Hi all,

First tech post so bare with me. I purchased an 02 SS m6 and recently started questing if one of the previous owners put 4.10's in the car due to higher than thought RPMS on the highway ( the last owner did not know much about the car in regards to mods to inquire).

I searched first to understand what expected rpm the engine should pull with stock tire height and stock 3.42's but couldnt find any definitive answers. Unfortunately I don't have immediate access to a jack to mark the wheel and count the drive shaft turns so hoping the experts can help me.

Car details
- 02 SS M6
-295/35/18 inch tires - 26.1 inches = stock tire height I believe
- odometer is in kms as it’s a Canadian car

Question
- what most likely gear ratio would I have based on the pics and tire size
- how far off is my odometer currently

Thanks in advance!

 

Here's how to find out.

1.) With a floor jack raise the rear end off of the ground and mark a line on one of the rear tires and another line on the fender

2) Mark a spot on the driveshaft yoke in line with a mark on the differential housing.

Then have somone rotate the tire one complete revolution while you count how many times the mark on the driveshaft passes the mark on the diff. If it goes almost 3 and 1/2 turns it's a 3.42 and if it goes 4 turns then most likely it has a 4.10 gear.

 

Thanks for the quick response, as mentioned I dont currently have access to garage over the next few weeks, but will use this method when available if it cant be determined by the experts!

 

Your Tachometer divided by Speedometer indicates an overall gear ratio of 2.07
Which is pretty close to 3.42 axle with .6 OD
.
.
.
RPM x Diameter
------------------ = GEAR
MPH x 336

 

Thanks so much, saved me from crawling on my back! FYI updated my post to reflect it being a Canadian car and in KMS not miles.