Locking differentials

[danebrewer]

Hi all,I know this is a question that is asked a lot and one that there is plenty of info out there on, but I'd like to ask the guys in the field, plus There re some things I don't get.

so here it is.

I will be rebuilding my '85 90 next year some time and am toying with the idea of putting a locker in the rear axle. I might have to upgrade the front diff too depending on whether I can get decent 10/23 spline half shafts.

I understand how air lockers work, that they provide th true performance of a locked diff then locked and true open diff performance when not locked, so no handling issues. replacing o rings seems like a routine maintenance thing, but a pain in the arse, sooo

Automatic lockwers and LSD

limited slip differentials, so I understand require at least some traction to either wheel for them to work in ATB (automatic torque baising), as if you are truly cross axled, then you're stuffed as the diff needs at least some torque being applied to the slipping wheel. so that one to me seems out of the picture

auto lockers,

these seem a bit of a conundrum

the some lockers like the detroit locker are either locked or not, and on corners only drive the nside wheel at the same RPM as the drive shaft causing (apparently) understeer and the unlocking and locking of the diif in corners apparently causes handling issues and uneven application of power. it seems that there is no "shade of grey" in it's locked/unlocked state

what about the Detroit truetrac, this seems popular with youtube users, anyone got one of these? I can't really find much reviewer info on these apart from what the manufacturers say.

ana lastly, the Kaiser locker, works with something akin to a needle roller bearing arrangement to lock and unlock the diff, anyone know of tny of these?

really what I'm tgrying to say is I'd like a locker for occasional use, prefferably one with no maintenance, and one that perorms well, smoothly and above all safely on the road, with no uneven application of power etc.

so have you guys got any ideas for my ramblings?

Cheers

DB

[martifers]

I understand how air lockers work, that they provide th true performance of a locked diff then locked and true open diff performance when not locked, so no handling issues. replacing o rings seems like a routine maintenance thing, but a pain in the arse, sooo

What do you mean by routine? I've personally had my ARB RD56 for 2 years and not had to replace a seal yet. I'll probably regret saying that now... It was second hand when I had it so I have no idea if was ever done before that.

[danebrewer]

well routine as it will have to be done some time, changing your gearbox oil is routine, but not something you have to do every day or week like checking the washer fluid water in the winter for example or whatever, I know changing o rings in air lockers isn't done every day, but it'd be a bit of a pain for the home mechanic.....

[jericho]

Truetrac is a torque biasing diff centre - I wouldn't write them off so quickly.

Quaiffe do a torque biasing diff,similar to truetrac,but I would thing much better quality.

You will get as many different opinions as people you ask,but I used a rear detroit in my landrover for a year or so,and thought it was great - no handling issues on the road and no clunking when disengaging.The only reason I changed to ARBs was because on very low traction surfaces the detroit would sometimes not unlock on a bend - which wasn't great for trialing.

Give the Kiaser a go,and tell us about it.

[danebrewer]

a quick note to the mods on here, I seem to have posted this in the wrong place, could I have it moved to the DEFENDER section of the forum please? thanks

DB

[ashtrans]

Hi DB,

although I may seem Biased, I am not as we sell all of these diffs, (apart from the detroit locker as they break and the manufacturer won't warranty them)

The ARB's are not rubbish but I fail to see any reason why you would buy one over our new airlockers, the ARB's break (housing shear), leak air (very common) and are expensive,(about to go up another £ 100 in about 1 month) ours don't break (very well tested, won Croatia etc), dont leak and are way cheaper,

Same story ref the Truetrac and our ATB, Truetrac is £ 425 + V, our ATB which has 6 gears each side like the quaife, not 3 like the Truetrac is £ 295 + V

the Kaiser is good, same principe as the Detroit but smoother and stronger but they are too dear, only £ 50 cheaper than our airlocker, thats the main reason they sell slowly and the airlockers are selling great,

