BTM - Brake Throttle Modulation (It works)

This recently worked for me so I thought I share.

Anyone not familiar with this, it is an off-roading technique used when your vehicle has lost traction and your differential is sends power to only the tire with little to no grip. I had never heard of this technique until I described my failed/lame attempt at "The Wall" on the Poughkeepsie Gulch trail in Colorado to a friend. My failure below:



He suggested the next time to try the BTM technique. Simply put, he recommended I apply the brakes while still on the gas. The way it works is by applying the brakes, it will slow down the axle that is spinning enough so that the diff will try to send some power to the non-spinning axle. Well it works. My last visit to "The Wall "was a success. I used it a couple times on the obstacle in the video below but the benefit is really evident where I lose traction at midway through. Just after I slightly smoke the tires.



Happy wheeling!

 

That's true. Poor man's ATRAC. I don't have ATRAC, but I do have a rear locker

 

I call it two-foot driving. If you do have ATRAC, having a foot on the brake will disable it. But I still use the technique in real tight situations.

 

E-Brake = Poor Mans E-Locker

 

Update to this thread..
I drive a 2019 Tacoma 4x4 SR5 w/o lockers(not yet) or A-Track. To activate the LDS system I use BTM as described above.
HOWEVER, be forewarned that because of the 'Unintended Acceleration' event Toyota experienced, it was decided that brake and acceleration would put the engine in idle.
The only way around this I found is to stop the truck. Put it in 4WD and Apply the brake(I usually use 4-Lo at this point). push on the accelerator until you get 1500 to 1800 RPMs and hold the accelerator there. SLOWLY release the brake and use the brake to modulate the truck speed. maintain a steady throttle. The engine will not drop to idle. The LSD will be sending torque to all wheels.
If you are wheeling in 4WD and just decide to apply the brake and not take you foot off the gas, a message will appear that brake and accelerator were applied simultaneously and the engine will go to idle.

 

You'd think that "safety" feature would be disabled when in 4-lo.

BTM is nothing more than a bandaid fix for not having an LSD or a locker. If I found myself having to use this technique, I'd be ordering a locker that very next week. Fortunately, I already have a locker in my Taco, and A-track in my 4Runner.

 

people do this with the e-brake too, pull it enough to apply some pressure and give it throttle..should send some power to the wheel on the ground

I've never tried it because


a.) I have an e-locker

b.) My e-brake cable is as loose as a stripper's faith in god

 

Hey now, some of them are just trying to work their way through nursing school...

I remember back in the day a guy I wheeled with had an LSD of some type (it was 20+ years ago, I don't remember which one), and he'd use the brake method to gain traction. If I remember correctly, the LSD needed a certain minimum resistance to "lock up" so applying the brakes helped get there.

However on an open diff, assuming your brakes are fully functioning (at least on older models) the brake pressure is equally distributed, so I don't see that being as effective since the wheel with less traction will *always* have less traction, brakes or no brakes. It may help control wheel speed, but that's not the same as traction.

 

Think of an open diff, one wheel up in the air spinning. By applying brakes, it will provide resistance sending power to the wheel on the ground.

Baja Buggy ran open diff with a "push-pull" steering brake to lock either right or left wheel. It was a blast for rapid turning!

ProRally Days, I had a "handbrake" that was plumbing inline with rear brakes. Hydraulic, operated both. I had a racket paw, so I could park on a hill long enough to place a rock or 4x4 under a wheel so it wouldn't roll away. Totally illegals modification but did function as a handbrake. One event I had overshot a "T" turn, over the hill, immediately right. I pulled up the handbrake, hoping to make the turn. Brake jammed, we went over a cliff! Oops.

 

I understand that, what I'm saying is that you're also applying brakes to the wheel that's already on the ground, so there is no real increase in the relative resistance between the two wheels.

In other words, I'm saying this technique is likely more effective at controlling wheel speed (good for not breaking stuff) than actually increasing traction for the wheel on the ground. In other words it allows you to "throttle out" without getting insane wheel speeds that snap CVs.

While it would be interesting to see a study on exactly how that works, by using torque and wheel speed censors at each wheel, etc, in that time you can just install a locker and not have to worry about it.