I put 3.42 gears in my car and took out 2.73's I havent changed the gear inside of the transmission. When I ran at the track just before I went through the traps the car began to buck. My time slip said I was at 93.3 mph and the speedo was pegged at 110. Was that bucking from my top speed limiter? I am not sure how the car registers how fast its going, I am assuming from the speedo gear in the tranny. I just wanted to make sure that is what happened, and that the bucking wasnt some other problem I am not aware of.

 

ttt Anyone?

 

http://www.bgsoflex.com/speedo1.html for Bowling & Grippo
speedo calibration

 

makes sense, i dont know how fast your speed limiter is (i thought it was 120) but "bucking" sounds like the computer knocking it back down

you're gonna need to change your speedo gears. there's 2, one on the driveshaft, and one inside the tranny housing. if you wanna get it perfect, you are gonna need a 15tooth drive gear and a 41tooth driven gear (assuming you have 25.7 or 26" tires). or you can do what i did and just put a 45 tooth (the biggest GM makes) driven gear on the outside so you dont have to pop back off. it's easier, cheaper, faster, and you'll only be off by like 2%, which is nothing at normal highway speeds.

you will have to get a different sleeve to hold the 45 tooth gear as what you have on there now (37???38????) takes a diff sleeve. anybody that has a clue what they're doing can find you the part numbers. i would go to the dealership though because i went 4 places before the pontiac place knew what i was talking about

 

:hail: :hail: Great info. I realy didnt want to have to go into the trany at all. I am not concerend with a small inacuracy. thanks again.

 

n/p.......

when you think about it, a 2% inaccuracy means that at 100mph you're really going 98. and if you're going that fast, i don't think it's really gonna make a difference if you get pulled over if you're going normal speeds it's off by much less, maybe 1.2%. so you dont even have to take it into consideration while driving.

this is something that you could probably do yourself. all that involves is popping out the driveshaft, and it's right there. i had to take mine to the shop because im at school, but just replacing the driven gear doesnt take much. it's better than spending $60 for an mecanic's hour to do it. the parts will be about $50, most of it for the sleeve.

i'd still go to your local dealership to get the parts. i'm 99.99999999% sure you've got an electric speedo, but there are two different sleeves, one for electric and one for cable driven and websites arent too descriptive in that regard.

good luck with it

P.S. -there's nothing more disconcerting than going by a cop and looking at your speedo reading 100 when you're really going 80 (which is how much yours is off now). get the thing changed and save yourself a heart attack