Faulty Speedo Cable Question

[keynsham1]

I have recently replaced my speedo cable on my RHD T25. As soon as I drove off, the needle flicked up and down like the cable was catching on something. I was very careful when I routed it and as far as I am aware there were no sharp bends. On further investigation, the cable seems faulty. If you hold it in a straight line and turn one end, it turns smoothly but as soon as you put any kind of curve in it, however small, as you turn one end, the other rotates in a constant jerky manner almost like it turns, gets, tight, and then flips round on every revolution. I took the speedo out nad I can replicate the issue when the cable has a curve but if I hold the cable dead straight, it is fine so it isn't the speedo!

Anyone else ever had this? I will need to replace the cable I guess as I think this one has had it even though it is basically new.

[Smiffo]

Can you drip some oil into it?

[keynsham1]

I don't think it would help. I think the inner cable might have a kink in ot somewhere. It is not impossible I damaged it when I fitted it. They are a bit of a bugger to get up through the dashboard and can get trapped with the spare wheel too if you aren't careful. 

On that note, does anyone know the proper routing for the cable under the van?
 

[maxstu]

Read Bigherb's comments as l feel this is correct. The cable should curve under to prevent water ingress.

viewtopic.php?t=159513

[keynsham1]

Read Bigherb's comments as l feel this is correct. The cable should curve under to prevent water ingress.

viewtopic.php?t=159513

I did see this but this cable is routed under the wire brackets on either side where the spare wheel will fit. I would have thought routing it over the top of those might be better? There doesn't seem to be a 'best' path!

[maxstu]

For what it worth, all four campers in 20 years have suffered speedo needle bounce, up to about 35-40mph, then clear. .
Get to live with it.

[slowcoach]

Yea it's all a bit rubbish like that

Sent from my Pixel 4 using Tapatalk

[TONYT25T25]

Mine only works in the Summer when its warmer, the milometer still ticks over adding the miles, but the speedo needle plays silly buggers, if I need to go on an extended journey I monitor the Satnav speedo on my phone App.

[DevonAid]

Looking at this thread with interest.
I thought I'd finally fix the noisy speedo cable and speedo bounce by replacing the cable; despite carefully routing the new one etc, it's now 3 times as noisy!
I can see in the link to an old thread the good idea of jacking up the nsf wheel and spinning it to see if the speedo end of the cable snags or is smooth.
Will try this when back from our trip.
Still not sure from the many comments if oiling the cable is a good one or not, though?

[keynsham1]

Werll I have just received my new speedo cable, and when you turn one end, it feels exactly like the old one! So I will fit it with great care, making sure it has a good route with no snags or sharp corners, and see what happens! I have been using an old phone with a speedo app on which is probably better anyway!!

[keynsham1]

So I bought a new cable and it is exactly the same. It seems to be the routing of the cable from the point where it comes through the bulkhead to the speedo. I cannot route the cable to align with the back of the speedo; it always comes downwards as it enters the speedo so kinks the cable as it enters , causing the clicking and kicking. If I drive and push the cable downwards as I drive (top off the dash) the noise goes and the speedo settles down, but the cable just cannot be routed in this manner.

Has anyone got any ideas?

[keynsham1]

I have fixed my speedo at last! There seems to be two issues when fitting a new speedo cable. Firstly. if there are any small curves or bends in the routing under the van, it makes the cable click as it turns, almost like it jumps 90 degrees at a time as it rotates. I found the best route was down the side of the radiator and over the coolant pipes and across the top of the two metal wireframes which locate the spare wheel. In this position, the cable rotates evenly. Next cut off the white reinforcing tube on the outer of the top end of the cable. It makes the top end too stiff and unable to bent properly, causing a kink where the cable enters the speedo.

It seems that the entrance to the rear of the speedo points down slightly but because of the brake servo, the cable route is limited enters the speedo at the wrong angle. After a lot of pondering, I eventually made a bracket to hook over and pull the cable downwards, held on by an existing screw location in the heater ducting, and ensuring the cable enters the speedo correctly inline

After a few hours, a lot of test drives and fiddling, I now have a steady needle and a quiet speedo!!

[cobblers]

The fault here is likely with your speedo itself.
All speedo cables will have a degree of "bounce" in their rotation, and the needle in the speedo is damped using what appears to be a silicone oil on the shaft. Over time this oil dries up and you lose the damping effect, so at certain speeds a resonance builds up and you get a lot of wobble.

[keynsham1]

Maybe, but the cable routing is what sorted out the issue. The way I routed it originally, it was literally rotating in 90 degree jumps.

[DevonAid]

I have fixed my speedo at last! There seems to be two issues when fitting a new speedo cable. Firstly. if there are any small curves or bends in the routing under the van, it makes the cable click as it turns, almost like it jumps 90 degrees at a time as it rotates. I found the best route was down the side of the radiator and over the coolant pipes and across the top of the two metal wireframes which locate the spare wheel. In this position, the cable rotates evenly. Next cut off the white reinforcing tube on the outer of the top end of the cable. It makes the top end too stiff and unable to bent properly, causing a kink where the cable enters the speedo.

It seems that the entrance to the rear of the speedo points down slightly but because of the brake servo, the cable route is limited enters the speedo at the wrong angle. After a lot of pondering, I eventually made a bracket to hook over and pull the cable downwards, held on by an existing screw location in the heater ducting, and ensuring the cable enters the speedo correctly inline

After a few hours, a lot of test drives and fiddling, I now have a steady needle and a quiet speedo!!

Appreciate you taking the time to report your findings - very helpful!
I don't suppose you took photos of this recommended cable route and cable support fixing location, that you could also share?
Thanks!