Should I retune after installing 4.08s ?

[SteveVQ]

I did a search on here and google, without definitive results.

Is a retune recommended / required after installing 4.08 gears to get the most out of them? or can I just plug and play?

Thanks,

[FrankEtier]

I have not researched but how do you correct your speedometer on a Z after a gear ratio change? Is it mechanical or corrected in the tune?

[Spooler]

Plug and play. It won't change how the engine was tuned.

[husam2012]

If you have rev matching then you'll need a tune to get it working along with the cruise control.

Speedometer doesn't have anything to do with gears, it's based on abs sensors on the axles.

[FrankEtier]

Originally Posted by husam2012

If you have rev matching then you'll need a tune to get it working along with the cruise control.

Speedometer doesn't have anything to do with gears, it's based on abs sensors on the axles.

Good to know. I was thinking about my old Jeep with a speedo gear on back of the Transfer Case.... Old school tech!

[SteveVQ]

Originally Posted by husam2012

If you have rev matching then you'll need a tune to get it working along with the cruise control.

Speedometer doesn't have anything to do with gears, it's based on abs sensors on the axles.

I've read the SRM goes out only if you track the car over 120+ mph with the 4.08s. Then you have to shut it down wait for a few minutes and turn it back on and it's working again. Also read its only going to be off by 2 or 300 rpms when it does work.

Cruise control I've read is hit or miss whether it will work with the 4.08s or not. Z is not a DD so no biggie either way.

Edit: CC works with 4.08s IF you have a manual. AT with 4.08 needs a tune to get the CC to work.

This is what I've read from various sources within the Z/G community forums across the net. Everything I'm reading could be dead wrong of course but this is what I'm seeing from people who've done this to the Z's/G's with the VHR and AT or MT.