I've seen a lot o people talking about changing the rear end gears to get more kick on launches. I have a friend that has a 2002 WS6 and he installed 4:10 gears. He said it made a big difference and he's happy with the mod, even having to cruise at higher RPMs. He said that now at 70mph the engine is reving at 2,300 (!?!!??!?!?)

My questions is what is the stock gear ratio on a 2001 WS6? If it's 3:73, is it a good idea to change to 4:10?

Thanks!!

Automatics got 3:23's and 6M cars get 3:42's. I have 3:73's in mine now and it's about right IMO.

In the past you would put 3.73's in an automatic car to get the same results as 4.10's in a standard car. Today? Anybody?

I dont know about them being the same. In older cars final drive is 1:1 so the gear ratio in the rear wont matter much.Cruising rpm would be the same in both if they have the same rear end ratio's.. Now-a-days with overdrives and such,high rear ratios can be used without affecting rpm's and milage as much. The 6 speed cars have 2 overdrives and thats why some people like 4:10's. Thats a bit much in a 4 speed auto causing cruising rpm's to be higher than desired,so 3:73's are a good compromise.

A guy I work with has an auto T/A with 3:73's and has had a 60' time of 1.98 on street tires. I have the same gears & drag radials and the best I've done is 2.05. I still beat him now by .4 at the other end

well all I know is that righ tin the SLP catalog they state and again I quote them " for an automatic that drives on the street you don't want to go any more agressive than 3.73's and in a manual 4.10's

Oh also Tyler my car came stock with the optional 3.42's and it is an auto.

Just passing it on.

Doug

The gears you go with totaly depends on what you want. If you are looking for a good launch, then the lower (higher numerically) the better, if you are looking for gas mileage the higher (lower numerically) the better. If you are looking for a good combination of both, then the standard 3.73 behind the automatic and the 4.10 behind the manual are probably the best choices. A 700R-4 or 4L60 or 4L60E with a 3.73 gear breaks down like this 1st gear final drive is 11.41, with overdrive with 3.73 the final drive ratio is 2.61. The six speed with a 4.10, 1st gear final drive ratio is 10.90, and then your final overdrive (6th) final drive ratio with 4.10 is 2.58. So, you can see that this should be about equal. Thanks to the 700R-4 low first gear, it works out for a steeper final drive then the 6 speed, but the 6 speed eventually get a better cruising speeed, but they are both pretty close. If you are more fimiliar with older trannies, like the TH350, then a 700R-4 with a 3.73 is lower final drive in 1st gear then a TH350 with a 4.10, and better final drive in overdrive then a TH350 with a 2.73 gear. Best of both worlds with either the manual or the automatic. If you want to figure out the RPM you would be running at a certain mph, and you know your tire size, you can play with this a bit. It let's you calculate the engine RPM by plugging in just about any transmission, what gear the transmission is in, your rear gear ratio, at whatever speed you want.
http://www.project33.com/tiresize.cfm
Just plug in your tire size such as 275/40/17 and it will calculate height, and then you can get the rpms by plugging in everything else.

Doug,thats a new one on me. Are you sure?

My car is a 6M and I have 3:73's. I would'nt want any lower since 1st gear is about useless in everyday driving. I can take off in 2nd most all the time. 1st is good at the track however.

If you want mucho maximum accelleration go for the 4:10's or 11's. If you want to keep it a little more conservative use 3:73's.

Tyler, I'm surprised, you got that mixed up. The final drive gear ratio in an older car with a top transmission gear of 1:1 is determined by the ratio of the rear end.

The rear end ratio in any car matters a whole bunch, even old ones, esp old ones, becuz they generally don't have an overdrive.

WS6, look on the drivers door and find the listing of the RPO codes. Then look for one of the following codes. The code that matches is the gears that are/were in your car from the factory.

GU2 - 2.73's
GU5 - 3.23's
GU6 - 3.42's

Hope this helps.

You either misread or I typed it wrong. My point is if to identical cars,one a manual & the other an auto,have the same rear drive ratio's and the final drive is 1:1 they will turn the same rpm's in top gear.

I can see where I confused you maybe. How's my edit to that post? Make better sense that way?

Sassy,

The code on my car is GU6, so I do have 3:42s. There is another post here that talks about the benefits (or not) of having the 3:73s.

Thanks everyone for the replies!

SLP says you don't want to go any mor eagressive than 3.73 in an auto and 4.10's in a manual. They say that is the max. it is righ tin the SLP catalog.

Doug

I know this is old news,

but yeah Tyler, my A4 also came with 3.42s from the factory. I forgot the RPO for it or I'd double check. Doug's car isn't a fluke!

(I think all 94 and at least up to 95 with the performance button had 3.42s)

My '95 A4, with the performance button, also has 3.42's according to the RPO codes.

Thanks for the question... I had the same one and you saved me the time...

I cnt find these codes anywhere on my driver's door...it has the vin number, and tire and weight information...i dont see any numbers that have a "GUx" anywhere...

Yours won't be on the door, they'll be in the glove box since it's a 95.

awesome i would have never figured that out...ive looked a couple times now...thanks!

checked mine last night, it's a 95 with the transmission perform button and it has the GU5 (3.23's)...so i geuss not all birds with the perform button have 3.42's...

mine does, what is weird is that when I called GM and gave them my VIN, they decoded it and told me I have 3.23 gears. my car is a 95 auto. When the time came to fix the differential to tow it over the border, I saw "3.42" etched on the side of the gear ring. now either the previous owner made the mod or something but the ring gear is an Original GM part. Guess i have to check the codes when I get a chance> also I'm assuming the Trans Perfm button is for auto's only.

Yea mine is a 95 auto too, and yes, the Transmission perform button is only on autos...but it has the GU5 which is supposed to mean 3.23's...thats strange...itll be interesting to see what you have for an RPO code...

Dude I know it's strange. I've come to think that error is prone everywhere.

Actually to get the 3.42's with the transmission performance button it had to be ordered that way otherwise they came with 3.23s standard with the performance button. Other then that the only cars that came from the factory with 3.42s were the 6 speed cars. Automatic came standard with either 2.73s or 3.23s from the factory, just depending on what the original owner ordered.

Weird. My car has the Transmission Perform button and my car's code is GU2 ...

That means that you have the 2.73 rear end in your car. You can still have the transmission perform button with either the GU2 or GU5.

so from what I remember, the higher the gear ratio like 4.10 means faster acceleration but decreased top speed. The lower the ratio then the higher the top speed but acceleration suffers. Suppose an 02 WS6 is bought off the lot stock. It has 3.73 gears...what is the top speed? what if it has 2.73? How much do the gear ratio decimals affect top speed?

Well since you can't get 3.73s on our cars from the factory it would be hard to say. But I can tell you this much, my 97 had 2.73s from the factory and with them in I ran a consistant 14.0 at approximately 97 mph in it, when I swapped to 3.42s my car now runs a consistant 13.6 to 13.5 at approximately 99.98-101.0 in the 1/4 mile. Hope that helps.

Uhhh....like Sue said in another post...you guys do realize that this thread started in 2003?

that is a very good example, it does help. i hadn't seen the 2003 date...it's all good though