Speedo fault

[Rustyoldjcb]

Hi!

Just noticed that the speedo in my F4 is stuck on 10mph when stationary and does not move when driving. Is this likely to be a fault with the speedo unit or some where else?
Thanks!

 

[Andy McGhee]

The cable might be broken - it'd be worth disconnecting it from the back of the speedo; if you then hold the end in one hand while edging forwards, you'll feel if the cable is turning.

 

[Rustyoldjcb]

The cable might be broken - it'd be worth disconnecting it from the back of the speedo; if you then hold the end in one hand while edging forwards, you'll feel if the cable is turning.

Many thanks! I will certainly try that. Would that account for it reading 10mph stationary though?

 

[Andy McGhee]

It'd be a good sign if the needle drops to zero when you disconnect the cable. Let's hope it's just the cable - they're easier to find than speedos! (You probably know, but there are different lengths of cables for LHD and RHD vehicles).

 

[Rustyoldjcb]

It'd be a good sign if the needle drops to zero when you disconnect the cable. Let's hope it's just the cable - they're easier to find than speedos! (You probably know, but there are different lengths of cables for LHD and RHD vehicles).

Thanks!!!

 

[Rustyoldjcb]

It'd be a good sign if the needle drops to zero when you disconnect the cable. Let's hope it's just the cable - they're easier to find than speedos! (You probably know, but there are different lengths of cables for LHD and RHD vehicles).

Cheers! How does it detach from the speedo? Does it unscrew or turn and unplug?

 

[jcarruthers2]

Hi

It depends on the age of your R4/make of speedo. The earlier types generally have a metal screw on/off end piece and the later ones have a white plastic end piece which has two small lugs, one on each side which need pinching inwards to remove. However, if you want to diagnose if the issue is with the speedo cable. I find it easier to disconnect the cable at the gearbox end. 10mm spanner size bolt holding the cable in place in the speedo drive casing. Once off, grab the protruding cable inner with your fingers and rotate. Get an assistant to check the speedo to see if the needle is moving or not. If the needle is not moving the cable inner may be broken or seized up.

 

[Rustyoldjcb]

Hi

It depends on the age of your R4/make of speedo. The earlier types generally have a metal screw on/off end piece and the later ones have a white plastic end piece which has two small lugs, one on each side which need pinching inwards to remove. However, if you want to diagnose if the issue is with the speedo cable. I find it easier to disconnect the cable at the gearbox end. 10mm spanner size bolt holding the cable in place in the speedo drive casing. Once off, grab the protruding cable inner with your fingers and rotate. Get an assistant to check the speedo to see if the needle is moving or not. If the needle is not moving the cable inner may be broken or seized up.

Thanks! Mine is the later plastic type. I've been reading on here the horrors of the gearbox drive. Really hoping it's not that!!!!

 

[Rustyoldjcb]

Try as I might I just couldn't detach the speedo cable from the gearbox, so I unplugged it from the speedo and jacked the car up. The cable turns when the wheels turn, so the gearbox end is good (phew). That means the speedo is at fault, will remove and have a gander. If up the spout are there still companies that can repair them, or does anyone have a good second hand unit for a 1987 F4 please??

 

[Rustyoldjcb]

Speedo removed and connected to a drill. The needle doesn't move until the drill is at some speed, then jumps up to about 40 to 45. Clearly in need of attention. I suspect it will be cheaper to find a second hand one than get it repaired? The circuit ribbon on the back is starting to come apart too.

 

[angel]

The needle shaft may be tight on its bushings. If you feel competent enough, take the instrument cluster apart and spray a little WD40 there, working the needle back and forth until it it feels free.

 

[Rustyoldjcb]

Thanks! I repaired it in the end. The pointer was warped and rubbing against the dial face. It was only when the speed got up to around 50 that there was enough force to free it. Bending the pointer back with some heat cured it.