Odd Odometer issue , any ideas?
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Odd Odometer issue , any ideas?
I drove my 71 today for the 1st time since this past winters projects were finished up.
1 major job was to replace the speedometer assy. since the odometer had quite working. It turned out that the gear in the main hs, was stripped, the odometer wheel gear was fine.
The speedometer worked fine, but milage was not be added at all.
I bought a NOS speedo for a 72 car, but other than color of the face plate the workings are the same as I understand.
So I used my 71 face plate and also swapped out my old odometer wheel to keep the milage as correct as possible, except for the 1K driven after the odometer stopped working early last year.
Well today my milege is adding up correctly, but the speedo is off by 10 to 15 MPH, it is reading too slow.
I used the tach and watch and as best as I can tell 1 mile was registed in the correct 1 minute at 60 MPH using ~2600 RPM w/3:55 gears
It seems that if the cable was not fully seated in the back of the speedo that the milage would also be adding up to slow.
What a mess, Of all the jobs on a C3, I think removing the driver side dash is about as bad as they come.
Thanks for any suggestions.
David
1 major job was to replace the speedometer assy. since the odometer had quite working. It turned out that the gear in the main hs, was stripped, the odometer wheel gear was fine.
The speedometer worked fine, but milage was not be added at all.
I bought a NOS speedo for a 72 car, but other than color of the face plate the workings are the same as I understand.
So I used my 71 face plate and also swapped out my old odometer wheel to keep the milage as correct as possible, except for the 1K driven after the odometer stopped working early last year.
Well today my milege is adding up correctly, but the speedo is off by 10 to 15 MPH, it is reading too slow.
I used the tach and watch and as best as I can tell 1 mile was registed in the correct 1 minute at 60 MPH using ~2600 RPM w/3:55 gears
It seems that if the cable was not fully seated in the back of the speedo that the milage would also be adding up to slow.
What a mess, Of all the jobs on a C3, I think removing the driver side dash is about as bad as they come.
Thanks for any suggestions.
David
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Hi, David...
You said that you set the speed at 60 mph and the distance of 1 mile was covered in 1 minute....which would mean that the speedometer was reading correctly. Why do you think it is reading 10-15 mph 'slow'?
You said that you set the speed at 60 mph and the distance of 1 mile was covered in 1 minute....which would mean that the speedometer was reading correctly. Why do you think it is reading 10-15 mph 'slow'?
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Thanks for jumping in
I used my watch and tach to determine what should have been a mile
when the odometer turned to a new mile , I watched for 60 seconds while taching 2600 RPM, after 1 minute the milage click over.
Not scientific, I may need to get my wife to drive beside me on the highway to be more sure if the odois reading correctly
Thanks
David
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Hey David..
You may be able to fix this yourself.. Everyone above is right.
If you moved the calibration arm on the speed cup when you were changing the face or installing the odometer this would cause your problem. The new speedometer first worm and magnet could have lost it's charge but they usually don't.
If you look at the picture below you'll see the speed cup. To the left is the cup retainer and the lever that controls the calibration.
Now you can adjust this in most cases by moving the arm as shown in the picture below..
but how...
If you have something you know is a fixed output RMP range on you can do it... or at least check it. The lever controls how much resistance is applied to the speed cup. If you have a drill that has the RPM's listed on it. Find something you can chuck in it and run up the speedometer. Move the lever to adjust the calibration as follows.
500 RPM's = 30 mph
750 RPM's = 45 mph
1000 RPM's = 60 mph
1500 RPM's = 90 mph
If you can't do this David.. yank it out and send it to me.. if it's a simple issue of calibration it takes about 10 minutes to re-set. If it's a matter of magnetism, then the first worm will need to be zapped for more charge.
You may be able to fix this yourself.. Everyone above is right.
If you moved the calibration arm on the speed cup when you were changing the face or installing the odometer this would cause your problem. The new speedometer first worm and magnet could have lost it's charge but they usually don't.
If you look at the picture below you'll see the speed cup. To the left is the cup retainer and the lever that controls the calibration.
Now you can adjust this in most cases by moving the arm as shown in the picture below..
but how...
If you have something you know is a fixed output RMP range on you can do it... or at least check it. The lever controls how much resistance is applied to the speed cup. If you have a drill that has the RPM's listed on it. Find something you can chuck in it and run up the speedometer. Move the lever to adjust the calibration as follows.
500 RPM's = 30 mph
750 RPM's = 45 mph
1000 RPM's = 60 mph
1500 RPM's = 90 mph
If you can't do this David.. yank it out and send it to me.. if it's a simple issue of calibration it takes about 10 minutes to re-set. If it's a matter of magnetism, then the first worm will need to be zapped for more charge.
Last edited by Willcox Corvette; May 2, 2010 at 10:14 AM.
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Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
HI Alan....
Thank you! It's me taking the pics and with just enough knowledge to get me in trouble on the editing. It seems to work out pretty good. I might take 50 shots to get the one I want, but in the digital age it's not a big hassle. Getting the lights right on the background can require multiple attempts.
The biggest hassle for me... keeping them sorted so you can find the one you want when you need it. I have thousands on end and that itself is another pain. But in the end it pays off.
Ernie
Thank you! It's me taking the pics and with just enough knowledge to get me in trouble on the editing. It seems to work out pretty good. I might take 50 shots to get the one I want, but in the digital age it's not a big hassle. Getting the lights right on the background can require multiple attempts.
The biggest hassle for me... keeping them sorted so you can find the one you want when you need it. I have thousands on end and that itself is another pain. But in the end it pays off.
