[My-74-SS]

Hi
I have a 1974 Nova SS, with a 1969 327, and a 4-spd tranny.
Ever since I owned the Nova, the speedo will go up to 50mph. and gets stuck there.
When my speed comes down to roughly 45mph, it gets unstuck and starts reading again.
Without having to replace the complete cluster, is there anyone who could provide me with some help on this.
Thanks
Gil

 

[LeftCoast Carl]

the inner speedo drive cable can sometimes break in the middle.at slower speeds the broken end grips the other sheared end enough to drive the speedo head and give you a reading.when the speed increases,the break comes apart and the speed head won't read any longer until the cable speed decreases and grabs the sheared end again.this may be happening to you.
another thing to try and nail down the problem is to remove the speedo cable inner drive cable from the outer sheath.undo the speedo cable at the transmission with waterpump(big sliding type)plyers.carefully pull/twist the cable all the way out of the outer sheath.be careful to keep it clean!!examine the whole length for flaws and if all is well,grease with lithium and re-install it until it's engaged in the speedo head.carefully attach a variable speed drill to the end and engage the power slowly.usually you can sit on the ground beside the lt rocker panel,engage the drill,and watch the speedo head at the same time.if it works,it just needed lubricating.if it doesn't,the problem is likely in the speedo head.
good luck,
leftcoast carl.

 

[My-74-SS]

Thanks, should have added

Thanks, I should have added that I replaced the speedo cable with a new one, It was just barely long enough, but that is what the book called for. A 61 inch I think.

the inner speedo drive cable can sometimes break in the middle.at slower speeds the broken end grips the other sheared end enough to drive the speedo head and give you a reading.when the speed increases,the break comes apart and the speed head won't read any longer until the cable speed decreases and grabs the sheared end again.this may be happening to you.
another thing to try and nail down the problem is to remove the speedo cable inner drive cable from the outer sheath.undo the speedo cable at the transmission with waterpump(big sliding type)plyers.carefully pull/twist the cable all the way out of the outer sheath.be careful to keep it clean!!examine the whole length for flaws and if all is well,grease with lithium and re-install it until it's engaged in the speedo head.carefully attach a variable speed drill to the end and engage the power slowly.usually you can sit on the ground beside the lt rocker panel,engage the drill,and watch the speedo head at the same time.if it works,it just needed lubricating.if it doesn't,the problem is likely in the speedo head.
good luck,
leftcoast carl.

 

[MTNNOVA]

The problem you're describing sounds more like a head issue to me. Bad cables usually quit or cause erratic readings. The stuck needle problem is more likely to be in the head or face. Check from all angles to make sure your needle is not contacting the dial or other components when it gets stuck. If it's not, the issue is internal. Sometimes you can pull the speedometer, examine the needle shaft, bushings, etc and spot a problem that might be cured with a little instrument oil or realingment of the parts, if any, that are interfering with the needle or shaft. If that doesn't work I would replace it or take it to a speedo shop.

MTNNOVA