I know you guys get this al the time, but what would be a good choice for gears without loosing more than 2,3, or 4 mpg?
everything is stock on my 92 rs 5.0 tbi except exhaust
will my speedometer still be accurate ?
any whinning problem ?

thanks in advance

Cedric

 

Most TBI guys will tell you to get 3.42 gears because they are still street friendly, but will get you moving a whole lot faster that the stock 2.73 or 3.08.

 

Yep, for a 305 TBI, 3.42 gears seem to be the best. I just got done doing this swap myself last week. Your speedometer will not be accurate anymore, you need to swap out the speedometer drive and driven gears (located towards the rear of the transmission). You shouldn't have any problems with whinning, unless the person that installs the gears does not set them up properly.

Here's a nice write-up on replacing the speedometer gears: http://sethirdgen.org/vss.htm

Also, when you swap to 3.42s, you usually need a 15-tooth gray drive gear and a 41-tooth yellow driven gear. But, to get the speedo as accurate as possible, there are some formulas on the internet that determine what tooth count is best for your car (I can't remember where to find them at the moment). Check the FAQ for all the part numbers for the different speedometer gears.

Here's the GM part numbers for all the parts you need since you have a 700R4 (if you end up needing 15 and 41 tooth gears):

8642620- Gray 15-tooth drive gear
25513048- Yellow 41-tooth driven gear
1358899- Tranny extension to case seal
8673526- Extension housing seal (or part number 9613S at most auto parts stores)

 

whao thanks a lot for the info, really helps
how much for gears and other part?
how much labor time since I have a good shop doing it for me

thanks a lot again
cedric

 

Gears are usually around $200 and you'll need a gear install kit which runs around $100. Check out Thunder Racing, Summit Racing, and Jegs and see what they offer. I don't really know how much it costs to install them professionally, when I did mine I just swapped out my 10 bolt for another.