Factory tachometer sticks around 1500 rpm - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**WIDESIDE72** · 10-15-2017, 10:06 AM

I recently swapped a factory tach into my 70 Longhorn. I used an aftermarket wiring harness and was pleased that when I started the truck, the tach needle swung up to 1k. My happiness was short lived when i gave it gas and the needle stuck at 1500 or so. I have fooled with several factory tachs and never seen this before. I figure it would work or not, not halfway! I guess I have been lucky as I used to pull tach clusters out of big trucks in the wrecking yard since back in the 80's and have never had one not work... go figure that when i go to use one of the last ones i had squirreled away, it goes hinky on me! Any ideas?

my56chevytruck · 10-15-2017, 10:13 AM

Bent needle arm, spring hung up? Never had this issue, strange for sure.

**WIDESIDE72** · 10-15-2017, 01:38 PM

Maybe it just needs excercise! I drove her to church this am and it goes to 2k and sticks now!

**WIDESIDE72** · 10-15-2017, 01:40 PM

Quote:

Originally Posted by my56chevytruck

Bent needle arm, spring hung up? Never had this issue, strange for sure.

The needle isnt interfering with anything, but i will have to disaasemble it to see if there is anything going on with the spring. This am as i was driving, I thought about that possibility as well

my56chevytruck · 10-15-2017, 09:34 PM

Quote:

Originally Posted by WIDESIDE72

The needle isnt interfering with anything, but i will have to disaasemble it to see if there is anything going on with the spring. This am as i was driving, I thought about that possibility as well

crank her up to around 5k and see what happens, lol

**LockDoc** · 10-16-2017, 10:11 AM

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I would just drive it for a while and see if it loosens up. I bought one from a board member that would only go up to25 or 2600 and after driving it for a while it started working OK.

LockDoc

**WIDESIDE72** · 12-20-2017, 01:01 PM

Quote:

Originally Posted by LockDoc

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I would just drive it for a while and see if it loosens up. I bought one from a board member that would only go up to25 or 2600 and after driving it for a while it started working OK.

LockDoc

it worked its self loose and is working well!

**LockDoc** · 12-20-2017, 02:47 PM

Quote:

Originally Posted by WIDESIDE72

it worked its self loose and is working well!

Good deal!

LockDoc

**Joesjunk** · 12-20-2017, 09:15 PM

I have a tach that does the same thing. I have been driving it for years hoping it will fix its self but it still stops at about 2600 rpm

demian5 · 12-21-2017, 11:55 AM

Quote:

Originally Posted by Joesjunk

I have a tach that does the same thing. I have been driving it for years hoping it will fix its self but it still stops at about 2600 rpm

Maybe you have a diesel...

**Dustmaker65** · 12-21-2017, 12:05 PM

Quote:

Originally Posted by demian5

Maybe you have a diesel...

Or maybe your foot isn't heavy enough

**Joesjunk** · 12-21-2017, 12:14 PM

Lol, well it's got 4:10 gears so it doesn't take much "heavy foot" to get to 2600 rpm 😉

**Curtb1971** · 12-21-2017, 05:35 PM

Quote:

Originally Posted by Joesjunk

I have a tach that does the same thing. I have been driving it for years hoping it will fix its self but it still stops at about 2600 rpm

I've taken a few of these apart and found little chunks of derbis/metal interfering with the needle swing. The magneto that induces current for the needle is magnetic and there is not a lot of space in between the two. You would be suprised at the little tiny junk that finds itself into this area of the tach. The glue that holds the cardboard dust shield tube to the gauge face around this area is very well disintegrated by now on all these factory tachs and kind of just flopping around (haven't seen one intacted yet) It may just need taken apart and delicately cleaned.

