Tach repair help
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Let me know what you find out, we've been getting hammered too. Flood gates are going in today.
Willcox
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
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My thoughts are with all of you in the midwest and upper southeast. You guys have been getting hammered with foul weather. No rain here yet but the wind has been relentless and the humidity's off the scale. I expect the t-storms to roll in this evening.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Wilcox,
are you saying that when you turn the ignition key to "on" the tach should read zero before starting?
I think i have a problem with my tach (a US shop replaced the circuit board for me) in that it sits below zero when at idle, but seems to increase faster than the engine does..
looking at your video, it seems as though I need to set my zero and adjust the potentiometer using your signal generator...
sorry for the Hi-jack....
are you saying that when you turn the ignition key to "on" the tach should read zero before starting?
I think i have a problem with my tach (a US shop replaced the circuit board for me) in that it sits below zero when at idle, but seems to increase faster than the engine does..
looking at your video, it seems as though I need to set my zero and adjust the potentiometer using your signal generator...
sorry for the Hi-jack....
Willcox
Racer
Joined: Apr 2011
Posts: 367
Likes: 7
From: Congupna Victoria
Wilcox,
thanks for the help - I can probably set the zero without having to take out the tach unit, just the plastic cover, correct?
then check the rpm on motor vs tach and if that reads incorrect, I'll have to remove the unit and adjust the "pot" - am I on the right track?
thanks for the help - I can probably set the zero without having to take out the tach unit, just the plastic cover, correct?
then check the rpm on motor vs tach and if that reads incorrect, I'll have to remove the unit and adjust the "pot" - am I on the right track?
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Wilcox,
thanks for the help - I can probably set the zero without having to take out the tach unit, just the plastic cover, correct?
then check the rpm on motor vs tach and if that reads incorrect, I'll have to remove the unit and adjust the "pot" - am I on the right track?
thanks for the help - I can probably set the zero without having to take out the tach unit, just the plastic cover, correct?
then check the rpm on motor vs tach and if that reads incorrect, I'll have to remove the unit and adjust the "pot" - am I on the right track?
You should watch the video if you have not done so...
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
I will make this real simple, as I had this problem and tried most of the things mentioned in this thread. I live near Ecklers, so I had their tech guys and convenience of returning parts that they readily accepted. I replaced my tach filter, then replaced about four different circuit boards from Ecklers with no help. My 79 tach needle worked, but bounced around and when it held steady, it seemed to be double the RPM's it should have read.
In the end, I bought a tach and circuit board unit from an 80 L48 model by a forum member. It only cost me $30 and bingo, I had a tach that worked perfectly. It didn't have the L82 logo and redline, but it worked flawlessly. You might consider going this route. You want a tach and circuit from the same car that was working. Don't mix boards and tachs, they aren't all the same, or so they tell me.
In the end, I bought a tach and circuit board unit from an 80 L48 model by a forum member. It only cost me $30 and bingo, I had a tach that worked perfectly. It didn't have the L82 logo and redline, but it worked flawlessly. You might consider going this route. You want a tach and circuit from the same car that was working. Don't mix boards and tachs, they aren't all the same, or so they tell me.
Racer
Joined: Apr 2011
Posts: 367
Likes: 7
From: Congupna Victoria
Red 69,
I also bought the replacement from Ecklers as the original was not working (Did not know about Wilcox at the time).
I need to convince myself it is correctly set up before I blame the circuit board, but at idle the needle sits below zero (off the scale), a slight blip of the gas sees it shoot up to 1000rpm, or something more believable.
The Tachometer needle is quite steady almost all the time, so I do not have that issue.
During driving, I'd say the needle climbs faster than what the engine noise would tend to indicate - but without a dwell meter or external tacho that I know is accurate, i cannot say with 100% confidence how far out it is.
I do know it isn't 100% right, but how far out is unknown right now.
Willcox - you say you can adjust the resistor on the board to change the Tachometer's behavior. Is this just a scaling adjustment?
I also bought the replacement from Ecklers as the original was not working (Did not know about Wilcox at the time).
