58 tach and speedo

[Bob W.]

Just put repo tach and speedo cables in and both the tach and speedo screech, tach gets pegged and speedo bounces all over the place. Speedo shows 100 to 120 in a 25 MPH zone. I lubbed the cables before install. First I thought maybe the cables were to tight so I loosened them same thing. any ideas?

Had the radiator cleaned out and a new water pump and now i get a trail of antifreeze following me. Another mystery, looking for ideas

[Joe L.]

Re: 58 tach and speedo

Just put repo tach and speedo cables in and both the tach and speedo screech, tach gets pegged and speedo bounces all over the place. Speedo shows 100 to 120 in a 25 MPH zone. I lubbed the cables before install. First I thought maybe the cables were to tight so I loosened them same thing. any ideas?

Had the radiator cleaned out and a new water pump and now i get a trail of antifreeze following me. Another mystery, looking for ideas

Bob-----


Did the tach and speedo work OK before you installed the new cables? Did you replace just the cable CORES or did you replace the complete cable assembly (i.e. core + sheath)?

As far as your coolant leak goes, the first thing I'd check is the possibility of a leak between the waterpump and the block. The motor mount bracket installs between the waterpump and block and this is a NOTORIOUS leak source for 55-62 Corvettes.

[Bob W.]

Re: 58 tach and speedo

Put new cables in not just cores. The car had been sitting for 10+ years and the tach cable was broke. The speedo cable was to long so I replaced it but when this was happening I put the old one back in and still doing the same thing. It seems to work fine up to about 20 then bounces all over the place any faster and screeches.

The antifreeze is coming from the overflow tube down under the radiator. Maybe it just has air in it.

[Joe L.]

Re: 58 tach and speedo

Put new cables in not just cores. The car had been sitting for 10+ years and the tach cable was broke. The speedo cable was to long so I replaced it but when this was happening I put the old one back in and still doing the same thing. It seems to work fine up to about 20 then bounces all over the place any faster and screeches.

The antifreeze is coming from the overflow tube down under the radiator. Maybe it just has air in it.

Bob------


Most likely, the tach and speedo instruments need to be repaired. You'll need to remove them and send them off to a competent instrument servicer.

You may have overfilled the radiator. However, if that's the case, you should fairly quickly get to the right level and then no significant amount of coolant should be "purged" on a continuing basis. If it keeps up, there's got to be some other problem.

[Dan H.]

Re: 58 tach and speedo

Bob, make sure your speedo and tach cable ends arn't too long and binding where you plug them into the instruments. Try loosening the retainer nuts so cables are a little loose and see if condition changes. Hang in there,
Dan

[Loren L.]

Re: 58 tach and speedo

Are the replacement cables the "bayonet" type or just square?

[Joe R.]

Re: 58 tach and speedo

"I lubed the cables before install"

Mistake #1!!!

Probably the lube has by now entered the speedo and tach head! They use an Air Gap technology and not a Grease Gap technology!

More than likely you will have to remove the tach and speedo. Take it to a speedometer repair shop and get them degreased!

New cables have sufficient lubricant to make them operate properly. By adding grease they become an efficient pump and drive the grease into the head rendering the tach or speedo useless!

Not the end of the world and all can be fixed but it's a pain to R and R!

JR

[Bob W.]

Re: 58 tach and speedo

They are the square type. When I lubed them I used a thin grafite based lube and only did the lower two-thirds figuring it would work its way up. I have tried loosening the cables with the same result.

[Ronald W.]

Re: 58 tach and speedo

If all else failed, check the shaft inside the generator tackometer housing. If the shaft slides back and forth in the housing than it has worn a indentation in the back of the housing. I repaired mine by milling a round slot in the back of the housing and pressing in a steel slug. You may also try filling the worn spot with weld.