Hello,

I recently purchased a beautifully restored 71 LT-1 and I am not sure what the axle ratio is. It has the M20 tranny. The dealer told me that the ratio was 3:73, now I know there was a 3:70, 4:11, 3:55 but I do not know what Chevrolet offered with the M20.

I am not sure what numbers to check to figure this out what came on the car when new.

Cruising at 55mph, the tach reads 2000 rpm.

Also, the performance seems a little bland. I thought the LT-1 had more pep. I feel like my 1990 L98 was quicker 0-80.

 

The easiest way to find out would be to just jack up the rear end and spin the tire once around. Count how many times the driveshaft spins. I usually just put a little chalk line on the shaft to make it easier to count.

 

3.08 is common, but there are also 3.36, 4.10, and 4.33 besides what you mentioned. Mark the drive shaft and the rear diff housing with a piece of chalk, count the rotations of the drive shaft to one rotation of the rear tire. A little more than 3 rotations is about a 3.08, 3 and 1/3 rotations is a 3.36, 3 and 3/4 rotations is a 3.75, and a little more than 4 rotations is a 4.10, and so on.

 

As Starship said the easiest way is to do the wheel turn driveshaft turn count. The only other way is to remove the differential. And if you are not rebuilding the rear and suspension, I wouldn't suggest that method. It takes quite awhile to remove the suspension components to get to the rear and then you have to remove the rear crossmember to remove the center section.

 

Some of the more common GM ratio's are 3.08, 3.73, 4.11, 4.56 [8D]

 

Beautiful '69. I have one too that I'm proud of. Click on the picture of a camera under my name and it will take you there. [8D]

 

The 70 thru 72 only came with the M-21 or M-22 transmission. You stated yours had a M-20. Could someone have changed it? You must get the RPM up above 4000 to get the power out of the LT-1 and keep it between 4000 and 7000 RPM to maxamize the power band. We used to say drive it like you stole it!

 

LT 1 Man, Nice Z. I have been a Camaro man for many years. I have owned 6 over the years. 3 first gens, 2 second gens and a fourth gen. Besides that I have owned a 68 Firebird 400 a 63 Impala SS convertible and a 70 Nova SS 396, 4 speed. Now I just have the 69 SS Camaro and the 69 L46 Convertible. Both are 4 speed cars. Have a great holiday season.