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Hi guys,

Does anyone know the GM parts number of the vehicle speed sensor of a '91 Chevrolet Caprice? Mine is busted and at rockauto.com there are several speed sensors.
Many thanks.
 

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Thanks, but there are lot of numbers in the SPID label, so how do I do this?
Pretty simple. They're in alphabetical order. If you notice in rockauto, they are looking for a D8something, like D8E, D8N, D8I etc.

They along with the speedo gear are different for different axle ratio/tire combinations to get the speed right. Hopefully, your axle is original and tires are about stock height.
 

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There are two different types. One is for 40 plus tooth driven gears, and the other is for less than 40 tooth driven gears.

Here is a resource: http://www.transmissioncenter.net/ go about 1/3 of the say down the page to "speedometer world" and click on it. About 1/4 of the way down the page are the 700R4 VSSs and gears.

If you are going to just replace the VSS, you have to know how many teeth are on the driven gear before you buy a new VSS. They are color coded for size (I can look it up for you). If you are going to change tire size, or rear gearing, a couple of the gears are not available.
 

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Discussion Starter #6
Thanks guys for the input. I took some pictures of labels but they are all pretty bad. Can anyone figure them out? I got a stock '91 5.0 V8 Chevy Caprice wagon with stock tires.
Thanks again.



 

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With the GU2 rear (2.73) and 225/75/15 tires, according to the FSM, you should have a 36 tooth (white) driven gear. That means you need the VSS for the smaller than 40 tooth gears.
 

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SPID says D8N. That is the reference to use on rockauto. Fred's link shows two housings but both are for cable driven speedometers. My 91 sedan does not use a cable. The housing is flat.
 

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You are really helping me, thanks! This is the only sensor at rockauto with D8N in the description: http://www.rockauto.com/catalog/moreinfo.php?pk=946028&cc=1037258
So, this is the right sensor to order?
There's also the acdelco one at the very bottom. And the very first one, a standard motors close out. Thought it doesn't say D8N, it references the same 10456088 gm part number as the other two. And, has the black connector that seems common to the other two and Fred's link. The others have white and/or speedo cables. My guess it should be the same
 

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Should be piece of cake. I just jack up the left side behind the front wheel and slide under. I use a catch pan as a little fluid will come out. Clean the area with a rag first to keep dirt out. I think it's a 10 or 12mm bolt. Simple open end wrench. Pull connector off first. Take bolt out. Twist housing a bit to loosen up. Little twisting back and forth as you pull out. Swap speed gear to new one. Little atf on oring of new one and reverse procedure. Whole thing may take 10 minutes.
 

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On a '91 civi, with 2.73 gears, and 255/75 R15 tires, you should have a:

18 tooth (Blue) drive gear, P/N 8640518.
36 tooth (White) driven gear, P/N 25513043
Installed in sleeve, P/N 10456088
 

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I would suggest a small line of RTV around the unit outside of the o-ring. The o-ring can leak, and new ones are almost impossible to get. Maybe they will send a new one with the new VSS. If they do, you probably do not need the RTV.
 

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silicone sealer. The one i got came with a new o-ring. All it needed was a coat of fluid. But is extra insurance
 
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