Hi guys. I'm using my tax return to put 3.73's into the 10 bolt rear end on my 87 305 trans am. My stock gears are 2.73's and I think this will be money well spent. Unfortunately, the rhode island area is very very limited on knowlegeble techs who have worked on f-bodys and even fewer of them will actually do the job since too many numb-nutts have been complaining about gear noise and try to get their money back.
So heres the myth.... The only 2 shops I can get to do the work are worried that my automatic transmission will not shift correctly with aftermarket 3.73's or that it will not shift to wide open throttle. One said I'd need to burn a chip. Neither shop seemed real sure about anything I've read the tech article about the 10 bolts and know a little but need help. Also, is there any danger I need to get a whole new differential to swap the gears? I think I have a 2 series, need a 3 series, and that sounds expensive for my $500 dollar buget. Sorry this was so long. Help if you can and thanks.

 

You can order 3.73 gears that are make to fit in the 2 series carrier that you already have. It is true that your tranny might not shift right. If anything it will shift much earlier than it does now and you will not be able to get anywhere near redline. This can be fixed with a governor recalibration kit. They are cheap and easily installed without removing your trans. It changes the springs or weights in your factory governor and is adjustable. And the 3.73 gears will be a little louder compared to your stock gears.

 

I agree.

 

Okay that makes sense. Does anyone know where I'd purchase this recalibaration kit? I don't see it in the summit mag and a quick google search came up empty. By the way, would putting a computer chip in there accomplish the same thing? I believe I could calibrate my shift points with that if needed...

 

If you call Jegs or Summit they probably have the recal kit. If not you could try a tranny shop. I think that its the same kit as a TH350 but I could be wrong. A computer chip would have no effect on your trans as the only thing the computer handles is the converter lock-up. Shift points are determined by the governer and the throttle valve (TV) not the ECM in our cars.

 

Thanks guys and 91 LE. I'll try calling them and just have the shop put the kit in when they do the gears. Many thanks.