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‘88 S4 auto trans replacing ‘86.5 S3 trans follow up
After 1.5 years, the retrofit is complete. I’m going to submit some lessons learned after this brief summary, but here’s the short if it.
1) did the S4 auto trans fit in the S3 ?
— yes, with absolutely no discernible interference. Spookily easily retrofitted.
2) all the attachment gear fitted back in, right?
— er, no. If you do this type retrofit, order the trans drive selector cable and all attachment brackets/parts, FIRST. Seems like a no brainer, but there are things that slip into the forgotten background.
— the Bowden cable: the Bowden cable attaches to the S4 trans seat just like it did in the S3, BUT that bolt eyelet on the cable housing that allows the cable to be secured to a front cover bolt so as to prevent the Bowden cable wobbling loose will not attach to a S4 front cover bolt because the bigger S4 cover doesn’t align with the cable housing eyelet.
Yes, you need to prevent the Bowden cable from wobbling. I just secured the cable to the trans by fixing it with a piece of flexible, galvanized construction strap and (goopy) JBWeld as in the picture. The cable can be easily freed from the strap if need be, but when secured, it won’t wobble. Lessons learned and debrief follow
Lessons learned:
first; thanks Kevin, the donor trans is fine.
why1.5 years to complete?
— reason #1: consider having qualified 928 pro mechanic do this job. Life can get in the way. For me it was age related medical stuff (MUCH better now). Wife and I cuda been stuck selling off lots of large, 928 parts plus a chassis. Car drives fine but you get my point. For the rest of you it could be new babies, children with developmental disabilities. Job transfer. Think about these things first.
— reason #2: I proactively replaced the donor trans TC converter bearings, front seal, front piston and pump seals. Not having done any of this type work before, MANY, MANY visits to forums and the manual were required. Often being set straight by Greg or Stan before critical activities. After making each measure of progress, I found myself having to stop and order some unique tool, lubricant part, and I’m some cases reordering a seal when I felt I had mistreated a seal on installation. Be prepared to spend between $40 - $60 dollars every five days for the duration of the project for very small parts, product-in-tubes and specialized tools. This particular part of the project really deserves considering having a pro 928 do the work. How much time do you have? Is just replacing the front pump/piston seals enough on a 30+ year old transmission? What about those hard reverse shifts and band-wear.
what about parts? I hear from our mechanics that some auto trans parts are only available in the world in a quantity that one guy could hold in his arms. If you ever feel inclined to get a full pro rebuild… maybe better get in line sooner.
For those of you wanting to do this type front end seal replacement, I can give the benefit of my experience as regards to supplies and tools you’ll need in a later thread. Bear in mind, I won’t tell you how to do it. Im a beginner. I’ll point to forum threads and of course there’s the manual.
Remember, I warned you. The forums illustrate more owners dropping their trans a second time to fix problems caused by their first seal replacement endeavor. 928 prices seem to be on the uptick. This may be the time to have that auto professionally rebuilt to complement the cosmetics you’ve invested into it.
Lessons learned:
first; thanks Kevin, the donor trans is fine.
why1.5 years to complete?
— reason #1: consider having qualified 928 pro mechanic do this job. Life can get in the way. For me it was age related medical stuff (MUCH better now). Wife and I cuda been stuck selling off lots of large, 928 parts plus a chassis. Car drives fine but you get my point. For the rest of you it could be new babies, children with developmental disabilities. Job transfer. Think about these things first.
— reason #2: I proactively replaced the donor trans TC converter bearings, front seal, front piston and pump seals. Not having done any of this type work before, MANY, MANY visits to forums and the manual were required. Often being set straight by Greg or Stan before critical activities. After making each measure of progress, I found myself having to stop and order some unique tool, lubricant part, and I’m some cases reordering a seal when I felt I had mistreated a seal on installation. Be prepared to spend between $40 - $60 dollars every five days for the duration of the project for very small parts, product-in-tubes and specialized tools. This particular part of the project really deserves considering having a pro 928 do the work. How much time do you have? Is just replacing the front pump/piston seals enough on a 30+ year old transmission? What about those hard reverse shifts and band-wear.
what about parts? I hear from our mechanics that some auto trans parts are only available in the world in a quantity that one guy could hold in his arms. If you ever feel inclined to get a full pro rebuild… maybe better get in line sooner.
03-23-2022, 04:36 PM
‘88 S4 auto trans replacing ‘86.5 S3 trans follow up
