Air lockers vs mechancial ones?

[up2nogood]

Does anyone run mechanical diff locks (like Detroit Lockers, etc)?

Can you get 'em for Rovers?

They seem a more economical alternative to air lock diffs and was wondering if I can get some pros and cons.

[daddylonglegs]

Detroit lockers, lockrights etc, do not go there. Hard on axles, cv Joints.
Occasional loss of control on firm slippery tracks. They get confused on offcamber downhill slopes,thinking that you intend to make a turn so unlock the wheels on the downhill side with potentially disastrous results.
they frighten pedestrians when maneouvering around shopping centre carparks. With Detroits built in the last 15 years or so, a broken axle usually breaks the teeth on the side gear also. Detroits do not like slightly uneven tyre pressures or axle housings that are not 100 % true and straight.They double the driveline backlash on constant 4wd's like Land/RangeRovers. Even the Manufacturers of Detroits acknowledge the overall superiority of selectable lockers and now offer electric difflocks similar in general design to ARB and JacMacs.

[Strange Rover]

I think that a full detriot locker would cost the same as an ARB locker and its the "lunch box lockers" like the lockright or ezelocker that are the cheap ones. Now these have all the same handling quirks that daddylonglegs described but as an added bonus are very weak. They rely on the stock hemisphere and the stock cross pin to operate and the way they load the cross pin makes them really weak.

If its a full on comp rig then you might consider running the detroit but their biggest drawback is that they generally self destruct when you break an axle or CV.

Ive read reports that a welded diff behaves better on the road than a detroit. At least with a welded diff it handles consistantly bad as opposed to a detroit that can sometimes handle well but mostly handles badly in a few different ways.

But then again Im sure you can find lots of guys that run detroits on the road and absolutely love them. I think you used to be able to get a detroit as a factory option on f trucks back in the day.

Sam

[Rainbow Warrior]

Does anyone run mechanical diff locks (like Detroit Lockers, etc)?

Can you get 'em for Rovers?

They seem a more economical alternative to air lock diffs and was wondering if I can get some pros and cons.

Forget Lockright in the front of a Landy, nearly undriveable.
There was a Salisbury rear locker around that had a big nut on the hub to lock the axles together.
Make sure you got a Salsibury diff for lockers or at least a later Discovery type diff with the larger axles, Rangie rear end isn't strong enough for an air locker if driven hard either.

[rick130]

They get confused on offcamber downhill slopes,thinking that you intend to make a turn so unlock the wheels on the downhill side with potentially disastrous results.

Bill, why does it do that ?

I thought they purely relied on differential axle speed to ramp and unlock ??

My only experience with a Detriot was testing a historic Group N XU1 in the wet on the track years ago.
It was effing horrible, clanging and banging, not sure if it wanted to lock or unlock as you tried to feed the power in on the corners, really upsetting the car.
That's sort of put me off the damn things ever since, although the newer 'soft locker' (IIRC, an 'S' suffix on the pt #) is supposedly better in this regard.

Rick

[daddylonglegs]

I don't really know why they do that Rick, but I also don't know why they occasionally decide that they are only going to drive one wheel for a couple of hundred metres when taking off from the traffic lights (scary)
The very early Detroits were at least very strong because all the teeth and dogs were cut and milled on steel forgings. When you look closely at Detroits built in the last 15 or so years you will notice that they are either investment cast or made from sintered metal. This probably explains why they self destruct when you break an axle wheras the early ones never broke. Tractec also quote an expected working life of only 10 years. Bitter personal experience suggests you would be lucky to get half that on a daily driver.
Bill.

[rick130]

Sounds like the ultimate setup (money no object) would be a Detroit ElecTrac, or a Tru Trac or Quaife ATB with Sam's traction control.
Benign and predictable on/off road handling with a torque biasing diff, and either selectable locker or TC when things get really hairy.
I'm not sure how strong the worm drive diffs are, particularly with the bigger tyres most people on here run.
That was always the attraction of the locker. You can't get much simpler than face dogs.

Some of the electronic diffs used in the upper echelons of racing (F1, WRC) are interesting, although they have no real application for us (cost alone, let alone the electronics involved) often using a gerotor pump in the hemisphere to hydraulically pre-load the plates. They can adjust them while driving from pretty much full open to fully locked.

According to the late Carroll Smith, one of the great race car engineers, probably the best auto locking diff was the Wiesmann Locker, used by all the winners in F1, Champ cars, F 5000, etc in the late sixties/seventies.

"..the Wiesmann consists of two one-way sprag clutches, each of which consists of an inner cam, an outer cam, a series of cylindrical rollers and a roller cage. The individual inner cams are each splined to a drive axle. The profiled outer cam is a unit with the diff carrier and the ring gear. The rollers are captured between the cams and located by cages. The cages are lightly pre-loaded to the inner cams by a spring captured in the inner end of each cage.

