Rear End Ratio Question (no Rpo Codes)

SinnerDC2 · October 11, 2009

I just got my first truck and wanted to see what the options it had. I found the RPO codes, but the glove box is not original. How do I know what rear end gear ratio I have? Around 70 I'm at 2,100 - 2,200 rpm and the truck is 2002 sierra lwb with an auto w/ 5.3 engine.

Thanks

Nick

2000DV4.8 · October 11, 2009

What size tires do you have?

Best way, other than removing the diff cover and counting teeth, is to jack up the rear of the truck, put it in neutral, spin the rear wheels by hand one revolution, and count how many times the drive shaft spins.

A little more than 3 should be the 3.23s

A little less than 3.5 should be the 3.42s

About halfway between 3.5 and 4 should be 3.73s

A little over 4 should be the 4.10s

Or you could PM MS3DALE and see if he can pull a build sheet for your truck.

SinnerDC2 · October 11, 2009

What size tires do you have?

Best way, other than removing the diff cover and counting teeth, is to jack up the rear of the truck, put it in neutral, spin the rear wheels by hand one revolution, and count how many times the drive shaft spins.

A little more than 3 should be the 3.23s

A little less than 3.5 should be the 3.42s

About halfway between 3.5 and 4 should be 3.73s

A little over 4 should be the 4.10s

Or you could PM MS3DALE and see if he can pull a build sheet for your truck.

cool thanks, I did a search and found this is a common question. My mistake :-)

pm26 · October 12, 2009

From the RPMs it sounds like you have a 3.73 ratio. My truck with 3.73 gears does about 2,200 RPM at 75 MPH in the top gear.

SinnerDC2 · October 12, 2009

From the RPMs it sounds like you have a 3.73 ratio. My truck with 3.73 gears does about 2,200 RPM at 75 MPH in the top gear.

i figure it was a higher ratio gear because I can jerk the hell out truck in first gear even with the ext bed and ext cab with just a little throttle, but this is my first v8. I think someone removed the torque management that Ive read about.

Spurshot · October 12, 2009

If that rpm is with a 31 1/2" dia tire, I agree, it sounds like 3.73 gears. But it could be 4.10 gears if you have some large dia tires. Why are you asking? Are you considering larger tires?