Traction Control

 

Because I like cheap thrills as much as the next guy.

I don't like modern automatic traction control. I've run into it twice and neither occasion was very pleasant. Twice that I know of that is. We won't talk about the uncounted times it saved me from a fate worse than death because ... because you never notice if it doesn't bother you.
    Anyway, first instance we had ice on the streets and I was trying to drive up a hill and the car just would not go no matter how hard I stepped on the gas. Nothing happened, the wheels didn't spin and the car didn't move, except maybe to slide backwards a bit. Wasn't my car, couldn't find the traction control button, not sure if I even knew if it had traction control.
    Second instance happened last week downtown in the rain. Sitting at the light in the left lane, need to get in the right lane by the next corner. Figure I'll just jump on it when the light changes. Most people aren't hot rodders, I'll be ahead of him and around the corner before he even notices. Light changes, step on the gas and BANG BANG BANG BANG and a few more BANGS for good measure before we have gone 20 feet. It was like the transmission was engaging and then disengaging. What happened to moderating the throttle? I hope I didn't break anything. Disconcerting and aggravating. If I'd know it was going to be such a stinker I would have turned it off and just dealt with the wheel spin myself.
    My truck (1999 Dodge Dakota) has old time four wheel drive, dogged engagement to the front axle, hi and lo range transfer case, no center differential, no limited slip. It comes in handy in the rain because if the front wheels are not engaged and you try and jump off the line to avoid getting hit by cross traffic it will just sit there and spin the rear tires and you will get hit. Engage the front axle and it will leap off the line like, well, like it would it on dry pavement, which, while not spectacular, is at least adequate.
    Anyway, all this got me thinking about old time four wheel drive's weak spot, which is that both of the front wheels or both of the back wheels need traction or you won't go anywhere. If both wheels on one side are stuck in a mud hole and spinning uselessly, you aren't going anywhere, no matter that both wheels on the other side are sitting on dry pavement. Or you are crawling over rocks and you end up sitting diagonally on a ridge with one front wheel in the air and the opposite side back wheel likewise hanging in the air. You are stuck.
    The typical gear heads solution to this problem is to install a limited slip (sometimes called positraction) or locking differential in the rear axle. This is a little difficult and can be a little spendy. Devoted rock crawlers belly up to the bar and fork over the cashola.
    I had the idea one time of adding a second parking brake lever (or pedal) for dealing with these kind of situations. Split the control of the two parking brakes between the two levers, left lever for left wheel, right lever for right wheel. You get in a jam where one of the rear wheels is spinning uselessly, you simply apply the parking brake for that wheel. Get out of the jam and release the brake and you're back to normal. Probably would want to disable the ratchet mechanism so that simple releasing pressure on the lever would release the pressure on the brake. Wouldn't work as a parking brake anymore, but hey, what do you want? To go places or not?
    Then I got the bright idea of combining these individualized parking brakes with a couple of servo motors and the speed sensors all vehicles come with these days (and some kind of little microcontroller) and you could have your very own limited slip differential for much less effort and expense than a conventional mechanical solution.
    There are one or two drawbacks to this idea. You will only have half of the torque available at the rear wheel that does have traction. With the other wheel stopped, the differential will act like a two-to-one speeder-upper, which will cut the torque in two. The other is that you need working parking brake cables. I never had a car with a working parking brake until I left Ohio. They use salt on the roads in the winter, which leads to corrosion. None of the cars I drove in Ohio had parking brakes that worked. Those cables were the first thing the rust got to. Locked 'em up solid. That's another reason that part of the country is known as the rust belt.