Hey everyone. I need to replace the transmission in my 91' NA. I was wondering if there are any differences between the S4 and S5 N/A tranmissions.

Thanks,
Andrew

 

The rear mounts are different. If you use the S4 trans you just need tyo use the S4 mount.

 

the s5 na transmissions had a slightly better cruising ratio

 

Well the S5's had a slightly taller 5th, which lowers cruisong rpm's, but it also means you'll have to shift more for going up hills since there'll be less torque at the wheel to push you up.

 

Yes, but on the other hand the S5 had just about that much more torque, so it was pretty much a non-issue in regards to the generation change; this only comes into play if you had an S4 n/a and you were changing to an S5 tranny. I bet you couldn't really tell the difference even then.

It would only show on the really sensitive butt-dyno. Would probably not really affect gas mileage unless you spend lots of time at highway speeds in 5th.

I would pick which ever ranny that was in the best condition, lowest miles and cheapest price. I would buy 'quality' first in your replacement. Don't worry too much about the ratio, it's not really a big issue

 

So I can toss a S4 transmission in my car and it'll be totally straightforward. I just need to use the S4 tranny mount as well?

 

Yes

 

I suppose, but I've got a ~0.800 5th in my car and it makes a noticable difference, it's a lot more eager to pull up hills and it's not even really worse on milage.