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Old 12-20-2013, 03:24 AM   #1
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Rubicon locking axle...limited slip when off?

If the lockers are not engaged does it act as a limited slip axle in the rear

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Old 12-20-2013, 04:33 AM   #2
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No it is an open differential. The traction control systems controls tire slippage through braking and engine power curving---it actually works quite well. The system is defeated in 4 WD low range.

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Old 12-20-2013, 04:33 AM   #3
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Originally Posted by gregg008 View Post
If the lockers are not engaged does it act as a limited slip axle in the rear
No. it acts as a opened diff in both the front and rear!
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Old 12-20-2013, 05:31 AM   #4
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Jeep's Rock-Trac video explains it very well.

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Old 12-20-2013, 06:11 AM   #5
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Seen that video a hundred times and still like watching it. Gives a good basic understanding of the systems.

I watched the comand trac video also, I think there is a mistake in it as it shows limited slip working only in 4-hi. It works in 2-wd also right?
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Old 12-20-2013, 07:06 AM   #6
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It's mechanical, always on.

If you don't off road much LSD is a good reason to get a Sport S or Sahara.
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Old 12-20-2013, 02:35 PM   #7
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Excellent video
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Old 12-20-2013, 02:44 PM   #8
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Would it be wrong to say the BLD on the Rubicon and non LSD equipped JKs provides near LSD performance on road ?
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Old 12-20-2013, 03:53 PM   #9
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Would it be wrong to say the BLD on the Rubicon and non LSD equipped JKs provides near LSD performance on road ?
LSD is proactive and smooth, BLD is reactive and jerky....
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Old 12-20-2013, 05:11 PM   #10
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Would it be wrong to say the BLD on the Rubicon and non LSD equipped JKs provides near LSD performance on road ?
Traction control works great, but it isn't a substitute for LSD. Just like BLD works great, but it isn't a substitute for lockers.

The biggest problem with traction control (or any brake based LSD system) is that it is reactive, and by using your brakes, it kills your momentum and robs you of power. That is OK is you are pulling from a red light, and every vehicle around you is slowly starting. But it is awful if you are turning from a standstill into fast moving traffic. That is the part that has nearly gotten me into multiple accidents.
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Old 12-20-2013, 06:37 PM   #11
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Sometimes I can feel it kick in but I find it smooth and painless.Many times I would have never known it kicked in except for the light flashing in the dash. Maybe its just me but I think it works well for the road.Maybe some of it is good tires preventing wheel spin in the first place. With the DT they do very well on wet roads
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Old 12-20-2013, 06:57 PM   #12
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Would it be wrong to say the BLD on the Rubicon and non LSD equipped JKs provides near LSD performance on road ?
My 2013 jku had LSD and I can tell you that it worked better on road then my jkur with just BLD. Huge difference no but still a difference. I am talking on snow/ice packed roads accelerating. I have too pull out onto a busy road in slick conditions when leaving my neighborhood and I can say that on my 13 jku I rarely had to shift to 4 wd to get traction and up to speed. On my Rubicon I usually end up putting it in 4 wd briefly. Both are running the same tires so tires don't come into play.
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Old 12-20-2013, 08:43 PM   #13
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Good information thanks for sharing.

Here is a good read if you have the time.

http://blog.chryslerllc.com/blog.do;...id=270&p=entry
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Old 12-20-2013, 09:01 PM   #14
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BLD is only active in 4hi/lo. Open diff axels and ribicons alike are "one wheel drive" in 2hi.
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Old 12-20-2013, 09:04 PM   #15
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BLD is only active in 4hi/lo. Open diff axels and ribicons alike are "one wheel drive" in 2hi.
pretty sure that BLD is active in 2hi it is however not active in 4lo
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Old 12-20-2013, 09:09 PM   #16
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BLD is active all the time,its part of the ABS system.
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Old 12-20-2013, 09:20 PM   #17
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I think the term BLD is confusing because it means two different things.

What most people call BLD, I call traction control (in order to avoid confusion). I consider BLD the more aggressive off-road software of traction control.

Basically...on road = traction control. Off-road = BLD
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Old 12-20-2013, 09:29 PM   #18
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Actually it is 2 separate things.
Traction control regulates wheel spin via the throttle.
BLD is 100% abs.
Traction control can be turned off but BLD can not.
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Old 12-20-2013, 09:37 PM   #19
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Think of it like this:

1. LSD's purpose is to put torque to the tire that has grip on an axle.
2. BLD's purpose is to ensure that both wheels spin at the same speed on an axle.
3. Traction control governs both 2wd or 4wd attempting to keep traction on all wheels being driven.

In that order.

ESP "traction control" turns off in 4lo, but BLD is always working and has a separate calibration for 4lo.

