Reliability in Africa - Standard Salisbury or Limited Slip Differential?

[roamingyak]

Hi Everybody,

I'm well out of my knowledge zone here, so thanks in advance for your patience!
In short, I need to replace my rear Salisbury axle, as the casing has cracked twice now. The diff has been fine - 400,000km in Africa and no problems at all 😉

Given I need to replace it, and getting the existing diff swapped over to a new casing will be problematic, buying a completely refurbed Salisbury axle might make sense.

The Salisbury is considered extremely reliable I understand? Certainly my experience.

But before I replace like for like, is it worth looking at any of the Limited Slip Differentials and would they be equally bullet proof? Reliability is everything.
https://ashcroft-transmissions.co.uk/product-category/limited-slip-differentials/

I do get stuck a lot 😉
https://www.youtube.com/watch?v=NXH0Y8Qxsro

Cheers, Darrin

 

[Gazzar]

What terrain do you get stuck in? I'm getting a truetrac lsd for my salisbury, as it looks like it's best for my concerns, ice, snow, mixed traction circumstances. But a locker is the other option, which works for rocks and places where one wheel might be completely airborne.

Both are apparently as strong as the original carrier from Rover.

 

[roamingyak]

Mud and water - swamp and bogs etc. Normally a problem when the axle/chassis grounds.

Sand is usually ok,  I now have an exhaust jack which is brilliant - at the rear I have a flat tank guard bolted to the chassis so it works really well...
But water logged quicksand is a big problem.

But best not to get stuck at all if possible...

 

[Stellaghost]

Unfortunately any diff locking device will not guarantee not getting stuck in those conditions...

Regards Stephen

[Snagger]

The best option for traction is always tyres, but the opportunity to do something to get a more capable and reliable axle under your present circumstances does pose your very sensible question.

In terms of diff reliability, nothing you fit will be more reliable than a Salisbury maintained properly.  They are just about bomb-proof.  The biggest issues you are ever likely to have with the rear axle (other than brakes and wheel bearings, like any axle), would be worn pinion seals and seal land and a dented or torn diff pan.  However, you have been very unfortunate and broke the casing itself, which is not unheard of but comparatively uncommon.

The repair methods on the other thread are your best bet by far for time, cost and also the quality of the outcome.  A replacement axle may already be bent or heavily internally rusted and weakened.  Proper deep welds and sleeving will give the strongest casing and at a fraction of the cost and inconvenience of replacement.

As for the diff itself, anything you substitute it with is likely to add capability, but at the cost of complexity and thus reliability.  A full locking diff would be the most appropriate for your use and location, without shadow of a doubt.  I’m a big fan of ATBs, but you will get much more positive traction in that environment from and on-off locker.  Which is up to you, but my gut instinct favours electric solenoid systems over air as they are less prone to leaks and require a lot less maintenance (no seals on the actuator to worry about).  It will still not have the simplicity of an open diff, and so will have a little more potential for failure, but should it fail open, then you will be no worse off than with the Salisbury, and should it fail locked, then it will not be an urgent issue until you start driving on tarmac again.

So, replace the diff for capability, but not out of concern over reliability or ruggedness.  Having the axle repaired, you would be wise to remove the diff from the axle to prevent contamination or damage to bearings or gears and to allow thorough internal cleaning on completion of repairs, and replacing the bearings and seal with new would, of course, be prudent, but you wouldn’t need to touch the shims.  If you replace the diff while you have this obvious opportunity, then the pinion shims will not need altering or even checking, as long as new bearings are genuine Timken of the same spec, but the diff centre will need setting up with new shim sets for preload and backlash.  It’s not as bad as most tell you on a Salisbury, but it is not an insignificant task.

[FridgeFreezer]

1 hour ago, Snagger said:

The best option for traction is always tyres

That and reading the road / walking anything you're not sure about, and removing as much weight from the truck as possible.

@roamingyak from those photos you have basically got road tyres so you're always going to struggle. Good quality AT or MT tyres would benefit you way more than any other mod you could do.

Also in Africa you may not be able to get the correct gear oil that some LSD's require, which could be an issue - a standard axle will tolerate a lot of variation in type & quantity, an LSD may eat itself with the wrong type of oil.

[Naks]

The Aschroft ATB uses standard LR diff oil, so no issues there.

[roamingyak]

27 minutes ago, FridgeFreezer said:

That and reading the road / walking anything you're not sure about, and removing as much weight from the truck as possible.

@roamingyak from those photos you have basically got road tyres so you're always going to struggle. Good quality AT or MT tyres would benefit you way more than any other mod you could do.

