Sideways slide Q's....

[XJ Dreamin']

Hey All..

I'm late into a well established thread but I''ve enjoyed following along and finally can't resist.

I grew up with gravel and tarred gravel roads: what they call down here in SE Texas "chip seal." Today I have access to guite a lot of well maintained gravel with ALOT of trees whippin' by the window.

When I was learning how to drive my Dad had two rules: "Do It Right!", and "You break it, you fix it!" A kid doesn't care about danger but the thought of spending weekends or vacation time trying to straighten out a car, or rebuild a motor would slow you down real quick.

What he taught me on gravel was this:
a) Get your braking done before the start of the curve - you can't break and steer at the same time;
b) Initiate the turn at the beginning of the radius with a slight flick of the wheel into the curve;
c) apply throttle to bring the rear end out (oversteer);
d) compensate for the oversteer but steer the line through the curve - the goal is to align the front wheels with the exit of the turn by the time you reach the exit: forget the "steer into/out of a skid" nonsense: point the front wheels where you want the rig to go and use the throttle to control the rear end.
e) done properly, by the time the the vehicle reaches the exit of the curve the front wheels and the vehicle centerline should be lined up with the road. By that time you should be using nearly full throttle.

DISCLAIMER: Remember, this isn't me, a noobie non-member, telling you what to do. I'm only saying what my Dad taught me.

In a nutshell: after braking, the throttle is used with the initial steering flick to the inside to start the rearend out. Combined with the initial steering flick to the inside it shouldn't take much throttle to start the rear end out. As the rear end swings out the line of the front end through the curve is controlled by steering while the extent of the swing of the rear is controlled by the throttle. Ideally, as you approach the exit of the curve the front and rear come smoothly into alignment with the exit. The closer the front and rear are aligned, the more throttle you can feed in. If you exit the turn with the rear end swung out you only waste time fishtailing trying to get it straightened out. If you exit in alignment with the road you can feed in as much throttle as needed for max acceleration.

Control the line through the turn with steering. Control the swing of the rear with the throttle. Of course, the two are connected by the rest of the car so it is a constant, delicate dance to get through on the optimum line, in the best time, with the greatest exit speed possible. That's the fun part.

The trip I took through the soybean field in Dad's '72 Grand Fury was not the fun part :doh:< me - Dad > :nono:

 

[Weasel]

actually thats a pretty good discription on how to do it.

And yes what ever you do, don't try to break while in the coner and steer at the same time. It doesn't work.

 

[Weasel]

Oh that's a question I was going to ask the rally guys, what's a good Camber setting for rally racing? I've noticed some cars the tire was leaning in so far that it looked like they had a broken ball joint (but it was a front wheel drive VW). Also does the solid front axle change the need for less/more Camber?

The idea behind have more or less camber is pretty simple. As you suspension moves up and down the tires on a IFS rig go through a arc and the surface tires of the tires vary. What racers try to do with adjusting the camber make tire patch contact will be the greatest, example for cornering. I don't belive there is any magic number but you just have to adjust it and try it out. On a solid axle suspension I'm not sure you would gain any benifts since the wheels are moving more up and down motion.

 

[XJ Dreamin']

I grew up with gravel and tarred gravel roads: what they call down here in SE Texas "chip seal." Today I have access to guite a lot of well maintained gravel with ALOT of trees whippin' by the window.

I forgot to say what I think of the XJ on the gravel I have these days. First, the XJ in question is a stock (no lift) 2WD '93 w/ 4.0 HO through the AW4 and an open D-35c on 6-ply 325/75R15 M/S AT's. Second, the roads are well maintained crushed limestone gravel with very little washboarding, although there are some sections that are native surface red clay. I won't say where since most of it is owned by my employer. I will say that the posted speed limit is 25 MPH.

That said, I find I like to keep the AW4 selector in 3rd when on gravel. I keep it in 3rd primarily because 3rd provides a good RPM range for gravel running, but also because I find that there is a significant delay waiting for the downshift from 4th. When it does finally downshift I get a big kick in the butt just as the weight has hit that outside rear tire. Operation with the stick in 3rd is much smoother. I agree that on long runs through rough terrain wheel travel wins out over sway control, but for the smooth roads I have here I would like a bit more sway control in the rear.

Also, I'd like to add traction control in my open D-35. You want both wheels loose so that the rear will move out. Spinning one wheel while the other is still gripping negates the whole point of drifting. All of my work XJ's have had TrueTrac but my personal XJ is open. I'm leaning towards the PowerTrax no-slip but I have no experience with auto-lockers.

A few years ago my work rig was a 2WD '91 HO with the 5-speed and I have to say, at least for fun factor, double clutching and engine braking added that much more to the experience.

I guess, bottom line, I'd like to go rock crawlin' some day, but at heart I'll always be a speed freak.

