Which Diff?

Author
Discussion

BIG DUNC

Original Poster:

1,918 posts

230 months

Thursday 19th August 2010
quotequote all
The car is a classic range rover, and it gets used for a mix of green lanes and pay / play.
The standard open diffs have been fustrating me for some time, and I have been looking out for some second hand uprated diffs. Being second hand, I thought there would not be much choice, so I would buy whatever I could find. Actualy, I have found nothing.

If I was to buy new, what would be the best way to go (and I have a bit of saving to do, so plenty of time to think about it)?

ARB Air Lockers is the obvious choice, or would be if money was no object.

Then there is the Kam option. Or really, several options. I could have a locker (similar to ARB in that it is driver operated, but electric rather than air operated). Or, a Kam LSD. Or the same diff can be limited slip, with the ability to lock it if required. Like ARB, Kams are expensive, but of course, no compressor is needed.

Then there is the "limited slip" types such as Quaffie, Detroit, True Trac. (although I understand they all work differently internaly, but have similar effect). These would all be cheaper than the ARB / KAM option, but dont offer complete driver controlled lock up. However, is that really needed for my use, or as long as each wheel on the axel is turning, does it matter if the gripping wheel is going slower than the spinning wheel?

Another thing to consider is do I want the same set up on each axle? Is there an advantage to this, or an advantage of having something different at each end?

I know that what suits one person / car / usage will not be right for someone else, but I would be interested to hear peoples thoughts & experiences before parting with my hard earned cash.

Or of course, if you have anything to sell me, then....

On the one hand I dont want to spend more than I have to on something that is too good for my needs. On the other hand I dont want to buy something cheaper, then upgrading in a year or two as I should have bought the expencive one first time round.....

I am posting this on several forums, as I want as much feed back as possible.



SystemParanoia

14,343 posts

205 months

Thursday 19th August 2010
quotequote all
weld it and spend the change on buying 50+ spare difs and halfshafts?

Kermit power

29,472 posts

220 months

Thursday 19th August 2010
quotequote all
I can't help thinking that maybe you need to give people a bit more of an idea of what you're looking to do this for?

I've got a factory-fit rear locker on my Shogun. I've used it to great effect a few times on P&P days, and used it once (last weekend) whilst out laning, and only then because I was trying to do a 3 point turn on top of a slope with two wheels bouncing off the ground! hehe

For P&P days I could see the logic of a locker on the back, but I'm really not sure it's worth the hassle of fitting one to the front axle, is it? That's a pretty serious bit of kit, and from what I've heard makes it pretty impossible to turn corners whilst it's on! I can't imagine you'd ever need it for laning, and if you do, it could be argued that you really shouldn't be on that lane.

More useful for P&P days I guess, but isn't half the fun taking it in turns to haul each other out of the mud from time to time? biggrin

300bhp/ton

41,030 posts

197 months

Friday 20th August 2010
quotequote all
BIG DUNC said:
The car is a classic range rover, and it gets used for a mix of green lanes and pay / play.
The standard open diffs have been fustrating me for some time, and I have been looking out for some second hand uprated diffs. Being second hand, I thought there would not be much choice, so I would buy whatever I could find. Actualy, I have found nothing.

If I was to buy new, what would be the best way to go (and I have a bit of saving to do, so plenty of time to think about it)?

ARB Air Lockers is the obvious choice, or would be if money was no object.

Then there is the Kam option. Or really, several options. I could have a locker (similar to ARB in that it is driver operated, but electric rather than air operated). Or, a Kam LSD. Or the same diff can be limited slip, with the ability to lock it if required. Like ARB, Kams are expensive, but of course, no compressor is needed.

Then there is the "limited slip" types such as Quaffie, Detroit, True Trac. (although I understand they all work differently internaly, but have similar effect). These would all be cheaper than the ARB / KAM option, but dont offer complete driver controlled lock up. However, is that really needed for my use, or as long as each wheel on the axel is turning, does it matter if the gripping wheel is going slower than the spinning wheel?

Another thing to consider is do I want the same set up on each axle? Is there an advantage to this, or an advantage of having something different at each end?