Also in Africa you may not be able to get the correct gear oil that some LSD's require, which could be an issue - a standard axle will tolerate a lot of variation in type & quantity, an LSD may eat itself with the wrong type of oil.

Everybody makes mistakes when driving all day in those conditions, checking each 20 metre long puddle would mean you'd be there until 2087 🤣 😉
The few times I have got stuck in about 400,000km in Africa is usually when I'm exhausted (ie: 1 coke for breakfast, no lunch, 11 hours of driving, 38 degrees, humid etc) and make a mistake... it's part of the deal, we are human, not driving robots 🙂

Nope, they are Goodyear Wranglers AT's. Good tyres, but in the clay and black cotton soils of Africa all tyres becomes slicks quite quickly I find. They work better when you're not grounded and there is something to get traction from obviously 🙂

Good point about oils thanks - need to stick to Castrol EP90 in all axles and diffs so I only need to carry one set of spare oil for them.
 

[roamingyak]

2 hours ago, Snagger said:

In terms of diff reliability, nothing you fit will be more reliable than a Salisbury maintained properly.  They are just about bomb-proof. 

The repair methods on the other thread are your best bet by far for time, cost and also the quality of the outcome.  A replacement axle may already be bent or heavily internally rusted and weakened.  Proper deep welds and sleeving will give the strongest casing and at a fraction of the cost and inconvenience of replacement.

As for the diff itself, anything you substitute it with is likely to add capability, but at the cost of complexity and thus reliability.  A full locking diff would be the most appropriate for your use and location, without shadow of a doubt.  I’m a big fan of ATBs, but you will get much more positive traction in that environment from and on-off locker.  Which is up to you, but my gut instinct favours electric solenoid systems over air as they are less prone to leaks and require a lot less maintenance (no seals on the actuator to worry about).  It will still not have the simplicity of an open diff, and so will have a little more potential for failure, but should it fail open, then you will be no worse off than with the Salisbury, and should it fail locked, then it will not be an urgent issue until you start driving on tarmac again.

So, replace the diff for capability, but not out of concern over reliability or ruggedness.

Thanks a lot for the considered reply. 
I forgot to add I have found a good axle casing to replace my old one with and somebody who can replace the diff professionally - they do all of the diff's, gearbox and transfer boxes in Namibia (British trained etc) and have the cleanest workshop in Africa 😉

Allow me to ask a dumb basic question:
If a LSD or locker 'fail' do they explode into pieces and stop the diff/axle rotating any more than the Salisbury would?
I can remove the prop shaft and half shafts and still drive in 2WD?

"replace the diff for capability, but not out of concern over reliability or ruggedness"
Key question for me then- how much more capability would either a LSD or Locker give me, and in what circumstances?
Appreciate it can only be a rough stab in the dark percentage  - but I'm guessing it doesn't add up to be worth it considering the increased price and reduction in bullet proofness of the Salisbury?

[FridgeFreezer]

45 minutes ago, roamingyak said:

I can remove the prop shaft and half shafts and still drive in 2WD?

You can do that with any diff - if nothing's connected to it it's just a dead weight.

I find I mostly use my rear locker on climbs especially where you may lift a wheel in the air / drop a wheel in a hole. In your situation (stuck in a zero-traction slick muddy puddle) I would not be sure that a locker would make a big difference - zero traction is still zero traction even if you could lock all 4 wheels you may not move any further than you're already getting.

Putting a locker in also allows you to break things more easily - you now have the ability to send 100% of the power to one rear wheel via one half-shaft.

[elbekko]

4 minutes ago, FridgeFreezer said:

You can do that with any diff - if nothing's connected to it it's just a dead weight.

I find I mostly use my rear locker on climbs especially where you may lift a wheel in the air / drop a wheel in a hole. In your situation (stuck in a zero-traction slick muddy puddle) I would not be sure that a locker would make a big difference - zero traction is still zero traction even if you could lock all 4 wheels you may not move any further than you're already getting.

Putting a locker in also allows you to break things more easily - you now have the ability to send 100% of the power to one rear wheel via one half-shaft.

Lockers also allow you to stay floating on swamp. Otherwise, it's easy to dig a hole through when a wheel starts spinning. That's how we sunk Mouse in Russia.

Lockers, a winch and a bunch of extension line are your friend. And a lot lighter and less bulky than a ground anchor. Winch reliability is mostly maintenance - give it a workout every service and you'll be less likely to be unpleasantly surprised when you need it.

