Anti-Spin Differential Rear Axle Options?

Tyler-98-W68

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While I haven't gone in any serious offroad situations or obstacles with my 4xe Sahara(No anti spin), based on how Jeep programs the brake lock differentials that brake each individual wheel I can't see how the anti-spin differential is really an upgrade as the BLD does the same thing, granted the LSD should in theory create less energy loss to heat (like the BLD). Some one should pull the ABS fuse and do a test of how the anti spin diff actually works without assistance from the BLD system, I think you'd be surprised at how poor it operates

 

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I almost always recommend getting the LSD in any vehicles. I worry about the clutch life issues that some people tend to bring up. Generally they will lose a little effetiveness with wear but typically don't fail or make the vehicle undriveable in any way. You have to keep in mind that the stock LSD is not super aggressive by any means and is simply meant to keep both tires spinning when on relatively flat ground like wet grass and snow. They are not meant to provide traction in hardcore off-roading like when one tire is completely off the ground or wedged by a rock. I've seen several people say the clutch packs are "shot" or worn out because it won't spin both tires in every situation, but that is just the nature of these as they are not a true locker or real aggressive LSD. Lockers and aggressive LSD's tend to have negative impact on day to day driving and handling on the road and why they are not offered stock (or are selectable so you turn them off when on the road).
 

entropy

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Mine's still going. 20k miles. It helps quite a bit, provides great traction. It is not a locker but it is much better than BLD alone. Just service it regularly.

You get a dana44 with the rear LSD. It is a no-brainer. I am replacing it with a locker next year and don't feel bad throwing money at the axle because it is a decent axle.
 

OSCAR II

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I almost always recommend getting the LSD in any vehicles. I worry about the clutch life issues that some people tend to bring up. Generally they will lose a little effetiveness with wear but typically don't fail or make the vehicle undriveable in any way.

Gotta agree with this. Usually when they fail they're just an open diff. Don't make any noise, just the LSD part doesn't function. I always found them to make more noise when they are working proper. Tight turns in parking lots they tend to chatter, tires chirp.


Lockers and aggressive LSD's tend to have negative impact on day to day driving and handling on the road and why they are not offered stock (or are selectable so you turn them off when on the road).
The selectable ones have no impact on day to day, Every ARB I've installed has been awesome. Its an open diff, press a button and its locked when I need it.

I've had many of GM's Posi's and safety "T" tracks.
The clutch cone; Man these suck, don't last long and aren't rebuildable. You have to replace the carrier
The clutch pack; Always worked fine, and wasn't hard to replace the clutch packs.
The Eaton gov lock; Always worked fine (locks up only between 5 to 25 MPH), rebuildable clutch packs. Just a lot of parts.

Unfortunately you never knew which one you were going to get.
 


mlkmet88

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I would not buy a Wrangler without it. For beach driving 4x4 high or 4x4 low with tires air down are move important factors.
 

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How do I know when it has kicked in?
Even my 2 seat convertable would flash on the dash when the rear tires would slip. (1999)
 

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IIRC you also get better tires when you select the LSD, so another reason to check that box.
 

west tex

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I wanted to get some more experienced takes on the Anti-Spin Differential Rear Axle option for a JL Sport S. I will be doing some fairly tame beach driving, but it seems like a good option for preventing getting stuck in the sand. What are your thoughts on this option for a 2023 JL Sport order? Thank you.

I have the LSD in my '21 2 dr 80th Edition. Soft sand? No sweat. Of course, I air down to about 18 psi before taking on sandy terrain and that makes a big difference. I also went over a number of Badge of Honor (and other) trails at Moab last year and the LSD was excellent. Wouldn't buy a new Jeep without it.
 

entropy

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How do I know when it has kicked in?
Even my 2 seat convertable would flash on the dash when the rear tires would slip. (1999)
It is always working. It is a mechanical device. It will transfer up to about 3 times the available torque to the tire with the most traction with negligible delay if any. It doesn't "kick in" like BLD. It is so smooth it is almost impossible to notice when it is working. If the torque bias between both tires is higher than 1:3, meaning the tire with traction needs 3 times more than available torque to move the vehicle forward, it wont work at all. It is a torque multiplier, the tire with less traction needs a little traction to work, then whatever that traction is gets multiplied by 3.

