Speedometer inaccurate and bounces

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Fjordlander

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Hi all, I searched the existing threads and couldn't find the answers I need so hear I am.
I have a 76 Scottsdale 4x4 and the speedometer was not functional when I bought it. I replaced the speedometer cable but the speedometer still bounces around and is totally inaccurate no matter how fast I'm going.
The odometer seems to be accurate so I think that rules out some of the gears but I'm put of my depth here and would appreciate any suggestions!
 

TJ1978

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If stock, did you lube the cable? Pull out the metal part and use some atf on it.. sometimes whether old or dry they can stick. If it's digital like dakota then I don't know.

If not the cable you'll have to check the gears and input into your Tcase.
 

DoubleDingo

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Get some Kable-Eez from the local auto parts store and lube the cable.
 

87chevy_com

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Hi all, I searched the existing threads and couldn't find the answers I need so hear I am.
I have a 76 Scottsdale 4x4 and the speedometer was not functional when I bought it. I replaced the speedometer cable but the speedometer still bounces around and is totally inaccurate no matter how fast I'm going.
The odometer seems to be accurate so I think that rules out some of the gears but I'm put of my depth here and would appreciate any suggestions!
inaccurate how? to fast or to slow?
details will help.
sounds like its working exactly as deigned but the gear ratio has been changed and the gears for the speedo need to be changed.

sine it spins the speedo gauge, the odometer counts. The speedo is "off" that could of a gear change? ... research what gears you have, research what gear you need to have installed in the transmission or transfer case and then see if what you have installed is what you should have based on your research.
 

Fjordlander

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inaccurate how? to fast or to slow?
details will help.
sounds like its working exactly as deigned but the gear ratio has been changed and the gears for the speedo need to be changed.

sine it spins the speedo gauge, the odometer counts. The speedo is "off" that could of a gear change? ... research what gears you have, research what gear you need to have installed in the transmission or transfer case and then see if what you have installed is what you should have based on your research.
It's too fast. I'll be going about 15 mph and the speedometer will say 90. It also bounces around and it's not consistently inaccurate. I'll look into the gears!
 

DoubleDingo

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81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
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Carb'ed Vortec 350; 1972 L48 350
THIS

You must be registered for see images attach
 

87chevy_com

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unless new cables come non greased, original poster stated he replaced his cable...
 

SDJunkMan

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I'm curious what you find, my CUCV speedo is acting up too. It started bouncing around from one extreme to the other, so I pulled the cable and lubed it. Now it still bounces a little, but is not accurate, and is not consistent on how far off it is. When it says 45, I am doing closer to 35, if it says 75 I'm probably closer to 55.

Is there a way to verify th the speedo drive is the correct one forvthe gearing?
 

Rustisbest

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The small seal in the housing is most likely worn. The spot on the gear where the seal rides can get worn also. Mine did the same until I replaced it. Mine is 2wd but I'm sure the 4wd is similar.
 

WebMonkey

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i'd check the coil spring/clock spring
it acts as a dampener.
most likely it is detached or deformed.

good luck
 

SirRobyn0

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One thing about speedo cables, is that they are woven metal. Overtime they actually get a little longer, heck even sometimes new cables are too long. The trick is to remove a little bot of the cable to shorten it back up. Doing an 1/8 of an inch at a time and reinstalling and retesting. See when it's stretched it puts pressure on the back of the speedo head and causes the bounce. At least that's the most common thing we see at the shop.
 

AllSquaredUp

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I had the same problems with my 84. I replaced the speedo with a new one and it corrected my speed and the odometer. Hope this helps.
 

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