[uninformed]

My preference for a rear locker in your Sals are , in order 

 

Jac McNamara,  then ARB. If Ashcroft did an Ashlocker for the Sals that would replace the ARB.  The ATB won’t help you much in your situations 
 

Re oils, you might want to do a bit more research for your climate, and I’d advise that the optimal oil won’t be the same as the front diff. 
 

 

[Snagger]

The four diff gears are all inside an enclosed carrier with two hefty cross pins, and each is twice the size of the two cheap diff gears and single cross pin in the open sided Rover diff, and the steel used in the carrier of the Salisbury is much thicker and of higher grade than the soft and thin casting of the Rover diff.  Honestly, to damage a Salisbury diff takes a tremendous amount of neglect and abuse.  As long as it has oil, you will not break it.

If you rebuild the other axle casing with you existing internals, leave the pinion bearing shims that are already in that axle, but keep the diff centre/carrier bearings that are on your current diff.  You would be very wise to run a mesh pattern with Prussian Blue to ensure correct mesh, but if you keep those shims as they are, even with new bearings, then it is 99% certain to be correct already - the tolerances in machining the casing and diff carrier are very small. Sleeving the replacement casing is still recommended.

The increase in vehicle capability by fitting an ATB (Ashcroft recently started making these for Salisbury, and you can also get them from Quaife, but I can no longer find them from Eaton) would be considerable.  For Africa, a full locking diff would be significantly better still, but is more effort to fit because of the control mechanism and controls and is more expensive.

Your front diff is the transmission weak point.  Ashcroft , Eaton (Trutrac) and Quaife all make ATBs for those axles.  Those diffs will vastly strengthen the front transmission and will also significantly increase vehicle capability.  Locking diffs are available for front axles, but they make steering difficult, even off road.  Be wary of spline count on the shafts - your early axles will have 10-spline shafts, which will be catered for by Eaton and Quaif, but Ashcroft only make a 24-spline ATB, so you’d need their special half shafts, which spare also much stronger than the type you currently have.  But for your use, I think the Eaton or Quaife with existing shafts would be fine.  But since most load and drive goes through the rear axle, if you do want to upgrade to any special diff, but budget limits you to one only, do the rear first.

I’d stick with EP90 in both axles if you can get it.  LR changed spec to W75 on later Defenders, but that is because EP90 is very hard to find in many markets and because in Arctic conditions, EP90 is a bit too thick.  It does offer much better abrasion and wear damage than W75 - the stench and the brownish deposits from EP90 are sulphurs, and that is what protects the metals.  Put a drop of W75 on an anvil or vice and hit it with a hammer, then do the same with EP90 and notice the difference in sound and splatter.

[miketomcat]

I've never run lockers (with the brief exception of Ladoga and that was rover diff) so can't really comment.

However my opinion and take on things is any long distance travel requires the strongest standard fitment item you can use. Anything aftermarket can be a problem when it breaks especially if it can't be replaced with a stock item. Both my trucks are daily drivers the 110 has a stock untouched Salisbury that is 40 years old and around 170k. The ibex I could of fitted any axle I wanted. A rover axle would mean lots of upgrade options. I figured a Salisbury was bomb proof as standard, yes fitting a locker later has distinctly limited options but so far I haven't felt the need (or been able to afford it ).

Mike

[Snagger]

I agree.  I suspect the ATB I have bought for my 109 is not as robust as the Salisbury it will be replacing.  I don’t know how great the difference in strength is, but I suspect it may be quite large.  However, I’m confident that the ATB is more than strong enough for most 110s and 130s, the comparative Salisbury having been so heavily over-engineered.  As for the front end, I know from persistent diff failure on a TDCI that the Rover diffs were rubbish, especially the late ones, so any ATB or locker would be an enormous increase in robustness.

[FridgeFreezer]

2 hours ago, miketomcat said:

However my opinion and take on things is any long distance travel requires the strongest standard fitment item you can use.

This, this, 1000 times this!

Stronger parts that interchange with standard ones are fine, but anything that means you can't throw a standard part back in its place if it breaks is going to bite you.

@Snagger I'd challenge your statement that the front diff is the weak point & fitting an ATB to it would make a big difference, front lockers don't see much use in my experience and @roamingyak is not exactly doing the sort of hardcore off-roading where it might really help - being stuck on a flat slippery / soft / rutted mud road you're gaining very little by being able to send power to the one remaining front wheel that might have a tiny bit of traction. With centre & rear locked if you're still not moving you're probably not going to be saved by a front locker.