" Please note that the wheel with grip receives 4 times the grip the other wheel can transfer to the road. It does not mean 100% of the engine torque can be used. Let’s say the engine puts out 300 Nm of torque and the spinning wheel can only transfer 50 Nm of torque to the surface it is on. In a regular open differential, the other wheel would receive 50 Nm of torque as well. The total amount of torque to the wheels is 100 Nm. In a Torsen differential with a 4:1 bias ratio, the other wheel will receive 200 Nm or torque. The total amount of torque to the wheels is now 250 Nm. "

https://www.kmpdrivetrain.com/differentials/torsen-vs-plated-limited-slip-differential/

Tires slipping doesn't mean your LSD isn't or is working. A lot of people confuse BLD with their limited slip, thinking that when BLD kicks that's the limited slip. it isn't
 
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6.2Blazer

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There are some good explanations of how the LSD works above. Just to address a few previous posts, this type of LSD does not "kick in". It is always working and attempting to keep both tires spinning, but as the traction difference between the left and right tires increases it will no longer be able to compensate at some point in time.

I'll use this example as it has worked for me in the past when explaining how most LSD's work. As mentioned above most LSD's can transfer anywhere around 2 to 5 times the torque to the opposite wheel. The higher the number the more "aggressive" it is. Factory options generally are less aggressive and close to the 2 times number where as aggressive aftermarket versions get up to around 5 times.

If both rear tires are on the exact same even surface theoretically the left side has 50% traction and the right side has the same 50% traction. In this case both tires would spin with just an open differential. However in the real world it is very, very uncommon to have a both tires with perfectly equal traction. Even the torque of the engine when accelerating causes unequal traction, and as soon as the left and right side are unequal only one tire will spin. This it the "one wheel peel" situation you almost always see in a vehicle with the standard open differential.

So what does the 2 to 5 times number mentioned above mean? Starting out with the extreme situation as one of the tires being completely off the ground and hanging in the air (like an extreme off-road situation). This means the tire on the ground has 100% traction and the one in the air has 0% traction. It basically takes zero torque to spin the tire in the air. Any number times zero = zero. If you have a factory LSD with a low torque transfer around 2, than 2 times zero = zero and the tire on the ground will no spin because it basically has no torque going to it. Even with an aggressive LSD that can transfer 5 times the torque you still have 5 times zero = zero. That's why actual mechanical locking diffs are used in hardcore off-road vehicles.

As another example the vehicle is on a mildly rutted muddy road with one tire having 40% traction and other 60% traction. With an open diff the tire with 40% traction will spin and the one with 60% will not. Now if you have the LSD that transfers 2 times the torque that is 2 times 40% = 80%. Since 80% is now greater than 60% both tires will spin.

As a final example, let's say one tire is on dry pavement with 80% traction and the other on ice with 20% traction. Obviously with an open diff only the tire on ice will spin. In this case 2 times 20% is only 40% and less than 80%, so still only the tire on ice will spin. However if you had a more aggressive aftermarket LSD that can transfer 4 times the torque you now have 20% times 4 = 80%, so the other tire should also spin.
 

entropy

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While I haven't gone in any serious offroad situations or obstacles with my 4xe Sahara(No anti spin), based on how Jeep programs the brake lock differentials that brake each individual wheel I can't see how the anti-spin differential is really an upgrade as the BLD does the same thing, granted the LSD should in theory create less energy loss to heat (like the BLD). Some one should pull the ABS fuse and do a test of how the anti spin diff actually works without assistance from the BLD system, I think you'd be surprised at how poor it operates
Based on the bolded statements your opinion is just that. An opinion. Inexperienced speculation. The BLD does not do the same thing the LSD does. They're very different tools.

The LSD in the JLs has a torque bias ratio of 2.7:1. That's not as aggressive as the aftermarket units but it is pretty close to 3:1 and aggressive for any road oriented OEM LSD which tend to be below 2:1. It is a mechanical unit that provides almost real time response.

BLD is slow to react, jerky, and unpredictable. Momentum is important even on crawling situations and with BLD you lose momentum. LSD will allow you to keep moving closer to how a locker will as long as both tires remain on the ground and you are able to stay close to the torque bias ratio.