I need to convince myself it is correctly set up before I blame the circuit board, but at idle the needle sits below zero (off the scale), a slight blip of the gas sees it shoot up to 1000rpm, or something more believable.
The Tachometer needle is quite steady almost all the time, so I do not have that issue.
During driving, I'd say the needle climbs faster than what the engine noise would tend to indicate - but without a dwell meter or external tacho that I know is accurate, i cannot say with 100% confidence how far out it is.
I do know it isn't 100% right, but how far out is unknown right now.
Willcox - you say you can adjust the resistor on the board to change the Tachometer's behavior. Is this just a scaling adjustment?
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Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I will make this real simple, as I had this problem and tried most of the things mentioned in this thread. I live near Ecklers, so I had their tech guys and convenience of returning parts that they readily accepted. I replaced my tach filter, then replaced about four different circuit boards from Ecklers with no help. My 79 tach needle worked, but bounced around and when it held steady, it seemed to be double the RPM's it should have read.
In the end, I bought a tach and circuit board unit from an 80 L48 model by a forum member. It only cost me $30 and bingo, I had a tach that worked perfectly. It didn't have the L82 logo and redline, but it worked flawlessly. You might consider going this route. You want a tach and circuit from the same car that was working. Don't mix boards and tachs, they aren't all the same, or so they tell me.
In the end, I bought a tach and circuit board unit from an 80 L48 model by a forum member. It only cost me $30 and bingo, I had a tach that worked perfectly. It didn't have the L82 logo and redline, but it worked flawlessly. You might consider going this route. You want a tach and circuit from the same car that was working. Don't mix boards and tachs, they aren't all the same, or so they tell me.
Now one thing that has not be crossed is the analog movement. Yes they do go bad. Is this normal.. No.. but it does happen from time to time.
I don't know where Ecklers gets their boards but if it came from us it will have Willcox on the board. We did this to avoid any confusion as to the boards origin.
The difference in the 1978-79 board and the 1980-1982 board is the calibration.. if you look at the faces they are not the same.
Red.. if you want to sell the extra tach I'd be a buyer.. mainly because I need cores.
Puzzi-
If a zero set is not done correctly the tach will be off at all points. Yes you can adjust our boards and they are as accurate as the original GM boards. (the video of the 1978-1982 shows this)... Our board was actually a bit closer in readings.
But.. to both of you and anyone reading this... If you want the tach tested and/or calibrated to match.. mail it to us.. This is a free service that we offer! Only cost is the return shipping.. If anyone wants to do this.. and I don't care where the board came from.. just call sales and get a RA number for the shop before you mail.
Willcox
Racer
Joined: Apr 2011
Posts: 367
Likes: 7
From: Congupna Victoria
Willcox,
i wish I'd known about you before i bought these parts! You seem so helpful.
I actually rang Ecklers to ask them for their advice on their part - the girl seemed to be taking while to find the info on installation/calibration. When she came back she referred me to a Youtube page - which was YOUR video!!
I had a look on your page and theirs and the circuit boards look almost exactly the same to the one in your installation instructions, but different to the one now showing as the new part available from you.
Maybe earlier ones were from the same supplier?
I might take you up on your offer of free calibration!!
i wish I'd known about you before i bought these parts! You seem so helpful.
I actually rang Ecklers to ask them for their advice on their part - the girl seemed to be taking while to find the info on installation/calibration. When she came back she referred me to a Youtube page - which was YOUR video!!
I had a look on your page and theirs and the circuit boards look almost exactly the same to the one in your installation instructions, but different to the one now showing as the new part available from you.
Maybe earlier ones were from the same supplier?
I might take you up on your offer of free calibration!!
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
I live in Ecklers neighborhood and I'd say forget about asking for advice. Most folks who answer the phone don't know answers to technical questions. I was in their showroom and we couldn't come up with a solution to my faulty tach. I was in and out five times changing parts in an effort to find what was wrong, to no avail.
WILLCOX The boards are not the same that is for sure. The pot we used on our board is a 15 turn pot.. and you have to physically turn the thing to make a change. Other boards have a 1 turn pot on them and you can tap it with your finger and the adjustment will change.
