Differential ratio?

bigg-limo wrote:

fla-gypsy wrote:
Did a check on my 6.8L/4.10 rear with the 5 sp auto and I was turning just 2350 RPM's at 75 mph. 3000 rpm's would indicate very low ratios in the 5 sp manual transmission

He could be running smaller tires, as well.

Stock Size

fla-gypsy wrote:
Did a check on my 6.8L/4.10 rear with the 5 sp auto and I was turning just 2350 RPM's at 75 mph. 3000 rpm's would indicate very low ratios in the 5 sp manual transmission

He could be running smaller tires, as well.

Did a check on my 6.8L/4.10 rear with the 5 sp auto and I was turning just 2350 RPM's at 75 mph. 3000 rpm's would indicate very low ratios in the 5 sp manual transmission

colliehauler wrote:

Old-Biscuit wrote:
RC is not part of your axle code
That is the 'regional code'

52 is your axle code

52 is Conventional non-Positraction Differential 4:10


Info

Thank you

You're Welcome!

Old-Biscuit wrote:
RC is not part of your axle code
That is the 'regional code'

52 is your axle code

52 is Conventional non-Positraction Differential 4:10


Info

Thank you

donn0128 wrote:
And your question is?

The sentence followed by a question mark. Old Biscuit answered it, thanks anyway.

The string method works on any vehicle, any tire size and note that some previous
owners (on used vehicles) change out their diff gears


2500 Suburban - How to determine ratio?
Diffratio diffratiostring diffstring

quote from above link

benk wrote:
Posted: 11/01/11 10:23am...ps...the links no longer work..buddy took down his web site


Several ways to check, but the most reliable is with an actual count.

There is a label in GM glove boxes that lists all of the options that
vehicle left the factory with. Called RPO codes and here is a link
to my buddies site with links to several RPO code sites:
http://aplsweb.com/Topics/RPO-URLS.htm
Some of those links are no longer and this one is the better of them
http://aplsweb.com/Topics/TopicPix/RPO.pdf

But, since buying used, the previous owner(s) may have changed out the
gear set.

Best to then tie/tape a length of string on the drive shaft. Note a
datum.

Then roll the vehicle one tire rev using the valve stem as a datum

Count the full turns and the fraction left. That is the diff ratio
and makes no matter what size tire or suspension lift, etc.

Remove the string.

Here are some of the codes. Note that there are some only for cars
and not for trucks


GM8: Axle - Rear (2.56 Ratio)
GT4: Axle - Rear (3.73 Ratio)
GU2: Axle - Rear (2.73 Ratio)
GU4: Axle - Rear (3.08 Ratio)
GU6: Axle - Rear (3.42 Ratio)
ZQ9 - Axle, performance ratio (4.10:1) (requires G80 & L78 or Z28)

RC is not part of your axle code
That is the 'regional code'

52 is your axle code

52 is Conventional non-Positraction Differential 4:10


Info

I have a 02 with 3.73 axles and the manual tranny. At 75 in OD I'm Turing 2500.

Doesn't sound right to me but I have no knowledge of the actual gear ratios in that manual 5 sp.