FirebirdX

Going to be getting 3.90 gears from Motive as a Christmas gift.
Was wondering if they came with a few different shims depending on what I will need for my Trans Am?

redbird555

iTrader: (14)

the gears wont come with any shims, sometimes you get lucky and you can just reuse the stock shims by switching them around. if that fails most hp shops sell shim kits which include shims that are adjustable. I have these on my car, they are about 35 bucks a set iirc and they have two interlocking halves in them and in the middle it comes with smaller shims that you stack and lock the two halves together thus increasing or decreasing the thickness.

bLack OFF

Looking into 3.90 gears myself, but haven't seen too many reviews compared to the 3.73 or 4.10. Let us know how you like them when you get them on the car

FirebirdX

Yeah I definitely will, I recently bought a hood, so ill have to wait a bit to change the gears.
I currently have 2.73's in my TA (stock, non ws6), im curious to see how much difference 3.90's will feel? lol

redbird555

iTrader: (14)

2.73s leads me to believe you have an auto. Why are you putting those gears in an auto? The car is going to be unbearable on the hwy most people who still DD their a4 go with 3.73s and if they do a lot of hwy they go with 3.42s

HioSSilver

iTrader: (8)

3.90's rock. I changed from 4.10 . I needed the extra mph to get threw the traps....I think 3.90 is a better gear for the tq curve of these engines.

FirebirdX

Yeah it is an auto. The car itself doesn't ever get driven on the highway unless I take it with me on vacation. I also plan to stop driving it daily to school when i start actually modifying it. My buddy has 3.90's in his Ta (auto) and its fast as hell.

redbird555

iTrader: (14)

Gears really dont make your car "faster" going from 2.73 to 3.42 might net you a couple tenths in the 1/4 and even that is up for debate. They do make the car feel faster though, however when you get up to 3.42-3.90 the feel will be minimal all you will really be doing is turning more rpm to drive around. I'd go with 3.73's at the most man, theres really not a place for those steeper gears in an auto since the 4l60e already has a 3.06 first gear.

If you really wanna go faster skip the gears altogether and go straight to a stall you will drop .5-.7 in the quarter and it will feel like a whole new car.

Isolde

iTrader: (4)

I did the stall with the 2.73:1 axle, albeit in a '95 Z28 convertible, but I truly hated it. That stall wasn't so annoying with 3.42:1 gears. I have done every ratio from 2.73 through 3.73, and the more, the better. But the 3.73s seemed like I was at the upper limit of practical. Cruising at 2200 RPM at 65 MPH wasn't any issue, but then I lost lockup, and 2400 at 65 was very irritating. Maybe just my choice of muffler? Anyway, with those 3.91 gears I'd want 27" tires rather than the usual 26" tires.