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CobraJay
08-21-2005, 01:28 PM
I just bought a 98 Cobra yesterday and it already has gears. The owner *didn't know* it was already modified. Anyway, Judging from driving by one of those radars on the side of the road to see how fast one is going, it seemed that the speedo is about 2 - 3 miles too slow when the radar said "35 MPH."

How do I know if a speed cal was used or a gear? Where does it install?

Should I buy a stock speedo gear and buy the speed cal?

I'm not exactly sure which gears are in the car.... 4.10 or 4.30. I was crusing at around 80 on th hwy and the RPM's were almost at 3000.

tazzracing1
08-21-2005, 11:49 PM
Sounds like 373's and they changed the speedo gear I would get the stock gear and a speedcal.

smashedheadcat
08-22-2005, 05:30 AM
I would pull out the speedo gear and look for wear. Probably a good idea to change it anyway. I would definately make sure it has a stock gear in there and then buy a speed cal. My speed cal is mounted just forward of the shifter (under the cd player actually) so to get to it, I just pull the shift knob off, and pop the plasic around my shifter off. I can get to the speedcal in no more than 30 seconds. I'm not saying that's where yours is, but it might be.... but I doubt you have one. From the sound of it.... you have 4.10 or 4.30 gears. You can jack the car up, put it on jack stands, put a mark on the driveshaft, and one on the back tire. Release the parking brake and put in neutral. Now watch the mark you made on the driveshaft. Rotate the rear wheel (the one you marked) one full rotation....... however many times the driveshaft spins around is your gear ratio. If the one rotation of the tires shows your driveshaft spin 3 and 3/4 times, you have 3.73 gears. 4 and a little bit... 4.10 gears. 4 and a little more.... 4.30's. 4 and a 1/2, 4.56's etc... if the driveshaft spins 3 and 1/4 turns... your gears are stock 3.27's. It's a pain in the a$$, but this is the easiest way to know for sure (in my opinion).

Josh

CobraJay
08-22-2005, 09:10 AM
Thanks Josh, I'll go ahead and do it probably this Wednesday. It just has to be 4.10's or higher. I had 3.73 in my previous Mustang and I don't remember the RPM's being that high at the same speed.

Thanks guys. I'll go ahead and shove a stock speedo gear and buy the speed cal. :thumbsup:

smashedheadcat
08-22-2005, 10:48 AM
Thanks Josh, I'll go ahead and do it probably this Wednesday. It just has to be 4.10's or higher. I had 3.73 in my previous Mustang and I don't remember the RPM's being that high at the same speed.

Thanks guys. I'll go ahead and shove a stock speedo gear and buy the speed cal. :thumbsup:

Anytime! Glad I could help.