PS to quantify 'don't leak' in a recent thread you may have noticed a post about us having to collect a locker from a customer that was leaking, we actually had 2 of these where the piston O ring was damaged when the locker was built and as the unit was tested with a workshop airline the air leak wasn't noticed, the test proceedure has now been changed so the unit is locked with a compact ARB air compressor, once the air comp has cut out we check it doesn't cut back in for 2 minutes to be sure there are no leaks,

sorry if this comes across as being too commercial, it is not meant that way, just my opinion,

if the mods think it sounds like an advert feel free to delete,

[Soren Frimodt]

I, for one is extremely satisfied with my Ashlocker. Not that I have ever had any problems with my ARB lockers, they have worked great as well, but even when I had a brand new RD128 it had a tendency to leak when the axles was spinning really hard (ie sand hills) the ashlocker NEVER leaks. But I can honestly say that the big thing for me when buying the ashlocker was the price, no doubt.

[kiwi_110]

Air Lockers are positive, either they're in or they're out. There's no doubt and no worries about steering problems, clicking noises and shuddering on-road etc. I went with ARB because they were the only air-locker available in NZ. I've had my rear locker fitted for 2 years and front one for 5 years and neither have had issues with air loss. If you're careful with the O-ring during assembly, there's no reason to worry about it. Since you have a choice in the UK, and Dave's shop has a good reputation, certainly give the Ashcroft ones a go, support local industry and save a few pound.

Ray.

[danebrewer]

Hi Ashcroft, you migh be geeing my gearbox next year then! am I right in saying that when an automatic locker like the kaiser or ruetrac or your own are disengaged that it only drives the inside wheel on the bend and the other free wheels? as my lany would soend a lot of it's time on road, on road handling is essential, so no clicking in and out of lock.

the only thing is that I really don't want to have to be dismantling axles and riffs every couple of years, though it's not a massive issue, for the home mechanic with only axle stands and a hi lift it could be a pain.

also am I right in saying that if you do have one wheel off the ground with an automatic locker that it won't work, unless it's a viscous coupling type? or will the ATB type like the truetrac, quaife or your Ashcroft ATB work with one wheel in the air? (I'm only intending to have the rear axle with the locker.

so of the automatic lockers, which would you choose?

it seems that of the auto kockers, the kaiser is the only one that allows both wheels on an axle to turn when one wheel on that axle is in the air, but that with all auto lockers, the inner wheel on a bend is not able to turn slower than the pinion gear or driveshaft on a bend as an open or unlocked air locker diff would...

Edited August 13, 2011 by danebrewer

[inaine]

got truetracs front and rear with TC....very nice

[tacr2man]

have maxidrives , apart from changing oil ,faultless since 1988 !

[ashtrans]

the Maxidrives are a very good product and one of the reasons for this is, like ours, the air system doesn't have a rotating air seal like the ARB, the cylinder is static,

Dave

[danebrewer]

but somewhere there must be an o-ring pressing agaist something that is rotating at some stage right? just the one rotating o-ring versus 2 in the ARB?

[tacr2man]

Maxi drives are vac operated, no rotating seals just a piston seal . You dont need compressed air , if pipe goes you can move them by your own suction

[danebrewer]

oh I see, so the piston remains atatic, and I guess there's a bronze bushing on the end of the piston which pushes against the (rotating) locking collar.... correct?

[Hybrid_From_Hell]

My 2p worth

I used to work for KAM - and so know a fair bit of whats out there.

I also run ARBs - RD56s which I belive are better than the latest version.

Your choices are manyfold, I could go on about the pros and cons of each etc, but heres a shortened version if it helps

I would not buy a New ARB full stop, and for price, Build qulaity (seen one) and performance the Ashcroft locker wins the fight hands down.

In fact as my ARBs are old, and have been repaired many times, and are showing their age, if one or both of these fail

then its a call to ashcrofts without a 2nd thought

HTH

Nige

[simonr]

oh I see, so the piston remains atatic, and I guess there's a bronze bushing on the end of the piston which pushes against the (rotating) locking collar.... correct?

The way the Ashcroft diff and I presume Maxidrive too work is a stationary piston which pushes against a rotating bit with some kind of thrust bearing between the two. Since the bearing only has to support a minimal load (100N or so) and then only when the diff is locked, it doesn't need to be anything fancy. A sheet of Phosphor Bronze, even glass filled PTFE would probably be fine. A roller thrust bearing would be ideal - but they take up a lot of space relatively.