I know that what suits one person / car / usage will not be right for someone else, but I would be interested to hear peoples thoughts & experiences before parting with my hard earned cash.

Or of course, if you have anything to sell me, then....

On the one hand I dont want to spend more than I have to on something that is too good for my needs. On the other hand I dont want to buy something cheaper, then upgrading in a year or two as I should have bought the expencive one first time round.....

I am posting this on several forums, as I want as much feed back as possible.
As others have said, we need more info. You say:

"standard open diffs have been fustrating me for some time"

In what way?? Most people with LR's break them more so than find their non locking ability an issue?

I admit I don't do much laning, but I don't see why you should need diff lockers at all for this use in the UK.

Ok pay and play maybe, but I can't see that you'd 'need' them.


Can I ask what sort of tyres and suspension you are running?


As for which diff, well LSD's are good on road if you have RWD, but you don't with a Rangie. So I think their appeal is somewhat limited. You might as well just go locking if you are going to spend the money as it will be better off road.

In terms of which axle, well a locking rear diff will have most affect, but it does depend on the terrain. A front can add benefits, but sort of relating to the question above. Even with lockers Land Rover's can be pretty capable.

KAM and ARB lockers - think it's just preference. both are good and both have supporters and fans.

Do remember the axles and diffs are probably the weakest part of a Land Rover. Adding a locker and especially if you abuse it will only result in lots of broken bits. So budget to upgrade all of the entire axle, shafts and all.

BIG DUNC

Original Poster:

1,918 posts

230 months

Friday 20th August 2010
quotequote all
Yes, all good points.

It has a 2 inch lift, and runs Grizly Claw tyres of a fairly modest size (standard wheels). I dont really want to get into cutting out arches or body lifts.

Its not so much the laning, but the pay & play. I see people drive through things & make them look easy, then I get hopelessy stuck, then discover that the car I watched had clever diffs. It happens quite a lot. I realise that they are not a "magic wand" and driver ability and tyres and ground clearance etc make a difference, but I cannot help thinking I could do more with one or two clever diffs.

I am currently on 10 spline shafts, and have a couple spare second hand one in the garage. When I first have to buy a shaft (whether because the new diff is 24 spline, or because I use up the spares), it will be a heavy duty item. Similarly for CV joints, if I have to replace one, it will be with a heavy duty item. I know the heavy duty shafts and CV joints are mega money, but I would hope that once I had them, I never broke them. Fitting standard parts (especialy second hand ones) means that it is only a matter of time until they break.

Thanks for your comments so far.

300bhp/ton

41,030 posts

197 months

Friday 20th August 2010
quotequote all
BIG DUNC said:
Yes, all good points.

It has a 2 inch lift, and runs Grizly Claw tyres of a fairly modest size (standard wheels). I dont really want to get into cutting out arches or body lifts.

Its not so much the laning, but the pay & play. I see people drive through things & make them look easy, then I get hopelessy stuck, then discover that the car I watched had clever diffs. It happens quite a lot. I realise that they are not a "magic wand" and driver ability and tyres and ground clearance etc make a difference, but I cannot help thinking I could do more with one or two clever diffs.

I am currently on 10 spline shafts, and have a couple spare second hand one in the garage. When I first have to buy a shaft (whether because the new diff is 24 spline, or because I use up the spares), it will be a heavy duty item. Similarly for CV joints, if I have to replace one, it will be with a heavy duty item. I know the heavy duty shafts and CV joints are mega money, but I would hope that once I had them, I never broke them. Fitting standard parts (especialy second hand ones) means that it is only a matter of time until they break.

Thanks for your comments so far.
Are you on LR4x4? Might be worth asking over there.

Personally I think I'd try the new leccy KAM lockers if I was starting from scratch.

Curious, what sort of lift do you have? So many of these off the shelf kits for LR's are more looks than function.

And sadly, yep driver. I compete in RTV trials. And it's amazing what will go were with ease, and then the next vehicle (often mine rolleyes ) fails at the same obstacle.

BIG DUNC

Original Poster:

1,918 posts

230 months

Friday 20th August 2010
quotequote all
Yes, the lecky Kam locker looks the best of everything. LSD most of the time, then when you want it, lock up at the press of a button. Dont even need a compressor. Shame about the price, but I am so, so tempted.

