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School me on LSDs or Locking diffs

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Post Options Post Options   Thanks (0) Thanks(0)   Quote duffer Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jan. 2022 at 1:41pm
This discussion is akin to the proverbial dead horse torture.  What works for one may not be the best for someone else.  It all comes back to use.  If you never plan to drive on ice or packed snow, an auto locker in the front is fine.  If you do have to drive in those conditions, you will not likely be using 4x4 mode.  It makes staying on the road a bit of a challenge.  An auto locker in the rear isn't much better in those conditions.

But if the only thing the Willys sees is trail use, by all means save a few bucks and go auto lockers.  As for LSD's, I had pretty good results with the Powr-Loc in my 3B rear axle for 4 decades.  Not as good on trails as a true locker but WAY better manners on the road than the auto locker I tried a couple of times.  As just about everything, a compromise.  That said, I have become a true believer in selectable lockers on both ends where that compromise is unnecessary.  If you have axles that can accommodate the available selection, they are absolutely worth the price.  I would no longer build a Jeep with axles that could not be fitted with selectable lockers.
1955 3B: 441sbc,AGE 4 speed transmission, Teralow D18w/Warn OD, 4.11:1 D44's/ARB's, glass tub & fenders, aluminum hood/grill, 8274, York OBA, Premier Power Welder; 67 CJ5: 225,T86AA, D18, 4.88's, OD
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Metcalf Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan. 2022 at 12:46pm
Originally posted by duffer duffer wrote:

This discussion is akin to the proverbial dead horse torture.  What works for one may not be the best for someone else.  It all comes back to use.  If you never plan to drive on ice or packed snow, an auto locker in the front is fine.  If you do have to drive in those conditions, you will not likely be using 4x4 mode.  It makes staying on the road a bit of a challenge.  An auto locker in the rear isn't much better in those conditions.

But if the only thing the Willys sees is trail use, by all means save a few bucks and go auto lockers.  As for LSD's, I had pretty good results with the Powr-Loc in my 3B rear axle for 4 decades.  Not as good on trails as a true locker but WAY better manners on the road than the auto locker I tried a couple of times.  As just about everything, a compromise.  That said, I have become a true believer in selectable lockers on both ends where that compromise is unnecessary.  If you have axles that can accommodate the available selection, they are absolutely worth the price.  I would no longer build a Jeep with axles that could not be fitted with selectable lockers.


Time to beat the horse again!

I've found selectable/selectable to be noticeably lacking compared to Automatic front and selectable rear. ( I own and drive both ) It has some noticeable quirks that have to be worked around, especially with current designs that like to stay locked ( especially in the front axle ) when you really want them to unlock to maneuver. You can drive around this to a certain degree with a LOT of extra steering force available to deal with the front spool and scrub radius, but even most hydraulic assist systems will run short on force. Even with the rear end unlocked, I constantly have to lock-unlock-lock the front axle. I've tried running it rear locker first.....then you get pushed wide through the turns that really matter. Very annoying.

In contrast, I have never felt the need for more steering force in my flatty with the automatic front locker and a selectable rear locker even with big dumb tires at ridiculously low pressures. The front axle has always been happy doing it's automatic lock-unlock-lock thing as needed without any input from me. I think the scrub and steering action actually helps the automatic locker unlock and ratchet....basically the opposite of what happens with the selectable in the front ( steering makes it lock up harder ).

The only good reason I can think of to use a selectable front locker over an automatic is if you have full time 4wd. With part time 4wd, and the rear locker open, I've never noticed any bad handling from having a front automatic locker honestly. The only quirk I notice is more return to center feeling through the steering wheel when on the power, and I don't honestly find that objectionable. The front tires just go where I point them. I'm not one to drive 100mph on icy roads. I have always just toggled 4wd in and out as needed on all my part time 4wd vehicles. I am not a put it in 4wd and forget it type driver. This could be one reason why an automatic front locker doesn't seem intrusive to me. I'm dang temped to throw one in the front of something for a winter driver just to test that theory out. Strangely, I actually prefer part time 4wd to full time 4wd in winter conditions too. With fulltime 4wd, especially with an open center diff, it is always roulette on which of the 4 tires will spin first. Very annoying. I find part time 4wd much more predictable. I see a lot of people inferring things about automatic front lockers that really make it sound like they have never tried it, especially with the rear diff open. An automatic/automatic vehicle handles completely different than an Automatic front / open rear vehicle. I think running automatic rear lockers has soured a lot of people in general. While I love automatic front lockers, I do not like them at all in rear axles. Some people just don't care enough to try anything different. 

