Speedometer rebuild question....Willcox??
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,369
Likes: 12
From: wichita kansas
Speedometer rebuild question....Willcox??
I'm rebuilding my speedo on my 68' vette. i purchased a new head unit that is actually a later 69' and up style (was told it would work fine, but i would have to change the speedo cable to later push on style, no problem)
i tore into it last night, and started putting the old parts (odometer wheel,odometer worm gear, trip wheel, and trip gears) on to the new head unit, then i noticed one other difference in the two units. while installing the old odometer wheel into place, i noticed that this unit has a "notch" in the raised lip that would normally act as a stop for the little tabs on each wheel, the old unit has a continuous "stop" and catches each tab on the numbered wheels as they rotate....WHY does this unit have a notch that allows the second numbered wheel to rotate a bit farther around, thus not allowing it to line up with the rest of the odometer numbers....(hopefully pics will help with my rambling! LOL
i tore into it last night, and started putting the old parts (odometer wheel,odometer worm gear, trip wheel, and trip gears) on to the new head unit, then i noticed one other difference in the two units. while installing the old odometer wheel into place, i noticed that this unit has a "notch" in the raised lip that would normally act as a stop for the little tabs on each wheel, the old unit has a continuous "stop" and catches each tab on the numbered wheels as they rotate....WHY does this unit have a notch that allows the second numbered wheel to rotate a bit farther around, thus not allowing it to line up with the rest of the odometer numbers....(hopefully pics will help with my rambling! LOL
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Well you’re in trouble... and I'll explain.
But first..
Sadly, I will not be answering technical question emails for the next few weeks. Norms is off on leave due to a family illness and it is really putting a strain on all of us here (this is the busy season). Tommy is over loaded, we've rotated people from other areas to relieve the pressure but they can only do so much. So.. I'm trying to fill in for Norm as much as possible and this will really limit my time.
Now to the speedometer…
The notch you see in your speed cup odometer retainer is there due to what was called “tamper" protection. In the later style head GM created that void and installed a plastic tamper strip on the back of the odometer to hold the wheel tab. In the early days people could force the wheels backwards and change the odometer reading and with this void and that plastic strip, it would just screw up the odometer.
How do you fix it.. You’ll need to bridge the gap. I can install tamper strips but I can not sell them. If I were you I’d find a thin strip of metal and glue it on the back.
But first..
Sadly, I will not be answering technical question emails for the next few weeks. Norms is off on leave due to a family illness and it is really putting a strain on all of us here (this is the busy season). Tommy is over loaded, we've rotated people from other areas to relieve the pressure but they can only do so much. So.. I'm trying to fill in for Norm as much as possible and this will really limit my time.
Now to the speedometer…
The notch you see in your speed cup odometer retainer is there due to what was called “tamper" protection. In the later style head GM created that void and installed a plastic tamper strip on the back of the odometer to hold the wheel tab. In the early days people could force the wheels backwards and change the odometer reading and with this void and that plastic strip, it would just screw up the odometer.
How do you fix it.. You’ll need to bridge the gap. I can install tamper strips but I can not sell them. If I were you I’d find a thin strip of metal and glue it on the back.
Last edited by Willcox Corvette; Mar 20, 2013 at 11:10 PM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,369
Likes: 12
From: wichita kansas
Well you’re in trouble... and I'll explain.
But first..
Sadly, I will not be answering technical question emails for the next few weeks. Norms is off on leave due to a family illness and it is really putting a strain on all of us here (this is the busy season). Tommy is over loaded, we've rotated people from other areas to relieve the pressure but they can only do so much. So.. I'm trying to fill in for Norm as much as possible and this will really limit my time.
Now to the speedometer…
The notch you see in your speed cup odometer retainer is there due to what was called “tamper" protection. In the later style head GM created that void and installed a plastic tamper strip on the back of the odometer to hold the wheel tab. In the early days people could force the wheels backwards and change the odometer reading and with this void and that plastic strip, it would just screw up the odometer.
How do you fix it.. You’ll need to bridge the gap. I can install tamper strips but I can not sell them. If I were you I’d find a thin strip of metal and glue it on the back.
But first..
Sadly, I will not be answering technical question emails for the next few weeks. Norms is off on leave due to a family illness and it is really putting a strain on all of us here (this is the busy season). Tommy is over loaded, we've rotated people from other areas to relieve the pressure but they can only do so much. So.. I'm trying to fill in for Norm as much as possible and this will really limit my time.
Now to the speedometer…
The notch you see in your speed cup odometer retainer is there due to what was called “tamper" protection. In the later style head GM created that void and installed a plastic tamper strip on the back of the odometer to hold the wheel tab. In the early days people could force the wheels backwards and change the odometer reading and with this void and that plastic strip, it would just screw up the odometer.
How do you fix it.. You’ll need to bridge the gap. I can install tamper strips but I can not sell them. If I were you I’d find a thin strip of metal and glue it on the back.
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,369
Likes: 12
From: wichita kansas
Well, Willcox said it better than i could have, but once i realized that worm gears are not usually the only problem, AND i found an NOS head unit pretty cheap, it was a no brainer....i knew going in that the speedometer cable hook up was different (no prob to change to 69' speedo cable, but then i ran into this STUPID NOTCH thing.....) thankfully Willcox explained why the notch was there and how to fix it. Rick
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Instructor
Joined: Dec 2009
Posts: 195
Likes: 0
From: Chesterfield Virginia
I'm aware, sent mine to you 
Hope it works out for you
Well, Willcox said it better than i could have, but once i realized that worm gears are not usually the only problem, AND i found an NOS head unit pretty cheap, it was a no brainer....i knew going in that the speedometer cable hook up was different (no prob to change to 69' speedo cable, but then i ran into this STUPID NOTCH thing.....) thankfully Willcox explained why the notch was there and how to fix it. Rick
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,369
Likes: 12
From: wichita kansas
well, here is a pic of the head unit after fabricating a short thin piece of metal to "bridge" the gap and JB weld it into place....should work fine. pic is not the best, but you get the idea. Rick
