Locking Diff question

[Anderzander]

I’ve never had an air operated locking diff - so a basic question: how quickly do they lock and unlock ?  I’m assuming there will be some degree of wheel rotation required for it to release and engage?

I’m asking because because when I was laning at the weekend I was wondering how it would work in a particular scenario:

On a very steep rocky hairpin, with a large rock on the apex and a big washout/hole in front of it - so when the front wheel climbed the rock and needed to go to full lock straight away, the back wheel was immediately dangling in the air. 

It struck me that a diff lock would have made the wheel hanging no issue - but it would need to disengage really quickly - once that hanging wheel hit the apex for the full lock turn ?

Don’t know if I’ve described that well enough to make sense ..

 

[Stellaghost]

My ARB locking diffs operate pretty instantaneously with regards to engaging and disengaging if wheels at front are turned the front locker may take slightly longer to disengage.

Obviously they need to be engaged before an obstical otherwise there is the chance of damage to the drivetrain if operated when wheels are spinning.

My vehicle turns great on loose surfaces with diff locks engaged, you would not have to disengage rear to complete the turn, the only difficulties come if all tyres have grip ie: on concrete or tarmac, mud and gravel are generally ok regards Stephen

[landroversforever]

Don't remember there being much of a delay to the operation of either my old ARB or later Ashlockers. Assuming you can let off the power (which you should anyway) they should unlock right away. As with Stephen, I never really found any issues turning with the rear locker engaged. 

[Escape]

My experience is the same as above, both with ARB and Ashcroft. Locking or unlocking without noticeable delay, certainly not comparable to the diff lock in an LT230. It's good practice to unlock the front in sharp turns (unless you really need the traction), a locked rear axle is no problem at all off road. Driving with the diffs locked on tarmac can be interesting, especially when they're not supposed to be on and you take a roundabout to find out they are on...

Filip

[FridgeFreezer]

25 minutes ago, Escape said:

Driving with the diffs locked on tarmac can be interesting, especially when they're not supposed to be on and you take a roundabout to find out they are on...

On the plus side, in the snow a rear locker enables fantastic donuts

Generally they engage in the amount of rotation it takes for the dog teeth to align, although as others have said leaving the rear locked is not an issue on most surfaces unless you're doing very tight turn.

[Anderzander]

3 hours ago, Escape said:

certainly not comparable to the diff lock in an LT230

Thanks - because that’s exactly what was in my mind as the only comparison I had.

[Chicken Drumstick]

As a different train of thought. An ATB would also likely have worked well in such a situation (maybe even if just in the front) and would require no user intervention at all for it to work.

[Anderzander]

If Ashcroft did 10 spline ATBs I’d be in there! 

[Hybrid_From_Hell]

Trutrac do 10 spline ATBs and also do different poundage’s for front and rear units 😎

[Bowie69]

True track would probably be my choice, no thinking, just works,  and helps keep you in a straight line on loose surfaces.

[Anderzander]

I’ve never had lockers though … and I do fancy some. 
 

@Hybrid_From_Hell The plan is to come and talk to you about a pair - I’m running P4 diffs at the moment - so I was thinking I’d talk to you about a 10 spline ARB with Ashcroft 4.12 ring and pinion.

I’m assuming that represents a totally over-specced CW&P strength wise - but I was thinking it would be new and the right ratio. 

[Snagger]

ATBs are control-free and will react the moment a wheel spins up.  They don’t fully lock, so won’t have quite the effectiveness with a dangling wheel as a full locker, but should keep or get you going.  They don’t need a potential pause to engage to avoid spline damage, though a full locker shouldn’t suffer significant spline grinding if engaged before the wheels spin up differently; the ATB is permanently “engaged”.  They will still provide the tractive benefits without having to be disengaged on the road, so provide the benefits on snowy road without trying to force skids while cornering.  Unless you are doing a lot of aggressive off roading, especial rock crawling or deep mud, ATBs should give better overall results than full lockers.

It doesn’t hurt that they are also cheaper, easy to fit with no control runs and casing drilling, and don’t need extra maintenance.

[Bowie69]

I knew they'd gone up, but over £1k each for ARB seems like poor value to me, (3K for a pair built up, maybe? Plus compressor) though appreciate if you want 10 spline lockers there's not much choice out there at the moment.

 

[Snagger]

On 7/4/2022 at 9:11 PM, Anderzander said:

If Ashcroft did 10 spline ATBs I’d be in there! 

Ashcroft ATBs are cheap enough compared to the Eaton to go a long way towards buying Ashcroft 24-spline shafts, much stronger than 10-spline.  Nige was very emphatic about that when I asked his opinion for my 109’s front axle, and his video on the different specs of shaft was quite compelling.

[Anderzander]

I’m fairly set on trying lockers this time. I love ATB’s and I’ve had auto locking diffs - but I think you’ve got to have an air operated locker at some point ? 
 

