Relocate speedo cable hole?

Bonnewagon

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Sep 18, 2009
7,826
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Queens, NY
My 1983 Bonneville speedometer has been jumping around ever since I rebuilt the manual transmission. Prior to that I had no speedometer for many years because the cable had touched the exhaust pipe, melted, seized, and broke the drive gear loose from the output shaft. So I had to take the entire transmission apart to secure the drive gear back in place. Since the car got a brand new speedo cable I was puzzled as to why the speedo was bouncing around so much. Today I put the car up and took the cable back out. It was fine, no rust, no kinks, and I cleaned and lubed it anyway. When I tried to get the cable back through the firewall and up to the dash I was confounded by all the junk in the way. That is when I realized that the convoluted path the cable must take is probably why the speedo is bouncing. When it was an automatic car I guess the cable path is less crazy. But now with the new clutch linkage directly in the way I can't even get the cable past the pedals. Worse, the Pontiac dash has a triangular shaped tunnel that the cable must pass through that goes through the ductwork and exits nowhere near the firewall hole. I need to make a new hole that is a straight shot to that cable tunnel in the dash. I fed a long rod through the tunnel to see where it ended up. It passed close to the neutral start switch on the clutch pedal and hit the firewall at a fairly empty spot. It got dark so I quit but I think the power booster may be in the way on the other side. Has anyone found a better place for the cable to pass through the firewall?
 

Bonnewagon

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Sep 18, 2009
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Queens, NY
No- I have nothing electronic in this car except the radio an gauges. KISS.
 
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Bonnewagon

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Sep 18, 2009
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Queens, NY
UPDATE: It took a while but I found a good spot. Just below the power booster and to the side of my clutch linkage and next to the bulkhead connector. After taking the washer fluid tank off I had a good shot at the firewall with the drill. It is a nice smooth sweep up from the bottom of the body along the combination valve, around the Z-bar, and over the clutch upper push-rod. As it enters it goes up pretty straight to the back of the speedo. More important- nothing inside was in the way. By the time I got everything back together it got dark again. I will test tomorrow to see if this finally cured the bouncy speedo. IMG_0108.JPG IMG_0111.JPG
 

Bonnewagon

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Sep 18, 2009
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Queens, NY
Well it's better, but not perfect. In fact MUCH better. But the speedo needle is still a little nervous. Is there a dampening mechanism in speedometers? If there is then it acts like that is not working. I know the gauges have a dampening fluid inside and when that leaks out they bounce around. This is acting like that. EDIT: I also managed to disconnect my neutral start switch on the clutch pedal. I had to claw my way back through the rat's nest of wires to get up there at it. I see what happened- the speedo cable passes right next to the switch- easy to knock the connector off. Endless headaches.
 
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pagrunt

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Sep 14, 2014
6,366
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Elderton, Pa
Well it's better, but not perfect. In fact MUCH better. But the speedo needle is still a little nervous. Is there a dampening mechanism in speedometers? If there is then it acts like that is not working. I know the gauges have a dampening fluid inside and when that leaks out they bounce around. This is acting like that. EDIT: I also managed to disconnect my neutral start switch on the clutch pedal. I had to claw my way back through the rat's nest of wires to get up there at it. I see what happened- the speedo cable passes right next to the switch- easy to knock the connector off. Endless headaches.
Does the cable need lubed with some grease? Might be transfering its rough ride to the speedo. I haven't seen them in ages but I remeber places like OPGI, Classic Industries & Year One used to sell an fitting to go on the trans side of thee cable to pump grease into it & might be what you need to lube it up.
 
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Bonnewagon

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Thread starter
Sep 18, 2009
7,826
113
Queens, NY
I lubed it to death with Super Lube which leaves Teflon behind when it evaporates. I got on the highway and it seemed better. Maybe it needs miles to work any kinks out?
 
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