GM dealer didnt know which one i needed so i could use a little help.

Ive got a 700R4, i'm putting a 3.27 (BW) in so which gears or color gears (what he said) do i need. Thanks. I'm going from a 2.73 if that makes a difference, dont think it will. Still on the stock 215/65/r15 tires.

-chillen

GM part # 25522497 (45 tooth) is probably the closest. It is for that gear ratio with the 245/50/16 tires, which are a tad shorter than yours. Both ratios use the same driven gear. Speedo will be very close, under just a little bit.

Pretty sure it's a red ring gear on the output shaft of the tranny, and a yellow gear in the tailshaft.

That's what I'm running and the speedo seems to be accurate, but I suppose it could be off. I bought a 3.27 and the guy gave me the speedo gears.

My 2.77 rear came with a red gear on the output shaft, so I didn't have to change. I imagine a 2.73 would be the same since it's almost the same ratio.

cool thanks, i'll give that a try. its a starting point at least. thanks.

-chillen

Hey People

Ok can someone walk me through the formula to figure out which gears I need (700R4 of course)

I have 255/50/16" Tires and I am going from 2.77's to 3.73's

So far I have figured out that I am 74.26% of my actual speed????

Does that make sense

I have seen the formula on the net but I am lost

I am guessing 15/45??

How close would that get me?

Those are the two gears used for 3.73 rears from the factory. They are for 215/65/15 tires, but extremely close. Worked fine for me with the same tire size and gear ratio.

Part#'s 8642620 for 15 tooth gear, and 25522497 for 45 tooth gear.