DIY BLD(Brake Lock Differential)

[nixit]

For those who don't know BLD is what some newer jeeps use, Its basically glorified traction control that's designed for trail use. The electronics and coding are no problem for me. But if anyone has any input about finding a suitable HCU, or other input about the system id appreciate it discussion helps the thinking process. I'm also going to implement my own Crawl-Control.
I have been holding on to a HCU from a 94 Lincoln for 4 years to do this with, but its gummed up now.

PS. I don't need any one telling me its not safe, The system will not be energized when its on the highway and will deactivate over x speed and sound an alarm so I don't forget to disconnect it.

 

[6872xtc]

Definitely a cool idea. Also neat that you have the skills to do it!
I don't have any help, except for asking why can't you clean the unit that you have?

Traction control came out on some semi trucks back in the late nineties, but it had some problems, probably due to working with air pressure .

 

[nixit]

Lots of tiny orifices, and the solenoids are pressed in. I'm going to try but I'm not really confident the needles and seats aren't a little rusty. It doesn't open up like a transmission valve body does.

 

[tRustyK5]

The traction control we have in the new Pete's and Mack MB's is marginal at best. It's gotten me stuck more than it's ever allowed me to get out of the soup. At least Mack has a Mud/Snow switch that nukes the traction control and allows for wheel spin...

I personally think it's much more useful in light trucks and cars.

 

[nixit]

I've owned several cars with "traction control" that should have been called wheel spin control. Because it does nothing to add traction. What I'm doing will compare left and right wheel speed and slow down the faster wheel. It won't care as long as they are spinning the same speed.

 

[tRustyK5]

The traction control on my 2013 Pete did that, between front and rear diffs, and side to side. When it worked right it was a little magical...the problem is around these parts it's uncommon for there to be tremendous differences in available traction. Where it sucked dick was climbing a slippery/muddy hill at the landfill. Wheel spin also caused a cut in power to the wheels...and it would cut power until wheel spin stopped, which usually meant the truck was stopped...in the middle of a narrow muddy hill. A little wheel spin isn't a bad thing, in it's place. ATC is dumb and blind in that regard, which is why Mack has the over-ride switch. I wish the Pete did.

 

[Fordum]

It sounds like the system my M-Class Mercedes uses. Except they go one better. Its full time 4wd, with fully open front and rear axles plus an open transfer case. Without the traction system, you could stop the car from moving by raising one wheel off the ground.
Instead, it will drive off with three wheels off the ground.
It has a solenoid pack behind the driver side headlight, with 8 solenoids. Four release, and four apply. Plus it has a high pressure pump.
As a result, it can apply or release the brakes to each wheel individually.
And the system is fast and very sensitive.

When I first got the car, I took it out in the woods with a friend following in my truck. My intention was to see what it would take to stick it. Since I was running street tires, I avoided mud, and went to soft sand.
All the soft sand beds that gave my truck problems, the darn car just drove across. The truck did not get stuck, of course, but with the mud grip tires, we had to put it in 4wd and drive a little aggressively to move through.
Finally I moved to a high sand mound. Put the nose of the car up it, and gave it a little gas. One front wheel started digging in, and a little triangle symbol started flashing in the dash.
I was very disappointed. I told my friend to watch what happened, and I was going to give it some gas and let it bury its self in the hill.
Then I would take some pictures, pull it out, and take it to the dealer to ask what was wrong with the system.

Big mistake.

I goosed it, and suddenly it sounded like some midgets went to work under the left front fender with tiny hammers. At the same time, the car started giving little jerks from side to side, and the next thing I knew, I had to get off the gas to prevent launching myself off the top of the hill.
The darn car crawled up that hill like a lizard running up a wall.
Looking at the tracks before I carefully backed back down, you could see little dig marks where the tires started to slip then stopped. The system watches the wheels, and applies the brakes to any wheel that starts to slip.
The secret is that it does it fast, and is constantly applying and releasing the brakes. It doesn't just lock down the slipping wheel, it applies some brake, and as soon as it stops slipping, it starts releasing it.
I don't know how long it took to develop the algorithm to control that setup, but they did a darn good job. The only part that is strange, is that when you get in the slick stuff, and a wheel starts slipping, you need to give it more gas rather than backing off to keep from spinning down.
It needs torque to do its thing.
It would be a major undertaking, and probably not worth the effort, but they made a Lot of those cars, and they are showing up in scrapyards pretty regularly now. If you had the time and inclination to do it, you might be able to transplant the entire system over.
It even has the lockout above a certain speed built in.
Mercedes M320, M430, probably others, starting in 1998

