i bought an si transmission and tried putting it in today... i have a d15b and the clutch in it was like new so i figured i would leave it alone.... when changing it i noticed that the shaft on my dx transmission (from a 90 crx dx) the input shaft had 20 splines on it.. the shaft on the si transmission i bought (not sure of the year) had 21 splines... the input shaft is also a little bit bigger but nothing noticeable... i had to use a micrometer to know that the si shaft was bigger

ive been told that the only transmission that has 21 splines is the 88 crx si transmission...

can anybody confirm this??? and can anybody tell me if it will be ok to use the flywheel on my d15b?

 

88 trannies had 21 splines and 89-91 trannies had 20 splines. You can use the 88 clutch and flywheel on your d15b. Thats what i had to do since it was the only clutch and tranny i had at the time.

 

is there any advantage to using an 88 si tranny... is the gearing the same as the 89-91 transmissions??

and can i use the flywheel that came on the d15?

thanks in advanced

 

The 88 Si tranny is geared the same as the other Si trannies. To use the 88 clutch you have to use the 88 flywheel to go along with it.

 

not trying to jack ur thread,but i bought an Si tranny to put in my 89 EF (d15b2) and we didn't check the splines or anything! now the prob is with the clutch pushed in and the car in gear it doesn't roll....now when the car is out of gear it rolls like normal! could the number of splines be the reason why its doin this??? i think the tranny came out of an 91 Si..........

 

If it was the splines the tranny wouldnt even fit...