2 inch lift with Springs / shocks by De Carbon. Extended bump stops, not sure who by, but the same colour scheme, so possibly also De Carbon.
Most of the modification work was done by the last owner, who competed in RTV's (very successfuly I understand). It probably is the nut behind the wheel which is the limiting factor, but if I can eliminate everything else....

Kermit power

29,472 posts

220 months

Friday 20th August 2010
quotequote all
BIG DUNC said:
Most of the modification work was done by the last owner, who competed in RTV's (very successfuly I understand). It probably is the nut behind the wheel which is the limiting factor, but if I can eliminate everything else....
That sets big alarm bells ringing!!!!!

If the previous owner used it to compete very successfully in RTVs without lockers do you really expect spending a lot of money on lockers to make a big difference on P&P days?

I would suggest spending a fraction of the money you're thinking to spend on lockers on a training day in your own truck first, then reassess where you think you need to spend money on it.

I've not done the above for off-roading as the TA did a pretty good job of training me up a few years ago, but I was absolutely gobsmacked at how much faster I could push my V8 round Brands Hatch after just 15 minutes of racing instruction. No shame in getting an expert to make sure you can get the most out of your tools before you decide your tools aren't good enough. smile


BIG DUNC

Original Poster:

1,918 posts

230 months

Friday 20th August 2010
quotequote all
I have had profesional instruction in the past (This has been on the track - I used to do a lot of sprinting, and in the mud, and on the road). Indeed, it is the one way of spending money that wont be wasted when you change car. I am sure that I will have plenty more days with an instructer in the future as well.

However, that does not answer the question about which is the best type of diff.

300bhp/ton

41,030 posts

197 months

Friday 20th August 2010
quotequote all
BIG DUNC said:
I have had profesional instruction in the past (This has been on the track - I used to do a lot of sprinting, and in the mud, and on the road). Indeed, it is the one way of spending money that wont be wasted when you change car. I am sure that I will have plenty more days with an instructer in the future as well.

However, that does not answer the question about which is the best type of diff.
Best I'm sure will be opinion based. Very few people will have truly owned and run both setups, let alone side by side.

As for the best - portals or some other axle swap to something not made from chocolate wink

BIG DUNC

Original Poster:

1,918 posts

230 months

Friday 20th August 2010
quotequote all
That is the trouble. Over the last few months I have asked loads of people what diffs they run, and what there opinion is. Every answer has been

"I have got XXX and suggest you get the same as they (or it) is great".

No one has said
"I have got YYY, and they are not so good. My last motor had ZZZ and they were better / worse because...."

Thats why I put it to the forums.
And so far, I dont think I know a lot more than before.

I dont really want to get into swapping axles, but from now on, any CV's / Half shafts I buy will be heavy duty items. To be fair though, its not as though I am breaking half shafts every week. In fact, it is several years since I last broke a shaft (probably due one now I have typed that). I do currently have a broken diff, which is what really started me thinking was this the time to invest real money. However, a friend is donating me a "believed good" diff for a very good price, so there is no immidiate panic. Just now I have started thinking about it, I really want to upgrade.

Kermit power

29,472 posts

220 months

Friday 20th August 2010
quotequote all
I think the reason you're finding the response you're getting is simply down to the fact that the locking diff on a 4x4 is, in use, basically an on/off mechanism.

With mine, I lose traction, I flick a little switch on the dash, I have traction again, I drive out of where I got stuck, and I flick the switch again.

That's it. That's all a locking diff does, and it either works or it doesn't. Consider then the amount of use the average 4x4 diff lock is going to get in this country, and you really shouldn't hear about them breaking.

Chances are most of the people you're asking won't be able to tell you that one form of locker is better than another because they're unlikely to have used more than one type, and even those who have will only be able to tell you if one broke on them, because the job they do is binary, and therefore the experience should be identical.

Given that we are all saying that what we've got is great, then the decision seems to just come down to price and whether or not you want a compressor involved.

