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LSD's vs. Lockers, context of trail class.


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I'd like to have an open discussion about When to go from LSD's to lockers as one climbs the trail class ladder. 

 

I, for one have heard "rumors" that there is a way to adjust LSD's to work almost as well as lockers. I mean, some of us is po'. 😁

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I'm pretty happy with the LSD in mine, but I'm not climbing any trail class ladders with it. An LSD is just an open diff with clutches jammed in behind the spider gears to make them harder to turn, so if you're looking to build a rock crawler that'll spend half the trip with a wheel in the air, the LSD will probably disappoint you. Short of that, and on a budget, LSD is good, or at least a hell of a lot better than an open diff.

 

The R50 LSDs were pretty nerfed, possibly for stability reasons (the WD21 LSD does make it pretty easy to get the rear end to step out in the snow). Hawairish did a great writeup on how to repack them to make them useful. Sounds like there's a limit to how tight you can go before you start breaking stuff.

 

If I was going to throw money at my diffs, I'd leave the rear LSD alone and put a ratcheting or air locker up front. But, yeah, some of us is poor, and my truck needs a lot of things more than it needs a front locker I might use once every couple of years. I don't think I've had it properly stuck since I put a decent set of tires on it. 

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Limited slip differentials are a more affordable way to get better rear end traction on most surfaces and in most driving conditions. However, in extreme cases such as rock-crawling or climbing very uneven and steep obstacles which could result in a rear tire having little to no traction, a locking differential provides the best solution in order to overcome the obstacle with the least potential for damage. Damage could be caused either by excessive wheel speed which could result in drivetrain damage, or excessive vehicle speed, which could result in loss of control, leading to undercarriage damage, body damage, and/or drivetrain damage. A very tight LSD could potentially cause some handling/cornering issues on pavement.

 

If you do little to no rock-crawling, the LSD could be a satisfactory option. In my case, the effort/expense of pulling the third member, repacking the clutch pack to increase the breakaway torque, then reassembling it, was not worth the risk of discovering that it still might still not provide enough performance benefit for my style of 4-wheeling. It is for this reason that I opted to just go all-in with an ARB air locker. My R50 is air-lockable both rear and front, but it took a decade of wheeling for me to get to that point.

 

Every driver's situation is different, so the approach to mods I would recommend is to run the trails you enjoy, get lots of seat time to learn how to drive within the vehicle capabilities, learn to choose good lines, and plan your vehicle upgrade path accordingly. Tires are probably one of the most important things to start with, with a lift being next. I would prioritize recovery equipment above drivetrain mods. A locking diff or tight LSD may only give you the ability to get you stuck further down the trail.

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7 hours ago, XPLORx4 said:

Limited slip differentials are a more affordable way to get better rear end traction on most surfaces and in most driving conditions. However, in extreme cases such as rock-crawling or climbing very uneven and steep obstacles which could result in a rear tire having little to no traction, a locking differential provides the best solution in order to overcome the obstacle with the least potential for damage. Damage could be caused either by excessive wheel speed which could result in drivetrain damage, or excessive vehicle speed, which could result in loss of control, leading to undercarriage damage, body damage, and/or drivetrain damage. A very tight LSD could potentially cause some handling/cornering issues on pavement.

 

If you do little to no rock-crawling, the LSD could be a satisfactory option. In my case, the effort/expense of pulling the third member, repacking the clutch pack to increase the breakaway torque, then reassembling it, was not worth the risk of discovering that it still might still not provide enough performance benefit for my style of 4-wheeling. It is for this reason that I opted to just go all-in with an ARB air locker. My R50 is air-lockable both rear and front, but it took a decade of wheeling for me to get to that point.

 

Every driver's situation is different, so the approach to mods I would recommend is to run the trails you enjoy, get lots of seat time to learn how to drive within the vehicle capabilities, learn to choose good lines, and plan your vehicle upgrade path accordingly. Tires are probably one of the most important things to start with, with a lift being next. I would prioritize recovery equipment above drivetrain mods. A locking diff or tight LSD may only give you the ability to get you stuck further down the trail.

Good solid advice, the only real way to figure out how to build and upgraded your R50 is to test it in the areas that it will be used the most. For example my R50 build is geared towards camping and some moderate Off-Roading. Lately I too have been throwing around the idea of installing an ARB Locker in the future.

