Tamaren

Hello all,
I have a 1980 928 that I've been doing a manual swap from an automatic on. Everything has gone well, bolted up nicely, except with the rear crossmember bolted to the body, and the torque tube bolted together, the transmission motor mounts are about an inch further back than they should be. Any guesses on to what could be causing this? Everything else has lined up very well, It's just like the torque tube is an inch too long or something.
All the donor parts were out of a 1979 manual.

Thanks!
Wesley

Bigfoot928

the auto has a different cross member than the manual.

Mrmerlin

call 928 intl and buy a used rear 5 speed crossmember

Tamaren

Understood- I have a 5 speed crossmember as well- from the same car.

Mrmerlin

.I have a 5 speed cross member as well- from the same car.

what does this mean?

Rob Edwards

What is the part number of the rear crossmember that was originally on your 1980 Automatic, and what is the part number of the rear crossmember from the '79 that you've installed?

How long (in cm or mm) is the torque tube from the '79?

What is the transmission model number and serial number printed on the bottom rear of the case?

Mrmerlin

because there are different rear cross members

Hold On

I did the same swap a couple years ago. 79 manual trans to 83 auto trans. Everthing from the 79, from flywheel back to cross member has to be used. I swapped all the the 83 suspension parts onto the 79 manual crossmember, before installing the entire assembly at one time. The manual trans does not fit the automatic crossmember.

Tamaren

Sorry for the confusion, I pulled everything from bellhousing/flywheel back off the ‘79 donor car. Including rear crossmember.

I will provide serials when I get back to the house, but the parts from the 79 donor car are flywheel, clutch, bellhousing, torque tube, transmission, and rear crossmember.

Tamaren

So- here's a breakdown of part numbers and lengths for parts:

Auto parts that got removed from the '80 automatic:
Transmission Serial: A22 922 321 101 3R
Rear Crossmember: 302810 0 80701

Parts that got removed from the '79 Manual donor car:
Transmission: G28/03 1190619
Crossmember: 928.331.131.14

Torque tube is approximately 144.75 cm, flange to flange, +- 5mm.

Rob Edwards

So the 144.7 cm torque tube is correct in a '79, and worked with a G28.03 transmission. That '79 TT is 30 mm longer than the '80-95 torque tube, because the G28.03 transmission sat 30 further back than the new-in-mid-1980 G28.05. transmission. (They moved the mounting of the G28.05 forward 30 mm to decrease the angle of the axles). PET says that the .14 rear crossmember is used only with the G28.05 transmission. So I'm a little confused how the .14 could have worked with the G28.03 in the '79 donor. You need a 928 331 131 13 rear crossmember, which superceded to a 928 311 131 17, either would work with the '79 trans.

Early vs. late torque tube dimensions:

Tamaren

Perfect, I knew something wasn’t looking right. Thanks for the help! I’ll get it sorted Monday with my parts house.

z driver 88t

After owning and maintaining my 928 myself for 11 years I usually think I know this these cars pretty well. And then I see a post like this and it reminds me there are guys on this forum who have forgotten more about 928s than I'll ever learn. Some of you really know your stuff. Glad to have Rennlist.

Bill Ball

Right, Chris...except Rob hasn't forgotten any of it.