Correct Speedo Required

[John Roach]

Hi,

Anyone happen to have a proper Stage 1 speedo surplus to requirements? Should have "1376" along bottom of face (info found on this site!).

Regards,

John

[sebking]

Ask Glencoyne

or contact

http://stores.ebay.co.uk/Landrovering-L ... %26otn%3D4

he's breaking a few

Seb

[John Roach]

Many thanks...will check them out.

Regards,

John

[Bumpkin]

John
What number speedo do you have. 1408 is also LWB.
Tel

[John Roach]

Hi Tel,

I have a "1408", which I thought to be a standard LWB speedo, and am sure its reading significantly under...confirmed with tacho showing about 20 miles less than satnav on a journey of 168 miles. Wouldn't the fact that Stage 1's have different diff ratios to standard 109"s mean they required a different speedo?

Many thanks.

Regards,

John

[Bumpkin]

Right then. Just to add to the confusion, i have had a look down the workshop.I have a dash set removed from a Stage 1 Station wagon with a 1376 speedo and a dash set from a late SWB Series 3 also has a 1376 speedo.I like to keep all my stuff relating to the Stage 1s. Looks as though you can broaden your search though to include late all late Series 3s which had 750 tyres.That will make one easier to find.Someone with more teck knolage will be able to tell you about the diffs relating to the speed. I thought it was the tyre size that goverened the speedo type.Earlier SWB SEries vehicles had 600/16 tyres whereas the LWB always had the 750/16. 1408 may be an early LWB speedo, as early SWB speedos ranged from 1500-1536.
Tel

[Andy Dawe]

Bumpkin you workshop sounds awesome. Full of treasures............

[John Roach]

Having done some research have learnt that the four digit number represents the turns, or revs, per mile...in other words a 1376 speedo requires 1376 turns of the cable for it to register exactly one mile. There are several variables to consider before being able to determine whether or not a correct speedo is fitted: tyre size, diff ratio and speedo drive gear ratio (the ratio between speedo cable and propshaft turns). There is a formula to calculate the required TPM for any vehicle:

TPM = (inches in a mile/circumfrerence of tyre)*(diff ratio/speedo drive ratio)

One should use the rolling circumference of the tyre (at correct pressure), rather than simply calculating from the tyre size. Do this by measuring either the distance from the centre of the hub to the ground then 2*pi*r or how far vehicle moves with one complete revolution of a (rear) wheel.

Also, found this company http://speedograph-richfield.com For a small fee (but more than a secondhand Series speedo!) they can recalibrate any Land Rover speedo. They give instructions on their site regarding the info required to do this...how far vehicle moves for one revolution of speedo cable, I think. This does mean that any speedo of unknown history may have been recalibrated, therefore not corresponding to its original TPM number. I am told that if one is sure what the correct TPM of a speedo should be then no other info is required.

Phew!

Regards,

John