That way, there are no rotary seals to worry about.

For my money, the Ashcroft Diff looks the best design overall at the moment.

Si

[Night Train]

am I right in saying that when an automatic locker like the kaiser or ruetrac or your own are disengaged that it only drives the inside wheel on the bend and the other free wheels?

I don't know of any motor vehicle diff, locking or otherwise, that operates that way. The only ones I have seen are on pedal tricycles and quadracycles.

If the diff operated as you describe then the vehicle would not be able to go in reverse.

Where did you get this idea from that the diff would only drive the inner wheel while the outer freewheels?

[ian_s]

I don't know of any motor vehicle diff, locking or otherwise, that operates that way. The only ones I have seen are on pedal tricycles and quadracycles.

If the diff operated as you describe then the vehicle would not be able to go in reverse.

Where did you get this idea from that the diff would only drive the inner wheel while the outer freewheels?

i thought the same, that the kaiser diff basically let the outer wheel turn freely, so i looked it up. quoting from www.kaiserlocker.com:

"In other words, Kaiser Locker allows the outer wheel of a curve to spin more than the ring in order to compensate on curves, but it does not allow any of the wheels from same axle to spin less than the ring/ pinion."

the detroit locker does something similar, but in a much harsher way.

[Daan]

I don't know of any motor vehicle diff, locking or otherwise, that operates that way. The only ones I have seen are on pedal tricycles and quadracycles.

If the diff operated as you describe then the vehicle would not be able to go in reverse.

Where did you get this idea from that the diff would only drive the inner wheel while the outer freewheels?

From the website? Thats exactly how a detroit or kaiser works. The freewheel works in both directions and allows 1 wheel to overrun the diff at any time.

Daan

[danebrewer]

well it looks like I might be getting an ashcroft air locker then at some stage......

not too keen on the auto lockers now as I wonder how they'd affect the handling on ice and snow..... and only having a 3 wheel drive vehicle on corners.....

it seems that air is the way forwards!

[simonr]

not too keen on the auto lockers now as I wonder how they'd affect the handling on ice and snow..... and only having a 3 wheel drive vehicle on corners.....

Actually, they give an advantage on snow, whilst steering at least. If you drive on snow/ice with a fully locked diff - chances are the vehicle will not steer at all or at least experience significant under-steer. I would say, 3 wheel drive on a corner is better than not making the corner at all!

I used to have a Detroit locker and thought it was pretty good under most situations. You have to be a little bit careful cornering because with the drive going to the inner wheel, which is following the shortest track round the corner, it makes the vehicle speed up. If you are cornering close to the limit of the traction available - it can make it oversteer. Once you get used to it - it's not a problem though.

The only reason I changed to ARB's was to allow me to fit fiddle brakes.

Si

[danebrewer]

naah, I meant on the road, I would only drive with lockers in a straight (ish) line! I can imagine how bad they'd be round a corner!

[muddy]

I have no experience with landrover locking diffs however you seem quick to assume that in a cross axle situation (i assume you mean one wheel on each axle having little or no ground contact) the diff would not have enough resistance across it to lock? Surely a dab of left foot braking would provide the necessary resistance to actuate the locking sequence?

Can anyone shed some light on this?

[danebrewer]

I have no experience with landrover locking diffs however you seem quick to assume that in a cross axle situation (i assume you mean one wheel on each axle having little or no ground contact) the diff would not have enough resistance across it to lock? Surely a dab of left foot braking would provide the necessary resistance to actuate the locking sequence?

Can anyone shed some light on this?

as I understand it, the only auto locker to lock with one wheel on the locked axle having no traction is the Kaiser, the other ATB (automatic torque biasing) diffs requite at lease tome torque and resistance being applied by the spinning wheel. but mainly what I don't like is the prospect of it being three wheel drive on corners, locking/unlocking on corners, and the fact that no wheel may travel slower than the pinion....

but no, I guess a dab of left foot brake would cause it to lock, you'd just have to keep on the gass I suppose to stop it unlocking, otherwise if the vehicle has TC then the locker will enhance the effect of TC.