This system is why an LSD equipped Jeep with BLD and Traction control is the best all around Jeep. If you need the utility of lockers, electronic sway bar disconnect, low gearing, etc. there is no substitute, but most do not so are benefitted most by LSD for their daily driver.

I do wish the stock LSD was Helical Gearing rather than a Clutch Pack, but a clutch pack is relatively cheap and serviceable when needed.
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Old 12-20-2013, 09:39 PM   #20
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pretty sure that BLD is active in 2hi it is however not active in 4lo
Absolutely incorrect. BLD is only active with the front axel engaged... And is actually more "aggressive" in 4lo
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Old 12-20-2013, 09:52 PM   #21
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Wrong BLD is always active no matter the mode.
A Jeep with BLD is better than a Jeep with LSD without BLD.
A Jeep with LSD and BLD together is somewhat better in certain situations than BLD alone and worse in others.Those are the facts jack quack quack !!
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Old 12-20-2013, 09:52 PM   #22
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Absolutely incorrect. BLD is only active with the front axel engaged... And is actually more "aggressive" in 4lo
I concede, I was thinking (TCS) traction control systems.
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Old 12-20-2013, 10:02 PM   #23
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Actually it is 2 separate things.
Traction control regulates wheel spin via the throttle.
BLD is 100% abs.
Traction control can be turned off but BLD can not.

It is really ESC and ERM that will cut throttle, not traction control. The problem is that all the systems are intertwined....so it is hard to say when one stops and the other starts. If you consider ESC and ERM part of traction control, then yes...it would cut throttle.

Here is the best way I've seen BLD described.
This is from the JK press release written back in September of 2006.

http://jeepin.com/news/2007wrangler

Quote:
Available for the first time with Jeep Wrangler models are Brake Lock Differentials (BLDs), which are incorporated into the Electronic Stability Program (ESP) algorithm. BLDs apply braking force to an axle’s spinning wheel in order to provide an equal amount of torque to each wheel and deliver greater traction for rock-crawling over severe off-road terrain. A separate set of BLD calibrations is designed for off-road operation and automatically activates when driving in 4 Low.
That is why I say there is BLD "the function" (as in a brake assisted locking differential) and BLD "the software" (as in the more aggressive off-road software that kinda, sorta, almost imitates lockers).

Traction control uses "a BLD"...just like most other new vehicles made.
But BLD "the system" is really something used for off-roading.

It is all hard to keep straight IMO.
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Old 12-20-2013, 10:08 PM   #24
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Talking So next you're going to tell say...

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Wrong BLD is always active no matter the mode.
A Jeep with BLD is better than a Jeep with LSD without BLD.
A Jeep with LSD and BLD together is somewhat better in certain situations than BLD alone and worse in others.Those are the facts jack quack quack !!
I don't think a Jeep with BLD is better than an old FJ40 with LSD.

Since you can't get a new Jeep with LSD an no BLD it's tough to say, but I'm certain I'd take LSD with BLD over just BLD any day of the week.

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Old 12-20-2013, 10:19 PM   #25
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You do realize that when you get one wheel in the air the BLD will kick in and send power to the other wheel and keep you going while the LSD alone will leave you sitting and spinning right ?
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Old 12-20-2013, 10:27 PM   #26
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Thumbs up Yes, yes I do!

That's why I have LSD AND BLD.
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Old 12-20-2013, 10:35 PM   #27
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To answer the OP's questions.

JK's? No...

TJ's Yes... TJ Rubi's had both a locker and limited slip in the rear. So if someone told you they do, they may have been coming from a TJ background.
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Old 12-20-2013, 10:55 PM   #28
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This video explains that BLD is active in both 4hi and 4lo. It does not state active in 2hi.. Nor do I recall BLD ever engaging while in 2hi. For instance I'd sit and spin on wet grass (one wheel -mud coverage on one side) and go nowhere without engaging 4hi. Hence the addition of truetracs.
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Old 12-20-2013, 11:12 PM   #29
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so in the snow a rubicon in 4hi....may not be as good as a normal jeep with an LSD.... even in 2wd mode?
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Old 12-20-2013, 11:33 PM   #30
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Correct!

Unless it's a TJ Rubicon with LSD.

Except for that 4hi vs 2wd mode question, I'd wager a Rubicon in 4hi would rule any 2wd vehicle in the snow. Also keep in mind that it's not optimal in all conditions to be in 4hi so LSD has a daily driver advantage.

Welcome to being a Jeep Wrangler Enthusiast, if you want AWD select another Jeep.

Here we have the Command-Trac Youtube video. It talks about Trac-Loc AND BLD in 2 wheel mode.


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