The JK's Brake Operated Limited Slip

[Karma]

HI All,
I have a question for you JK owners. How well does the stock brake operated limited slip rear differential (if it can be called a limited slip) actually work? I've heard good things about it. The comparison I would ask is how it compares to a fully locked rear such as ARB. I fear that those who have given it good marks have never driven a fully locked rear so their basis for comparison is limited (no pun!!).

Thanks, Sparky

 

[jdzl]

Im pretty sure the BLD (brake locking diff) works on both axles, not just the rear. I have the optional trac-loc limited slip diff in the back and between that and the BLD it seems pretty capable - I haven't really had a chance to wheel a whole lot though so ymmv.

A locker is better because it's locked 100% whereas the BLD only happens when the ECU decides enough slip has occurred and whatever other variables are met. Supposedly it works best with steady throttle and a reasonably slow speed. It also has trouble if all four wheels lose traction as it wants to brake all of them. So you probably get a huge amount more capability for "free" with the BLD but I think there are times when a locker would be much better.

You hear about the guys that use their handbrakes with pretty good success - this is just a more sophisticated version of that.

 

[Karma]

HI idzl,
I believe the brake lock only works on the rear wheels.

Sparky

 

[jdzl]

Good writeup from Chrysler here: http://blog.chryslerllc.com/blog.do?p=entry&id=270 -- They mention "BLD looks at individual driven axles" which sounds like it would work on either axle - but they don't explicitly say that, so I'm not sure. Anyone?

Edit: Also an interesting discussion on technique here: http://www.jeepforum.com/forum/f96/bld-technique-discussion-1192827/ -- Some disagreement about whether it works on both axles or just the rear.

Edit again: I can only imagine that it if there is BLD in the front it would only engage in very specific circumstances - slow, front wheels straight (using the steering angle sensor) etc... Otherwise seems like the potential for "plowing" to happen on a gravel road would be quite high - but then I guess the ESP probably gets priority over BLD... Too many TLAs!

Edit AGAIN: Video from Chrylser confirms that BLD is on both axles: (BLD discussion begins at 1:44 or so)

 

[Karma]

HI idzl,
Good piece of research. It sure does appear the brake lock works on both axles. I'm try to figure out how to control torque to both front and rear at the same time. It's not clear to me. If you don't mind I'm going to copy the link fro another form where we are having the same discussion.

Thanks, Sparky

 

[voodoojk]

It works pretty damn well. Still not a true locker but works well. I have followed rubis all over Colorado and Moab for the last 4 years in my Jk and it has done great. Drive smart and let the system work and you will be amazed

 

[iMTB]

My TJ had totally open diffs and my KJ has brake lock. It makes a huge difference. As for fully locked vs brake lock, I don't know from experience.

 

[Septu]

I guess it depends on the type of wheeling you do. If you want wheel spin (snow/mud), it'll get you stuck.

 

[mmcan]

If you can have lockers, why wouldn't you?

 

[Overlandexpeditionspecial]

I guess it depends on the type of wheeling you do. If you want wheel spin (snow/mud), it'll get you stuck.

Exactly, doesn't really work in snow because of the compromise between forward momentum and braking, but works great on slickrock in Moab. As I have said before, especially with a programmer to change your throttle response.

Compared to my Detroit in the TJ it is lacking, mostly that you don't know for sure that it is going to lock up everytime that you want it to (or more precisely you may get some wheel spin and then it grabs, versus the Detroit pushing forward continously).

If this is your daily driver and you only take it heavy wheeling a few weeks a year, then I would say the factory system is plenty (especially with a programmer), as you get to maintain good road manners. If your going with an ARB then you keep the road manners versus driving a Detroit, but its money that you might be able to spend on something else.

Even with the on road quirks that the Detroit has, I still love it, just knowing it will get you through pretty much anything anytime, BUT I would not put one in my JK at this point, it is not necessary for its current driving duties.

 

[JPK]

I have a 2010 Rubicon and so have direct comparisons between the BLD and lockers at the flip of the switch (since the Rubicon's axles have BLD as well as lockers.) The system works and it beats the hell out of lockers around town in the snow, except for deep snow. In fact BLD is better than lockers most of the time in snow where you need to do any amount of turning or when you're off camber. BLD is helpful everywhere off road but doesn't compare to lockers. When you need lockers you need lockers. BLD works in 4 hi too, as opposed to the oem locker set up.

A good combination for less technical off road use and around town would be the rear limted slip and the front BLD, which is a combination available in the Sahara trim. Want to handle more technical situtations? Add a front locker. None of the locker issues in the snow, but limited slip for getting moving, no lockers to get you sliding off camber, front locker for when you need it. Probably the best all 'round combination really.

BTW, I still think manually moderating your brakes and throttle makes the system work better...

 

[jdzl]

Good info JPK.

I've seen quite a few posts that echo that as well - the BLD with the Trac-Loc rear is the way to go. FYI it's an option on the Sport on up to the Sahara (on the Unlimited at least)

 

[HOOLIGAN]

BLD works on both axles, but I hate calling it BLD since it gives the impression that it is a locker. It's really got nothing to do with the differential. The computer controls wheel spin through engine speed and braking. It does work well, but in no way would it replace a locker. Now in the earlier JK's you could get a limited slip differential. I've got one in mine and it SUCKS. They wear out incredibly fast and I realy haven't noticed any difference. In the past I could get my LSD to kind of "lock up" by finessing the brakes and throttle and you could feel it grab. I've never really felt my LSB work like that.

 

[Hilldweller]

IBLD is helpful everywhere off road but doesn't compare to lockers. When you need lockers you need lockers....

Quoted for truth and video added.
I was on a steep hill with a little ledge on top and lots of loose rock. Too much speed and I could wheelie and do endos all the way back down... ...too little speed and you need a locker to overcome the ledge due to the loose footing.
What happened is that the computer detects wheelspin and the combination of gravity and brake left the JK jittering like an epileptic.

 

[Karma]

HI Hill,
Yes, the obstacle was difficult but you did make it. Actually, pretty impressive performance.

Sparky