 

Chris.

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One of my favorite topics.  I'll take a different path to promote further discussion, but for starters I'll say an LSD (even a repacked one) isn't a true substitute for a locker.  They're great for having a street and trail balance, and they can be made to do very well off-road, but they're simply not a locking differential.

 

If there was a traction level chart that was specific to our trucks based on available device options, it might look something like this:

 

Level - Front Diff, Rear Diff, Suitable Trail Use (Green/Blue/Red)

0 - Open, Open, Green

1 - Open, LSD, Green

2A - Open, Mechanical, Green/Blue

2B - Open, Selectable, Green/Blue

3A - Mechanical, Open, Blue

3B - Selectable, Open, Blue

4A - Mechanical, LSD, Blue/Red

4B - Selectable, LSD, Blue/Red

5A - Mechanical, Mechanical, Red

5B - Selectable, Selectable, Red

 

Clarification points:

  • For LSDs, there's obviously a scale between OE-spec LSD units and re-packed units, but they're still in the same traction level.
  • "Mechanical" refers to auto-lockers (auto-unlockers, lunchbox, etc.) like Lokka (front) and Blokka (rear) units.
  • "Selectable" refers to any locker that can be disengaged on demand, regardless of actuation (air, electric) : ARB, TJM, TRE
  • Selectable lockers always have the advantage over a mechanical locker because they can be disengaged.  This is particularly important when in tight steering situations, and everyday street driving.  (This discussion ignores the use of manual hubs.)
  • Levels 0 & 1 are still fully trail-capable, provided all tires stay on the ground.  Once one tire lifts off the ground, especially on an incline, limitations immediately kick in.  Notably, it's relatively easy to lift a tire with IFS.
  • When coming from Levels 0 or 1, I advocate locking the front diff (level 3) before locking the rear (level 2), mainly because of issues that can occur when a front tire is off the ground and not rotating in unison with the other tire.  That is, if you have a front tire spinning off the ground and you land on it, it's bad on the CV, mmmmkay?  I'd skip level 2 for the most part.
  • Level 4 & 5 do great for wheeling, provided you're mindful that an LSD is not a locker and that, at some point, it will start to act like an open diff.  Red usage would basically warrant a re-packed LSD.
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  • 1 month later...
On 6/5/2023 at 7:50 PM, hawairish said:

One of my favorite topics.  I'll take a different path to promote further discussion, but for starters I'll say an LSD (even a repacked one) isn't a true substitute for a locker.  They're great for having a street and trail balance, and they can be made to do very well off-road, but they're simply not a locking differential.

 

If there was a traction level chart that was specific to our trucks based on available device options, it might look something like this:

 

Level - Front Diff, Rear Diff, Suitable Trail Use (Green/Blue/Red)

0 - Open, Open, Green

1 - Open, LSD, Green

2A - Open, Mechanical, Green/Blue

2B - Open, Selectable, Green/Blue

3A - Mechanical, Open, Blue

3B - Selectable, Open, Blue

4A - Mechanical, LSD, Blue/Red

4B - Selectable, LSD, Blue/Red

5A - Mechanical, Mechanical, Red

5B - Selectable, Selectable, Red

 

Clarification points:

  • For LSDs, there's obviously a scale between OE-spec LSD units and re-packed units, but they're still in the same traction level.
  • "Mechanical" refers to auto-lockers (auto-unlockers, lunchbox, etc.) like Lokka (front) and Blokka (rear) units.
  • "Selectable" refers to any locker that can be disengaged on demand, regardless of actuation (air, electric) : ARB, TJM, TRE
  • Selectable lockers always have the advantage over a mechanical locker because they can be disengaged.  This is particularly important when in tight steering situations, and everyday street driving.  (This discussion ignores the use of manual hubs.)
  • Levels 0 & 1 are still fully trail-capable, provided all tires stay on the ground.  Once one tire lifts off the ground, especially on an incline, limitations immediately kick in.  Notably, it's relatively easy to lift a tire with IFS.
  • When coming from Levels 0 or 1, I advocate locking the front diff (level 3) before locking the rear (level 2), mainly because of issues that can occur when a front tire is off the ground and not rotating in unison with the other tire.  That is, if you have a front tire spinning off the ground and you land on it, it's bad on the CV, mmmmkay?  I'd skip level 2 for the most part.
  • Level 4 & 5 do great for wheeling, provided you're mindful that an LSD is not a locker and that, at some point, it will start to act like an open diff.  Red usage would basically warrant a re-packed LSD.

