tach cable keeps breaking!
Thread Starter
Racer
Joined: Nov 2009
Posts: 384
Likes: 2
From: Tulsa OK
tach cable keeps breaking!
Alright guys, I need some advice.
I've got a 68 327/300 vert that keeps breaking the tach cable.
The guy I bought the car from broke two or 3 cables and then bought a 90 degree angle adapter to put on the tach drive thinking it was the tight bend exiting the distributor causing the problem.
I bought the car recently and installed the 90 degree adapter and a new tach cable. Seemed to work ok at first, though the tach needle bounced a more than I thought it should from the jump.
I only drove it about 10 miles and the distributor started making a racket. I thought the distributor was going to go bad, but soon after the tach cable snapped again. The racket went with it.
Why would this keep happening?
I've got a 68 327/300 vert that keeps breaking the tach cable.
The guy I bought the car from broke two or 3 cables and then bought a 90 degree angle adapter to put on the tach drive thinking it was the tight bend exiting the distributor causing the problem.
I bought the car recently and installed the 90 degree adapter and a new tach cable. Seemed to work ok at first, though the tach needle bounced a more than I thought it should from the jump.
I only drove it about 10 miles and the distributor started making a racket. I thought the distributor was going to go bad, but soon after the tach cable snapped again. The racket went with it.
Why would this keep happening?
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
First if you need a 90 degree adapter your distributor is clocked wrong.
Second, did you replace just the inner cable or the sheath too?
If you just replaced the cable the insides of the sheath are probably messed up.
If you did replace the sheath, then I'd look at the speedo
Second, did you replace just the inner cable or the sheath too?
If you just replaced the cable the insides of the sheath are probably messed up.
If you did replace the sheath, then I'd look at the speedo
Thread Starter
Racer
Joined: Nov 2009
Posts: 384
Likes: 2
From: Tulsa OK
replaced cable and sheath (didn't know you could replace without the sheath)
If distributor was installed incorrectly how would it run (and it runs reasonably good, thought very difficult to cold start)
If distributor was installed incorrectly how would it run (and it runs reasonably good, thought very difficult to cold start)
Melting Slicks
Joined: Apr 2006
Posts: 2,084
Likes: 14
From: Airdrie Alberta
First if you need a 90 degree adapter your distributor is clocked wrong.
I fried my tach cable when I first fired mine up. There should be a paper floating around from Lars on Corvette distributer installation, solved all my problems
Pro
Joined: Jun 2008
Posts: 673
Likes: 2
From: Melbourne Victoria
I got one of those repair kits and made the mistake of not measuring twice before cutting- Hmmmmm inches short!!!!Buggar. I just put the dash back together & really wanted the tach working so as a "Bubba" fix I discovered that my Dremel tool's flexible attachment shaft fit perfectly.Haven't had any probs yet
(it's been 3 months) and the needle doesn't bounce around anymore. Being right hand drive my cable doesn't have an easy
path & I'm not using a 90 degree adaptor either.
Good Luck
Cheers
GAV
(it's been 3 months) and the needle doesn't bounce around anymore. Being right hand drive my cable doesn't have an easy
path & I'm not using a 90 degree adaptor either.
Good Luck
Cheers
GAV
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I got one of those repair kits and made the mistake of not measuring twice before cutting- Hmmmmm inches short!!!!Buggar. I just put the dash back together & really wanted the tach working so as a "Bubba" fix I discovered that my Dremel tool's flexible attachment shaft fit perfectly.Haven't had any probs yet
(it's been 3 months) and the needle doesn't bounce around anymore. Being right hand drive my cable doesn't have an easy
path & I'm not using a 90 degree adaptor either.
Good Luck
Cheers
GAV
(it's been 3 months) and the needle doesn't bounce around anymore. Being right hand drive my cable doesn't have an easy
path & I'm not using a 90 degree adaptor either.
Good Luck
Cheers
GAV
IMO those mechanical tachs are a freeking disaster from the git go and it was one of the very first things to go, I got lucky and swapped my old dizzy for a '75 tach, and never looked bach.....
Thread Starter
Racer
Joined: Nov 2009
Posts: 384
Likes: 2
From: Tulsa OK
thanks guys
still not clear to me what is breaking the cable so quickly even with a 90 degree adapter to remove the bend
In reading the responses, am I correct that rotating the distributor to "reclock" means removing it first, rotating engine to TDC, rotating distributor shaft to have rotor point to #1, then reinstalling at the new position (or something similar)?
Do you think the gears in the distributor itself for the tach drive (not sure how it's put together) could be the problem?
still not clear to me what is breaking the cable so quickly even with a 90 degree adapter to remove the bend
In reading the responses, am I correct that rotating the distributor to "reclock" means removing it first, rotating engine to TDC, rotating distributor shaft to have rotor point to #1, then reinstalling at the new position (or something similar)?
Do you think the gears in the distributor itself for the tach drive (not sure how it's put together) could be the problem?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
My first suggestion would be to check those gears. I'm surprised no one has suggested it before. The brass fitting on the outside of the distributor shaft will just screw off [CCW] and you can remove the 'drive' gear to check it out. Then you can use a penlight to look into the dizzy shaft hole and check out the 'driven' [worm] gear on the shaft. Wipe the grease off, as best you can, and look for any damaged area(s) that might want to bind up. Also note if there is any debris in the gear set. The cable needs to see smooth, free rotation to operate well. If the action is jerky for any reason, that could be your problem. The bushing which operates with the drive gear can bind up if it is damaged, also.
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Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
My first suggestion would be to check those gears. I'm surprised no one has suggested it before. The brass fitting on the outside of the distributor shaft will just screw off [CCW] and you can remove the 'drive' gear to check it out. Then you can use a penlight to look into the dizzy shaft hole and check out the 'driven' [worm] gear on the shaft. Wipe the grease off, as best you can, and look for any damaged area(s) that might want to bind up. Also note if there is any debris in the gear set. The cable needs to see smooth, free rotation to operate well. If the action is jerky for any reason, that could be your problem. The bushing which operates with the drive gear can bind up if it is damaged, also.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I think if the cable binds at a certain spot in its rotation, it tends to whip and flex rather than turn smoothly. It's like taking a piece of thin flat stock and bending it back and forth. Eventually, it will break apart from the flexing action.