JCW

905 posts

214 months

Friday 20th August 2010
quotequote all
Kermit power said:
I've got a factory-fit rear locker on my Shogun. I've used it to great effect a few times on P&P days, and used it once (last weekend) whilst out laning, and only then because I was trying to do a 3 point turn on top of a slope with two wheels bouncing off the ground! hehe
It was because you were struggling to follow a Land Rover. driving

To the OP. Seriously, for the type of off roading you're describing it sounds like overkill to me and the chances are that having fitted them, when you do get stuck, you're going to be well and truly stuck!

Kermit power

29,472 posts

220 months

Friday 20th August 2010
quotequote all
JCW said:
Kermit power said:
I've got a factory-fit rear locker on my Shogun. I've used it to great effect a few times on P&P days, and used it once (last weekend) whilst out laning, and only then because I was trying to do a 3 point turn on top of a slope with two wheels bouncing off the ground! hehe
It was because you were struggling to follow a Land Rover. driving
shoot

I think you'll find it was actually because I was having to keep well clear of a Land Rover in case it's wonky suspension fell on top of me! hehe

bigblock

778 posts

205 months

Friday 20th August 2010
quotequote all
BIG DUNC said:
That is the trouble. Over the last few months I have asked loads of people what diffs they run, and what there opinion is. Every answer has been

"I have got XXX and suggest you get the same as they (or it) is great".

No one has said
"I have got YYY, and they are not so good. My last motor had ZZZ and they were better / worse because...."

Thats why I put it to the forums.
And so far, I dont think I know a lot more than before.
It is very unlikely you are going to get a definitive answer to your question "which is the best locking diff". However if you know the use you are going to put your vehicle to then you can try and make an informed choice from the experience of others.

I can understand your frustration when you have asked about suitable lockers and are told you don't require them. If you are willing to spend the money then they are a useful tool for off roading.

For what it's worth I would say that if your 4x4 is mainly for off road use then a Detroit locker on the rear and a Kam elctric locker on the front is probably the optimal setup for long life and ease of use.

The Detroit system locks up automaticaly when required and is totaly self contained and extremely strong. The Kam system avoids the need for a compressor and the electric solenoid is contained within the new diff housing. It also gives you the ability to lock the front diff as required and then unlock it when you need steering input.

This maybe more than you require but it is what I would describe as the ideal system. I am sure a few people on here might disagree argue

normalbloke

7,714 posts

226 months

Friday 20th August 2010
quotequote all
I have a 1979 5.9 CJ7.
Full Quadratrac drivetrain through a TH400 box.
Front Trutrac.
Rear full Detroit.
Seamless in its operation and reliable to date.It is handling about 350bhp and a lot of torque and right foot.Best thing for me is its transparency onroad.

Good luck.

eliot

11,727 posts

261 months

Saturday 21st August 2010
quotequote all
I run an ashcroft 4 pin diff in the front and a LR oem 4 pin diff in the back (Milspec or LR110 I think) all with 24 spline shafts. Broke loads of 2 pin diffs, due to the large wheels and bouncing up and down which bends the pin on the diff. This was all in the days of the 3.9v8, never broken any of that stuff with the 5.7 turbo ironically.

Hooli

32,278 posts

207 months

Saturday 21st August 2010
quotequote all
I used to love the rear Detroit in my Disco, coupled with a tru-trac in the front it made an incredible amount of difference to where I could go without hassle.

BIG DUNC

Original Poster:

1,918 posts

230 months

Saturday 21st August 2010
quotequote all
Thanks guys.
Its time I started saving.


JWH

498 posts

271 months

Monday 23rd August 2010
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Hooli said:
I used to love the rear Detroit in my Disco, coupled with a tru-trac in the front it made an incredible amount of difference to where I could go without hassle.
I used to drive a 300 Series Discovey that had a lift, dislocation cones and anti-roll bars removed. The previous owener had also fitted a Detroit locker to the rear axle. This is my only experience of driving anything with a locking diff, however it performed very well for me. Clearly the diff requires no input from the driver and it certainly helped keep the truck moving over surfaces that were flexing the suspension a lot, I couldn't fault it in any way and it was virtually unnoticeable on sealed surfaces.
There's certainly some truth in the the theory that, with lockers, when you get stuck you get very stuck though!