I tried to adjust one of the new boards with no result.
Finally, after much frustration I took a forum member up on his offer to sell me a tach and board he had in storage. As I said, that was my solution.
WILLCOX Red.. if you want to sell the extra tach I'd be a buyer.. mainly because I need cores.
I am going to hold the L-82 tach for possible future repair. Thanks for the info you have posted, it is nice to have a pro's offering advice.
WILLCOX The boards are not the same that is for sure. The pot we used on our board is a 15 turn pot.. and you have to physically turn the thing to make a change. Other boards have a 1 turn pot on them and you can tap it with your finger and the adjustment will change.
I tried to adjust one of the new boards with no result.
Finally, after much frustration I took a forum member up on his offer to sell me a tach and board he had in storage. As I said, that was my solution.
WILLCOX Red.. if you want to sell the extra tach I'd be a buyer.. mainly because I need cores.
I am going to hold the L-82 tach for possible future repair. Thanks for the info you have posted, it is nice to have a pro's offering advice.
Last edited by Red 69; Apr 28, 2011 at 11:06 PM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I live in Ecklers neighborhood and I'd say forget about asking for advice. Most folks who answer the phone don't know answers to technical questions. I was in their showroom and we couldn't come up with a solution to my faulty tach. I was in and out five times changing parts in an effort to find what was wrong, to no avail.
WILLCOX The boards are not the same that is for sure. The pot we used on our board is a 15 turn pot.. and you have to physically turn the thing to make a change. Other boards have a 1 turn pot on them and you can tap it with your finger and the adjustment will change.
I tried to adjust one of the new boards with no result.
Finally, after much frustration I took a forum member up on his offer to sell me a tach and board he had in storage. As I said, that was my solution.
WILLCOX Red.. if you want to sell the extra tach I'd be a buyer.. mainly because I need cores.
I am going to hold the L-82 tach for possible future repair. Thanks for the info you have posted, it is nice to have a pro's offering advice.
WILLCOX The boards are not the same that is for sure. The pot we used on our board is a 15 turn pot.. and you have to physically turn the thing to make a change. Other boards have a 1 turn pot on them and you can tap it with your finger and the adjustment will change.
I tried to adjust one of the new boards with no result.
Finally, after much frustration I took a forum member up on his offer to sell me a tach and board he had in storage. As I said, that was my solution.
WILLCOX Red.. if you want to sell the extra tach I'd be a buyer.. mainly because I need cores.
I am going to hold the L-82 tach for possible future repair. Thanks for the info you have posted, it is nice to have a pro's offering advice.
Willcox
Racer
Joined: Apr 2011
Posts: 367
Likes: 7
From: Congupna Victoria
Wilcox,
I do have a quick question re Tach "Zero-ing"
Your vid shows you "tap" the needle onto the shaft.
The question is do you:
1. pull off the needle then re-attach it onto the shaft so it shows zero or
2. Can rotate the needle whilst it is on the shaft to zero with no need to remove the needle at all
Thanks
I do have a quick question re Tach "Zero-ing"
Your vid shows you "tap" the needle onto the shaft.
The question is do you:
1. pull off the needle then re-attach it onto the shaft so it shows zero or
2. Can rotate the needle whilst it is on the shaft to zero with no need to remove the needle at all
Thanks
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
To do a zero set:
You must have power and ground going to the tachometer. This powers it up but with no input (0). Before you put the needle back on, (make sure as the video shows) that the spindle is not pulled outward with the back side of your finger nail.
When you sit the needle back on the tach you don't want to press it, you want the needle to be barely sitting on the spindle allowing it to rotate on the shaft.
To make it rotate gently bump it with your finger until you hit zero and only then do you tap it with your finger to snug it up. It may take you a couple of times to get this right.
Willcox Inc.
You must have power and ground going to the tachometer. This powers it up but with no input (0). Before you put the needle back on, (make sure as the video shows) that the spindle is not pulled outward with the back side of your finger nail.
When you sit the needle back on the tach you don't want to press it, you want the needle to be barely sitting on the spindle allowing it to rotate on the shaft.