When you need momentum or both tires to spin, BLD will fail as it will aimlessly alternate torque from tire to tire. From personal experience wheeling before I installed my front locker I can tell you BLD alone sucks.

Pair this with BLD's ability to "lock" outside of the torque bias ratio band and you have a pretty good setup right there with the LSD.

However, at the end of the day it will never be remotely as good as a locker. Jeep should've just thrashed the rear LSD and throw a rear locker instead. Jeeps are not the best for sand, mud, or speed offroading. Jeeps are good on the rocks and low speed offroading. They should have lockers and not these limited traction devices.
 

Tyler-98-W68

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So you have no videos to disprove my opinion? I've had many jeeps with BLDs and they 100% lock the wheel spinning and transfer power to the wheel with traction, this however only works in vehicles with 4x4 low as it takes twice the amount of torque to spin the wheel with traction vs using a mechanical device like the LSD.

BLD does function like an LSD, i've had it on all of my jeeps and learned to use it quite well when the jeeps I had did not have mechanical lockers or LSD.

So you are telling me with zero BLD intervention, you can get into a cross axle situation with 1 front and 1 rear tire in the air, while trying to go up an incline, and without BLD the LSD will work better?

I'd love to see a test of this because i've looked all over youtube and can't find a single example of someone doing this.

I do extensive testing and monitoring of the 4x4 systems in all my jeeps, so my opinion isn't just because I think it won't work. It's like how everyone said the ELSD in the WK2 Grand Cherokees wasn't a locker.....but I tested and prove 100% it did lock 100% and actually could be commanded to lock and unlock just like the lockers in Wranglers.

https://www.jeepgarage.org/threads/...is-more-of-a-locker-than-people-think.220617/

So, instead of giving me diagrams go pull your ABS fuse rely 100% on the LSD and show me how well it works
 

entropy

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So you have no videos to disprove my opinion? I've had many jeeps with BLDs and they 100% lock the wheel spinning and transfer power to the wheel with traction, this however only works in vehicles with 4x4 low as it takes twice the amount of torque to spin the wheel with traction vs using a mechanical device like the LSD.

BLD does function like an LSD, i've had it on all of my jeeps and learned to use it quite well when the jeeps I had did not have mechanical lockers or LSD.

So you are telling me with zero BLD intervention, you can get into a cross axle situation with 1 front and 1 rear tire in the air, while trying to go up an incline, and without BLD the LSD will work better?

I'd love to see a test of this because i've looked all over youtube and can't find a single example of someone doing this.

I do extensive testing and monitoring of the 4x4 systems in all my jeeps, so my opinion isn't just because I think it won't work. It's like how everyone said the ELSD in the WK2 Grand Cherokees wasn't a locker.....but I tested and prove 100% it did lock 100% and actually could be commanded to lock and unlock just like the lockers in Wranglers.

https://www.jeepgarage.org/threads/...is-more-of-a-locker-than-people-think.220617/

So, instead of giving me diagrams go pull your ABS fuse rely 100% on the LSD and show me how well it works
No I am not saying that. You said that BLD does the same thing as LSD which is blatantly wrong. You also said there is no point getting LSD.

BLD will be better than LSD alone in many situations just as LSD will be better than BLD in other situations. Pair them together and you have pretty nice setup. My rear is BLD+LSD and it is good enough I am keeping it for a while. My front was BLD alone and I threw a locker in it because the BLD just doesn't cut it. BLD+LSD gives you a chance on obstacles where you need to have a locker. BLD alone doesnt. I wheeled through hard obstacles with BLD and it just sucks. I dont care what all these internet experts say about it. On the trail, it sucks.

The difference between your opinion and mine is that yours is coming from youtube videos. Mine is coming from trail experience.
 

Tyler-98-W68

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Ok so LSD transfers power to the tire that has traction.

BLD does not transfer power to the tire that has traction?

The difference between my formed opinion is based on testing and trail experience from the following jeeps.

FDII Patriot
FDII Compass
Active Drive 2 Cherokee KL
Trailhawk Cherokee KL
WK2 Grand Cherokee with Quadra Drive 2

All i'm saying is if the LSD works so much better and different than BLD make a video and prove it

 

ATO4x4
 
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