calibrating a speedometer ??

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Sep 17, 2003 | 06:15 PM

Rick Williams

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Burning Brakes

Joined: Oct 2000

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From: Portsmouth,Va USA

calibrating a speedometer ??

I am having a complete rear drive train installed after damage to my other one. The new assembly has the 3.07 gear ratio from an 1988 and I had the 2.59 before in my 1987.
Since I also have the 17" wheels does anyone know what is required to have the speedometer calibrated to the new rear end.I am told it is electronic and not gear driven.??? ANY SUGGESTIONS APPRECIATED.

:flag

Sep 17, 2003 | 08:14 PM

MrRenoman

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Joined: Jul 2003

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From: Reno/Sparks Nevada

Re: calibrating a speedometer ?? (Rick Williams)

Here's a link to the gears you need. Your going to need to change sensors. I found that out when I went from my 2.73 to 3.07. It's a discontinued part and had to use a dealer to locate where any were located in stock. I bought the first one I came across. It was $108 plus the new gear at $6. I didn't have to change the gear on the output shaft, just the one on the sensor that slides into the side of the tranny. http://www.corvetteforum.net/c4/vett...Gearshtm.shtml
and here's a link to the tire size calculator. http://www.miata.net/garage/tirecalc.html If you type in the 255-50x16 in the stock tire size you can compare it to the 17" tire size you have. If the tire size is significantly different you may have to change gears to compensate, but if it's close to the same diameter you won't have to.
:cool:

I just did the calculation. If you're running 275-40x17 you are almost the same diameter as the 255-50x16 and looks like you can go with the green gear for the 3.07 installed on a new sensor. Look at the 89 and it lists the same gear for both tire sizes.

[Modified by MrRenoman, 7:23 PM 9/17/2003]

Sep 17, 2003 | 08:34 PM

CFI-EFI

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From: The Top of Utah

Re: calibrating a speedometer ?? (Rick Williams)

For P255/50R16 OR P275/40R17 tires, you keep your red, 17 tooth, drive gear. The orange, 35 tooth driven gear gets swapped for a green, 42 tooth, driven gear, part number, 25513049. The sensor needed is part number, 25007339. These numbers are from my 1984-1989 Corvette parts book, dated 1989. The numbers MAY have been superceded in some cases, and as has been mentioned, discontinued. Good luck, and...

RACE ON!!!

Sep 17, 2003 | 09:34 PM

MrRenoman

Melting Slicks

Joined: Jul 2003

Posts: 2,384

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From: Reno/Sparks Nevada

Re: calibrating a speedometer ?? (Rick Williams)

I just pulled the box the sensor came in and found the dealer list. Both show the 25007308 number so it should still be good. I did find that the part number had changed as mentioned. Might want to check both. Here are the name and numbers of the dealers. Some names listed are not dealers but were on the list.
Pam Oil Inc. (208) 383-1141 or (800) 456-1770
Richland Chevrolet (661) 399-5133 or (800) 564-6553
Crest Chevrolet (909) 883-9458 or (909) 883-8833
Harbor Chevrolet (562) 424-8161 or (562) 426-3341
Tracy Chevrolet (209) 835-4544 or (209) 835-4500
A I D San Jose (866) 323-7278

I don't know if anyone has one, I did find one from one of these guys I don't remember which one. But at least it's a start.

[Modified by MrRenoman, 10:17 PM 9/17/2003]

Sep 18, 2003 | 07:38 AM

Dark-Knight

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Joined: Feb 2003

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From: ~The DARKSIDE Group~

Re: calibrating a speedometer ?? (Rick Williams)

Will the tow truck pay for the reclaibration since they did the damage to your diff?

Sep 18, 2003 | 09:43 AM

Rick Williams

Thread Starter

Burning Brakes

Joined: Oct 2000

Posts: 863

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From: Portsmouth,Va USA

Re: calibrating a speedometer ?? (Beautiful Beast)

WOW, you guys are great..I will definately be using all this info..
Here in the East we are in the middle of a Hurricane right now..
so I am under generator power for a while.. Will check back later..
Thanks a lot
Stay safe