Jumpy Speedo

ed4ferrets · Post by **ed4ferrets** » Sat Aug 19, 2006 9:23 pm

I know this is a common (damn annoying) affliction but what causes it? Is it the cable which can be remedied or is it the speedo itself? The speedo in my 200k+ BX is rock solid but the other one is all over the place

DavidRutherford · Post by **DavidRutherford** » Sat Aug 19, 2006 9:28 pm

It's caused by a duff speedo cable.

What happens is that if the car is left for any period of time, the inner develops a "set" in it where it goes round corners. (the inner becomes a bit bent) This induces whip in the cable, as it always wants to sit in its "set" position, so as you're driving at a continuous speed, the cable jumps out of it's comfortable position, and snaps round 360deg back to its comfortable position.

Once started, it can only get worse, as when the car is parked, the speedo cable will of course tend to sit in its "set" position, thus the bend can only get worse.

The only cure is a new cable, and not leaving the car parked for extended periods of time.

ed4ferrets · Post by **ed4ferrets** » Sat Aug 19, 2006 9:38 pm

That's good news, I was thinking swapping speedo's which would'nt make much sense from a mileage point of view

cacaolat · Post by **cacaolat** » Mon Aug 21, 2006 1:32 pm

Hi, My BX has the same speedo problem, although it only has done 73k...

pinfold · Post by **pinfold** » Mon Aug 21, 2006 1:35 pm

Is it a big job to replace?

Dosnt bother me to much, but a bit dodgy going through a gatzo!

saint gaz · Post by **saint gaz** » Mon Aug 21, 2006 3:46 pm

It's not a big job as such, it took me about 40min to do last year.
Disconect from inside the engine bay, and pull old cable through the rubber gromet in the bulk head. I then got some insulation tape and taped the new cable to the old one. At the spedo itself once you have removed it just unclup the cable then just simply pull through. Be careful as there is not much space for the cables to run they go in between the heater duct's just take your time. Once through just simply remove tape discard old cable then conect new one. Then push the other end in to the gromet back in to the engine bay. and reconect. As a side note while you have the spedo out if you have any blown instrument panel bulbs now is the time to replace

pinfold · Post by **pinfold** » Mon Aug 21, 2006 3:50 pm

yes i have, all of them

hence my sudden interest!

DLM · Post by **DLM** » Mon Aug 21, 2006 5:39 pm

I recently replaced one and would suggest that the degree of wander has a lot to do with cable routing. On my most recent BX, the cable was jumping allover the place and making a lot of noise. End result: it broke. The previous BX (see "For Sale etc..") had rock-steady one. I was able to observe the following when chanfging the cable and using the rock-steady one as the "here's one somebody got right earlier" comparison.

(1) The rock-steady cable was routed behind the heater ducting on its way to the grommet which is the route into the engine bay, and which you find by removing the glovebox. Overall this route gives a series of gentle curves.

(2) The "jumper" had been routed round the front of the heater ducting, the end result being a couple of vicious bends and an overall s-shape.

Needless to say, the replacement cable went round the back of the heater ducting.

Oscar · Post by **Oscar** » Tue Aug 22, 2006 4:05 pm

My speedo cable broke on my first BX. I ran it for two years, including MoT, without a cable.

Luckily the rev counter was working, which served as a guid i.e. 2000rpm in 3rd = 30mph.

My only worry was that I'd get a tug and the copper would notice that the trip meter was at zero. I'd reset it hoping that this would magically make the speedo work again.

Oh well, you live and learn.

Oscar

Geoffrey Gould · Post by **Geoffrey Gould** » Tue Aug 22, 2006 8:38 pm

Hi mine does the same thing even at 10 mph. I have a horrible feeling that the dash will have to come out as it is impossable to move the cable by pulling at either the speedo end or glovebox end. It is as far as I know the original and seemes to be clipped.
I was thinking (difficult) and havnt actually looked properly (therefor its possible that I'm talking a complete load of bo**ocks.) would it not be possible to drill a hole through the bulkhead inline with the speedo as this would mean only one bend, which could be quite gentle. Will see.
Cheers.
Geoff.

Post by **docchevron** » Wed Aug 23, 2006 1:56 am

They aint to bad to change. My valver was a pig (not helped ny having to the job twice since the top cable GSF provided didn't work

) but never taken long in any other car.
The routing has alot to do with how well the speedo works (and how accurate it is).
It was a bit of a botch from the design stage, i.e. it's patentley obvious the car was intended for left hand drive and designed as such.
You dont find many left hookers with crap speedos!
I feel a move to the algarve coming on

Cheers
Chris G

sleepy0905 · Post by **sleepy0905** » Wed Aug 23, 2006 8:12 am

Did the cable on my previous BX but it still had a little wobble on the speedo so i just lived with it .

DLM · Post by **DLM** » Wed Aug 23, 2006 1:55 pm

I have a horrible feeling that the dash will have to come out as it is impossable to move the cable by pulling at either the speedo end or glovebox end. It is as far as I know the original and seemes to be clipped.

Dash out? Only maybe.

If the old cable won't move then it could be popped off the speedo end, pulled through the bulkhead at the glovebox end, and I wouldn't be at all surprised if a new cable could be threaded through next to the old one, leaving it harmlessly in situ.

Geoffrey Gould · Post by **Geoffrey Gould** » Wed Aug 23, 2006 2:06 pm

Thanks DLM I tried very hard to shift the cable when the speedo was out for bulbs and things also when the glove box was out to replace the fuse board (burnt) it did not want to move at all, I could feel the cable actually stretching as opposed to moving. I guess leaving the old one in place may well be an option, there sure as hell dosnt seem to be much room in there.
Cheers.
Geoff.

Vanny · Post by **Vanny** » Wed Aug 23, 2006 2:49 pm

So here's the thing, i always thought the speedo issue was caused by wear in the upper cable (and pretty much confined to RHD cars) as a result of vicious bending in the cable. I've seen these things correctly routed before and as mentioned they should go off towards the rear of the heater unit and reduce the degree of bend before connecting to the console, so i thought as i was having the dash AND blower unit out i may well have a go at changing the cable. Bought a brend new Citroen upper cable (very different to the older style one and much easier to remove from the console, squeezy clip), however its made not the blindest bit of difference!

So i guess the bottom one can seize up withing the outer sheath and cause a similar problem, but could it be caused by the worm drive? I've got a couple sitting about so no problem to change it (i even have a digital one!) but it seems so simple that i can't imagine a way that it could possibly cuase a fault (i mean the worm runs dirrectly from the diff, straight through to the cable, theres not really any give or way for it to go wrong is there?), any body experienced a problem worm drive?

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