10-15-2017, 10:06 AM	#1
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,494	Factory tachometer sticks around 1500 rpm I recently swapped a factory tach into my 70 Longhorn. I used an aftermarket wiring harness and was pleased that when I started the truck, the tach needle swung up to 1k. My happiness was short lived when i gave it gas and the needle stuck at 1500 or so. I have fooled with several factory tachs and never seen this before. I figure it would work or not, not halfway! I guess I have been lucky as I used to pull tach clusters out of big trucks in the wrecking yard since back in the 80's and have never had one not work... go figure that when i go to use one of the last ones i had squirreled away, it goes hinky on me! Any ideas?

10-15-2017, 10:13 AM	#2
my56chevytruck Registered User Join Date: Feb 2016 Location: Hebron Posts: 1,123	Re: Factory tachometer sticks around 1500 rpm Bent needle arm, spring hung up? Never had this issue, strange for sure. __________________ RUBBER DOWN AND HIT THE ROAD!!! 1940 Ford Dlx Coupe 1969 Mach1

10-15-2017, 01:38 PM	#3
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,494	Re: Factory tachometer sticks around 1500 rpm Maybe it just needs excercise! I drove her to church this am and it goes to 2k and sticks now!

10-16-2017, 10:11 AM	#6
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,331	Re: Factory tachometer sticks around 1500 rpm - I would just drive it for a while and see if it loosens up. I bought one from a board member that would only go up to25 or 2600 and after driving it for a while it started working OK. LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

12-20-2017, 09:15 PM	#9
Joesjunk Senior Member Join Date: May 2001 Location: Independence MO. Posts: 7,689	Re: Factory tachometer sticks around 1500 rpm I have a tach that does the same thing. I have been driving it for years hoping it will fix its self but it still stops at about 2600 rpm __________________ 72 3/4t Custom Deluxe 402/auto 66k Original paint 71 3/4t 4x4 Custom Deluxe 10k original miles Original paint 71 3/4t Cheyenne 402 70k original paint 72 3/4t 4x4 Custom deluxe 72 3/4t 4x4 Custom deluxe 91k original paint 72 Cheyenne/30 Dually 69 Camaro SS396 4-speed 13 GMC 2500HD Duramax I bought new 05 Jeep Wrangler "Willys Edition" 12k miles (I bought new) 85 3/4 ton 4x4 Scottsdale 33k miles original paint 86 1 ton 4x4 SRW Silverado 454 restored 80 1 ton 4x4 SRW Silverado 9,434 original miles!! original paint 95 GMC 1 ton dually 4x4 my dad bought new 95 GMC 3/4 ton 4x4, regular cab 454, 31k original miles 2002 2500HD 4x4 regular cab 6.0L 67k miles 2002 2500HD 4x4 regular cab 8.1L 28k miles 2003 GMC 2500HD 4x4 regular cab Diesel 93k miles 67-72 Parts for sale

12-21-2017, 12:14 PM	#12
Joesjunk Senior Member Join Date: May 2001 Location: Independence MO. Posts: 7,689	Re: Factory tachometer sticks around 1500 rpm Lol, well it's got 4:10 gears so it doesn't take much "heavy foot" to get to 2600 rpm 😉 __________________ 72 3/4t Custom Deluxe 402/auto 66k Original paint 71 3/4t 4x4 Custom Deluxe 10k original miles Original paint 71 3/4t Cheyenne 402 70k original paint 72 3/4t 4x4 Custom deluxe 72 3/4t 4x4 Custom deluxe 91k original paint 72 Cheyenne/30 Dually 69 Camaro SS396 4-speed 13 GMC 2500HD Duramax I bought new 05 Jeep Wrangler "Willys Edition" 12k miles (I bought new) 85 3/4 ton 4x4 Scottsdale 33k miles original paint 86 1 ton 4x4 SRW Silverado 454 restored 80 1 ton 4x4 SRW Silverado 9,434 original miles!! original paint 95 GMC 1 ton dually 4x4 my dad bought new 95 GMC 3/4 ton 4x4, regular cab 454, 31k original miles 2002 2500HD 4x4 regular cab 6.0L 67k miles 2002 2500HD 4x4 regular cab 8.1L 28k miles 2003 GMC 2500HD 4x4 regular cab Diesel 93k miles 67-72 Parts for sale



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