Need speedo gear help
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Instructor
Joined: Sep 2003
Posts: 150
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From: Pecatonica IL
Need speedo gear help
Can some one tell me what direction I need to go with the speedometer gears? I have got the TH350, but changed to 3.54 gears in the rear. I currently have the 8 tooth drive gear and a 20 tooth driven. At least that what the trans shop told me. He would have changed it but did not have any gears in stock and I wanted the car back for Labor day weekend. Anyway, the speedo seems to run approx 7-8 mph fast.
Which gear do I need to order so I can do it myself????
Which gear do I need to order so I can do it myself????
Le Mans Master
Joined: Aug 2000
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From: Brazos TX
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Go with a 22 tooth driven gear. I just did this on my Vette. I was reading about 5 fast so I went from a 20 to a 21 and now I'm within 1 or 2 mph at 70.
Le Mans Master
Joined: Sep 2000
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From: Westfield Indiana
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yep, Eric is right. If you're speedo is reading fast, you go to a gear with more teeth. As for the number of teeth you need, that depends on how fast your speedo is reading. Mine was 10% fast so I went with approximately 10% more teeth and now it's almost dead on. My speedo now reads 1% slow, which doesn't matter at all. Also, you can check to make sure things are correct by comparing your odometer mileage with mile markers. The longer the distance, the better the evaluation. My odo reads 99 miles for every 100 mile mark on the highway.
Last edited by Captain Morgan; Sep 8, 2004 at 11:50 AM. Reason: Added information
Le Mans Master
Joined: Aug 2000
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From: Brazos TX
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Hey Avery, how's it going! It's nice to see you made it around here I haven't seen a post from you in a while . I guess things are still busy for you?
On the note of speedo calibration. I use the mile markers to check the speedo as well as the odometer. Just drive a consistant 60 mph and time a mile. You should cover it in 60 seconds. You can use the time you get to calculate the actual speed if it is different from 60 seconda.
On the note of speedo calibration. I use the mile markers to check the speedo as well as the odometer. Just drive a consistant 60 mph and time a mile. You should cover it in 60 seconds. You can use the time you get to calculate the actual speed if it is different from 60 seconda.
Le Mans Master
Joined: Sep 2000
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From: Westfield Indiana
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Hey Eric,
Yes, things have been very busy around here. 1 1/2 years of school left. I'm really looking forward to being done. We had a bad storm in June that did quite a bit of damage by taking out 11+ garage door openers and many, many shingles as well as some electrical damage when lightening hit one of the buildings. We also had several vacancies at the apartments over the summer, with very few phone calls, but then last month, everybody decided to rent at once. We eliminated almost 11 vacancies (out of 84 total units) in less than two weeks. This job definitely has it's ups and downs. I just haven't been around the forum much because it makes me want to spend money on the vette.
Hope all is going well for you. I'm sure we'll talk again between now and May.
And yes, I've checked speed as well using the timing method.
That was one of my measures during the time the speedo cable was broken.
Yes, things have been very busy around here. 1 1/2 years of school left. I'm really looking forward to being done. We had a bad storm in June that did quite a bit of damage by taking out 11+ garage door openers and many, many shingles as well as some electrical damage when lightening hit one of the buildings. We also had several vacancies at the apartments over the summer, with very few phone calls, but then last month, everybody decided to rent at once. We eliminated almost 11 vacancies (out of 84 total units) in less than two weeks. This job definitely has it's ups and downs. I just haven't been around the forum much because it makes me want to spend money on the vette.
Hope all is going well for you. I'm sure we'll talk again between now and May.And yes, I've checked speed as well using the timing method.
That was one of my measures during the time the speedo cable was broken.
Last edited by Captain Morgan; Sep 8, 2004 at 11:15 PM.
