Speedometer Cable Discovery!

[1987 GMC Jimmy]

I’ve been diagnosing abysmal speedometer performance after a rebuilt speedometer and new cable. After a battery of tests, I found that the speedo was working much better with the 33 year old, worn out OEM cable. I noticed something very different about the two cables also. The original one has a large, crosshair shaped bushing on the end and minimal protrusion past that point. When the cable turns, it’s as straight as an arrow. It is also fixed in one place so it’s not relying on the speedo gear and speedo head to sandwich it where it’s supposed to be. The aftermarket cable can slip back and forth in the sheath like butter, and the bushing is so small in it that it does nothing, and the cable end flops around like a fish when it turns. I ordered an AC Delco cable, and hopefully it’s made the right way. My aftermarket cable is a Pioneer POS, but I’d watch out for the ATP and Balkamp cables as well.

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[Rusty Nail]

Good lookin out.

 

[yevgenievich]

I had new atp cable fail for those reasons within couple of weeks of use

 

[1987 GMC Jimmy]

Did you go with the AC Delco cable?

 

[yevgenievich]

Did you go with the AC Delco cable?

Just driving without a spedo for now

 

[1987 GMC Jimmy]

Alright. I’ll report back with the new one. Supposed to be here Monday. If it’s the same BS, I’ll have to make the old one work somehow, but if not, that’ll be good news. I’m expecting it to be made right, though.

 

[ali_c20]

Every time I changed my speedo cable the needle started to jump again at low speed after 2 weeks...3 different brands all without that crosshair bushing. no delco, one for sure was pioneer.

 

[Obwonkonobe]

I’m curious too, I lubed up my new cable and it bounces everywhere too, I’d defenatly buy a new one if this is the fix

 

[Battlac40]

Thinking about doing a digital display head unit. Broke all my **** 3rice over; stomping dodge d100's

 

[75gmck25]

I bought a replacement cable several years ago and somehow made it work. However, when I pulled the cluster to switch to a voltmeter (instead of ammeter) and LCD lights I could never get the cable to snap in correctly again. The cable had a larger knurled fitting with threads in it, like your picture, and the flexible clip on the cluster would not hold it tight enough.

I finally compared pictures online and found that the cable sold by Autozone looked like it had a different end that would really snap into the cluster and hold tightly. The cable from Autozone does not have the large knurled fitting, but instead has a smaller smooth fitting that flares out to a larger end.

When you push the new cable into the back of the cluster, the larger end goes past the spring clip and then the clip pops forward and holds tight against the smaller part of the fitting. It holds really tight and I don't get any jumping of the speedometer.

This was the cable I got for my '75 K25. I had to do a web search to find a place that had it in stock, but that wasn't really a problem. https://www.autozone.com/drivetrain...oneer-speedometer-cable/1667_0_7079_1277_6891

Bruce

 

[1987 GMC Jimmy]

The results are in. I was not optimistic about the AC Delco cable because, while it looked and felt better made, and the cable wasn’t flopping around everywhere inside the sheath, it wasn’t designed with that really stable end like the OEM cable. I didn’t want to reuse the old one out of fear of it seizing up on me this winter like the previous one despite my many efforts to lube it. I went ahead and tried the new cable and wow... You’d think the car had an electronic speedometer. The Pioneer cable was not only sloppy, but it was also seizing if the cable was at a certain angle, and it would max out at about 30-35 MPH regardless of speed. Total piece of crap, waste of money. So disappointed because the company is based in Meridian, MS two hours away from my hometown. I’m going to town tomorrow to see if I can collect my ten dollars and change back from whoever the hell I bought it from on grounds of defective trash. The initial tests show a lot of promise for the Delco cable, and I feel it was worth the $22 extra.

 

[1987 GMC Jimmy]

Just wanted to share some perspective on my cheapskate life. I went to Autozone to return the cable thinking that I could buy my meal for the day with the refund, got $9.62 back, and went a few blocks down and got a qtr. slab rib plate for $8.83. I guess in the end the ****** old cable was worth something.

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[CorvairGeek]

That's good to know.
Parts are such a problem now, especially when everything you own is obsolete, from defunct companies that spun off and bankrupted their suppliers first before their own pseudo/phony bankruptcies.
Good lunch! My lunch yesterday!

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[crpntr78]

I had the same problems as you all did, bouncy speedo, I changed out the junker thinking it was broken in some fashion but it wasn't. I too put an AC Delco speedo cable and now speedo works like it should. Made in Mexico but at least it's on the same continent!

 

[1987 GMC Jimmy]

Ahh, man. I’m jealous. The one in Tuscaloosa is one of the nicer ones I’ve been to. I’m glad you got to go, and I hope you enjoyed it. I miss being up that way. Hope things are going well with move-in, orientation, etc. Anyway, you’re right. I’m glad the Delco cable worked out. I’m sure the original one would have made it to where I’m at now, approaching 265,000 miles, had it not been poorly lubricated or been lubricated in the first place. I’ve removed and installed cables and clusters so many times now that if there was a pit crew position for that, I could do it. That 9C1 speedo is really sensitive compared to the civilian one, which really made the problems manifest themselves when I switched out the original speedometer.