Bezerk Speedometer

[KaipoDa510]

Hello,
I just swapped my auto trans for a 5 speed dog leg.
Everything went well except for when I got up to about 80mph the speedometer went crazy.
It started making some strange noises and it sounds like something in the dash is just going to break.
has anyone experienced this before?
what to do?

[vgwagon]

sounds like a binding speedo cable.
Either it's not lubed enough, to tight of a bend, or rust seized.

[datzenmike]

The auto cable should fit the dogleg, is this what you used? Which pinion drive did you use, the one in it? Undo the tranny end and slide the inner cable out. It should look like a tightly wound spring and be smooth, uniform and very flexible. If rusty then suspect a break in the outer sheath which will let in water and dirt. If you drive in freezing weather the cable will break from this. If the cable is frayed it will rub and catch on the outer sheath and momentarily hold as the cable behinds continues to turn and then suddenly release causing the needle to jump violently. For lube there is graphite powder or molybdenum disulphide.

[KaipoDa510]

Hi guys,
Thanks for the suggestions.
Yes, I did use the one from the auto tranny.
It may have a bit of a tight bend. I don't remember it being rusty, but maybe it needs more lube.
Is there a possibilty that I could have tightened it too much?
I will post a pic of what it looks like on the weekend.
I don't get much time during the week to work on the car.
Kids keep me busy.
Thanks again.

[KaipoDa510]

Hi Again,
I undid the cable at the tranny end. Looked at it and it looks okay. Not rusted or anything.
However there was a tight bend that I took out by re-routing it.
I took it for a test drive and the noise had gone away.
I did more unrelated work to the car and took it for a test drive again and the noise is back.
The needle is actually not jumping violently, but it is making this horrible noise behind the dash.
What to do?

[defdes]

I would make sure that it's fully engaged in the back of the speedo, pull it out lube and re install.

[qwik510]

I know that on the automatic 510s, there is a piece on the back of the speedometer that is not on the speedometer of the manual trans cars. I am not sure what it does but maybe this is the issue?

I have one at home I can take a picture of later if you need to see it.

[Byron510]

It really does sound like a binding issue within the speedo cable itself.
You said you took a look at the tranny end, did you pull the inner cable out of it's sheath? It's quite long, but I would do this, lubricate as mentioned above and thread the cable back into its sheath. Any binding of the cable will very soon lead to failure. If there is already damage or a kink, it may be too late. The good news is that Napa has (on year ago) s cable that is automatic length (without the speed switch on the firewall) for $35. Just in case.

Byron

[KaipoDa510]

Hi guys, Thanks for your help.
Well, I am assuming is fully angaged because the needle works and is fairly accurate.

Is there an easy way to get to the back of the speedometer under the dash. I tried yesterday, but gave up on that idea.

David, a picture would be great. Thanks.

I did not pull it out all the way to inspect it. Maybe I'll try that tonight. Is it easy to put back in and have it line up at the other end (under the dash).

In case it is damaged, do you know the part number I need to order it and from where I should order it.

Worst case scenario. I think I will disconnect it and use my GPS as a speedometer...LOL

[okayfine]

New or old cable? Hard to tell from the posts here. Either way, though, the lube advice is spot on. New cable has likely been sitting on a shelf for 20+ years. Old cable has gone who knows how long between lubrication.

If everything at the speedo was working fine before the swap, it is unlikely (but certainly possible) that something would break coincident with your swap, given what you've told us.

[KaipoDa510]

This is the old cable. The one that was used with the auto tranny.
It was working just fine before the swap. so it may be coincidental.

I will pull it and check it. Does it just pull out easily from the tranny end?

[okayfine]

The internal "cable" is a square flexible rod/springy thing. It rides inside the sheath (outer "cable"). It should easily pull out if removed from the car.

[defdes]

This is the old cable. The one that was used with the auto tranny.
It was working just fine before the swap. so it may be coincidental.

I will pull it and check it. Does it just pull out easily from the tranny end?

You can pull it out from either end, just remove both fittings first (tranny side & speedo side).

[datzenmike]

I believe it will only pull out from the tranny end as there is a small sleeve crimped on that end that locks it to the pinion drive. I don't think it is small enough to pull up through the sheath. The speedometer end of the cable is squared off and when inserted (from the tranny end) will find it's way into the speedo head, or will jump in once the car is in motion and the cable begins to turn.

IIRC The inline thing on the automatic cable is a speed sensor to indicate that the car is in motion for the emission switches on the carb and the retard set of points. Standards have a switch in the speedo head that operates at 10 MPH.