I do think there is a gap between open rear and spool rear where things could be 'better'. I find a limited slip rear in a part time 4wd vehicle using rwd helpful in most conditions. When I first built my flatty, it had a powerlok rear and an automatic front locker. All in all, I thought that was a GREAT 'no button' combo for medium hard trail stuff. I could drive in circles around most people running auto/auto or LSD front/Auto rear. While adding the selectable rear locker made it ultimately more capable in a few situations, the open setting did give something up to the limited slip in a lot of milder situations.

This is written to get people thinking, not just assuming. Try something different.


42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nothing Special Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan. 2022 at 9:22pm
It's really inconsistent what people find objectionable or not objectionable with automatic lockers, and that's fine.  It really comes down to whether you value the pluses enough to outweigh the minuses.  And that's where the dead horse comes in.  There isn't one right answer that everyone can eventually agree on, just a bunch of options that all have pluses and minuses.

For me, I really don't mind a rear automatic locker.  Yes, it tends to push corners a bit wide (off-road especially).  And Brennan would hate that.  And yes it gives some jerks to one side or the other at times driving on the road and can make it easier to spin out on snow.  And some people would hate all of that that.  But personally I find those issues pretty minor and very easy to live with.  And none of us is wrong.

As to a selectable in the front, I agree with Brennan that it needs to be toggled off pretty soon after turning it on.  But at least the OX in my Bronco hasn't annoyed me by being difficult to unlock.  I have to saw the wheel back and forth a bit sometimes, and some might find that a disqualifier.  But it hasn't been a problem for me.  And again, none of us are wrong.

I have very little experience with an auto locker in the front.  I do tend to believe Brennan that a front auto locker and a rear limited slip or selectable might be the easiest to use and most effective combo.  But the more return to center feel when on the power that Brennan honestly doesn't find objectionable I really didn't like.  I can certainly imagine being willing to live with it in a trail vehicle in exchange for the performance.  But it would be a negative for me.

And for driving on snowy freeways I will never consider a front auto locker again.  First of all, I really don't understand why people don't use 4WD on snowy freeways.  Yes, it lets you drive faster than your brakes and steering can handle.  But that's your choice, it doesn't MAKE you drive too fast.  And a truck in 4WD is so much more stable on snow than it is in 2WD.  I don't understand why you wouldn't take advantage of that.  It's OK if you choose not to, I don't need to understand something for it to be OK for you.  But I don't understand.  Anyway, with a front auto locker when one front tire loses traction that stronger return to center feel becomes just the opposite, a strong tendency to turn toward the tire with no traction.  On a freeway that can put you in the next lane before you can catch it.  But again, that's driving on snowy freeways and doesn't apply to most trail rigs that rarely see snow and almost never see freeways.

I do value reading other people's perspectives in these discussions.  I really want to try a front auto / rear selectable combo sometime.  That's mostly from reading what Brennan has written, and I really think I might like it for a trail rig.  So like Brennan, I hope people read these things with an open mind.  I'm certainly not saying that everyone will like what I like.  But since people like different things I think it's good to hear different things so you can try to make a judgement about what you might like.
Bob

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Post Options Post Options   Thanks (0) Thanks(0)   Quote duffer Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jan. 2022 at 10:43am
Originally posted by Nothing Special Nothing Special wrote:

And for driving on snowy freeways I will never consider a front auto locker again.  First of all, I really don't understand why people don't use 4WD on snowy freeways.  Yes, it lets you drive faster than your brakes and steering can handle.  But that's your choice, it doesn't MAKE you drive too fast.  And a truck in 4WD is so much more stable on snow than it is in 2WD.  I don't understand why you wouldn't take advantage of that.  It's OK if you choose not to, I don't need to understand something for it to be OK for you.  But I don't understand.  Anyway, with a front auto locker when one front tire loses traction that stronger return to center feel becomes just the opposite, a strong tendency to turn toward the tire with no traction.  On a freeway that can put you in the next lane before you can catch it.  But again, that's driving on snowy freeways and doesn't apply to most trail rigs that rarely see snow and almost never see freeways.