 

[noJeepshere]

The traction control we have in the new Pete's and Mack MB's is marginal at best. It's gotten me stuck more than it's ever allowed me to get out of the soup. At least Mack has a Mud/Snow switch that nukes the traction control and allows for wheel spin...

I personally think it's much more useful in light trucks and cars.

I found with my motor coaches in Alaska the best way to get around was to turn the traction control system off via the switch in the dash, leaving the stability control on, and engage the air locker as needed.

 

[noJeepshere]

For those who don't know BLD is what some newer jeeps use, Its basically glorified traction control that's designed for trail use. The electronics and coding are no problem for me. But if anyone has any input about finding a suitable HCU, or other input about the system id appreciate it discussion helps the thinking process. I'm also going to implement my own Crawl-Control.
I have been holding on to a HCU from a 94 Lincoln for 4 years to do this with, but its gummed up now.

PS. I don't need any one telling me its not safe, The system will not be energized when its on the highway and will deactivate over x speed and sound an alarm so I don't forget to disconnect it.

I was thinking you were talking about a hydraulic system to brake each rear tire manually in a setup similar to what drift cars use.

 

[nixit]

Fordum has it right. One of those hcu's would be perfect. I don't think transplanting the whole system would be practical, you'd have to deal with the tooth count of the wheel speed sensors and a bunch of junk. I just want the pump and valve body. looks like they go for a grand new, I wonder what the pick and pull price is?

I thought about just using cutting brakes like drift cars, rally cars and sand buggies use. But like Fordum said the system has to be fast it would be a PITA for a human, and they take up allot of cabin space.

 

[Fordum]

It might still be practical. On my '98 model, the wheel bearings are separate and replaceable. They are sealed multirow ball bearings, but the hubs are not unitized like the new trucks. Which means the tone ring might be accessible.
Depending on their size and what have you, you might be able to remove them and attach them somewhere on your truck. The main problems I see, are that the brakes need to be disk on all four wheels.
Drums just would not apply and release fast enough.
Plus, if you had lockable hubs, you would have to turn the system off with the hubs unlocked if you were reading axle speed. There might be a slight problem with large tires, due to the vehicle moving faster than the tone rings would indicate.
Also, you would not want any kind of locker or limited slip units. You want the power to go to the wheel with less resistance, because in a properly functioning system, that is the one with the most traction, the brakes having supplied more resistance than the ground.

Also, be advised that there was a problem with some of the early units. The front control pack that fires all the solenoids has an internal wiring problem. But its fixable. You pull the headlight, and the washer fluid tank out, and there are four, I think, tiny metric screws that hold the front cover of the pack on. When you pull it off, all the coils for the solenoids comes off as one piece. In the back side of the pack, there is a circuit board with all the coils mounted on the other side of it. There is also a large red wire that goes into the pack, and is soldered to the circuit board.
From what I can tell, it does not do anything in the pack, just solders to a foil trace which goes across the board, and another red wire is soldered to the other end and comes back out.

That wire is the main power lead for the pump, and the computer tests the pump whenever you turn on the engine. I don't know what the heck was on the end of those wires, but solder will not stick to them.
You have two cold solder joints. Which means you get an ABS/TRACTION CONTROL warning light when you crank the car up. And the system is locked out.
The fix, according to the factory, is to replace the pack for a large sum. I pulled the pack off, cut away some of the soft potting compound, and repaired the connections.

I use very good rosin core solder, and it would not even try to stick. I removed the old solder, used a sharp knife to shave down the wire and foil trace to bare, shiny copper, then it stuck. No more warning lights.