Locker vs Open

[craig]

It's like Keith described. With the rear locked, the center diff (transfer case) open, and the front wheels still pulling the vehicle will barely crab walk at all.

With the center diff open, it will send power to the front wheels if traction is equal. If one of the axles is slipping though all the power will go to that axle. This substantially limits the amount of crab-walk.
C

 

[michaelgroves]

It's like Keith described. With the rear locked, the center diff (transfer case) open, and the front wheels still pulling the vehicle will barely crab walk at all.

With the center diff open, it will send power to the front wheels if traction is equal. If one of the axles is slipping though all the power will go to that axle. This substantially limites the amount of crab-walk.
C

With the rear locked, and the centre diff unlocked, the total torque allowed to the rear axle will be limited to the equivalent of the weakest front wheel traction. While I agree this configuration will limit crab-walk compared to a locked rear and centre, it also generally provides less torque (traction) than centre diff locked and rear open (and only a tiny improvement over everything open*).

Having said that, I guess that it may be an advantage(?) to the rear-locked, centre-unlocked configuration, that when a wheel does spin, it will invariably be a front wheel.



* All open diffs: total traction = 4 x traction of the weakest wheel
* Open centre and locked rear: total traction almost always = 4 x traction of the weakest front wheel
* Locked centre: total traction = (2 x traction of the weakest front wheel) + (2 x traction of the weakest rear wheel)

 

[michaelgroves]

You shouldn't take it personal. If you have something contructive to add, then type away.

I'm not taking anything personal.

Although MuddyMudskipper's advice obviously applies to everyone, I don't think he was addressing you, TeriAnn

 

[Yorker]

If you drive very far ie. a hundred yards or so, on solid traction like pavement with the CDL locked you will break it. Not sure about disco's but defenders have a decal inside the truck that says not to use the CDL untill traction has been lost or eminent.
Years ago we had a 30 plus inch snow storm and I was running down an unplowed road @ night and suddenly hit a plowed spot in a turn, I had the cdl locked and it blew before I could pull over and unlock it.

That doesn't inspire much confidence in the LT-230, are you sure there wasn't something already wrong with it?

 

[R_Lefebvre]

That doesn't inspire much confidence in the LT-230, are you sure there wasn't something already wrong with it?

I almost forgot to reply to the original comment about this.

Last summer while doing to yard work, I'd had the CDL locked because i was pulling a trailer through a muddy field. When I pulled out onto the road, I forgot to unlock it, and was halfway through a 90* turn. I tried to unlock the diff, but it was all bound up and wouldn't unlock. I ended up finishing the turn with as wide a turn as possible. I tried to drive the truck forward and back to get it to unlock, but no luck. I did have to drive about a 1/4 mile to go to a wide open field where I could spin the tires to unwind the drivetrain, at which point it unlocked. My CDL didn't break during the whole event. I'd hope it's not as weak as you'd suggest.

 

[Hank]

I've seen the two piece cross-shaft break in the LT-230's....once. You hear of this from time-to-time, but not very often at all. Hardly ever, actually.

I've never seen, or heard of, a one piece cross-shaft breaking. You can get the one piece cross-shaft from a Maxi-Drive, or from the old BW case.

The LT-230 is very tough, basically bullet-proof. Having the center diff locked on dry pavement was probably not what caused Maryland 110's LT-230 to break. There is probably more to that story.

 

[R_Lefebvre]

Care to explain that one? Just trying to learn here.

Here is my non-Rover wisdom: I don't understand the point of a LSD, front or rear. Perhaps it is because I am Rover deficient (though drool often), perhaps it is the conditions I drive, but I seem to want an axle totally open or totally locked. TeriAnn's locker/lsd combo makes sense for a dedicated expedition rig, adding some traction to the front when needed without the wear of a locker.

For me, winter time means on road snow and summer means wet rocks and decomposing granite. In the winter, a clutch based LSD achieves near full lock at the worst possible times and in the summer I have trouble getting enough traction. This was the case both with an old Pathfinder and a Trooper.

After driving a dedicated trail rig with Detroit lockers front and back, I can understand why people go that way, but I need a vehicle that is far more balanced for multiple uses.