My exact thoughts and experience.  I am always in 4x4 mode on ice or snow and it makes a big difference.  

Maybe more due to my more youthful driving style several decades back, but the Detroit Locker in the rear of my 3B was plain damn scary on pavement.  That was no doubt due in part to a light vehicle and the 381 that resided under the hood.  In short, if you went into a corner too fast, you were screwed as when you took your foot off the accelerator and the locker unlocked, you had best hope there was some room on both sides because you were no longer aimed in the same direction.

And yes, I end up toggling the selectables a lot but I have not found the disengagement to be a problem-unless perhaps I'm in the JK where those switch positions were some fiat engineer's brain fart.  But then the whole JK is a fiat engineer's brain fart.
1955 3B: 441sbc,AGE 4 speed transmission, Teralow D18w/Warn OD, 4.11:1 D44's/ARB's, glass tub & fenders, aluminum hood/grill, 8274, York OBA, Premier Power Welder; 67 CJ5: 225,T86AA, D18, 4.88's, OD
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Metcalf Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jan. 2022 at 11:16am
Originally posted by Nothing Special Nothing Special wrote:


And for driving on snowy freeways I will never consider a front auto locker again.  First of all, I really don't understand why people don't use 4WD on snowy freeways.  Yes, it lets you drive faster than your brakes and steering can handle.  But that's your choice, it doesn't MAKE you drive too fast.  And a truck in 4WD is so much more stable on snow than it is in 2WD.  I don't understand why you wouldn't take advantage of that.  It's OK if you choose not to, I don't need to understand something for it to be OK for you.  But I don't understand.  Anyway, with a front auto locker when one front tire loses traction that stronger return to center feel becomes just the opposite, a strong tendency to turn toward the tire with no traction.  On a freeway that can put you in the next lane before you can catch it.  But again, that's driving on snowy freeways and doesn't apply to most trail rigs that rarely see snow and almost never see freeways.



I'm just wondering, have you tried a front auto locker ONLY in the snow, or was it along with an autolocker/spool in the rear axle?

I just don't get the behavior you describe with my front autolocker only. It will do what you describe IF I have the rear locker turned on (spool). I've found 9/10 times most of the quirks are coming from the REAR locker, not the front. Having the rear locker on magnifies all the negative qualities of any front locker. On my selectable/selectable rig having the rear locker on makes the front end harder to turn, turns wider, and takes longer to unlock the front. I think is has something to do with the different speeds the front and rear axles need to go to go when turning.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Nothing Special Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jan. 2022 at 10:17pm
Originally posted by Metcalf Metcalf wrote:

I'm just wondering, have you tried a front auto locker ONLY in the snow, or was it along with an autolocker/spool in the rear axle?

I just don't get the behavior you describe with my front autolocker only. It will do what you describe IF I have the rear locker turned on (spool). I've found 9/10 times most of the quirks are coming from the REAR locker, not the front. Having the rear locker on magnifies all the negative qualities of any front locker. On my selectable/selectable rig having the rear locker on makes the front end harder to turn, turns wider, and takes longer to unlock the front. I think is has something to do with the different speeds the front and rear axles need to go to go when turning.

Not yet.  My only experience with an auto locker in the front was an F-150 with LockRights in both axles.  If / when I get a trail rig with an auto locker in the front and a selectable in the rear I might try it on a snowy freeway.  Or maybe I won't as I really do think it's very dangerous.

I really get most of what you say about a rear locker making a front locker seem worse.  Going around a corner a rear locker will tend to push you straight (a selectable maybe more than an auto, but I've only had autos in the rear) and that would tend to aggravate anything the front axle is doing.

