Replaced the speedo & tach cables

[donco]

I finally got around to replacing the cables today. The old ones were toast & were hanging loose under the dash when I bought it. I was able to remove the collar nut for the tach cable near the water pump by coaxing it with a large screwdriver, & put the new one back on the same way. The speedo cable attachment to the trans was easy to reach with water pump pliers & the heat shield slides out of the way to route the cable without dropping the exhaust.

The tach fired up right away. I took it for a roadtest to try out the speedo & had to tap on the speedo to get the needle to move, but it works too. Seems like it reads about 10 mph too high just by guessing. The odometer is working too. The tach cable started making a clicking noise right away & then I remembered a trick from my 58 356A and loosened the collar nut on the back of the tach & it quieted right down. Both of the new cables came dry so I slid the inner cables out & lubed them with 10W30 synthetic oil. Good to have all the gauges working again. I don't know how long it's been since they were working. It's showing 81k & the previous owner estimated 120k on the car when he sold it to me. Everything has been rebuilt at least once so it's kinda a moot point.

donco
69 roundtail

[gprocket]

Perfect timing on your post - I was just about to replace my tach cable. You didn't need to remove the radiator I presume.

My speedo works fine except it too reads about 10 over at 50 MPH. Have you looked into recalibrating it?

- Rich D.

[donco]

I didn't have to mess with the radiator for the tach cable. I approached it from under the car & had a straight shot at the end of the cable along its axis. I pondered removing the fan but seemed a bit more involved than I cared to get into at the time & looking at it, it didn't seem that would gain me much advantage, so tried a long wide flat-blade screwdriver. If you jam the screwdriver in there just right, you can twist it to apply a tangential force on the collar nut & it will spin off after numerous iterations. I got lucky with both the old & new collars have coarse straight cut knurls on them & was able to apply a tangential force without applying too much radial force & they spun without difficulty.

I think the proximity of the cables to the exhaust headers cooks them & causes them to become dried out & brittle prematurely, so I'll try to rig up some sort of heat shield, same thing with the brake light switches at the firewall, & I've got to add more heat shielding to the floorboard, the exhaust cooks my right foot on the gas pedal if I drive barefoot.

I'm in no hurry to have the speedo calibrated, that type of refinement is way down the list of things that need tending to. It's a daily driver in basically good shape & the 10 over speedo might help curb a few tickets in a flashy red convertible. They must have sold me the wrong speedo cable, the trans end wouldn't cinch up all the way so I had to machine a split washer to catch on the step of the cable end to hold it into the socket all the way -- worked well.

donco
69 roundtail

[Worthit]

Who did you buy your cables from? I took my tach out to replace the light bulbs and now the tach needle vibrates almost all of the time. Shortly after that repair, the speedo and odo quit working and the needle is stuck at 18 MPH, about the amount over speed that I think it had been reading. Would the speedo cable fail because I messed with the tach housing? Or just another happy coincidence?
Dan

[donco]

I bought the speedo cable locally from an indie repair shop. They didn't have a tach cable for it so I bought that from IAP. They have the same ends on them but the tach cable is shorter. My has them routed thru separate holes in the firewall. It's possible you could have disturbed the speedo cable when doing the tach bulbs but could be coincidence also. Check to see if it might have detached from the back. Also take a peek under the car to see if the cable is intact. My old speedo cable was severely damaged where it passes behind the headers.

donco
69 roundtail