A curious issue

Hey everyone,

Its been flipping ages since I posted anything, so I thought Id make this one a doozy! The entire time Ive owned my Landy its had a very unusual speedo related issue. The speedo works as well as they do generally, needle stays still with no wobble, reads about -10% due to bigger tyres fitted but that's ok.

The issue is that its lazy. After about 5 mins on a dual carriageway/motorway (I live in Cornwall so have the former more than the later, but did once drive it to Bristol) the needle starts to head home to the lower end of the speedo dial. Eventually chilling out at about 25/30 mph once I've been going for 20 mins+

Its not the biggest issue as I normally have waze on which displays the GPS speed, I'm just absolutely flummoxed how its possible. The speedo cable is in good condition and turns freely and the dial in the dash works just fine most of the time, only dropping at speed and longer drives.

Any insight from the brain trust very gratefully received. (Picture for interest)

Sam

Wow! Excellent conundrum.

Logic (bits to look at):

1) worm that drives the cable, the big gear in the rear output casing on the transfer box.

Are there too many shims and as the box warms the clamping force on the worm reduces causing it to slow down?

2) cable.

Is it binding when it's warm?

3) clock

I never looked at one of these, but if 1 & 2 are eliminated, then send it off to be checked out. Or you could go clever and fit a digitalised original version. That takes a remote signal from a clever gadget fitted to the gearbox.

Hey man, thanks for the reply.

1) its had two different transfer boxes, both produced the same issue/result, so I think I can rule that out, also it is fine hot at lower speeds, only seems to be sustained driving at 50-60 that does it.

2) I think we are onto this now.

3) This is next (The get it checked replaced route, I've got a bit of a thing against digital/led stuff in series Landies, put a usb socket in the dash once and have to tape over it's infuriating blue LED)

Ill come back to the post once I've swapped the cable and let you know if it cures it

The way the outer cable attaches to the back of the speedo isn’t the best. This could be worse with a cheepo cable. I pulled a zip tie really tight, round the outer cable where it fits on the back of the speedo, to get mine working after it stopped one day. Basically the inner wasn’t quite reaching the speedo.
I did first order a replacement speedo cable but it didn’t even latch on the speedo. So took a few photos of the issue and they refunded me and I binned the new cable. Did my temporary fix 3 years ago now.

Oh yes. Britpart cables. avoid. Charlie ECU on eBay is supposed to sell good ones, no experience, mines original.

I'm in agreement with the over electronic thing. I do have a radio and a CB, that's plenty semi conductors for me.

If you want semiconductors buy a modern defender. If you want reliable semi conductors buy a Japanese built Toyota.