Following miketomcat's excellent logic I would be fitting the strongest version of a front diff (a pegged one from Nige probably) that will go with your standard shafts IF you needed to replace the front diff. The fact that in 400k roamingyak has not mentioned any major issues with breaking shafts etc. suggests the drivetrain is within its happy limits - small tyres and soft ground probably help that - so throwing thousands of pounds at the drivetrain is a waste. Likewise standard salisburys pretty much last forever barring the odd pinion bearing every 20 years or so unless you fill them with mud or something.

[landroversforever]

I think given the use case I'd stick with the stock open centre. If you've got a rear llimited slip of any type, it's going to get you further into the mire before you stop making recovery harder.

 

[Snagger]

4 hours ago, FridgeFreezer said:

This, this, 1000 times this!

Stronger parts that interchange with standard ones are fine, but anything that means you can't throw a standard part back in its place if it breaks is going to bite you.

@Snagger I'd challenge your statement that the front diff is the weak point & fitting an ATB to it would make a big difference, front lockers don't see much use in my experience and @roamingyak is not exactly doing the sort of hardcore off-roading where it might really help - being stuck on a flat slippery / soft / rutted mud road you're gaining very little by being able to send power to the one remaining front wheel that might have a tiny bit of traction. With centre & rear locked if you're still not moving you're probably not going to be saved by a front locker.

Following miketomcat's excellent logic I would be fitting the strongest version of a front diff (a pegged one from Nige probably) that will go with your standard shafts IF you needed to replace the front diff. The fact that in 400k roamingyak has not mentioned any major issues with breaking shafts etc. suggests the drivetrain is within its happy limits - small tyres and soft ground probably help that - so throwing thousands of pounds at the drivetrain is a waste. Likewise standard salisburys pretty much last forever barring the odd pinion bearing every 20 years or so unless you fill them with mud or something.

Given the carrier wear around the cross pin on the standard rear diff of the 2009 90 I had, at little over 50k with no towing or off-road use, that would shear the roll pin securing the cross-pin and cause it to slide out against the ring gear and hit the pinion, I stand by my remark that a Rover diff is a weak point.  Nige has made that same point often enough. As I said, I think the standard front half shafts would be adequate for what is being asked of this 110, so they would only be worth replacing if a 24-spline front diff was used.  But if replacing a Rover diff for something more robust, why would anyone use a 4-pin open diff when an ATB is similar money?  I don’t disagree that a locking front diff is not going to make a world of difference in this application, just as I haven’t pushed the case hard for a rear locker vs retaining the Salisbury.  It is inescapable, though, that the vehicle will have enhanced capability from them, and a front unit may enable a vehicle to climb out of ruts that would otherwise need a winch, so is not to be dismissed out of hand. 
 

My points have centred on the fact that the Salisbury is very rugged and reliable, and there will be no reliability improvement from swapping that rear diff for something else, but the front is the opposite case.  So, a rear swap should only be considered if unhappy with performance, while the front swap benefits performance and reliability.  Pegging would indeed make it better still.

[Daan]

If it were me, I would fit a 4-pin diff at the front (possibly P38 center, if that fits) and 23/24 spline Ashcroft shafts at the front, and the jack mcnamara manual diff lock kit (the one where you push the shaft in on the drive member) for the rear axle if you can find it. This keeps the parts mainly standard and removes the weak 2 pin front diff center.

You already have the early 23/24 spline 2522 CVs, judging from your drive members, so these are the strongest standard CV's. I doubt you break anything in this setup, perhaps a CV if you try very hard, but this is easy to swap in the field.

 

[uninformed]

A couple of points from Australia where we have somewhat similar conditions but maybe not the supply chain issues.

MaxiDrive was born out of remote outback touring and off roading on roads that were horrible, not competition. These upgrades were based on vehicles that ran factory size tyres or close there to. The idea was to create reliability in parts that were unreliable and failing. Their diff locks came about for the same reason. These greatly improved hemisphere strength and reliability whilst also offering better traction and in the hands of a sensible driver can reduce damage or fatigue done to other parts. 
 

Ashcroft essentially offer the same products.

Unfortunately there is no factory 23/24 front inner shafts. 
 

Im fairy certain the McNamara old manual locker is rear only (can’t see how it works through a CV etc) 

For remote touring I personally would not hesitate in upgrading the axle assemblies and in fact would hesitate to run anything factory. 
 

while my personal vehicle is being built more radically, it is still based on reliability in hot and rough conditions. 
 

At a minimum, and for simplicity, the OP could install an ATB in rear and a front 4 pin HD hemisphere, The ATB will be an improvement traction wise, but not that of a true locker.
 

I think his biggest concern is getting the rear housing sorted properly. 

Edited March 5, 2023 by uninformed

[Snagger]

Again, why fit an expensive 4-pin open front diff when an ATB costs the same and has similar strength?

