One quick question!

[pitbulls'n'blazers]

Hi guys,
I have a little bit of a problem. I'm replacing the rear of my 87 K5 ( 10 Bolt) with of course a FF 14 bolt. The problem is I'm not 100% sure but I think the gears are 3.73's? My question is, in the 1987 Chevy K5 did they put different ratios in other than 3.73? If so, what's the best way to find the ratio? I'm sorry if this has been asked before but I have to know pretty quick.

Thanks!!
Jason

 

[randy88k5]

Yeah, I'm pretty sure the stock gearing was 2.73. Mine was.

Easiest way to check is to either pull the cover and count teeth on ring and pinion. Divide ring by pinion -> ratio. Or look for ring and pinion teeth count stamped onto the side of the ring. Or lift the rear, mark a reference on tire and driveshaft, put tranny or tcase into neutral, and spin, counting the revolutions of the driveshaft to one complete turn of the wheel. That would give you an approximation, then you can determine which gear it is by the available close ratios.

 

[Hogback Fabrication]

Pull the cover on both diffs. There are a bunch of numbers stamped on the side of the ring gear (on both diffs). Near (or at) the end of this string of numbers, there should be two 2-digit numbers (something like 40 11). Divide those two numbers and that is your gear ratio.

 

[pitbulls'n'blazers]

Thanks guys. I will pull the covers off, and try to find those numbers or like you said count the teeth.

Thanks alot!
Jason