Speedometer & Tachometer Housing
Thread Starter
Racer
Joined: Nov 2008
Posts: 350
Likes: 0
From: Guyton GA
Speedometer & Tachometer Housing
I have a 1978 L-48. We recently purchased & found several items not working. Among the things not working is the speedometer & tachometer along with all the lights in the dash Cluster housing. Just to clarify, I have not even began to look at the center gauge cluster, but all of them do seem to work (& I believe they are reading correctly but have not verified).
After reading several thread on here, I removed the speed & tach. I also removed the lens & housing (plastic casing with the printed circuit on back). I found the upper cable housing not fully engaged on the speedometer itself. I greased the upper speedometer cable & replaced. While I had the housing out, I checked the tachometer & back of the housing. I found the Tach board with a large burn spot & have ordered a new one. This brings me to my question...
Upon inspecting the housing & the printed circuit, I found a rather large burnt spot where the circuit looks to have shorted & burnt a hole in the plastic. The housing also has several significant cracks. I am thinking I need to replace it, but cannot find it anywhere on the regular shops... Any suggestions on what to do or where to look?
After reading several thread on here, I removed the speed & tach. I also removed the lens & housing (plastic casing with the printed circuit on back). I found the upper cable housing not fully engaged on the speedometer itself. I greased the upper speedometer cable & replaced. While I had the housing out, I checked the tachometer & back of the housing. I found the Tach board with a large burn spot & have ordered a new one. This brings me to my question...
Upon inspecting the housing & the printed circuit, I found a rather large burnt spot where the circuit looks to have shorted & burnt a hole in the plastic. The housing also has several significant cracks. I am thinking I need to replace it, but cannot find it anywhere on the regular shops... Any suggestions on what to do or where to look?
Instructor
Joined: Oct 2006
Posts: 219
Likes: 0
From: Jupiter FL
The tach boards and the speedo and tach flex circuits are readily available. I have both. There are several out there so make sure you get a quality one. Let me know if I can answer any questions you may have. www.harrisonspeedometer.com
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
It sounds to me as if your problem may have been a shorted circuit board.
The plastic housing the tach and speedo sit in usually don’t go bad and may be susceptible to cracking but they usually don’t cause the problem.
The fingers where the connector on the circuit board plugs in can become unlamented and when this happens they can touch each other. This may be what caused your short.
I think I would replace the board in the tach, replace the circuit and before installing test the wires on the circuit board. You can follow which wires are the ground wires simply by looking at the circuit. The grounds tend to go to multiple connections on the board while the hot wires usually only go to one place.
Willcox
The plastic housing the tach and speedo sit in usually don’t go bad and may be susceptible to cracking but they usually don’t cause the problem.
The fingers where the connector on the circuit board plugs in can become unlamented and when this happens they can touch each other. This may be what caused your short.
I think I would replace the board in the tach, replace the circuit and before installing test the wires on the circuit board. You can follow which wires are the ground wires simply by looking at the circuit. The grounds tend to go to multiple connections on the board while the hot wires usually only go to one place.
Willcox
Thread Starter
Racer
Joined: Nov 2008
Posts: 350
Likes: 0
From: Guyton GA
Thanks for the input so far guys!
I was already in the process of ordering the flexible circuit & Circuit board (I am sure both of these are bad). What I'm trying to figure out is where or how I can get a replacement housing. Most of the screw holes are broken or cracked. The inside is very scratched & damaged. Any suggestions where I can get a new housing & if you can purchase it with the flew circuit or not, etc... Thanks for the quick responses!
I was already in the process of ordering the flexible circuit & Circuit board (I am sure both of these are bad). What I'm trying to figure out is where or how I can get a replacement housing. Most of the screw holes are broken or cracked. The inside is very scratched & damaged. Any suggestions where I can get a new housing & if you can purchase it with the flew circuit or not, etc... Thanks for the quick responses!
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
We may have a used housing; I’ll have to check to see.
The stripped holes can be repaired with Plastic Fusion or Plastic Weld. This is a two part epoxy made specifically for ABS plastics. If you smear some in the holes and then re-tap them it will repair the holes for about 6.00. The glue can also be used to repair any other damage on this housing. It is sandable and can be painted over when dry.
The inside black part of the housing is painted black and can easily be re-painted. If you do find a used housing, I’d say the chances are it will have some of the same issues and more then likely will need to be repainted as well.
Willcox
The stripped holes can be repaired with Plastic Fusion or Plastic Weld. This is a two part epoxy made specifically for ABS plastics. If you smear some in the holes and then re-tap them it will repair the holes for about 6.00. The glue can also be used to repair any other damage on this housing. It is sandable and can be painted over when dry.
The inside black part of the housing is painted black and can easily be re-painted. If you do find a used housing, I’d say the chances are it will have some of the same issues and more then likely will need to be repainted as well.
