Need to tune after Diff swap?
 

My 94 is at BEGI as an S4 system mule. I'm thinking about going to a 3.63 or 3.9 rear end gears to make better use of the power. Will changing the rear diff have any effect on the tune? Not sure if they are going to be using xede or MS yet.

They are tuning it and if the rear diff gearing makes a difference I want to get that in before they are done not after I get it home! Any of you guys that did the swap have any trouble or changes you had to make after?

it shouldn't you'll accelerate slower, but it wont change the tune really.

Think of it this way... Your ECU does not know what gear you are in anyway, so changing the rear end ratio is not much different than just shifting from one gear to the next. The cruise RPM for a given speed will change of course so if you are trying to run lean in the cruise region that could make a difference but probably not a big deal.

But dang if your car is at BEGi they can tell you for sure.

I'd love to get the 3.6 ring and pinion myself. It is on my list of future mods, after a clutch upgrade and charge cooling.

I didn't seem to think it would make a difference either. Steph wanted to get it in before the car goes to the dyno for tuning though. I'd need to find the part ASAP if that's the case. If it doesn't matter I can wait until the right part at the right price comes along.

Thanks for the responses!

Brain, congrats on the forum. Hope it's working out for you.

He didn't buy it if that's what you're talking about, Rick just made him an admin because Scott is a good babysitter.

Wha happened to Philip? There were a few months I wasn't active here after deciding to send the car off to BEGI. Come back and filips gone and Brains the Admin! I stupidly assumed that Brain bought it!

Philip sold the forum to Rick and Rick made Scott an admin. Have you not noticed all the great changes/additions to the forum? Philip would never do shit compared to what Rick did in the first week.