Rear Axles

[M S G Benning]

Are the above common to both Jup & Jav, or is there anything specific that tells you what to look for on one for a Jup? Steph.

[Keith Clements]

There are early and late axles on the Jav and a different one on the Jup. Although a Late Jav axle can be made to fit a Jup but it has a different ratio so will not be any good for motorway driving.

See the technical notes for details.

[M S G Benning]

So you can't tell by looks alone then? Meaning presumably they have to be taken apart for a teeth 'count'? Oh & the technical notes you refer to, where might they be found?

[David Morris]

Hi, if you are lucky, there should be a metal tab about the size of a postage stamp, secured by one of the bolts to the differential cover plate, giving the ratio of the axle. As Keith says, the Javelin ones have a different ratio to those fitted to Jupiter's.

Both are good old Salisbury units, fitted to lots of classics, especially early Series Landrovers. I did hear somewhere that Jowett's bought-in the differential housing, complete with innards, but fitted their own manufacture outer tubes and mounting lugs etc. Personally, I doubt this, as the outer bearings are taper rollers, adjusted by shims, which is a really good arrangement. When you look at the miserable set-up with ball bearings that Jowett fitted to the front wheels, they would have thought taper bearings on the rear axle were just not necessary? No, I suspect Salisbury gave them a price for the complete rear axle that made it look attractive. Jowett's probably then just welded on their 'bits' to fit the upper and lower arms?

All the best,

David

[richard turner]

Jack up one rear wheel.
Hand brake off.
Make a mark on elevated wheel rim.
Make a mark on crankshaft pulley.
Select fourth gear.
Ask your assistant to turn engine over and count the number of revolutions it takes for the watched rear wheel to complete one revolution.
The answer is the diff ratio.
The same may be completed on a removed axle with one wheel locked and turning the pinion.
Rich

[David Kemp]

Isn't there also a width difference between Javelin & Jupiter rear axles?

[richard turner]

The Jupiter has a wider track. I've never checked but I have wondered whether the axle tubes are pegged into the diff casing and whether or not they could therefore be extended to suit a Jupiter. Javelin axles do look odd when fitted to a Jupiter.