hi. I'm working on the broken speedo in my 1964 Olds Super 88. It looks like the cable has broken at the dust cap end. Does anyone have a reliable source for a new cable?

I'm new to the speedometer cable repair idea - I have done nothing except for removing the dust cap to expose the cable end. now, do I just pull the cable out of the cable guide which ends at the speedometer at the dash and insert a new cable?

TIA

Robert

 

If the cable is broken, you can get a replacement cable and end most anywhere. If your ‘64 is like my ‘66 it’s a pretty simple system using the front left wheel to drive the cable at wheel speed.

The actual speedo spiral wound drive cable sits inside another spiral wound cable which you can think of as the housing. To have an accurate speed reading you want the inner cable spinning as freely as possible within its housing. The usual problem is that the inner cables break, or bind, or kink, or don’t have enough lubrication to spin freely. Or your dust cap nylon female fitting can snap. Fix these problems and your speedo will go another 50 years without too much attention.

First check the dust cap. In the middle you should see a nylon round pin with the center squared out to retain the square end of the inner speedo cable. It should be 1-1.5” long. If it’s shorter or snapped off, you have a replacement challenge. GM used these dust caps in many cars in the early-mid-60’s before they went to driving the speedo off the transmission. Check for dust caps for all the GM brands to see if you can find one that fits. Or hit up a classic junkyard and have them send one. It shouldn’t be too expensive. I’d guess <$50.00. In the extreme you can repair yours by retrofitting another nylon pin from a sacrificial wrong-size part.

Next take the whole cable system (inner & outer) off the car. At the speedo head end the outer cable just unscrews by hand. At the wheel end, you’ll need a 5/8” open end wrench, or maybe an offset one to wheedle the outer cable housing from the back of the drivers front wheel. This is a dirty job. Use gloves, patience, old clothes and time.

Once the cable is on your work bench, you’ll probably find part of it covered in plastic from the ‘60s’ and part of the plastic burned off from decades of exposure to exhaust manifold heat. This is normal. Next check the outer housing for kinks that could cause the inner cable to bind. If it’s got a severe kink, like where the A-arms have been going up & down for 60 years, you may be on the hunt for a new outer cable. I think there are companies that make these, but I’ve had trouble figuring out just how they measure ferrules, ends, tangs and so on. When in doubt, buy a replacement cable 1-2” too long, but not more than that.

If your outer housing is not badly kinked, blast a bunch of Brakleen through it to get the crud out. Then if you want, you can replace the burnt plastic for all or part of the outer housing with vacuum hose, split lengthwise then hog ring or zip tied in a spiral pattern around the outside of the outer cable. By reinsulating it, you have a chance at keeping replacement lubrication in for longer.

Then you go off to the auto parts store and get a replacement inner cable, cut it to the same length as your original making sure that you cut the not-squared off end... Crimp the speedo head drive tang on the top, then lube it up with whatever you like. I think I used Amsoil grease last time, but mainly you want the lube to be thin enough to almost pour in, but thick enough to stay in and not leak out too quickly.

If you do a search under “cfair” you’ll see a few posts I’ve done in the past few months that may have a few more tips.

Best wishes & good luck.

Chris

 

hi cfair and thanks for the reply. I'll have a look at the inside of the dust cap in the morning. I need to examine the cable end, remove the whole cable assembly from the car, and then follow your detailed instructions. a few questions. "the tang." is that a fitting on the speedo end of the cable? and it comes off and can be attached to a new, replacement cable? "a replacement cable from a parts store." do those come in standard diameters with standard squared ends?

my outer cable housing has no signs of wear or kinks. I wonder if the inner cable just came free from the hub "female end" and just needs to be reconnected. I'm guessing a mechanic who does not know the cable needs to be connected might just put the wheel bearing, castle nut, and retaining pin on after a brake job without connecting the cable. if that's the case, then I'll just lube it and reattach. fingers crossed.

thanks again.

robert

 

Robert
Happy to help. If the dust cap isn’t enagaging with your inner cable, that’s the beginning of the problem.

As valuable as these cars are to us, younger mechanics wouldn’t necessarily know that the dust cap needs to engage the squared off end of the speedo cable for the speedo to work. I wouldn’t be too critical personally. It’s not like I know much about magnetos, muskets, or steam engines either.

The inner cable has the squared off end which engages at the wheel. And, yes, the “tang” end simply crimps onto the correctly sized (cut) non-squared off end. Try to crimp the speedo head end tang centered and true. Otherwise your speedo may waver and drive you crazy. If you had your front bearings just regreased, there’s good chance your inner cable simply isn’t being driven by the dust cap. But if not, look at the inner cable critically for kinks. If it didn’t engage, it may have bent badly when it didn’t get put back right.

If I were doing it, I’d get the outer cable in place, bolted back onto the driver’s wheel, then slip an _uncut_ inner cable in just to get the length exactly right. What you’re looking for is complete engagement of the square cable end into the nylon retainer, but not have the inner cable so long that it binds on the inside of the outer cable from too much length. Getting that length just right probably means measuring the head end once the wheel end is firmly, completely in the dust cap, with the dust cap installed on the wheel. Then measure, cut it maybe .5” too long, just in case you need to do it twice and crimp the head end tang when you think it’s right. The replacement cables aren’t expensive, so don’t worry if it takes a try or 2.

If you really want to see how weird speedo cables can get, check out my posts on Perfect Circle cruise controls from the ‘60’s. Mechanical, arcane, and interesting.

Cheers
cf

 

hi cfair and thank you for the followup. I'll give it a go this morning. sounds like a pretty easy job if I don't have to crawl under the dash and remove the speedo end. if anything comes up I'll post on the board.

robert

 

If you’re going to fit a new inner cable, you’ll need to crawl under the dash, in my experience. You’ll be feeding the square wheel end in from the top. You could go the other way but you’d need to accurately precut the new inner cable and crimp the tang on in the car.

My preferred method for under dash work is to move the front seat back all the way put my head by the gas pedal or the transmission hump and have one foot on the ground. Sometimes I hook my right leg over the open front door just for comfort. Then I just use my right hand to feel around for the cable that is not a wiring hardness.

You’ll feel the speedo cable retention nut. Then it just unscrews front the rear of the speedo. Then push forward on the cable to dislodge the firewall grommet and make it easy to pull through the firewall for removal.

 

hi cfair. this turned into an excellent project. And super easy. I removed the speedo assembly from the back of the speedo as you mentioned. The whole assembly came out easily. I took the whole assembly over to the local O'Reilly's store and we measured the cable, end to end. After some computer time the sales guy went into the back and appeared with a box from Pioneer Automotive Industries. Part #CA-3002 The cable inside the housing is a perfect replacement. It's exactly the right length with squared ends and tang in place. Incredible. Turns out the dust cap bits were undamaged. After inspecting for kinks and other issues, we sprayed some graphite in the old cable housing, ran the old cable thru to clean the old housing, inserted the new cable, and Done!

My guess is the CA-3002 is actually made for one end to be attached to the transmission. Both ends are the same with speedo cable retention nuts as you described.

The whole project cost less than $10 and your instructions and support made it happen easily.

Thanks again
Robert

 

Robert
Very glad to help. In the set of all Oldsmobile projects, the speedo cable is a particularly satisfying and light duty one.

After all these years, it’s really fun to get an easy one, no?

I wish you equal success on your other projects.

cheers
chris