I have read your post mentioned at the top. A page scroller as usual. And I do think I'm going the repacked route. Just a little more oomph.

 

Now, with the statement about locking the front diff first, would it then be rational to pack the front diff a little tighter than the rear?

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2 hours ago, 98dreamer said:

I have read your post mentioned at the top. A page scroller as usual. And I do think I'm going the repacked route. Just a little more oomph.

 

Now, with the statement about locking the front diff first, would it then be rational to pack the front diff a little tighter than the rear?


Yeah, I’m long with words sometimes. 
 

No LSD options for the front, so nothing to repack. 

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Well I've had great success with the good ol' Lincoln locker, or in my case "Hobart locker". :D

It sure would be nice to have a selectable ARB in the front, but now that I've got the mandatory locking hubs that MUST precede the installation of such a 'locker' for going anywhere on pavement I've definitely noticed a slight increase in mpg versus the open diff with the slugs, and a definite and more noticeable increase in uh... 'pepp'? when I drop a gear and floor it since the front driveline isn't connected and forced to rotate when not in use. I haven't haven't popped a CV since installing that diff, and aside from the steering being pretty stiff I'm able to crawl through stuff I had to use a bit more momentum to get through before. Now it just GOES just about anywhere its pointed when the hubs are locked.

For these reasons I've come to the conclusion that the welded front diff is likely staying unless I get a GREAT deal on an ARB, simply due to the fact that unless I need 4WD the hubs will be unlocked anyway for the better performance and fuel economy.
But hey, if anyone here has an ARB they can't get rid of I'd probably take it off your hands for the right price just to save wear and tear on my power steering pump when I'm out on the trails, and possibly gain a bit more control in 4x4 on on icy roads at slightly higher speeds, which IMO are the only two reasons to have selectable lockers to begin with.
Otherwise... I still have one good spare PS pump on my spare engine. ya know... right next to my TWO (complete with transfer cases, driveshafts, clutch lines, etc. etc.) spare 5-speed transmissions and TWO sets of front and rear diffs.

Anyway... that's my 2¢ on the front locker debate.

God help us all if I need the spare uh... 'unibody assembly' I guess you would call it?? sitting by the shop. 🤣😂 In any case I don't intend to break down any time soon, at least not for too long anyway. LOL

Edited by Forsaken
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I imagine a welded front would be fine on a dedicated trail rig, or, yeah, one that only has the hubs locked off-road. I leave my hubs locked all winter because I'm in and out of 4x so much dealing with snow, so the old Lincoln locker ain't for me.

 

There are LSDs out there that you can swap into the front end (at least on the WD21, I assume on the R50 as well), but from what I've read, they also tend to make the handling a little spooky. Mr. 510 ran (runs?) one that's ramped, so when you get on the power, it grabs tighter. I forget his exact description of its handling quirks in the snow, but it did not sound like fun.

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Sounds like a viscous LSD was installed. I vaguely remember reading about someone getting it to work since the rear R200 donors were also the same spline (29) as our fronts. 

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He said it was the Nismo version of the clutch LSD from an '87-'89 Z31/300ZX turbo. Not sure what's involved to install it. Joshua Ellis on the NPORA Facebook page said the Hardbody C200 LSD (also clutch, same design as the H233B) will work, but the Fronty C200K won't. There's a threaded insert that a stub axle bolts to, so you have to tear it down to swap that over from the open diff. He said he tried it, and played around with the shims, but ended up swapping it out for what he called a "pressure ring" LSD, probably that same Nismo unit if I had to guess. Others mentioned the Infiniti J30 as a potential donor, but I have no idea if that's viscous or clutch or what it is. 

 

I checked my notes and found 510's posts on the handling quirks, and they do not make me want to try it out for myself. Whips the steering wheel straight if it does find grip, spins both fronts and effectively loses steering if it doesn't. He said it was a liability more often than it helped, and that he'd never run anything but a selectable or an open front diff again.