Ernie
Last edited by Willcox Corvette; May 2, 2010 at 01:16 PM.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Charley
Thanks for jumping in
I used my watch and tach to determine what should have been a mile
when the odometer turned to a new mile , I watched for 60 seconds while taching 2600 RPM, after 1 minute the milage click over.
Not scientific, I may need to get my wife to drive beside me on the highway to be more sure if the odois reading correctly
Thanks
David
Thanks for jumping in
I used my watch and tach to determine what should have been a mile
when the odometer turned to a new mile , I watched for 60 seconds while taching 2600 RPM, after 1 minute the milage click over.
Not scientific, I may need to get my wife to drive beside me on the highway to be more sure if the odois reading correctly
Thanks
David
Use the road side markers to determine a 'mile'. Use a GPS unit to verify speedo accuracy and confirm a measured mile.
If both your odo and speedo are off, it's the gearing. If just the speedo is off it needs to be calibrated.
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Hey David..
You may be able to fix this yourself.. Everyone above is right.
If you moved the calibration arm on the speed cup when you were changing the face or installing the odometer this would cause your problem. The new speedometer first worm and magnet could have lost it's charge but they usually don't.
If you look at the picture below you'll see the speed cup. To the left is the cup retainer and the lever that controls the calibration.
Now you can adjust this in most cases by moving the arm as shown in the picture below..
but how...
If you have something you know is a fixed output RMP range on you can do it... or at least check it. The lever controls how much resistance is applied to the speed cup. If you have a drill that has the RPM's listed on it. Find something you can chuck in it and run up the speedometer. Move the lever to adjust the calibration as follows.
500 RPM's = 30 mph
750 RPM's = 45 mph
1000 RPM's = 60 mph
1500 RPM's = 90 mph
If you can't do this David.. yank it out and send it to me.. if it's a simple issue of calibration it takes about 10 minutes to re-set. If it's a matter of magnetism, then the first worm will need to be zapped for more charge.
You may be able to fix this yourself.. Everyone above is right.
If you moved the calibration arm on the speed cup when you were changing the face or installing the odometer this would cause your problem. The new speedometer first worm and magnet could have lost it's charge but they usually don't.
If you look at the picture below you'll see the speed cup. To the left is the cup retainer and the lever that controls the calibration.
Now you can adjust this in most cases by moving the arm as shown in the picture below..
but how...
If you have something you know is a fixed output RMP range on you can do it... or at least check it. The lever controls how much resistance is applied to the speed cup. If you have a drill that has the RPM's listed on it. Find something you can chuck in it and run up the speedometer. Move the lever to adjust the calibration as follows.
500 RPM's = 30 mph
750 RPM's = 45 mph
1000 RPM's = 60 mph
1500 RPM's = 90 mph
If you can't do this David.. yank it out and send it to me.. if it's a simple issue of calibration it takes about 10 minutes to re-set. If it's a matter of magnetism, then the first worm will need to be zapped for more charge.
Thanks Wilcox for the detailed assistance.
If I end up sending to you , what is the turn around time?
Also, what is a price renge?
Thanks
David
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
David...
Going on the assumption that it's a simple issue of the arm out of position.. it will take me about 5 minutes to dial it in... I'm not going to charge you for that you just pay the shipping.
If it's a case where the magnet has lost is magnetism then I'd guess about 35.00. That can be a pain zapping it back in sometimes.
How long.. I can do it the day it arrives.. I'd say maybe 2 days. I have to finish up a 58 wiper motor and a few other gauges.. but it would be pretty fast.
Willcox
Going on the assumption that it's a simple issue of the arm out of position.. it will take me about 5 minutes to dial it in... I'm not going to charge you for that you just pay the shipping.
If it's a case where the magnet has lost is magnetism then I'd guess about 35.00. That can be a pain zapping it back in sometimes.
How long.. I can do it the day it arrives.. I'd say maybe 2 days. I have to finish up a 58 wiper motor and a few other gauges.. but it would be pretty fast.
Willcox
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
David...
Going on the assumption that it's a simple issue of the arm out of position.. it will take me about 5 minutes to dial it in... I'm not going to charge you for that you just pay the shipping.
If it's a case where the magnet has lost is magnetism then I'd guess about 35.00. That can be a pain zapping it back in sometimes.
How long.. I can do it the day it arrives.. I'd say maybe 2 days. I have to finish up a 58 wiper motor and a few other gauges.. but it would be pretty fast.
Willcox
Going on the assumption that it's a simple issue of the arm out of position.. it will take me about 5 minutes to dial it in... I'm not going to charge you for that you just pay the shipping.
If it's a case where the magnet has lost is magnetism then I'd guess about 35.00. That can be a pain zapping it back in sometimes.
How long.. I can do it the day it arrives.. I'd say maybe 2 days. I have to finish up a 58 wiper motor and a few other gauges.. but it would be pretty fast.
Willcox
I can not beleive that I have to take this dash back out. What a learning lesson
I am goint out of town and have a car show that I want to make on 5-15
I will then get it out and off to you after that.
Any issues with tack accuracy that I should send it also to check?
It seems like it has always been right, But I do not want to take a C3 dash apart again after this one.
Thanks
PS , thaks for the offer to not charge if the job is the simple version
David
Thansnaks Wilcox
Last edited by dmayhew; May 2, 2010 at 07:49 PM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
David-
No problem.. if it is just moving the lever it's so simple I'd feel guilty charging you. You can send in the tach and I can check it for you at the same time.
I hope that is all it is.. a simple move of the lever would be nice!
I know too.. that dash is a real pain.
Willcox
No problem.. if it is just moving the lever it's so simple I'd feel guilty charging you. You can send in the tach and I can check it for you at the same time.
I hope that is all it is.. a simple move of the lever would be nice!
I know too.. that dash is a real pain.
Willcox