For the rear, for the use this car has, a full locker would likely be better than an ATB - I think ATBs in the back end are better for driving on mixed surfaces with lots of moderate to tight turns, like European roads and lanes, but not for the long, straighter roads of Africa..  Neither is significantly stronger than the Salisbury, though, and May in fact be weaker and less reliable.

[uninformed]

Some people would argue that they could get a HD 4 pinion for cheaper or that an ATB in the front affects driving characteristics….

Personally I just use full lockers, end of story. For the OP I was trying to keep it simple. 
 

Regarding the rear , I already said my preference was for a full locker but apparently they are too complicated and unreliable for some 🤦🏻‍♂️… so again I offered the cheaper and more simple idea of the ATB.

The Salisbury hemisphere is strong but doubt it stronger than a Jac McNamara locker hemisphere. MaxiDrive used the standard factory fitted one so they are equal. ARB I personally would not run but the number of Dana 60 lockers being abused in the USA suggests they are fine. Unless the Ashcroft ATB is noticeably smaller in size I’m not sure it would be automatically weaker.

The only reason I would not recommend the MaxiDrive Salisbury locker for the OP is it requires cutting and welding of one of the axle tubes. Some aren’t capable to do it themselves and I can not say it won’t create a stress point given his current situation and the conditions his vehicle is used in. 

Pegging will only help crown wheel deflection and this seems to be the least of his problems, not to mention you have to machine the hemisphere CW support flange down to fit the support bolts.

But we can agree that anyone suggesting that the front differential is NOT the weak link in the OPs vehicle has rocks in their heads!

 

[Snagger]

I don’t see why my comments are being twisted into an anti this or that posture - they aren’t.  My comments about the complexity of a locker relate to DIY installation, with all the ancillary bits that go along with the diff, and the maintenance that is needed when the air seals start leaking (hence my preference for an electric solenoid locker), not the driver operation.  If you have a lot of mechanical experience and the facilities to install a locker yourself, then it’s not too bad, but if you have to pay someone to fit it, it all adds up to an expensive job.  It may or may not be worth the expense, depending on what the driver wants.  Their decision.  That is the full extent of my limited concern over their “complexity”.   Keeping the Salisbury avoids all of that.  I also said I don’t have concerns over the strength of the lockers or ATBs, just that the Salisbury is very strong, possibly a little stronger.  None of those comments have been negative.

[Nonimouse]

Some interesting comments above

On standard width tyres, a cross axle locker, in most silty/sandy/loose mud will get two holes instead of one. You need width for floatation and low weight.  It's the kind of mud you will get stuck in. Use aggressive tyres and you just go deeper.

Air down to 20psi and uses reasonable momentum. Enough to overcome the resistance of the diff pumkins against the centre of the ruts, but not driving like you stole it. Except that you are going to lose forward momentum and when you do, stop and reverse back, don't sit and dig. Look for witness marks of previosu vehicles. Walking might take time, but sometimes there's no option.

Strength/reliability is in the hands of the driver. The standard set up is fine, unless you drive hard. Use vehicle sympathy, this isin't a competation of a photoshoot

[uninformed]

3 hours ago, Nonimouse said:

Some interesting comments above

On standard width tyres, a cross axle locker, in most silty/sandy/loose mud will get two holes instead of one. You need width for floatation and low weight.  It's the kind of mud you will get stuck in. Use aggressive tyres and you just go deeper.

Air down to 20psi and uses reasonable momentum. Enough to overcome the resistance of the diff pumkins against the centre of the ruts, but not driving like you stole it. Except that you are going to lose forward momentum and when you do, stop and reverse back, don't sit and dig. Look for witness marks of previosu vehicles. Walking might take time, but sometimes there's no option.

Strength/reliability is in the hands of the driver. The standard set up is fine, unless you drive hard. Use vehicle sympathy, this isin't a competation of a photoshoot

I absolutely disagree with your first comment. As someone who has spent the vast majority of their off-road driving experience on factory size tyres, locker’s definitely help get through conditions that would leave non locked bogged and don’t lead to more digging if standard common sense driving is applied. One example I can share was the demonstration of a 100” coil sprung rig bogged to its axles in soft river sand (750-16 tyres) no forward or rearward movement just one wheel each end spinning sand flying, digging in. Lockers engaged, low 2nd and light revs and the vehicle slowly dug itself out. 
 

You are much more likely to lose forward momentum and start digging unlocked, regardless of tyre size. 
 

Id also argue that remote touring is more serious than competing given what being stranded can mean. Often no help, and far from resources. I’d not take those risks on some of the stock components here in our outback.