 

That said, Towndawg sounded pretty happy with the front Lokka in his R50. Not sure if that's a testament to the Lokka over the LSD, or just two different rigs wheeled in different conditions by different people.

 

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14 hours ago, Slartibartfast said:

He said it was the Nismo version of the clutch LSD from an '87-'89 Z31/300ZX turbo. Not sure what's involved to install it. Joshua Ellis on the NPORA Facebook page said the Hardbody C200 LSD (also clutch, same design as the H233B) will work, but the Fronty C200K won't. There's a threaded insert that a stub axle bolts to, so you have to tear it down to swap that over from the open diff. He said he tried it, and played around with the shims, but ended up swapping it out for what he called a "pressure ring" LSD, probably that same Nismo unit if I had to guess. Others mentioned the Infiniti J30 as a potential donor, but I have no idea if that's viscous or clutch or what it is. 

 

I checked my notes and found 510's posts on the handling quirks, and they do not make me want to try it out for myself. Whips the steering wheel straight if it does find grip, spins both fronts and effectively loses steering if it doesn't. He said it was a liability more often than it helped, and that he'd never run anything but a selectable or an open front diff again.

 

That said, Towndawg sounded pretty happy with the front Lokka in his R50. Not sure if that's a testament to the Lokka over the LSD, or just two different rigs wheeled in different conditions by different people.

 


Interesting. I may dig back into it.

 

Lokkas are just fine up front, given manual hubs. I ran one for a while. I’ll ask Towndawg how his is holding up…I’ll see him in 5 minutes, lol. 

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From a technical standpoint, I can’t add anything to the gurus above. To the uninitiated, I can’t emphasize enough how much it matters HOW you drive your truck. I have 2 R50s with the AWD option & I love it for packed snow, sand, dirt, gravel & road travel in wet or snowy weather. I also have a 2018 4Runner & have a bit of buyer’s remorse that it only has part-time 4WD, especially on paved roads with varying traction.

In particular, I caution anyone new to all this & used to the LE transmission - drive a Lokka equipped truck before you put one on your truck. There will undoubtedly be a wide variety of opinion but I personally did not like the feel of the Lokka on road at all. It’s an opinion & not shared by all, but I wouldn’t want it on a daily driver or something that saw a lot of road time - it was noticeably stiff & quirky. A dedicated or highly off road truck would be a different situation entirely.

I sold my Lokka & found a front ARB locker. That and one of Hawarish’s super-packed rear LSDs are waiting to go on my Pathy. As much fun as the Pathy is, I just spent ~18mo with my QX4 all over Southern OR & Northern Northern California & that rear LSD works great for the vast majority of offroad exploring & camping I usually do. Of course, I’m fortunate to have the ‘02 LSD. Each truck has its pros & cons. It was refreshing to get back into an OEM+ R50 & see just how capable & pleasant it was to drive.

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The Lokka is doing great. Just as good as the day I installed it. It's taken my rig through some incredibly challenging trails and never really gave me any reason for regret. Having driven HawaIrish's fully air locked rig, my Lokka equipped rig and a stock rig, an airlocker is hands down the best performance for trail use but may not be what everyone needs. A proper line choice, good spotter and quality tires will get an open differential truck through a lot of challenging terrain.

 

 The Lokka is the best bang for your buck if you want a huge gain in trail performance on a budget but comes at the cost of a substantial change in the driving requirements and limited street use. 

 

When it snows here I use 4WD on the street and highways without issue but that's the only time it sees use on pavement as my hubs stay unlocked and the truck in 2WD the rest of the year

 

Still need to install my super packed LSD. I think HawaIrish set it up for 200-ish ft lbs? When compared to the OEM LSD it should be very nice improvement. It's been shelved with the 4:1 t-case gearset, 4.6 diff gears and my rear disc brake setup. I plan to get those installed for the next trail run in Colorado. Moab trip was a perfect example of where air lockers reign supreme but I'd wager the front Lokka and rear super packed LSD would have done well. 

 

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On 7/13/2023 at 4:55 PM, RainGoat said:


Ha, are you in town?

Haha, I was…briefly! Tuesday was All Star Game and festivities, and Wednesday seeing J&L and my bro and his fam, then back on the road Thursday. Super short visit. Thought about you when we were flying through Medford, wish we could’ve stopped but we had a long drive ahead of us. Hope you’re well!

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