Salisbury Axles 371m72

Salisbury Axles

fact or fiction

by Andy Marshallsy Quite a few people understand the Rover axles found under most of our vehicles, yet when talking about the heavy-duty Salisbury axles, there is almost always a sharp intake of breath and folk lore seems to take over, with tales of woe such as ground clearance, weight, collapsible spacers and case spreaders. Some are true, some are nothing to be afraid of, and some can be worked around with a little imagination and planning. Why bother with a Salisbury axle anyway? Well you might not have a choice if you’ve got a 101,109 or a 110, chances are you’ve got at least one already. Some people like myself consider them an upgrade and have retrofitted them. Have you got a Salisbury axle? They are quite easy to tell apart from Rover axles, if you have a look at the piccie of my rear axle, you’ll see the (red) diff cover is a separate bolt on, whereas with the Rover axle, this is welded into the casting. There are of course many other differences, but to ID an axle that’s all you need to spot. Mine has been modified for increased ground clearance, so that’s one myth dispelled already

What about ‘Salisbury’ what’s that all about? Well that one is easy – they were made in 40

Salisbury, no not our local Cathedral City, but Salisbury in the USA. They were made by the Dana Corporation and are a variant of the Dana 60 axle that is held in high reverence by US off-roaders as the weapon of choice for tough terrain, big tyres, and even bigger horsepower. Of course Land Rover doesn’t make our life straightforward, and supply us with bullet proof axles, no, where is the fun in that. They lumber them with thin halfshafts and regular CV’s. That is unless you are lucky enough to own a 101, in which case they then play their trump card with drum brakes, 6 stud wheels, and weld the swivel to the axle housing, just to keep us on our toes. All of which can be overcome with upgrades ingenuity and sometimes a blindfold will suffice! So what is in a Salisbury axle then, and where does all this folklore emanate from? A rear axle is straight forward, they are all the same, just slightly different widths, and the later 110 versions come with discs brakes and not drums. They follow the same layout as a Rover axle, half-shafts and differentials etc. Unlike a Rover the differential is more of a a diff centre, and when removed doesn’t come encased in cast iron like a Rover diff. A front axle can again draw parallels from Rover axles, a differential connecting to half-shafts, and then onto CV’s or Hooke ts depending on the model. The strength in a Salisbury axle is in the differential, they are beautifully built and engineered, and this pays dividends for the heavy duty . With the diff pan removed you can see the www.shirelrc.com

ring gear, that the large circular gear that makes part of a matched pair of gears known as a ring and pinion. Also the very heavy duty bearing caps can be see either side of the diff carrier. In the picture the diff carrier is an ARB locker, which also explains the presence of the airline to the right hand bearing cap Case spreading Now is a good time to dispel the case spreading myth. It is quoted in the workshop manuals that in order to remove the diff, the case needs to spread, by a tool that looks like a medieval torture device. The reason for this, the diff is a force fit, by 0.125mm so as to load the bearings. The case spreader can spread the case a maximum of 0.5mm before the case is distorted and damaged!! There is an easy alternative however looking at the above picture, remove the bearing caps – they just unbolt. Pulling the half-shafts is essential too – even for the gifted mechanic – eh Mr Stringer. Put a ring spanner on a ring-gear bolt, the one near the top bolt of the left hand bearing cap, it will rest on the case pointing upwards. The diff-centre can then be levered out from the bottom right. This is surprisingly easy. I’ve removed three diffs, and they’ve all come out in less than 5 minutes, the stock diff carrier is easier because there are more places to lever from. www.shirelrc.com

Putting the diff centre in the freezer enables it to drop straight back in. But encouraging it with a piece of 2”x4” is also easily done. With the diff carrier removed the pinion gear is visible. What surprised me was the oil ways in the nose of the diff to keep the pinion bearings oiled.

Here is a close-up of the pinion, it’s on this shaft that the infamous collapsible spacer lives. The pinion is secured by a 1 ¼” nut that is torqued up in excess of 300lb/ft That’s something like 3 times the torque of a wheel nut. Even if you are changing a pinion oil seal, you need to remove the nut and collapsible spacer. However is not a bad as you might think. If a long breaker bar will not undo the nut, my technique was the use a trolley jack to jack up the breaker bar handle – that will do it. 41

Replacement has a knack too. Brookies will sell you a collapsible spacer for about a fiver. Fit the spacer, oil seal, washers etc. Do the nut up, to take the slack out of the bearing races NB it has to be really bloody tight just to do this. When all the slack is out, you need to tighten it just a bit further to add some preload to the bearings. With the wheels off the pinion should be firm to rotate by hand, but not slack or need any leverage. I was checking this about every 1/16” turn on the pinion nut, at this stage the spacer is collapsing and adding preload to the bearings quickly, hence the fractions of a turn and checking, its worth taking it slow and careful, go too far, and the spacer is junk, and you’ll have to start again. That’s as far as most people will need to delve inside a Salisbury axle, and it’s just as well. I’ve gone further and changed gearing and fitted ARB’s. It’s not for everyone, but I’ll outline some of the issues. Replacing the pinion This will only ever be necessary if changing the diff ratio. Behind one of the bearing races are shims. You have to drift out the race, refit it with no shims. Then a dial gauge is needed to measure how high the pinion is in relation to the bottom of the bearing cap. There are then some calculations in the factory workshop manual which tell you what size shims you need. So you have to remove the pinion, drive out the bearing race, fit the shims, and reassemble it again. The dial gauge needs setting on a block 30.93mm high, just to make life even more complicated!! Setting the backlash on the gears It’s important for the gears to have an optimal patch for low noise and high strength. On a rover axle this is set with threaded collars. The Salisbury axle uses shims again. The bearings need to removed from the diff carrier (it’s a job for a good 2 leg puller). The bearing then needs heating to 200ºC (in www.shirelrc.com

the oven while the wife is out) to replace it easily. I am assuming you don’t have easy access to a 10 ton press. This is probably the point where Mark McFarlane is looking smug The diff is then refitted loosely. It’s slid from one side to the other – it will only slide maybe 1-2mm, this distance needs to be measured accurately, again with a dial gauge. There are maths in the workshop manual that tells you how to turn this measurement into the total size of shims required. Oh I forgot the pinion has to be out at this time. You then refit the pinion, and the diff loosely, and take this sliding measurement again, the measurement will be smaller this time because the ring gear and pinion will mesh. Again there are more mathematics which tells you which proportion of shims you need on the right and on the left bearing cap. Come on hands up who has got a calculator in their toolbox? Remove the bearings, fit the shims, replace the bearing, and throw it all back together. By this time – trust me you’ve had enough, and a seized weakened or noisy axle seems trivial, and it will be just fine, so no double checking happens, and it gets thrown back together !! So it is possible to build a Salisbury axle at home, but you’ll need to spend at least £50 on the average tool kit for the dial gauge and possibly a puller. I entitled this article ‘Fact or Fiction’ I wrote it with the opinion of fiction; because I have built a diff from scratch (rebuilt another and cannibalised a third). Yet having re-read the article I realised just how tenacious I’ve had to be, I’ve read the factory manual many times, as well as performing much crossreferencing with the internet, and the ARB fitting manual. So maybe there is something in this folk lore after all. 43