Rear End Gear

[oakeydoke]

Is there anyway i candetermine the gear in my car I just bought it and the guy said he thought it was stock, but it sure turns up awfully fast to be stock
Thanks in Advance!!!

 

[Michael Yount]

Jack the back of the car up (both rear wheels). Place a mark on the driveshaft and a mark on the tire. With the car in neutral, rotate the tire exactly one time and carefully note how many times the driveshaft turns. If it's about 2 and 3/4 turns - that's a 2.73 gear; if it's a little over 3 that's a 3.08; if it's about 3 and 1/4 that's 3.27; if it's about 3 and a half, that's 3.55; if it's about 3 and 3/4 turns, that's 3.73's; if it's a little over 4 that's 4.10. Some will tell you to look for tags on the axle or to decode the VIN - that only works if you know the complete history of the car and you know the rear end has never been swapped and the gears have never been replaced.

 

[88_GT_5_oh]

wow i always thought the only way to be sure is to open it up and count teeth.... but that is way easier, wish i woulda known that when i was shopping for gears.. i just assumed they were 3.27's.

 

[super302]

do what michael yount said....i think if you go in 4th gear at 70mph, just divide the rpm's by 1000??

Correct me if i'm wrong, heard this a while ago.

 

[Michael Yount]

"i think if you go in 4th gear at 70mph, just divide the rpm's by 1000??"

You could come up with an algorithm like this, but it would vary with tire size -- so it won't work on every car/every tire size. Counting turns is the easiest/surest.