But the snowy freeway issue I think is different.  As I touched on above, it's related to the strong return-to-center feel you talk about.  When you put power to a front tire it tries to move forward (duh!).  But it would be very happy to move forward and leave the vehicle behind by turning the steering in the opposite direction (i.e. the right front tire tries to turn the steering to the left and vice versa).  But that vice versa is what is normally the saving grace.  As long as both front tires are pulling they cancel each other out.  And with an open front diff, which always sends the same torque to both front tires, it always cancels out.

But with an auto locker, when you go around a corner it unlocks because the outside tire is trying to go faster (and that's what unlocks an auto locker, one tire trying to go faster than the ring gear).  So with it unlocked it only is driving the slower inside tire.  If you get on the power like that the inside tire tries to turn the steering in the opposite direction, which means back toward center.  Since it's unlocked the outside tire isn't being driven so it doesn't cancel out that effect and you get the strong return-to-center feel (or torque steer trying to straighten you out).

The other time the steering forces don't cancel out with an auto locker is when one front tire loses traction.  When that happens with an open diff the diff will still send the same torque to both tires so there's no torque steer.  But an auto locker will lock and send torque to the tire with traction and that tire will try to turn you toward the tire with no traction.  And since that tire has no traction it can't counteract it.  Now you get torque steer that's trying to turn you toward the tire with no traction.

On a snowy freeway this bites you on a lane change.  Often the driving lanes are relatively free of snow, but there's a ridge of thick, heavy snow between the lanes.  The first time I drive my truck in those conditions, on the first lane change when the left front tire hit that ridge of snow and lost traction the torque steer jerked the steering wheel to the left.  I wrenched it back straight and let off the gas which brought it back in control, but the truck had already moved 10 feet to the left!  Fortunately I was trying to make that lane change and I knew the lane was empty.  But if I had just been drifting a bit left while someone was passing me, or if I had drifted onto the left shoulder, it could have been very bad.  When I changed lanes back to the right I tried to be ready for it but the truck still jumped over several feet before I caught it.

The physics of why that happens are very clear, and I don't see how a rear locker would make that worse.  You say you haven't noticed it, but from what you say about how you use 4WD in the snow, I'm pretty sure you would be in 2WD on a freeway with the driving lane relatively free of snow.  And that's what I did the rest of that winter.  After that second lane change I shifted into 2WD and didn't use 4WD except at low speeds until after the next summer when I pulled the LockRight out of the front diff.

As I said above, you've given me a lot to think about regarding which diff should go where.  All of my trail experience has been with an auto rear and an open or a selectable front.  I really like the rear auto / open front most of the time, and I really like adding the front selectable for the rst of the time.  But from what you've written I really think I might like a front auto / rear selectable even more on the trail, and I hope to try it sometime.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Metcalf Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jan. 2022 at 10:39pm
Originally posted by Nothing Special Nothing Special wrote:


The physics of why that happens are very clear, and I don't see how a rear locker would make that worse.  You say you haven't noticed it, but from what you say about how you use 4WD in the snow, I'm pretty sure you would be in 2WD on a freeway with the driving lane relatively free of snow.  And that's what I did the rest of that winter.  After that second lane change I shifted into 2WD and didn't use 4WD except at low speeds until after the next summer when I pulled the LockRight out of the front diff.

As I said above, you've given me a lot to think about regarding which diff should go where.  All of my trail experience has been with an auto rear and an open or a selectable front.  I really like the rear auto / open front most of the time, and I really like adding the front selectable for the rst of the time.  But from what you've written I really think I might like a front auto / rear selectable even more on the trail, and I hope to try it sometime.


Yup, just haven't noticed anything like that. If the road conditions where bad enough I would have it in 4wd, but I don't drive around in 4wd unless I have to. I just haven't noticed any jerky behavior that was made THAT much worse from the front locker. Driving over a big berm of snow in the middle is always going to get some wiggle and 'grab' in the wheel that you have to counter-steer.

My general thought is that the rear locker is definitely changing things. I definitely notice more tendency to get pushed through turns ( understeer ) with the rear locker followed VERY closely by 'sporty' oversteer wagging the rear end out under power.

