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Speedo head woes

Extreedoc

Extreedoc

Big Landy Fan
The speedo just gave up the ghost on my 1978 109. First it started oscillating over a ten MPH range, then later it wouldn't run past 40 MPH, now, it oscillates wildly and won't run past about 30MPH. I swapped it out for an 88 speedo head I have and that works perfectly, except of course, due to different gearing, it runs slow. I stripped the 109 head and can see no obvious fault and on testing it with an old speedo cable and my combi-drill running in reverse it worked perfectly. On reinstalling it, it was back to its old tricks. You might think that the problem lies with the cable or the gearbox end but if so, why does the 88 head work perfectly? I thought it might be due to a worn square where the cable enters the speedo head but the odometer works perfectly, just the speedo plays up.

Another anomaly: The 109 speedo head is marked as '1376' which according to my data should be for 900x16 tyres. My Land Rover is fitted with 750x16 tyres but the speedo reads accurately or at least it did before my current problem, this is the data I have which I acquired from this site years ago:
1376 for tyre 9.00x16
1408 for tyre 7.50×16 (235/85 r16)
1504 for tyre 6.50×16 (205/80 r16)
1536 for tyre 6.00×16 (205/70 r16)
Can you see any errors in the above data?

Any fresh thoughts would be welcome, I am thinking about getting the faulty head refurbished; too fiddly for my old eyes to attempt. Can you name a good outfit for the job?

PS: I checked the gearbox output flange for tightness, it was tight, I rebuilt this gearbox a few years ago.
 
Bugger, I just gave a 109 Speedo head away!

That's no help to you though. I think the magnets get weaker over time, and the only company I have heard of that repair them is

Gauge Repairs & Conversions - Speedometer Repair | Speedy Cables

Gauge repairs, restorations and conversions for speedometers, tachometers, monitoring gauges, fuel, pressure, temperature and clocks.
speedycables.com speedycables.com

But, I know they aren't what their name suggests, as they take a while. About £150 iirc.
 
Thanks to those who replied, I will keep these companies in mind. Actually there has been a further development: This morning I refitted the 88 speedo and while it works ok it seems to have developed a slight oscillation, not as bad as the other head but enough for me to suspect a problem. So, now I am wondering if the cable is the problem. I know that cables can cause oscillation so perhaps I should try a new cable before anything else. I've heard bad things about Britpart cables with badly made square ends; have things improved or can you suggest a better brand of cable? Speedy Cables could probably help but until I can be sure that it is the cable, I'd prefer not to spend too much.
 
The more I think about it, the more I think that mine is the wrong head. Mine is definitely a 1376 for 900 tyres. I need a 1408 for 750 tyres so there doesn't seem much point having this one refurbished. I need to find a 1408 and hope for the best. Keep looking on ebay it is then.
Just ordered an OEM cable from Paddocks
Thanks for the replies, some useful contact info there.
 
Here's some info I gathered on the Smiths speedometer part numbers used by Land Rover.
(If your vehicle has 3.5 diffs it's going to need a 1000tpm speedo or Defender speedo).

Hope this helps XX
 

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Big Sandy said:
You may find that arrives in a blue bag. A lot of their 'OEM' stuff does. You can't trust those three letters any more. I hope you can prove me wrong.

My last was from X mod too. It was spot on.
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You might be right Sandy but I remember the tale of your propshaft, blue bag but GKN shaft if I remember correctly? X mod cables are sold out...

Mr Stein: Thanks for the info, that goes straight in my Land Rover file. Do you know if the Defender speedo will fit in the hole and the cable from the series fits?
 
Just had a rummage in the instrument box whilst out in the shed and I have a 1376 from the S3 swb I broke up a few years back. It was running on 205x16 tyres - just checked one of the old wheels I have. It looks, from the label on the side, as if it was a replacement at some time. I had a quick 'twizzle' with a nail up the spout and it seems to work. I would gladly post it to you to see if it solves your problems - if you want to keep it then we can agree a nominal cost or you can send it back. The reason its a bit rusty on the back is that some vandals smashed all the window glass a few years before I got the vehicle from where it was laid up in PO's woodland camp. Facia is in really good nick. PM me with your address if you are interested.

20240904_193231.webp 20240904_193240.webp 20240904_193252.webp
 
Grid Man said:
Just had a rummage in the instrument box whilst out in the shed and I have a 1376 from the S3 swb I broke up a few years back. It was running on 205x16 tyres - just checked one of the old wheels I have. It looks, from the label on the side, as if it was a replacement at some time. I had a quick 'twizzle' with a nail up the spout and it seems to work. I would gladly post it to you to see if it solves your problems - if you want to keep it then we can agree a nominal cost or you can send it back. The reason its a bit rusty on the back is that some vandals smashed all the window glass a few years before I got the vehicle from where it was laid up in PO's woodland camp. Facia is in really good nick. PM me with your address if you are interested.

View attachment 545937 View attachment 545938 View attachment 545939
Click to expand...
That should be the correct speedo for a 109" or 88" on 750 tyres (or equivalent) with standard 4.71 ratio diffs :)
 
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Grid Man said:
Just had a rummage in the instrument box whilst out in the shed and I have a 1376 from the S3 swb I broke up a few years back. It was running on 205x16 tyres - just checked one of the old wheels I have. It looks, from the label on the side, as if it was a replacement at some time. I had a quick 'twizzle' with a nail up the spout and it seems to work. I would gladly post it to you to see if it solves your problems - if you want to keep it then we can agree a nominal cost or you can send it back. The reason its a bit rusty on the back is that some vandals smashed all the window glass a few years before I got the vehicle from where it was laid up in PO's woodland camp. Facia is in really good nick. PM me with your address if you are interested.

View attachment 545937 View attachment 545938 View attachment 545939
Click to expand...
Thanks Gridman, that's a very kind offer; can I get back to you if the new cable doesn't cure the problem?
I really don't understand why there are so many 1376s around, so many of the ones for sale on ebay are 1376s, Why? There aren't that many 1 ton LRs around, how many Land Rovers do you see on 900x16 tyres? Anyway, thanks again, the speedo cable came today and I'll be fitting it in the next few days and I'll report on the results shortly after.
Mr Stein said:
That should be the correct speedo for a 109" or 88" on 750 tyres (or equivalent) with standard 4.71 ratio diffs :)
Click to expand...
Not according to the data I posted above but there's something wrong somewhere...
 
Extreedoc said:
Mr Stein: Thanks for the info, that goes straight in my Land Rover file. Do you know if the Defender speedo will fit in the hole and the cable from the series fits?
Click to expand...
The Defender speedo will go in and the cable will fit if you trim a bit off the end of the speedo cable connector.
However it will only read correctly if you have 3.5 diffs and 750 tyres.
 
Extreedoc said:
Thanks Gridman, that's a very kind offer; can I get back to you if the new cable doesn't cure the problem?
I really don't understand why there are so many 1376s around, so many of the ones for sale on ebay are 1376s, Why? There aren't that many 1 ton LRs around, how many Land Rovers do you see on 900x16 tyres? Anyway, thanks again, the speedo cable came today and I'll be fitting it in the next few days and I'll report on the results shortly after.

Not according to the data I posted above but there's something wrong somewhere...
Click to expand...
The data I got was from the Smiths Jaeger website.
 

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