Willcox
Thread Starter
Racer
Joined: Nov 2008
Posts: 350
Likes: 0
From: Guyton GA
We may have a used housing; I’ll have to check to see.
The stripped holes can be repaired with Plastic Fusion or Plastic Weld. This is a two part epoxy made specifically for ABS plastics. If you smear some in the holes and then re-tap them it will repair the holes for about 6.00. The glue can also be used to repair any other damage on this housing. It is sandable and can be painted over when dry.
The inside black part of the housing is painted black and can easily be re-painted. If you do find a used housing, I’d say the chances are it will have some of the same issues and more then likely will need to be repainted as well.
Willcox
The stripped holes can be repaired with Plastic Fusion or Plastic Weld. This is a two part epoxy made specifically for ABS plastics. If you smear some in the holes and then re-tap them it will repair the holes for about 6.00. The glue can also be used to repair any other damage on this housing. It is sandable and can be painted over when dry.
The inside black part of the housing is painted black and can easily be re-painted. If you do find a used housing, I’d say the chances are it will have some of the same issues and more then likely will need to be repainted as well.
Willcox
Thread Starter
Racer
Joined: Nov 2008
Posts: 350
Likes: 0
From: Guyton GA
Finally Completed...
Hey guys!
Just an update on my Speedo/Tach Cluster...
I removed the housing, patched the crack with Perma Proxy Plastic Weld, Sanded, & repainted with a balck Satin Paint made for plastic.
I ordered my Tach Circuit Board & flex circuit for the back of cluster from Willcox Corvette. The product was great, arrived quickly, & cost less than other sites I compared.
Upon removing the fried flex circuit, I broke a clip that the tach plugs into.
NOTE: If you ever need this clip, Call your local Chevrolet dealership and ask them if they have or can search other dealerships for part# 8986000. They can do this for you
It took me a week to find who might have the parts. After I found them, it was quite straightforward.
I did use crome/mirrored tape inside the housing to improve the light some & it did seem to help.
I do have one problem resulting from the removal, repair, & reinstallation of the cluster: I removed the needles from the tach & Speedometer to clean the face & upon replacement the tach seems to be about 500rpms off, & the speedo IS 5MPH off...Any suggestions? Also when I turn the car off the tach needle bounces up to about 1000rpms & stays until I crank it again, at which time it drops back down. Thanks again!
Just an update on my Speedo/Tach Cluster...
I removed the housing, patched the crack with Perma Proxy Plastic Weld, Sanded, & repainted with a balck Satin Paint made for plastic.
I ordered my Tach Circuit Board & flex circuit for the back of cluster from Willcox Corvette. The product was great, arrived quickly, & cost less than other sites I compared.
Upon removing the fried flex circuit, I broke a clip that the tach plugs into.
NOTE: If you ever need this clip, Call your local Chevrolet dealership and ask them if they have or can search other dealerships for part# 8986000. They can do this for you
It took me a week to find who might have the parts. After I found them, it was quite straightforward.
I did use crome/mirrored tape inside the housing to improve the light some & it did seem to help.
I do have one problem resulting from the removal, repair, & reinstallation of the cluster: I removed the needles from the tach & Speedometer to clean the face & upon replacement the tach seems to be about 500rpms off, & the speedo IS 5MPH off...Any suggestions? Also when I turn the car off the tach needle bounces up to about 1000rpms & stays until I crank it again, at which time it drops back down. Thanks again!
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
To reset the needle on the tach to zero remove the tach from the car, remove the needle, power up the tach without a pulse wire attached. Once powered up, the tach will set to zero on its own. With the car powered up re-install the needle.
On the speedometer, you’ll have to remove it and the needle. With the speedo sitting in your hand install the needle lightly. Turn the needle counter clock wise and begin pushing downward as you come around. When you get real close to zero push a little harder inward and this should allow you to get the needle to zero.
If you don’t get zero on the first try with either one, just do it over until you do. A couple of tries and you should get it.
It sounds to me on your tach as if you have a short or corrosion on one of the wires. You should inspect the connector at the back where the unit plugs in and make sure you don’t have corrosion on any of the terminals at the pinch connector.
Willcox Inc.
On the speedometer, you’ll have to remove it and the needle. With the speedo sitting in your hand install the needle lightly. Turn the needle counter clock wise and begin pushing downward as you come around. When you get real close to zero push a little harder inward and this should allow you to get the needle to zero.
If you don’t get zero on the first try with either one, just do it over until you do. A couple of tries and you should get it.
It sounds to me on your tach as if you have a short or corrosion on one of the wires. You should inspect the connector at the back where the unit plugs in and make sure you don’t have corrosion on any of the terminals at the pinch connector.
Willcox Inc.
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