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LarryH57

Lwt Speedometer Repair

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Posted (edited)

The speedometer in my Lwt decided on the way home from WPR, not to work properly. It still counts the milage but the speed sticks at about 20mph until I go over 50mph when it sort of shows the right speed. In truth I know my speed by the noise it makes but I presume its needed for an MOT later in the year, though how they would know if it doesn't go on the rolling road to test the transmission (hand) brake is anyones guess!

I have been told it may be a broken spring inside it so before I order a new one, and remove the existing, is it possible to take a Lwt Speedo apart and mend it?  

The speedo I need has the lights in it for oil pressure, beam  and the choke.

Edited by LarryH57

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Have you disconnected the cable from the gearbox end and turned it to make sure the cable is good?

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Well thanks for the manual; presumably someone will sell the parts if the internals are broken.

As for the speedo cable I think it is good as the mileage still works and the speedo still flicks around on the speed - would it do so if the cable was broke. I assume it would just be dead?

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BTW - my speedo was in Km/h on the outer ring rather than MPH but I guess the standard arrangement would still read the correct speed?

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Posted (edited)

Abt.  1979/80  , L'wt changed to a kilometer clock - so Km larger on the outside + odo  =  Km.

Always check you have a genuine Lightweight speedo cable Part No. 579435 ,  IIRC the length difference is shorter to a civilian cable.  It is important that the curvatures are correct & the route is well off the front exhaust pipe.

Never use a non-genuine , a Britpart drive end is a triangular shape and does not work.  Always worth a check of the square Bowden drive at the gearbox speedometer housing - the securing plate (disc) is held by three cup head screws ISTR  2BA and access is not good.   A easier check is at the speedo head - the grey plastic bayonet fitting has a clip , undo and pull the bowden in case about to snap. Best to have assistant at gearbox end to turn, better still fit a new one & check the original off vehicle.  Springs !  don't believe it , by all means open up _ I did then taught myself how to clock a clock. 

It sounds to me like the air-gap has crud or lubricant from the drive cable (I have had that on a VW Beetle).  Basically the needle has a cup or disc on its spindle and it is driven by a rotating magnetic disc.  The correct air gap is very important - I normally spray it with electrical cleaning fluid.  You may find a needle spring (actually a coil hair spring) on the needle spindle - yes this could be busted or just cruded.

Edited by ruxy
spelin

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Thanks Ruxy,

The Speedo has been working fine for the last 14 years of ownership, so I suspect it might need a bit of maintenance.

I note prices for PRC 2605 are extortionate!

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10 hours ago, LarryH57 said:

Thanks Ruxy,

The Speedo has been working fine for the last 14 years of ownership, so I suspect it might need a bit of maintenance.

I note prices for PRC 2605 are extortionate!

I have only checked Craddocks price as a benchmark

https://www.johncraddockltd.co.uk/other/military/parts/instruments-and-cables/prc2605-speedometer-with-trip-series-3-600650-x-16-tyres-and-101-fcontrol-k-p-h.html

 

Actually ,  I don't consider it to be excessive in price , you may find cheaper at Paddocks,  Derbyshire LR   etc.

This will be a OEM from ISTR a firm in Wales that took over some of the interests of Smiths Industries.

Of course a  PRC 2605 in a "Genuine" Land Rover box would be extortionate - I dare not check it out (and I would expect a 40% counter discount at a franchise dealer).

Apart from that - lots of bits specific to L'wt are now extortionate, too many people wishing to re-build on a new chassis , thus far few being broken for spares.  A top $  L'wt needs to be kept Solihull original,  6.50 x 16 size tyres are still best, but only one manufactured looks good - just very expensive, competition needed..

 

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Ruxy,

As you know I still after some 6.50 x 16 size tyres to replace by Deestones

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1 hour ago, LarryH57 said:

Ruxy,

As you know I still after some 6.50 x 16 size tyres to replace by Deestones

http://www.northhantstyres.com/main-tyre-pages/sta-tyres/650-16-sta.html

 

For a show truck - this is all there is, correct size & look the part, presently available new - that I am aware of.   Can't be worse then the Goodyear Hi-Miler Extragrips that were manufactured in Morocco (in my experience the side-walls cracked out early) , the ones marked Made in Britain were better.

I also use  205R16 /  205 80R16 - choice hardly exists for a tread-pattern that looks correct.  

Just to make myself unpopular  -  never fit 7.50's  -  truly awfull.

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