63-7 corvtte speedometer insight
Thread Starter
Heel & Toe
Joined: Jun 2008
Posts: 19
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From: greenville sc
63-7 corvtte speedometer insight
just a little info to help you guys out. The biggest problem that mid year speedos have is the speedo works but the odometer and trip odometer quit. This is a very common problem. This happens because of the way that the odometer and trip odometer sit side by side and this produces alot of resistance on the secondary worm which runs along the bottom of the speedo head and the magnet first worm which gets driven from your speedo cable. Your magnet first worm and second worm need to be replaced. if you replace just the second worm it will probly lock up the speedo head. You need to replace both and the second worm must be STEEL!!! do not use plastic it will not last. Just something to help you guys out with a problem i know alot of you have.
Melting Slicks
Joined: Nov 2002
Posts: 2,460
Likes: 5
From: Wheaton IL
I have the inverse problem. Maybe you could offer me a sugguestion.
Before I pulled the cluster, my speedo worked, odo worked, trip odo did not work. I replaced my tachometer and when I put everything back together, my speedo was broken, odo worked, and trip odo worked.
Now my speedo hangs out at about 20 and goes a little higher if i'm at highway speeds.
Brian
Before I pulled the cluster, my speedo worked, odo worked, trip odo did not work. I replaced my tachometer and when I put everything back together, my speedo was broken, odo worked, and trip odo worked.
Now my speedo hangs out at about 20 and goes a little higher if i'm at highway speeds.
Brian
Thread Starter
Heel & Toe
Joined: Jun 2008
Posts: 19
Likes: 0
From: greenville sc
thats strange, if your odometer and trip are both working that means that the cable is still driving the magnet and first worm gear as well as the others. the problem is most likely with the speed cup. if the speed cup dos not have enough play between the center jewel in the magnet and the one at the top off the frame that will make it stick and not move very much.
Thread Starter
Heel & Toe
Joined: Jun 2008
Posts: 19
Likes: 0
From: greenville sc
speedo help
I have the inverse problem. Maybe you could offer me a sugguestion.
Before I pulled the cluster, my speedo worked, odo worked, trip odo did not work. I replaced my tachometer and when I put everything back together, my speedo was broken, odo worked, and trip odo worked.
Now my speedo hangs out at about 20 and goes a little higher if i'm at highway speeds.
Brian
Before I pulled the cluster, my speedo worked, odo worked, trip odo did not work. I replaced my tachometer and when I put everything back together, my speedo was broken, odo worked, and trip odo worked.
Now my speedo hangs out at about 20 and goes a little higher if i'm at highway speeds.
Brian
matt
Le Mans Master
Joined: Apr 2006
Posts: 5,347
Likes: 36
From: San Clemente CA
While we're on speedo problems, here's mine. After replacing my dash harness and taking the cluster apart for cleaning paint etc., and putting everything back together ( of course) I noticed the needle for the speedo rests at the 6:00 position instead of at 0MPH. Can that be fixed by just popping of the needle and repositioning it or am I assuming too much? Any help appreciated.
Don
Don
Melting Slicks
Joined: Aug 2004
Posts: 2,056
Likes: 553
From: Sun Prairie WI
Because this system is so fragile & labor intensive to repair once it craps out, I find it useful to take the trip function out of solution before the failure. By fabricating a "Z" bracket, fixed it to the inboard leg of the U-bolt that pinches the mast jacket, the trip set button is held in "up" position rendering it inoperative. The speedo needle & odometer still drive accurately, while the load on the gear train is greatly reduced.
Thread Starter
Heel & Toe
Joined: Jun 2008
Posts: 19
Likes: 0
From: greenville sc
While we're on speedo problems, here's mine. After replacing my dash harness and taking the cluster apart for cleaning paint etc., and putting everything back together ( of course) I noticed the needle for the speedo rests at the 6:00 position instead of at 0MPH. Can that be fixed by just popping of the needle and repositioning it or am I assuming too much? Any help appreciated.