The cages themselves are each keyed to a strong "C" spring located between the inner cams so that they cannot rotate independently of each other. The inner cams are preloaded against paper clutch plates located between the outboard ends of the inner cams and the housing. This allows the inner cams to rotate with respect to the housing/outer cam without galling parts. The preload is effected by a central Belleville washer.

Under trailing throttle (over run) conditions, there is not enough torque to force the rollers up onto the outer cam. Under differential wheel speeds they roll on the surface of the inner cams and the diff is, for all practical purposes, open. When torque is applied any attempt by one wheel to overspeed forces the rollers, hard, against the ramps of the outer cam. this wedges the rollers like crazy against the inner cams and the unit is (100%) locked - no slip at all. So the Wiesmann is open on the over run and locked under power - the ideal combination."

If you'd like, I could see if I can scan a small B&W piccy of it. Apparently its one big disadvantage, other than it isn't being currently manufactured, is that it is really sensitive to lubricants, operating by friction, and not tolerating any moly, nor possibly synthetic oils.

Rick.

[Davidh]

Sounds like the ultimate setup (money no object) would be a Detroit ElecTrac, or a Tru Trac or Quaife ATB with Sam's traction control.
Benign and predictable on/off road handling with a torque biasing diff, and either selectable locker or TC when things get really hairy.

There was discussion about the ElecTrac on Discoweb earlier in the year and people had been trying to find out availability of the diff for Rover diff's. It's supposed to be WAY down on the list of their applications.
Eg, 3-4 years!

[ISUZUROVER]

Sounds like the ultimate setup (money no object) would be

maxi-drive or mcnamara selectable lockers with Haultech ETC.

Many manufacturers have successfully implemented ETC systems that work well on-road. So a set up like the Haultech ETC for on-road and easier off-roading and then manual lockers for when you need 100% transmission of drive.

[daddylonglegs]

Rick, do the Wiseman lockers differentiate in reverse? Reversing isn't too important on circuit racing cars so one way sprag clutches shouldn't present any problems, but may not be ideal on street driven offroaders.
Bill.

[ISUZUROVER]

So the Wiesmann is open on the over run and locked under power - the ideal combination."

Rick.

Which means that it would be no good going down a steep hill - which is where you need your rear locker most of the time in a 4x4 to keep it straight and stop it from "running away" when it gets cross-axled.

[rick130]

Which means that it would be no good going down a steep hill ....

I thought that too Ben.

What it means from a general driving point of view is that eliminates the corner entry understeer you get from any sort of mechanical locker, be it auto or selectable (when engaged). So you get the on road and off road characteristics of an open diff, until you apply power, then it locks 100%
Better off road than the torque biasing diffs, much more sophisticated than a Detroit locker, with some of its drawbacks.

Rick.

[Scott Lloyd]

I have had a detroit rear in two Rangies now. I have been very happy with their performance . I have run 33's on both, the only thing i noticed on road was an occasional clunk as it engaged but no handling problems. I tried pushing moderatly hard through corners in the wet and got no percevable understeer. Yes i did break a set of standard axles on the spline trying to get up a ledge, i now have maxidrive axles . I have never had selectable lockers so i dont know how they compare. I understand detroits may have some down points on muddy side slopes but the majority of my off roading is on sandstone with some mud and loose rocks. They have performed well for me so i am happy. I am still considering what to do in the front but i am leaning towards the helical gear limited slipper from detroit for the front.

[asafk]

on the rearend, an automatic locker is just right. I know some defenders (including mine) runing detroits in the rear diff- no problem. in the open (lighter) 110, when cornering very tight, the locker is somewhat noticeable (no damage- just a scarry sound), on the heavier SW, the vehicle weight is enough in order to keep the locker quiet.
the auto locker is easier on the axleshafts, to my opinion. on situations woth a large torque difference between two wheels, the locker will open, rather than braking one of the shafts.
another advantage is the instalation. the detroit for salisbury is a"lunchbox locker"- installes inside the original case, no need for ring- pinion adjustment. no air lines or electrical installation reqired.
the auto locker is less likely to fail- no engagement mechanism to fail, no air lines, no O-rings etc...
the only problem with auto locker is on sideslopes. and with that said... all you need is a little practice- and you will be fine with that, as well.
part than that- you don't even know it's there. just point the veicle forward, and go. it'll take you there.
my experience with auto lockers (detroit, lockright, no-slip etc.) is very positive (I had a No-slip on my Jeep, and most people here are using auto lockers since it's much cheeper). for a landrover, there is only the expensive detroit locker available (I bought it used- not as pricy as new).

in the front- no auto locker will work. only selectable locker, like already written.

asaf.

[asafk]

and... don't forget- you'll have to put some strong axleshafts with any kind of locker- auto or selectable, to replace the original sh#t.

asaf.