Order Jeep -> Lose Rebate??

On 09 Dec 2003 07:30 PM, CRWLR posted the following:

That's fine. I disagree with the assertation that ABS leads to longer stopping distances, but as long as we can discuss the pros and cons like reasonable men I have no problem with the debate. What I don't like is the misleading blanket statements that ABS is "crap" that a poster is better off without, particularly when you may not be familiar with their driving conditions or ability.

It is another tool in the toolbox. No tool devised by man will ever be perfect.

---------------------------------------------------- Del Rawlins- del@_kills_spammers_rawlinsbrothers.org Remove _kills_spammers_ to reply via email. Unofficial Bearhawk FAQ website:

What he said!

On 09 Dec 2003 08:42 PM, L.W.(?ill) Hughes III posted the following:

The ABS is designed to revert to a standard braking system when it is disabled. It is nothing like disconnecting the power brakes. The vacuum booster is unrelated to the ABS and what you have, in effect, is a big expensive version of the proportioning valve in a non ABS rig. I drove my former truck around for a couple weeks like this until the dealer could replace an ABS wheel sensor and there was no adverse impact on normal brake action except that there was no ABS.

---------------------------------------------------- Del Rawlins- del@_kills_spammers_rawlinsbrothers.org Remove _kills_spammers_ to reply via email. Unofficial Bearhawk FAQ website:

On 09 Dec 2003 08:17 PM, L.W.(?ill) Hughes III posted the following:

I never said my TJ had that exact system, but that doesn't mean that all ABS equipped vehicles are that way. I have even driven a rig with ABS only in the rear, now that was a messed up system to be sure. Point being, that ABS can control the braking force applied to multiple wheels simultaneously, something which you and I cannot do. Well, I do it in airplanes, but that doesn't count. 8^)

If you want to pick nits, yes, the ABS in the TJ can only send one input to the rear brakes, so the braking force is limited to the maximum that the rear wheel with the least traction can take without locking. But since the majority of the braking is done by the front wheels, which * are* individually modulated, my point still stands.

The crucial thing that the rear ABS must do is keep the rears from locking to maintain directional control. Getting the maximum braking performance out of the rear wheels just isn't important since they contribute so little to stopping the vehicle in a panic situation, when most of the weight has transferred to the front axle. So there isn't much benefit to separate brake lines and ABS inputs to the rear wheels, as long as there is SOME means of keeping them rolling while the front wheels do the work.

---------------------------------------------------- Del Rawlins- del@_kills_spammers_rawlinsbrothers.org Remove _kills_spammers_ to reply via email. Unofficial Bearhawk FAQ website:

depending on the road surface conditions.

• * * Matt Macchiarolo
  formatting link
  formatting link
  formatting link

when their foot released the pedal when the ABS kicked in and startled them.

• * * Matt Macchiarolo
  formatting link
  formatting link
  formatting link

No Bill, disconnecting the ABS only affects the ABS, doesn't affect normal braking at all. Nothing's changed since the last time you posted this.

• * * Matt Macchiarolo
  formatting link
  formatting link
  formatting link

Del, all Jeeps have rear ABS. Or they have had it since the late 70's anyway.

It is called a combination valve which prevents the rear wheels from locking up so you can track straight in a panic stop.

If the rear wheels lock, you will do a 360 faster than you can blink.

That rear ABS is a real pain with an automatic tranny. The rear wheels will keep pushing you on snow when you want to stop. They can and will push you right through an intersection unless you drop it into neutral.

Mike

On 10 Dec 2003 07:32 AM, Mike Romain posted the following:

The proportioning valve is NOT ABS and if you try you can and will lock up the rear brakes. The benefit to the valve is that you will generally lock up the front wheels first, but not necessarily. It is only a passive system, and can't actively modulate pressure to the wheel cylinders based on sensor input like ABS does.

The problem you refer to is a characteristic of a 2wd vehicle with an automatic, and isn't necessarily caused by the proportioning valve. The front wheels lock up, because they can, and since the rear wheels are still being driven you have to drop into neutral to stop. It may or may not be caused by the proportioning valve, but that still doesn't make that valve ABS. Personally I'd rather just shift the thing into neutral when approaching the stop and not lock up at all. My '73 2wd pickup will do this but it is a non-issue if you are expecting it and know how to deal with it. And of course as I'm sure you know, shift into 4wd and the problem ceases to exist.

---------------------------------------------------- Del Rawlins- del@_kills_spammers_rawlinsbrothers.org Remove _kills_spammers_ to reply via email. Unofficial Bearhawk FAQ website:

On 10 Dec 2003 09:08 AM, L.W.(?ill) Hughes III posted the following:

The fluid is directed from the master to the wheel cylinders when the ABS is disabled for the same reason that the brakes work normally until the ABS engages when the ABS isn't disabled. The ABS modulator unit also contains the proportioning valve, which is why the brakes act as a standard braking system until the ABS engages.

The solenoids, pumps, accumulators, and whatever else runs the ABS don't even come into play when the ABS is not operating; they are transparent to the system until the control unit detects a lockup at one of the wheel speed sensors, at which point the ABS hardware activates to modulate pressure to that wheel. As far as the braking system is concerned, it doesn't matter whether the ABS isn't on because the fuse is pulled, or if the driver just isn't braking hard enough to engage the ABS, the result is the same: Normal braking. No morphing required.

---------------------------------------------------- Del Rawlins- del@_kills_spammers_rawlinsbrothers.org Remove _kills_spammers_ to reply via email. Unofficial Bearhawk FAQ website:

You're a Newfie? Never would have guessed.

Is actually the slowest way around most corners, but a helluva lot of fun. I raced for a dealer that had one rule: Win the damn race or be leading the thing when you trash the car.

To this day, I still can't enjoy sports car racing footage unless I hang myself upside down with hot oil dripping on my head.

The claim from testing wasn't that the noise startled the driver as much as the excessive wheel turn rates per second scared them enough to back off the brakes rather than the darn wheel.

Admittedly the ABS on a ZJ is a bit noisier than I'm used to on more modest vehicles. But highly effective.

Actually the increased fatality rate from ABS appears to be largely due to the doofus factor and the increased steering capability. A sliding wheel is more able to ignore suicidal wheel movements.

Del:

Mike is correct in that you cannot lock up the rear brakes on most TJ's, even without ABS. Try it sometime.

Raise up the rear end. Transfer case in 2-HI, transmission in gear, engine at idle speed. On my '02 TJ with auto trans and 3.73 rear end, you can mash the brake pedal with all your might and the rear wheels will still roll, even with the engine at idle speed. If you apply the parking brake it will stop the rear wheels easily.

The non-ABS TJ's are designed so that less than 10% (my estimate) of the braking force goes to the rear wheels. It is actually quite dangerous at slow speeds on ice or snow. With an auto transmission, you have to get into the habit of quickly shifting to neutral so the rear wheels don't push you right through stop signs at icy intersections.

My rear brakes are adjusted, and working properly.

Tom

snip

Bill, blow the cobwebs off your imagination and think of a vehicle on a slick surface with their front wheels locked up, sliding straight down the road. Now think of what the vehicle does when you crank the steering wheel to either direction. Still sliding straight down the road.

• * * Matt Macchiarolo
  formatting link
  formatting link
  formatting link

• * * Matt Macchiarolo
  formatting link
  formatting link
  formatting link