Speedometer Problem

[72Chebby]

Hi Guys,

I have a 72 Chev Fleetside. Speedo cable replaced today but not reading correctly. I realize tire size can throw this off but not by 30-40 mph. When I am doing 60mph it registers about 100 mph on the gauge. Ever hear of this or know of a fix for it? Thanks

[JimKshortstep4x4]

It is possible that the speedometer itself is causing the problem but I would suggest checking the speedometer gears in the transmission first.

If the rear end gear ratio has been changed the speedometer reading can be affected substantially.

Jim

[68gmsee]

Originally Posted by JimKshortstep4x4

It is possible that the speedometer itself is causing the problem but I would suggest checking the speedometer gears in the transmission first....If the rear end gear ratio has been changed the speedometer reading can be affected substantially. Jim

See if you can locate a speedometer at a j-yard so you can be certain, but those speedometer gears in the transmission will sure throw you off.

When I converted my 69 from a 6 to a v-8 it threw my speed off by a bunch. I think the rear axle used to be a 4.11. Later I swapped it for a 3:08 and it sure helped. If you throw in overized wheels or tires you can see where that may really mess you up.

[LockDoc]

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Like the other guys said, trans change, rear end change, tire change can all affect it. If the spedo is working I would say you just need to change the speedo gears in the tranny.

Here are a couple of web sites that may help.

http://www.bgsoflex.com/speedo1.html

http://www.transmissioncenter.net/sp...n_______va.htm

LockDoc