Hey I swapped out my 4.10 diff to a 3.90 diff in my 86 rx7 na, i tried to swap out the gear drive, with a gear drive from a 89 gtu(22 teeth vs 21) but it was larger diameter than the one that was already in my tranny. Does anyone know what the procedure is to make my speedometer have a accurate reading with the 3.90 diff i''ve installed in my 86 rx7?

 

Sorry, typo. it was a 4.30 not a 3.90. Can anybody help? Can't find anything in forum about how(what) to change out for the drive gear.

 

You need to swap out the speeds gear at the tranny with a gnus one.

 

GTUs version. Or a good speeds shop can make you an adapter.

 

Speedo shop. Damn spell check............

 

Wait, you swapped out a 4.30 GTUs dif and installed the 3.90???

 

LOL He ment to say 4.3 when he first typed 3.90.

Can someone recite what color the gear is out of a GTUs? I believe an automatic is yellow/orange, and a 4.1 is grey. That has been talked about before, so to get a for sure answer the search function should find you a thread that will make that clear.

 

do u know the part# of the gtu speedo gear?