Also the 80” has narrower axles - so I’d need to go with spacers to fit the Ashcroft HD shafts and go the 24 spline route …. and I wouldn’t want to move away from the tracta joints in the front … I’d really like to restrict the changes to the diffs and in truth - I drive it very gently. 
 

I’d also use the compressor for airing down and back up again. 

[Escape]

Sounds like you've thought it through and made your decision. I'm sure you'll be very happy with your air operated lockers. 👍

[FridgeFreezer]

I like manual lockers for the same reason I like a manual gearbox - it does exactly what you tell it to when you tell it to! Off-road I really want everything to do what I want, not what it thinks is best.

[Snagger]

4 hours ago, FridgeFreezer said:

I like manual lockers for the same reason I like a manual gearbox - it does exactly what you tell it to when you tell it to! Off-road I really want everything to do what I want, not what it thinks is best.

I would never have an electronically controlled system for that very reason.  Terrain Response has a good reputation, but I think an old Defender with locked diffs and sensible tyres, springs and dampers would easily beat any of the new models off road.  Having electronics operate diff locks and muck about with engine and transmission would make them less predictable to the driver, so could cause a lot of problems rather than cure them.  I see TR as a band aid for the inexperienced and untrained off road driver, a bought-in substitute for knowledge and learning.  Of course, those cars are also optimised for road driving, so have to be reconfigured to cope off road, so it does that too.

But locking diffs vs ATBs or LSDs is a different argument, I think.  They are not unpredictable or transparent to the driver.  While I can see the benefits of locking diffs to the more extreme conditions, they provide 100% lock but can only be used in typically under 10% of driving.  The ATBs and LSDs will provide 70-80% locking effect and are useful in 100% of conditions, but that remaining slip might still hobble the car in extreme conditions.  So, both have their pros and cons.

[garrycol]

I have had a Detroit Softlocker/Unlocker in the back of my 101 for 12 years - never had an issue and you would never know it is there.  No ARB air seals to fail as they tend to do.

[FridgeFreezer]

4 hours ago, Snagger said:

I would never have an electronically controlled system for that very reason.  Terrain Response has a good reputation, but I think an old Defender with locked diffs and sensible tyres, springs and dampers would easily beat any of the new models off road.

On the contrary - I'm fairly sure the modern stuff will walk all over the old school stuff with less drama, less user interaction/skill required and in a safer and more controlled manner... but that's not really why we do this!

If I just needed to cross terrain with minimum fuss I'd go for modern stuff every time (reliability/survivability factors notwithstanding) much like I'd choose a full size Disco or Range Rover with all the gizmos if I had to tow a trailer all the time.

[Anderzander]

Uh-oh - I’ve started the diff question 😬😀

[Nonimouse]

It's very much the way you use it. I drive a G wagen off road ( a lot) with heavy trailers on (breaking the 600kg rule). Manual lockers, strong driveline. But I've driven a lot of LSD equipped vehicles over the years. My intention , next year, is to fit ATB's to the DIsco. I'd prefet truetrac's but the ATB costs less and is almost as good. If I had the shekles, I'd fit a manual locker in the front and an LSD in the rear - because that's my personal 'most comfortable' set up.

Just buy the damn things and try the out. If you don't like them, it's not like you'll lose a lot of money.

[Daan]

14 hours ago, Anderzander said:

I’m fairly set on trying lockers this time. I love ATB’s and I’ve had auto locking diffs - but I think you’ve got to have an air operated locker at some point ? 
 

Also the 80” has narrower axles - so I’d need to go with spacers to fit the Ashcroft HD shafts and go the 24 spline route …. and I wouldn’t want to move away from the tracta joints in the front … I’d really like to restrict the changes to the diffs and in truth - I drive it very gently. 
 

I’d also use the compressor for airing down and back up again. 

I know you just spend a load on your shafts, but you could try 109 Salisbury shafts. They are 24 spline and shorter than normal shafts, because the diff is much wider. Not sure by how much, but worth a hit.

Edit: I do know how long they are!:

576767 - Halfshaft R/H LWB Rear Series 3 (johncraddockltd.co.uk)

Daan

[Anderzander]

That’s a good thought Daan. Worth being aware of. The sizes are listed as shipping dimensions though ? 
 

Some of their shafts have the same length listed for the long and short side …

[Ed Poore]

I'd agree with @FridgeFreezer on the diff / modern stuff side of things. Owning both a 4.4TDV8 L322 and a 110 with X-Deflex, front and rear Ashlockers I'd say that on some stuff the 110 has it - chiefly where the KM2s offer better traction. In most other situations the standard L322 is on par with the Defender and far easier to control (both being an automatic and if you select the correct traction control setting it does make things rather effortless).

@Anderzander - just go ahead and buy them - you probably won't regret it and if you do then I'm sure you can sell them on for very little loss.