Don
Don
Matt
Race Director
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From: Clayton NC
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Drifting
Joined: Jul 2007
Posts: 1,671
Likes: 10
From: california
just a little info to help you guys out. The biggest problem that mid year speedos have is the speedo works but the odometer and trip odometer quit. This is a very common problem. This happens because of the way that the odometer and trip odometer sit side by side and this produces alot of resistance on the secondary worm which runs along the bottom of the speedo head and the magnet first worm which gets driven from your speedo cable. Your magnet first worm and second worm need to be replaced. if you replace just the second worm it will probly lock up the speedo head. You need to replace both and the second worm must be STEEL!!! do not use plastic it will not last. Just something to help you guys out with a problem i know alot of you have.
that is exactly the problem i found on my 64 when i did the first restore many years ago. the worm gear was worn out so the speedo worked great and the odo didn't work at all. i'm only interested in in how fast i'm going, not how far, so i just set the odo at 00099- that has got me some interesting comments over the years...
do you sell those gears and how much??
Safety Car
Joined: Feb 2006
Posts: 4,142
Likes: 704
Gaugetech...I am wondering if you could use my picture below and identify the three main drive gears so that we are all on the same page. I have labeled them A, B, and C. If you could attach a name to all three I can modify the picture for future referance.
Also, here is a picture of gear B. Old one on top. As you can see it has worn so bad that it no no longer functions.
And here is a close up of C. Still in good shape. I may re-use this gear as the replacement is plastic.
Also, I assume that if you replace A and B gears, you will need to get the speedo head re-calibrated??
Also, here is a picture of gear B. Old one on top. As you can see it has worn so bad that it no no longer functions.
And here is a close up of C. Still in good shape. I may re-use this gear as the replacement is plastic.
Also, I assume that if you replace A and B gears, you will need to get the speedo head re-calibrated??
Drifting
Joined: Jul 2007
Posts: 1,671
Likes: 10
From: california
buns' that straight cut gear at the top of pic 2 is the one that i remember stopped my ODO from working. it looked just like that and this is when the car was only 15 years old. this is if i remember correctly, but i'm pretty sure i do...
Melting Slicks
Joined: Nov 2002
Posts: 2,460
Likes: 5
From: Wheaton IL
thats strange, if your odometer and trip are both working that means that the cable is still driving the magnet and first worm gear as well as the others. the problem is most likely with the speed cup. if the speed cup dos not have enough play between the center jewel in the magnet and the one at the top off the frame that will make it stick and not move very much.
matt
matt
brian
Le Mans Master
Joined: Apr 2006
Posts: 5,347
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From: San Clemente CA
Le Mans Master
Joined: Feb 2001
Posts: 7,226
Likes: 399
From: Northern CA
This is going to be my primary "Winter Project" this year. My speedo works fine... but my odometer and trip don't function anymore.
Is there a step-by-step tech paper somewhere that explains how to make this repair? I'd like to try it myself. I enjoy working on the car, no matter how tedious the task. Also, where can I get the parts? Looks like metal gears are more durable... who sells them?
Thanks!
Is there a step-by-step tech paper somewhere that explains how to make this repair? I'd like to try it myself. I enjoy working on the car, no matter how tedious the task. Also, where can I get the parts? Looks like metal gears are more durable... who sells them?
Thanks!
Safety Car
Joined: Feb 2006
Posts: 4,142
Likes: 704
Corvette Central sells gear B...p/n 392259. That is where I got the new one shown in the 2nd picture.
LICS sells all three gears as a set but the magnet doesn't look right to me. Picture from their website below.
Safety Car
Joined: Feb 2006
Posts: 4,142
Likes: 704
Here is a picture of where the speed cup is located. You will have to remove the gauge to fix this.
You need to make sure you have enough clearance between the thrust washer on the stem and the bushing in the housing. I believe that maximum clearance is .015". With no clearance the stem will bind and the needle won't turn.
Last edited by buns; Jul 2, 2008 at 01:40 AM. Reason: old age, sars, crs...you name it...I got it.
Former Vendor
Joined: Aug 2006
Posts: 76,656
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
This may offer some help.
http://willcoxcorvette.com/repairand...lp.php?hID=145
http://willcoxcorvette.com/repairand...lp.php?hID=145
Last edited by Willcox Corvette; Jul 2, 2008 at 08:11 AM.
Thread Starter
Heel & Toe
Joined: Jun 2008
Posts: 19
Likes: 0
From: greenville sc
speedo worms
GM used steel worms for a reason and that is because they knew this was the most durable part for the speedo. Steel or plastic what do you think will last longer? I do this for a living and I here people tell me all the time that their speedo repair did not hold up and when I see the repair it is a plastic worm. Plastic worms were used from 53 to 62 and from about 70 to 82. Mid year corvettes must use steel worms!
Thread Starter
Heel & Toe
Joined: Jun 2008
Posts: 19
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From: greenville sc