 

[8Mud]

My thoughts on the camber, when I mentioned it, was to help a bit, with sidewall roll and to help the contact patch/wieght, stay a little closer to the center of the tread.
Noticed on tires, that do a lot of lefts and rights (sharp turns) they tend to wear on the outside edge. A little added camber might produce some strange wear patterns (like a little on the inside of the tire), but may help keep some of the wieght closer to the center of the tread, helping the sidewall, not to roll over as much and/or catch an edge and really start the body rolling to the front outside corner (rutted/bermed roads). Also noticed the alignment and camber/castor geometry, seems to change as the turn gets sharper.
Various techniques, snatch left, turn right, to induce some sway and to force some wieght to the rear/outside. Snatch right turn right, to cause pretty much the same effect. A quick yank on the parking brake, all for the same reason to induce some oversteer.
Understeer, is what will get you in serious trouble, your turning, the Jeep isn´t and extra gas pedal, mostly just makes it plow more. Brakes just keep it going in the same direction, can´t really steer while braking.
Some technical solutions, may be to raise the rear a little, so it breaks first in a curve. A little added camber. Stiff shocks and a flat stable platform, frame braces and HD sway bars. Though a flat/hard platform may cost some in traction, it is much easier to predict what will happen, from uneven road surfaces and wieght shifts, at speed. It will let you steer/predict the vehicle, instead of the road and suspension steering/dictating it for you. Seen professionals get in trouble, with too much flex and wheel travel, works really good, until it gets tied in a knot, stresses, then unwinds. A stiffer platform may be a little slower and uncomfortable, but much easier to predict in most situations.
Mostly it just boils down to practice, in steps and stages, so you don´t get in over your head.
Funny spent a lot of time, high speed dirt roading in South Carolina, Death Valley and Baja. Many of the techniques are the same, at 140-160 MPH on the autobahn (except the steering wheel jerk). The tires get light and you have to read the road surface, well in advance. Understeer will kill you. Really can´t brake hard and steer at the same time, at speed.

 

[racerdave]

One note for you when practicing, please make sure the area you are driving in (roads, dirt or gravel) are not really rutted too deep. If you are sliding, wheather its a rally flick or powerslide, and you hit a rut this will cause your rig to "bicycle" (especially a top heavy, fairly narrow rig i.e. Jeep) and you will go on your lid. Gravel is good until you hit a berm. I personally totalled a Roush mustang that way on an asphalt road course. They had some run-off room then piled the gravel up around the turn, I was ok (even thinking" I can save this") untill the car caught the berm, then it was "this is gonna be bad" :skull2: :dunce:

 

[Weasel]

thats pretty much how I rolled my first XJ and something I always watchout for. Hard to them sometime though, so I will ethier run that section slow and the rerun it again, or just take the corners a bit slower.

 

[kreature]

I race at Rausch Creek's rally park in PA, there is one turn that always screws me up. It's a long right at a base of a hill then a long climb up the hill and into a gradually tightening left bend. About 2/3rds up the hill you'll get to about 40-45mph when the turn starts getting tight and then levels off, the turn eventually comes to a very tight 90% left and then drops off down the hill.

Don't know if my explanation does this turn justice but it's a bitch to handle. You're running up the hill as fast as possible into the turn but then due to the change in grade and tightening turn you're forced to brake HARD in mid turn. If you set it up right you *should* be able to slide into the exit of the turn (the crest of the hill) with a little momentum. In reality it is a truly evil turn and defies most textbook racing methods. The last time I ran it I almost rolled the Jeep bigtime just at the crest of the hill and I was gong UNDER 10MPH at the time! It was packed gravel with just a little rock protruding from the surface and caught the right rear sidewall.

Anyway I agree with most of this thread but my point is, what *should* be done is often impractical for real world conditions. Get out there and beat the crap out of your Jeep, or better yet your friends Jeep... sorry Paul :laugh3:

 

[XJ Dreamin']

Anyway I agree with most of this thread but my point is, what *should* be done is often impractical for real world conditions. Get out there and beat the crap out of your Jeep, or better yet your friends Jeep... sorry Paul :laugh3:

Absolutely!! When I studied karate the instructor was certified through the Japan Karate Association. The training philosophy of the JKA was BASICS! BASICS! BASICS! As my instructor put it: "If I teach you 1000 defenses against knife attack, your first real world attacker will use attack 1001. But, if you have practiced the basics you will react properly to any attack."

My point is, we're talking about maneuvers composed of complex suites of techniques, some applied sequentially, some in unison intended to accomplish a goal: i.e. getting through the turn in as little time possible with the highest exit speed possible. "Power Slide" and "Drift" are not, of themselves, single techniques that can be practiced as one "trick" to get you through any and all circumstances. In the real world, you will encounter conditions that require techniques be applied out of sequence, or in combinations that would seem ill-advised under "normal" conditions. Your ability to adapt to adverse conditions will be directly related to your level of skill in each of the basic techniques required by the conditions at hand. Skill that can only be acquired through practice.

Of course, some conditions defy training and skill. Then your fate is in someone else's hands.

One last point. I see from picture galleries that rock crawlers don't wear helmets much. I would have no idea what the risk level is for rock crawling, but I do know that high speed maneuvers on variable surface roads carries extremely high risk levels. Please wear protection and... be careful out there.