How to fix your Jumpy Speedometer

[Negative Boost]

Alot of old cars have jumpy speedo's. In my MA61 when i used to reach 70km/h my speedo would jump from 66 to 72 to 69 to 75 while staying at a constant speed. The following is an easy inexpensive way to fix this problem.

1. You have to remove the speedo cable from your car. This isn't as scary as you think. You'll need to remove the cluster from the car to access the the speedo cable. Unclip the speedo cable from the back of the cluster. Now pop the bonnet and you'll see where the speedo cable comes through the firewall and pull the speedo cable through. You'll need to unscrew the cable from the gearbox and there's usually a couple of clips on the chassis holding the cable close to the body.

2. Once you have the cable out of the car, the actual speedo cable inside the speedo cable 'housing' can be pulled out. This is the actual cable, be careful with this as you dont want to kink it. Place your speedo cable into a pan. This is best done wound up. Then pour enough Kero over it to cover the cable. I left mine for a couple days in the kero before cleaning it but it should be fine after an hour to clean. You leave it in the Kero for a time to loosen the dirt and grime. Then grab an old stiff brush and carefully clean the cable by 'brushing' over it with Kero.

3. To clean the speedo cable 'housing' you can simply pour some oil down it. You dont need much but make sure oil comes out the other end. This is done best by holding one end of the 'housing' up in the air so the oil can freely run down and out the other end. The oil helps to flush out any dirt/grime in there and also lubricates the speedo cable, which helps the cable to freely rotate while working.

4. Put everything back together again, this is just the reverse process of taking it all apart. Take the car out for a drive and you should not see any fluctuations in the speedo anymore.

I used to get big fluctuations in my speedo at 70km/h. After cleaning the cable i dont see any fluctuations at all in my speedo Hope this helps a few people as i know it used to annoy the heck out of me especially when travelling over the 70km/h bridge here in Hobart with fixed speed cameras!

Sam

[ViPeR_NiPPleX]

oh fantastic. mine was bad at 70 too... i think they all are by now.

one thought, should the cable be greased up or will engine oil be sufficient for extended periods of time?

[Negative Boost]

Thats one thought i didnt have. When i pulled the cable out of the 'housing' it didn't have any noticeable grease on it. So i guess it should be okay. If it starts fluctuating again, i shall put some grease on the cable.
Anyone else's thoughts on this?

[LeeRoy]

The AE92 did it on my car but it turned out to be that the cable was seperating where it joins. However, it was also starting to be hard to turn so i think it was binding up a little and that was adding to it jumping. I bought another cable from a wrecker but i would imagine some grease like the stuff you use for wheel bearings would do the trick as it wouldnt run out and it would stay in there for a long time.

Anyways good write up
- LeeRoy

[allencr]

Remove the gauge cluster, or unscrew it from the gauge cluster. Pull out the cable, wipe it down, grease it lightly,
squirt a little oil down the outer housing, push the cable in, pull it out to inspect for dirt/grime/smegma and clean & repeat if necessary, push it in, turn it until it engages and goes in a little furter, reconect to gauge cluster.
It's a real waste of time to remove it(outer housing) from the body & trans.

[JustCallMeOrlando]

Looks like I have something else to do down the track, noq i'm into the non-spendy modifications

[Ribfeast]

Mine jumps around at low speed and improves the faster you go, but mine has a partly melted speedo cable casing at one point under the car so may not respond well to this fix. Great writeup though!

[Hydra]

Dammit Negative Boost, I cannot give you any more rep until I spead the rep around more!

[Negative Boost]

Lol, thanks for the comments guys. Thats alright Hydra, just keep me in mind untill you spread the love a bit more

[clubagreenie]

Another issue that eventually rears its head is, due to the way it's made, it will stretch. To check hold on end in each hand so the cable loops down. Twist one side and it should cross over itself immediately. If there is any delay then what will happen is the cable will store the rotational force then release it causing it to jump.

The cable is essentially a loong piece of thin wire wound around a core, at the ends it's pressed into its square shape. The cleaning method will remove any lubricant that is congealed inside and causing it to bind and jump while when its stretched then it's all over rover.

Instrument specialists can remake the inner cable a lot cheaper that buying original complete cables. just lube it, but not with oil. This eventually thickens up and you are back to step one.

[Negative Boost]

Awsome stuff mate. Looks like next time it will be greased up and not some oil or a new aftermarket item.

[v8supra]

One thing I saw my father in law do, is putting a few drops of oil down it and then connecting it to an electric screwdriver. It freed it up a lot and made it turn easyer (and stop jumping).

[v8supra]

Thinking about it more, I'm sure it was grease not oil. like wheel bearing grease

[CrUZida]

I fixed mine by removing it completely and replacing it with a digital sender.

Funnily enough she doesn't jump around anymore

[JustCallMeOrlando]

Tis all well and good if you want to install a new dash and trim it with carpet