Auto Transmission swap
03-03-2013, 12:00 AM
#1
Racer
Thread Starter
Auto Transmission swap
Hi,
I have a 1986 16v Euro S2 (S4 suspension and brakes) with the standard A28/04 auto transmission.
Can anyone tell me if it is a straight swap to fit an A28/16 auto box from an S4 ?
Thanks
I have a 1986 16v Euro S2 (S4 suspension and brakes) with the standard A28/04 auto transmission.
Can anyone tell me if it is a straight swap to fit an A28/16 auto box from an S4 ?
Thanks
03-03-2013, 06:30 AM
#2
Rennlist Member
Its not quite a straight replacement.
But its definitely doable with very simple mods.
I've done what I ASSUME is a very similar swap, replacing USA 84 -- A28-01 4speed with the 89 S4 box, same one you reference. A28-16.
You will want the S4 shifter cable and will need the S4 bowden cable.
Shifter cable is a direct replacement. (it is slightly longer than 16V cable because it has to go around a bigger torque convertor on S4)
Bowden will need mods at engine-end. Basically, you need to remove some of the hard shield from the cable and free-up more of the bare inside cable so it fits the 16V throttle body mount.l
You will need the S4 torque converter and cover, along with trans, hopefully as one piece -- not separated ( people seem to have lots of problems putting TC back onto trans ). Your car's existing torque converter is not compatible with the new transmission.
The S4 TC/trans assy are wider than the one being replaced. The S4 TC / cover may just contact the body/tunnel, depending on condition of your motor mounts and trans mounts.
Mine did not. I had started to whack the tunnel just a bit with a small sledgehammer to allow more space, but after a few whacks I aborted that because I couldn't figure out just where it might make contact. I figured if it rubbed and was annoying, I could take it down again later and do that mod. Again, not needed, even after 30K miles.
Torque tube should be a direct swap, use your 86 or the 89, whichever is better. Great time for Constantine clamp (and Constantine TT bearing install if TT needs bearings).
If for some reason you swap to the S4 axles, too, be sure the tooth count on the outer hub is the same (for antilock).
Take a look at the filler reservoir, existing v. 89. Check to determine if there will be any exhaust contact -- should be okay. And the cooling hoses --- I think the early ones will fit the later trans; might need to swap fittings.
Trans swap is a wonderful improvement, btw. The 89 gearing is perfect for the 16V car.
But its definitely doable with very simple mods.
I've done what I ASSUME is a very similar swap, replacing USA 84 -- A28-01 4speed with the 89 S4 box, same one you reference. A28-16.
You will want the S4 shifter cable and will need the S4 bowden cable.
Shifter cable is a direct replacement. (it is slightly longer than 16V cable because it has to go around a bigger torque convertor on S4)
Bowden will need mods at engine-end. Basically, you need to remove some of the hard shield from the cable and free-up more of the bare inside cable so it fits the 16V throttle body mount.l
You will need the S4 torque converter and cover, along with trans, hopefully as one piece -- not separated ( people seem to have lots of problems putting TC back onto trans ). Your car's existing torque converter is not compatible with the new transmission.
The S4 TC/trans assy are wider than the one being replaced. The S4 TC / cover may just contact the body/tunnel, depending on condition of your motor mounts and trans mounts.
Mine did not. I had started to whack the tunnel just a bit with a small sledgehammer to allow more space, but after a few whacks I aborted that because I couldn't figure out just where it might make contact. I figured if it rubbed and was annoying, I could take it down again later and do that mod. Again, not needed, even after 30K miles.
Torque tube should be a direct swap, use your 86 or the 89, whichever is better. Great time for Constantine clamp (and Constantine TT bearing install if TT needs bearings).
If for some reason you swap to the S4 axles, too, be sure the tooth count on the outer hub is the same (for antilock).
Take a look at the filler reservoir, existing v. 89. Check to determine if there will be any exhaust contact -- should be okay. And the cooling hoses --- I think the early ones will fit the later trans; might need to swap fittings.
Trans swap is a wonderful improvement, btw. The 89 gearing is perfect for the 16V car.
Last edited by Landseer; 03-03-2013 at 07:10 AM.
