My buddy bought a 95 z28 m6 with 4:10 gears in it and the speedometer is off by about 15 mph . I told him to buy a hypertech programmer and that would fix it,but he dosent want to spend $400 on it . Is there a cheaper way? or what other options does he have.

 

I had the same problem in my 5.0 when it had 3.73s in it. My tranny had a speedo gear that connected right into the side of the tranny on the drivers side, it was held on by a 10mm bolt and had a wire going up through the firewall. They sold different gears for different rear end gear applications on Jegs and whatnot, but you have to know how many teeth you need.

And Im not even sure if his tranny is set up the same way...but check it out and see, because the new gears are like 10 bucks. I just searched them on Jegs.com. Good luck and I hope this helps.

 

I have absolutely no idea what you just said there.

But to the OP, The hp tuner, getting a mail order tune, or a dynotune will take care of that. I'm pretty sure there is no other way. He has to tell the computer electronically that there is 4.10s in the rear for the tach and MPH gauge to recongnize. Either way its going to cost a few bucks. But really, he shouldn't of bought the car if he can't afford that just my worth less than most .02 cents.

 

Might be just a Mustang thing. I thought maybe the Tremec trannys had speedo gears too. But I could be wrong. Just trying to help the OP. I guess hes gonna have to buy the tuner. That sucks...

 

I have also been looking for an answer to this question for a while now. I have heard about the speedo gears but I'm 99% positive the T-56's don't have them. My tuner also told me that he couldn't re-calibrate my speedo through tune. I'm pretty sure Dakota digital makes a speedo recalib. device that will work.. http://www.summitracing.com/parts/DAK-SGI-5/

It seems to be the only way. I can't find a decent write up on how to install one of these tho..

 

I am sure that T56s dont have the gear on the side of the tranny like the T5s do in mustangs ,that is a mustang thang.Collier341 if that dakota digital thing works that would defently be the cheapest way to solve my buddys problem that i have found. Is there anyone out there that has used this and how did it work.

 

Idk where you are from but try to find a lsx performance shop in your area, they should offer a $150 tune that would take care of your speedo.

For instance speed inc does this:
http://www.speedinc.com/catagory.cfm.../%20Electrical

 

Third gen camaros/firebirds were the same way, but switched to it being all electronic sometime around '91.

 

I found this for some speed density (1993) automatic guys....

https://ls1tech.com/forums/lt1-lt4-m...libration.html

Not much help to you but someone may find this usefull...