I will definitely say there is no perfect answer, but I have been pretty disappointed in the LX45 with selectable/selectable/selectable ( cause of the full time 4wd transfer case ). Maybe there is something else going on, but it is pretty annoying how much more input it requires from the driver and how obtrusive the front selectable. Going forward, my first choice for any part time 4wd vehicle would be an automatic front and selectable rear.

Hopefully locker technology will change in the future and give us even more options to experiment with. I know I have a few different ideas I would like to try.

Thanks for the good tech talk. I appreciate that.
42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nothing Special Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jan. 2022 at 11:23pm
Originally posted by Metcalf Metcalf wrote:

....  Thanks for the good tech talk. I appreciate that.

Thank you!  I always enjoy a good tech talk and as I said, I've learned a lot from you.

And maybe I touched on this but I thought I'd make sure I was clear, the dangerous handling I'm talking about is strictly a high speed issue.  When driving slower there's enough time to react.  So this wouldn't apply to most trail vehicles that are rarely if ever driven on a freeway and will likely never see a snowy freeway.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slowjunk Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan. 2022 at 11:12am
I put a rear Dana 44 from a M38 or M38A1 in my CJ2A and then put a Detroit Locker in it.  I had always heard these horror stories about clunking and jerking when going around corners, but I have to say I was pleasantly surprised by how docile the Detroit Locker was in the rear axle.  I am very happy with it and I would do it again.  I have not been on slick ice and then maybe my opinion would change. In dirt and mud the locker in the rear really digs in and it keeps going like it is 4wd (I forget to engage the locking hubs in the front pretty often).  I have a Powr-Lok for the Dana 25 and I look forward to finding out how that it because I have heard divergent views on how much it affects the steering effort.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wfopete Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan. 2022 at 11:35am
Question.  How much does tire selection impact the characteristics of a locker; particularly on the rear axle? I run military style tires 6:00x16 NDT.  Would a wider tire impact the turning action of the locker more or less or does it make zero difference?  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nothing Special Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan. 2022 at 12:11pm
Originally posted by wfopete wfopete wrote:

Question.  How much does tire selection impact the characteristics of a locker; particularly on the rear axle? I run military style tires 6:00x16 NDT.  Would a wider tire impact the turning action of the locker more or less or does it make zero difference?  

It shouldn't make any difference.  What people don't realize about auto lockers is that they don't really ever "lock".  They don't slip, I'm not saying that.  But they will always freely let the outside tire turn faster.  Really nothing will change how that works. 

When you go around a corner an auto locker only drives the inside tire.  With one-wheel-drive like that you can get some weird handling characteristics from the torque steer of only pushing on one side of the vehicle.  Those will be more apparent with a tire that gets better traction.  Or said the other way, a tire with worse traction will spin more easily.  Either of those effects might be better or worse, depending on your perspective.  But it won't affect how the locker unlocks.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Metcalf Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jan. 2022 at 11:14am
Originally posted by Nothing Special Nothing Special wrote:

Originally posted by wfopete wfopete wrote:

Question.  How much does tire selection impact the characteristics of a locker; particularly on the rear axle? I run military style tires 6:00x16 NDT.  Would a wider tire impact the turning action of the locker more or less or does it make zero difference?  

It shouldn't make any difference.  What people don't realize about auto lockers is that they don't really ever "lock".  They don't slip, I'm not saying that.  But they will always freely let the outside tire turn faster.  Really nothing will change how that works. 

When you go around a corner an auto locker only drives the inside tire.  With one-wheel-drive like that you can get some weird handling characteristics from the torque steer of only pushing on one side of the vehicle.  Those will be more apparent with a tire that gets better traction.  Or said the other way, a tire with worse traction will spin more easily.  Either of those effects might be better or worse, depending on your perspective.  But it won't affect how the locker unlocks.


With the weight typically transferring to the outside of the turn....un-weighting that driven inside tire....I always see rear automatic lockers 'cycle' while under power when turning. The inside tire slips....then the outside tire grabs, then the inside tire slips, rinse, repeat. Most of the time you have to try and 'coast' through corners.

I do think some of the newer Detroits changed things when they started messing around with the 'timing' rings on the side gears (I think this was the 'soft-locker' change) I've never been able to find a really good explanation on that. I do know that removing the timing ring seems to make the locker 'better' for a lot of front axle applications.




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