To make it rotate gently bump it with your finger until you hit zero and only then do you tap it with your finger to snug it up. It may take you a couple of times to get this right.
Willcox Inc.
Racer
Joined: Apr 2011
Posts: 367
Likes: 7
From: Congupna Victoria
Wilcox,
thanks, maybe I'm a bit slow to pick up what you're saying - but if I do understand, you want to fit the needle to the shaft ONLY when it is pointing to Zero.
You DO NOT want to have the needle firmly on the shaft, THEN have to move it to zero (turning the shaft at the same time)
Have I got that right?
thanks, maybe I'm a bit slow to pick up what you're saying - but if I do understand, you want to fit the needle to the shaft ONLY when it is pointing to Zero.
You DO NOT want to have the needle firmly on the shaft, THEN have to move it to zero (turning the shaft at the same time)
Have I got that right?
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Wilcox,
thanks, maybe I'm a bit slow to pick up what you're saying - but if I do understand, you want to fit the needle to the shaft ONLY when it is pointing to Zero.
You DO NOT want to have the needle firmly on the shaft, THEN have to move it to zero (turning the shaft at the same time)
Have I got that right?
thanks, maybe I'm a bit slow to pick up what you're saying - but if I do understand, you want to fit the needle to the shaft ONLY when it is pointing to Zero.
You DO NOT want to have the needle firmly on the shaft, THEN have to move it to zero (turning the shaft at the same time)
Have I got that right?
Check out the video and you should see how I did it.
Willcox
Racer
Joined: Apr 2011
Posts: 367
Likes: 7
From: Congupna Victoria
Wilcox,
did the Zero in the car, a bit difficult since it was getting dark and bit hard to see - I guess I should have got a lead light!!
Anyway, 1st go got it within 100rpm on the low side, next try was 50rpm on the high side, next was 50rpm on the low side.
Funny thing was that when I kept checking the needle seemed to be high by 50rpm
I will probably be happy with that as it is..
did the Zero in the car, a bit difficult since it was getting dark and bit hard to see - I guess I should have got a lead light!!
Anyway, 1st go got it within 100rpm on the low side, next try was 50rpm on the high side, next was 50rpm on the low side.
Funny thing was that when I kept checking the needle seemed to be high by 50rpm
I will probably be happy with that as it is..
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Wilcox,
did the Zero in the car, a bit difficult since it was getting dark and bit hard to see - I guess I should have got a lead light!!
Anyway, 1st go got it within 100rpm on the low side, next try was 50rpm on the high side, next was 50rpm on the low side.
Funny thing was that when I kept checking the needle seemed to be high by 50rpm
I will probably be happy with that as it is..
did the Zero in the car, a bit difficult since it was getting dark and bit hard to see - I guess I should have got a lead light!!
Anyway, 1st go got it within 100rpm on the low side, next try was 50rpm on the high side, next was 50rpm on the low side.
Funny thing was that when I kept checking the needle seemed to be high by 50rpm
I will probably be happy with that as it is..
Racer
Joined: Apr 2011
Posts: 367
Likes: 7
From: Congupna Victoria
OK...so what exactly was your tach problem and the solution? Someone else with a similar problem, it might be me, could find this thread in a future search and be left wondering. Tach problems seem to be an enigma, but understanding specific problems have specific solutions can demystify the working of the unit. Thanks to you and Willcox for sharing the message thread exchange.
the original Tach circuit board was fried and did not work.
I got a local (in the US) shop to replace for me.
They obviously only fitted the board and nothing else!
When power was supplied to the tach, it sat well below the ZERO.
Upon starting, at idle, it still sat below ZERO, by approx 500rpm - a little blip on the gas brought it up.
At highway speed the Tach seems to read high and when accelerating the tach needle seemed to climb faster than the engine note would suggest.
When I zero-ed the tach as per Wilcox's instructions (albeit in the car), when power is suppied, it reads zero and upon starting, at idle, it reads a believable figure.
I need to follow up to confirm it is reading accurately with a dwell meter AND at higher rpm's - then take it out for a drive