Hoopdie91

Hey guys I have Deen looking into upgrading to a si 5speed from my 91hatch std 4speed and I was wondering if I would be able to reuse my cluchplate since it's still just about brand New or would I have to get a New one and cv axles any help is apreseated thanks again guys

rallypoint_1

Depends on your fly wheel. There are two different spline counts. I forget which one. So if your spline count doesn't match you would have to swap out the fly wheel to match the new trans. I swapped my 4spd but that was in 1995 so I may have forgotten a few things.

Hoopdie91

Ok I'll look into that so if they are different I have to get another clutch too right. I remember changing my cv axles and I thin they were like 32 or 28 can't remember was like a year ago so I'll have to figure it out but i bet If I go to a pick a part I could just grab it all if its there

rallypoint_1

You can use the same STD axels. But Ya, the clutch disk would have to be replaced if the splines are different.

v4lu3s

the 1988 models hav eth different spline count.
if you have a 1988 and get a 1988 transmission you should be fine.
if you have a 1989-1991 you will do best to get teh 1989+ transmission, or else you would need a new clutch disc.

jpciii

Literally, all you need is an 89-91 Si transmission (not 88). You can re-use everything else from the STD.

Pro tip: If you car has its stock STD engine (d15b1), swapping the camshaft and ECU from a d15b2 is the easiest and cheapest 20 horsepower you will ever get.

rallypoint_1

^true!! The PM5 is a better ecu than the PM9. I noticed that the idle was smoother and overall ran better. Cam would be good too. But besides that 4sp, the dpfi is the Achilles heal in that motor.