Cadillac CTS-V - Changing Diff Gears

Has anyone attempted to change the read diff gears to a 3.42 from a regular CTS for better milage? How did it work out? Are these diffs hard to set up?

You'd have to adjust the computer as well. Our cars weigh an aweful lot to go up in gear ratio to 3.42. It would be nice on the highway though.

3.73 to 3.42 is not a noticeable difference at all. I doubt youd see any difference at all in performance or MPG.

How will that not help MPG at 70mph it will change the RPM from 1900 to 1750

How will that not help MPG at 70mph it will change the RPM from 1900 to 1750

my guess is you wouldnt even see a 1mpg difference in MPG from that change. If thats what your aiming for go for it. Better check becuase i thought the rear in the V was limited slip and the ones in the SRX and 3.6 were not.

3.73 to 3.42 is not a noticeable difference at all. I doubt youd see any difference at all in performance or MPG.
That is a huge difference in both departments. I've gone from 3.42 to 3.73 and gained almost 1/2 a second in the quarter.

I know in a 02 Mustang from 3:55 to 3:73 it killed almost 2mpg's

That is a huge difference in both departments. I've gone from 3.42 to 3.73 and gained almost 1/2 a second in the quarter.

I have a 94 Mark VIII. I went from 3.07 to 4.10 and dropped .5 in a quarter.
Dropped about 2 mpg on the freeway. :engarde:

I'm rollin 4.10s. Gas mileage is not pretty whatsoever with the maggie. I don't use 1st gear either. Have not fixed the speedometer yet.

I'm rollin 4.10s. Gas mileage is not pretty whatsoever with the maggie. I don't use 1st gear either. Have not fixed the speedometer yet.

I can imagine 1st gear is a useless.

With a maggie car 1st gear is a waste with the stock 3.73 gears.... I've thought about going to 3.42's just to add a little "length" to first and second gears, and because my current diff whines really bad.

I'm rollin 4.10s. Gas mileage is not pretty whatsoever with the maggie. I don't use 1st gear either. Have not fixed the speedometer yet.

you have 4.10's in your V1?
please share details...
part #'s
costs?
labor?
shop?
ET's?

--Jerry

you have 4.10's in your V1?
please share details...
part #'s
costs?
labor?
shop?
ET's?

--Jerry


Dana 44 Viper differential not sure about part #s right now.
Looks like about 8k in parts/labor from Corvette Shop in San Diego.
I feel if you did it yourself it could be done cheaper. I plan to remove it in less than 2 months and reinstall it so I can fix a small gasket leak and become better acquainted with the setup. So far as I can tell, there's a bracket on the passengerside near the front of the diff that sorta serves like a pinion brace. The diff is held in place by two massive bolts through the rear cover that has had brackets tig welded on. I know, pics pics pics....

No ETs yet. Hopefully by October. If I could hook up 1st and second it would be a monster already, but I'm putting a blower cam and meth from my old car in it.

Only complaint about the setup is a small amount of bushing squeak, or spring squeak. I haven't had the time to find it so I can't be completely certain it's diff related.

Yeah the Viper setup doesn't seem too hard to do, but most (including me) just aren't willing drop the money and/or dont have the time to attack this themselves.