Speed/distance reads 10% faster than accurate

Hey guys,

Figured I'd run this little quirk by you all while I'm putting my car back together. Maybe somebody has an answer for me 😉

Maaany years ago I replaced my odometer gear as the stock one had stripped its teeth off. I remember that the gear itself was recommended to me by somebody on the forums, but it's been so long I can't remember the part#

Ever since then my odometer and everything in my travel computer would read 10% fast. So at ever my mile marker on the road it would tell me I'd gone 1.1 miles. The travel computer would show the same, a 10% increase in distance, speed, fuel efficiency, etc.

I've always had the stock size wheel on the car, so it's not due to a small wheel rotating faster.

Has anyone dealt with this before? It's never been a huge deal, but it is annoying and I've never liked the odometer showing that I put 10% more miles on the car than I really have lol.

I'm not sure exactly how to troubleshoot this issue, and it'll be a bit before the car is back together, but I wanted to run this by you guys to see what you thought. Any help appreciated, thanks!

-Zach

What size tires are you using?
What color is the speedo gear (how many tooth)?

Whatever gear you have installed now, you need to go up one size/tooth count to 'slow down' the signal output. Or a larger tire

Current tire size is 215/45 R17. I think that is technically 0.1" shorter than stock? Little fuzzy it's been a while since I upgraded my rims. However, I think it is the odometer gear as well, but I wasn't sure if that would effect the travel computer too or if the issue was with the speed sensor on my tranny.

If it is indeed the odo gear, can anyone link me to a source for them? I think it's been over a decade since I popped a replacement gear in there lol.

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Originally Posted by tryingbe

What size tires are you using?
What color is the speedo gear (how many tooth)?

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I remember the gear being a pretty standard white nylon shade. Don't remember how many teeth it had, though.

I just realized that you guys are probably talking about the speed sensor in the transaxle lol. My question still stands though, does anybody have a source for those gears? I can count the teeth on mine and get one with +1 tooth. The tranny isn't even in the car right now so it'd be easy as pie to work on it.

The parts catalog I have here does not show a white speedometer gear but they do exist obviously.

4567883 red/18 tooth
4567880 yellow/19 tooth
4567881 blue/20 tooth

To prevent damage to the gear the VSS should always be pulled before removing the axle for any reason. Unless you break an axle that gear should last almost forever.

Quote:

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Originally Posted by 135sohc

The parts catalog I have here does not show a white speedometer gear but they do exist obviously.

4567883 red/18 tooth
4567880 yellow/19 tooth
4567881 blue/20 tooth

To prevent damage to the gear the VSS should always be pulled before removing the axle for any reason. Unless you break an axle that gear should last almost forever.

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I misunderstood at first and probably just made things more confusing.

For some reason I thought you guys were referencing the odometer gear at first. THAT is the gear I replaced from here: https://www.odometergears.com/produc...e+Vehicles/125

As far as the pinion gear in the transaxle, I'll have to take a look at that next time I'm out at the shop. My service manual says I should have a Yellow (19 tooth) gear installed.

Quote:

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Originally Posted by 135sohc

To prevent damage to the gear the VSS should always be pulled before removing the axle for any reason. Unless you break an axle that gear should last almost forever.

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I have heard that and used to do that, but for many years now I have pulled axles with the VSS in place. So far I have not had a problem nor have I seen any sign of damage to a gear...

Anybody ever see an issue?

Quote:

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Originally Posted by c2xejk

I have heard that and used to do that, but for many years now I have pulled axles with the VSS in place. So far I have not had a problem nor have I seen any sign of damage to a gear...

Anybody ever see an issue?

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I always forget

i'm going to look at adding a table to the t-cals to allow adjustment to the speed calculation. it's basically a formula that counts how many "interrupts" have taken place over a specific period of time. should be able to manipulate that count fairly easily so the remaining calc is adjusted. when i did the v6 508 cal i detailed out how it works.

Quote:

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Originally Posted by c2xejk

I have heard that and used to do that, but for many years now I have pulled axles with the VSS in place. So far I have not had a problem nor have I seen any sign of damage to a gear...

Anybody ever see an issue?

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I have a selection of ruined gears that would say otherwise. Once or twice I have forgotten to pull the vss before the axle and had a oh **** moment right afterwards.. I only scarred one and was able to clean up the burred tooth with a razor blade.


One 10mm bolt vs a discontinued part is not a hard choice for me to make. Even the VSS if it is stuck in there pretty good, I'd rather take a pair of channel-locks and twist it out to save the gear vs the sensor that is readily available at most parts stores in stock.

I'm pretty sure white is 21 tooth.

Thanks
Randy

Quote:

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Originally Posted by 135sohc

The parts catalog I have here does not show a white speedometer gear but they do exist obviously.

4567883 red/18 tooth
4567880 yellow/19 tooth
4567881 blue/20 tooth

To prevent damage to the gear the VSS should always be pulled before removing the axle for any reason. Unless you break an axle that gear should last almost forever.

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Hey all,

I was able to check the VSS pinion gear yesterday. Had a heck of a time trying to get the sensor out, and eventually I just tipped the whole transaxle up, positioned a light, and checked the gear inside lol.

I do have the yellow (19 tooth) pinion gear, which is what my car is supposed to have, so that's not the issue. It looks like I'll have to put a pin in this one until I have the car back together to further troubleshoot.

Easy to change gears to get things to read right though if possible. My daytona is supposed to have 225/50's. but I run 205/60's. Blue gear IIRC which is what it's "supposed to have" odometer reads dead nuts. But if I went to the stock 225's it'd be off and I'd have to change speedo gears.

i added a table to allow the vss to be adjusted through the tune. i'll post up the changes in a separate thread. fwiw.