Rear End Ratio Help Needed

[CAJUN C4]

I have a 95' 6 Sp. and a 96' 6 Sp.Both supossedly have the GM3 or 3:45 Ratio.However,the 95' definatly has a lower Ratio than my 96'.At 75 with my 95' I'm at 2,000 RPM. With the 96' I'm at 11 or 1200 RPM approx.I know my 96' has a GM3 but the 95' I don't know if some where along the way the Tag (Says GM3) was changed or something.Can I be sure from the VIN# ? If so how do I go about finding it out from the VIN?

 

[Hib Halverson]

There was only one, stock axle ratio for manuals in 95 and 96, 3.45:1.

It is possible that, at some time in it's life before you purchased it, one of the cars has had an axle ratio change and, perhaps, that is the source of the difference.

 

[CAJUN C4]

Hib

Had to have been changed along the way. I also thought that 3:45 was the only ratio offered.

I'll have to jack it up and turn the wheels and count the drive shaft revolution amount or visa versa.

Is there any other way to tell? Maybe a Tac reading in 4th gear at 60 MPH or something to compare with other forum members ratio's?

 

[vetteoz]

.At 75 with my 95' I'm at 2,000 RPM. With the 96' I'm at 11 or 1200 RPM approx.

In what gear?
ZF6 with 3.45 @ 2000 rpm
45mph in 4th (1:1)
60 mph in 5th
91mph in 6th assuming 26.5" tire.

MOTOR - A Rear Axle Calculator

Is your tacho reading correctly

 

[toptechx6]

One other possibility that occurs to me would be a slipping clutch, comparing your RPM to someone else will not clarify that. I would jack it up, count the driveshaft revolutions, then you will know, good luck.

 

[MBDiagMan]

Simply raise both rear wheels off the ground and support it SAFELY with jack stands. Turn one wheel one complete turn while counting the turns of the driveshaft. The number of turns of the driveshaft is your ratio. Example, the driveshaft turns 3 1/2 turns, then it is a 3.45 or whatever the standard ratio in that bracket is.

 

[CAJUN C4]

In what gear?
3.45 @ 2000 = 45mph in 4th /60 mph in 5th / 91mph in 6th assuming 26.5" tire.
MOTOR - A Rear Axle Calculator

Is your tacho reading correctly

I was in 6th Gear. I assume these figures are for 4th Gear 1:1 ?

Tach Seems Fine and Clutch No Slip

If for 4th Gear I'll check it on the way home tonight.

 

[clydeyb]

Interesting information. Anyone know what rear end ratio is in a 93 automatic?

 

[toptechx6]

Stock ratio for an A4 coupe is 2.59, convertibles got 2.73.

 

[CAJUN C4]

There was only one, stock axle ratio for manuals in 95 and 96, 3.45:1.

It is possible that, at some time in it's life before you purchased it, one of the cars has had an axle ratio change and, perhaps, that is the source of the difference.

Hib,I do suspect that because my Cooling Fans come on earlier than stock.Someone had to change that as well.

 

[jonszr1]

it sounds like you have 392 gears in the car thats doing 2000 at 75. i have 392s in my 92 zr1 and thats what it reads at 75.hope this helps .

 

[CAJUN C4]

it sounds like you have 392 gears in the car thats doing 2000 at 75. i have 392s in my 92 zr1 and thats what it reads at 75.hope this helps .

This helps alot. I really appreciate all you guys input.BTW...Who makes a 392 Set?

 

[bucket]

i found my ratio with the RPO code inside my console...
there is a code like" GU3" or whatever indicating yer ratio...at least in 92 ..thats the way it wuz...
you can search up the codes...

 

[vetteoz]

i found my ratio with the RPO code inside my console...there is a code like" GU3" or whatever indicating yer ratio...at least in 92 .
you can search up the codes...

Only if it still has the original gears which the OP obviously does not

 

[bucket]

WOW...!!!
I'LL TRADE YA FOR A 2:59....
LOL

 

[jonszr1]

the zr1 that has the 392s came that way from callaway.its a 475 super natural.if you go with 410s go with the super viper gears they will handle just about anything you throw at them