Speedometer Gears
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Speedometer Gears
Have an '89 corvette with 2.59s and Im swapping to a dana 44 with 3.54s. With 285/35zr18 tires I calculated a diameter of 26" which told me I needed to switch to a 15 tooth grey and a 41 tooth yellow. Can someone double check this? And can I reuse my vss by turning it upside down?
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Have an '89 corvette with 2.59s and Im swapping to a dana 44 with 3.54s. With 285/35zr18 tires I calculated a diameter of 26" which told me I needed to switch to a 15 tooth grey and a 41 tooth yellow. Can someone double check this? And can I reuse my vss by turning it upside down?
I would think it closer likely to 43 tooth but if you bought anywhere from a 41 - 43 you could do it and then it would be a minor adjustment from there. I'm pretty comfortable with the 43 tooth calculation. Do you have the tires now? Are they mounted and on the car?
Many have mentioned success with rotating the VSS and I have an image somewhere of how to easily modify the retainer so that it maintains the 180* rotation. The question is "how long will it last?" - No one knows just how consistent the mesh of the gears is when it's rotated. The only way to accomplish that is to use a spare extension housing, cut a window in the opposite side and install the gears to check the mesh of them. Is it worth being concerned over? I'd think so. The gears are getting substantially more difficult to find.
Last edited by WVZR-1; Apr 19, 2014 at 07:00 PM.
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From: Anaheim CA
This chart may be helpful:
I'm really curious about the "turn the VSS over" thing. As far as I could tell my VSS had the shaft centered. I have heard that the VSS for the higher gear ratios is offset so that the gear meshes correctly. I'd like to see a side by side comparison of the two types of VSS to see how this all works.
I have a 3.07 rear axle ratio so I have the red/green gear combination with the 25007308 VSS housing. I assume the 25007224 is the one with the offset gears. My housing is black. I have heard that the other one is a different color (white? gray?).
I'm really curious about the "turn the VSS over" thing. As far as I could tell my VSS had the shaft centered. I have heard that the VSS for the higher gear ratios is offset so that the gear meshes correctly. I'd like to see a side by side comparison of the two types of VSS to see how this all works.
I have a 3.07 rear axle ratio so I have the red/green gear combination with the 25007308 VSS housing. I assume the 25007224 is the one with the offset gears. My housing is black. I have heard that the other one is a different color (white? gray?).
Last edited by Cliff Harris; Apr 20, 2014 at 02:53 AM.
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I believe that even with your '89 I'd do a mechanical correction as it seems you understand the requirements.
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From: Maple Grove Minnesota
While I’m rebuilding my 700r4 this is the perfect time to change out the speedometer gears? Just how are the new gears calculated? I went from a Dana 36 with the 2.59 gears to a 44 with 3.45’s and also running 270/40/18 rear tires in place of the original 17’s.
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Post back the real tire size you'll be using and I'll tweak that but you will for sure need the 15 tooth drive for the build. Get a new retainer also.
8642620 for the gear and 6271681 for the retainer.
What year is your car for the correct VSS?
Last edited by WVZR-1; May 21, 2014 at 02:57 PM.
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I changed the post above to reflect 39 for a couple of reasons - if we use advertised diameters rather than rolling radius it takes something greater than 40 to make it work BUT your VSS that you have now will do all the way to 39 so I believe I'd buy the max the VSS will take and try that. I'll do some more math but I think given the prices of the correct VSS I'd be inclined to try that first.
Knowing that people have rotated the VSS to accommodate the larger tooth counts if you needed a 40 to get it closer you could buy the 40 and rotate it. It's not the way I prefer to do it but it can be done. You'll need to just slot/notch the VSS retainer to index it and I've got a snapshot of how I'd do it.
25513046 for the 39 tooth and 25513047 for the 40 tooth
Knowing that people have rotated the VSS to accommodate the larger tooth counts if you needed a 40 to get it closer you could buy the 40 and rotate it. It's not the way I prefer to do it but it can be done. You'll need to just slot/notch the VSS retainer to index it and I've got a snapshot of how I'd do it.
25513046 for the 39 tooth and 25513047 for the 40 tooth
Last edited by WVZR-1; May 21, 2014 at 03:25 PM.