Speedometer Recalibration

[Wesman]

Hey guys,

I just bought a 98 T/A M6, and the guy who owned it before me swapped out the stock 3.42 gears for 4.10's. The problem is he never recalibrated the speedometer/odometer to match the new gear set.

I'd like to fix it, so I have an accurate speed reading, as well as keep the mileage from racking up too fast. Whats the best way to go about doing this?? Something like a Handheld programmer or can I just swap the speedo gear out of the trans?? I've heard its easy to fix with the Programmer, but I'd rather not spend $400-$500 just to recalibrate my speedo :umm:

I also have aftermarket 17" rims on low profile tires, were the stock ones 16" and does that counter the 4.10's inaccuracy somewhat??

[t/as&dds]

It's gotta be done electronically. If you're not planning on any other mods and don't want to get a handheld, you should do a mail-order tune. There are a lot of good programmers out there who will do it for $250-$350. I currently have the same problem and I'm waiting for my handheld to be fixed so I can do the same thing. My mileage is racking up pretty quick as I went to 4.10s also but my handheld gave me a stupid error message...

[Wesman]

Thanks for the response. I was kind of hoping I could recalibrate it with a different speedo gear, but I guess everythings electronic with the newer systems.

What exactly is a mail-order tune?? Do I have to send in my ECU to them and have them reprogram it?? Or do I just tell them what I want and then they send me a reprogrammer/chip?? What companies would you reccommend??

If I have to send in the ECU, I'll probably just end up going with a handheld tuner :rolleyes:

[2001NBMZ28]

There should be a shop near you that can reprogram for the gears, look for one that does dyno/tuning. Around here you can get it done for an hour minimum shop time - only takes a couple minutes. Another option is a used HPP3 if you can find one for your year - but make sure it's been returned to stock. I sold my old one a couple years ago for $120 shipped.

[t/as&dds]

There's a site that will actually send you a tuned PCM that will have your VIN and everything you need already done and then you just send them your PCM as a type of 'core'. That may be the route to go or, as posted before, go to a dyno-tuner. You'll get the best results that way but the pricing may be out of your budget???

[2001NBMZ28]

Car doesn't have to be on a dyno to change the speedo, what I meant was any shop that can do dyno tunes will have the software to change it - $60 here, they can also delete codes, reset fan temps, etc.

[Wesman]

Car doesn't have to be on a dyno to change the speedo, what I meant was any shop that can do dyno tunes will have the software to change it - $60 here, they can also delete codes, reset fan temps, etc.

That sounds like the solution to me, unless I can get one of those Hypertech Power Pragrammers off eBay for cheap or something.

Thanks for the help guys.