Speedo Correction Gears???

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Jul 23, 2003 | 06:33 PM

Dougs 90

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Burning Brakes

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From: Rolla Mo

Speedo Correction Gears???

I have done a search and havent found quite what I am looking for. I have a Dana 44 with 3.55's and need to put the correction gears when I get the tranny rebuilt. I have seen a list or a calculator somewhere but now can't find it. I lookd at this one:http://www.corvetteforum.net/c4/vettenuts//SpeedometerGearshtm.shtml
It is going into my 1990 automatic. Should I just go with grey and purple? Anyone have the part # for the clips?

Thanks,
Doug

Jul 23, 2003 | 07:59 PM

Mr Mojo

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Re: Speedo Correction Gears??? (Dougs 90)

This is what I used on my '93 with 4L60(not "E") and Dana 44 with 3.45 gears

25513050 and 8642620

and a new sensor 10456089

Jul 23, 2003 | 09:30 PM

CFI-EFI

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From: The Top of Utah

Re: Speedo Correction Gears??? (Dougs 90)

I can look that up for you. What tire size are you running? I'll never make THAT mistake, again. The clip for the drive gear is a 6261781.

RACE ON!!!

Jul 23, 2003 | 10:47 PM

Dougs 90

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Burning Brakes

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From: Rolla Mo

Re: Speedo Correction Gears??? (CFI-EFI)

I run 275/35/18

Thanks,
Doug

Jul 24, 2003 | 01:54 PM

Dougs 90

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Burning Brakes

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From: Rolla Mo

Re: Speedo Correction Gears??? (Dougs 90)

ttt

Jul 24, 2003 | 09:00 PM

CFI-EFI

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From: The Top of Utah

Re: Speedo Correction Gears??? (Dougs 90)

Quote:

I run 275/35/18

Thanks,
Doug

My 1984-1989 parts book only covers the stock, 16" and 17" tires for those years. I can figure it manually if you can give me an accurate rolling diameter for that tire. I can tell you how to measure it if need be. Good luck, and...

RACE ON!!!

Jul 24, 2003 | 09:40 PM

Dougs 90

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Burning Brakes

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From: Rolla Mo

Re: Speedo Correction Gears??? (CFI-EFI)

Tell me how, I believe it is the same diameter as the 17" wheel, or real close. you tell me how to do it and I would appreciate the info!

Thanks,
Doug

Jul 27, 2003 | 02:31 PM

CFI-EFI

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From: The Top of Utah

Re: Speedo Correction Gears??? (Dougs 90)

My chart show the gears for P255/50/16 tires and also P275/40/17 and P315/35/17's. Since we started this, I have seen a speedo gear chart posted at: http://www.corvetteforum.net/c4/vett...Gearshtm.shtml
However, I don't see any 18" tires listed. If you KNOW that your tires are the same circumference, or rev/mile as one of thoses listed, go with the chart. Otherwise, mark the tire at the ground. Mark the ground at that same spot. Move the car any convenient number of tire revolutions, and mark the ground where the tire mark meets the ground, again. Measure the distance between the marks on the ground and divide by the number of revolutions made. This is the loaded, rolling circumference of YOUR tire. I can take it from there. Technically, one revolution is sufficient, but more revs, minimizes or averages any "error". Good luck, and...

RACE ON!!!

[Modified by CFI-EFI, 12:34 PM 7/27/2003]