures tomorrow while taking them both apart for bearing change.

Peter F

Vilhuer,

if you could take some pics on the individual steps on the TT bearing change that would be really cool.
Including the tools needed to do this as well.



Cheers/Peter

Vilhuer

That's the plan Peter.

Jim bailey - 928 International

Erkka correct if you are willing to run a drill bit up through the trans clamp and make a new "groove" in the drive shaft you can bolt it together. I see enough drive shaft problems that I would not recomend this to be the best way to do the conversion. I have also seen the drive shaft simply welded to the input shaft(fifth gear) that car would drive as well.

slate blue

Porsche shortened the t/tube so that the driveshafts would have better alignment with the wheels, I suspect a very minor part of that may be less stress on the boots. With the shortened t/tube also come a different crossmember. To do this job properly, you will need a new shorter tube and a new/later model crossmember.

As always your pics Erkka will be valuable. I'm especially waiting on the one of the pinion in the GTS!

Cheers