When I read this, I'm not sure if you're aware that clutchpack LSD's haven't really entered into this discussion. I'm very much not a big fan of clutchpacks in any application. They're cheap to manufacture and... that's about it. The *only* advantage they have over a helical LSD is that they will provide some (small) amount of traction even if one wheel is in the air, which a helical won't.

My desire is not to be doing trails that will result in wheels in the air. Call me a pansy, but if it's beyond the point of where my truck can't articulate through it, then it's just too much for me. On rare occaisions it happens, I'd prefer to winch through it instead. That's why I think a TruTrack is more appropriate for me. The only problem is now that I'm hearing they can lead to crab walking.

 

[RonL]

Maryland 110 breakage could of happen because of a shock load. If the tires were spinning at a high rate when in the snow and then get traction on the plow road(dry), things break when this happens.....

Lockers give you slow speed control like no other. With LSD(clutch or gears) you need more speed to get them to work. Detroit are good lockers, but they are locker all the time when power is applied to the diff, only when coasting these it unlock. This "locked all the time" has got to add extra stress to the diff, axles, and driveshafts when on dry pavement.

All lockers and LSD will give you a "crab walking" if on a side slope and you lose traction. This is where LSD and Detroit are dangerous, because you can't turn them off. This is a whole other topic, you can get in to it if you.

 

[Yorker]

When I read this, I'm not sure if you're aware that clutchpack LSD's haven't really entered into this discussion.

AFAIK there aren't any clutch pack LSD's available for LRs, there are Quaifes and True Tracs both are geared type.


Dan-

That was pretty much my understanding of the LT-230, I've never seen one blow up like that and I've been around them a long time, though to be completely honest I've never owned a vehicle that used one. I have an LT230 put away for a future project but that is converted to part time.

 

[Alaska Mike]

Wouldn't a Dana 60 clutch-type LSD work in a Salisbury, if the spline counts matched?

 

[TeriAnn]

When I read this, I'm not sure if you're aware that clutchpack LSD's haven't really entered into this discussion.

That's presumably because that type of LSD is not available for Land Rovers Just Quaife and Trutrac helical limited slips. I've had both on my front axle and have never had sideways crabbing issues. Of course that could be because I have a real issue with heights and work hard to stay of steep side slopes or along narrow cut out trails in the side of a vertical cliff. All I've really noticed with the limited slips up front is that my Land Rover does a better job of following where I point the front tyres on slippery surfaces than it did with an open diff.

My desire is not to be doing trails that will result in wheels in the air. Call me a pansy, but if it's beyond the point of where my truck can't articulate through it, then it's just too much for me.

Series Land Rovers have very crappy front axle articulation so will lift a front wheel way earlier than most other rigs. So lifting a wheel is no big deal. With a limited slip you ride the brakes when a wheel is off the ground so the diff doesn't think it is off the ground. That way you still get power to the front wheel that is still on the ground. It is also why I like having a few hundred pounds more on the rear axle. The rear axle articulates better and because of the weight distribution, the vehicle is more apt to keep both rear wheels on the ground.

 

[Maryland 110]

When I blew that case I went from deep unplowed snow to a sharp turn on plowed pavement @ 30ish mph (not spining). There were three quick chirps and a bang. This was in an 89 Classic with a transplanted lt230 from an 87 ($250 cheapy) . Tires were 255.85.16 Trixus. There were no prior issues and the case worked and shifted great. I would have expected a spider gear in the front diff or a cv to let go first. I got a replacement from Roverguy.com (Will Tillery) and that fixed it. The truck still drove so I think what broke was just the difflock ? Have to admit I haven't spent anytime inside a lt230.

 

[michaelgroves]

Then quite possibly the problem was that the dog that locks the diff was only partially engaged, and the shock load stripped engaged part of the dog splines?

 

[craig]

Looks like a Tom Woods double double cardon?

 

[michaelgroves]

Now for a locker question. Who here has changed the side gears on an ARB before? Is it difficult? I'm thinking of swapping my 10 spline front shafts for some 24 spline shafts on my series truck.
Jason T.

I can't help, but I'm sure ARB-USA would advise you on this? They're a very helpful crowd.