rear abs

[NoDaK]

i understand that abs was relatively new technology in '89, but i have yet to see it work on my truck. no abs light, but the truck just slides on the snow with no abs chatter. does this abs function differently then modern day abs?

 

[87crewdually]

There is no electric motor & pump to control it, this older system only proportions/dumps pressure.

 

[NoDaK]

so basically what your saying is its gimmicky/useless?

 

[pybyr]

Other than my current truck (89 7.3) the other vehicle I had was a 1991 Ranger with Ford's "RABS" system. It _did_ do a very good job of avoiding the tendency that pickups have, when unloaded or lightly loaded, if you end up in a panic stop, to have the back wheels lock up and the rear of the truck start coming around on you sideways. It's not the same as modern 4 wheel ABS, but I would not say it's useless. I sort of like the way it does keep the truck stable side-to-side, but gives you full control, with no interference, on the front brakes, which do the bulk of the stopping in any event.

 

[RedTruck]

I did some work on a friends ABS system in his '94 Dodge pickup. It had a proportioning type system. The problem with this system is that while it controls the rear wheels it bleeds off pressure and has no way of adding more pressure to the system unless you pump the brakes again. The ultimate problem (I have read) is that you could run out of pressure with a single brake pedal push and not have brakes. I would imagine that is the reason why they only put that system on the rear wheels.

If you don't have a light on, I'd add some weight to the box and try again.

Have you got any pictures of your new rig?

Paul

 

[SparkandFire]

I did some work on a friends ABS system in his '94 Dodge pickup. It had a proportioning type system. The problem with this system is that while it controls the rear wheels it bleeds off pressure and has no way of adding more pressure to the system unless you pump the brakes again. The ultimate problem (I have read) is that you could run out of pressure with a single brake pedal push and not have brakes. I would imagine that is the reason why they only put that system on the rear wheels.

If you don't have a light on, I'd add some weight to the box and try again.

Have you got any pictures of your new rig?

Paul

You are absolutely right... The system just bleeds off pressure by opening a solenoid in the proportioning valve and letting a pintle move up on the rear circuit.

I dissected one of those valves once off a '89 bronco, once the valve lets the pressure off the line, the only way to repressure it is to pump the brakes again.

It DOES keep the rear from comming around the front, but it is not a true active abs system like the newer ones.

 

[NoDaK]

If you don't have a light on, I'd add some weight to the box and try again.

Have you got any pictures of your new rig?

Paul

should the light come on when the abs is being used? i figured no light = gtg



im running through the car wash today, ill snap some pics

 

[SparkandFire]

My experience has been that the ABS should function without a light.

The light will only indicate a fault in the system, and not that it is in use.

 

[Agnem]

You are absolutely right... The system just bleeds off pressure by opening a solenoid in the proportioning valve and letting a pintle move up on the rear circuit.

I dissected one of those valves once off a '89 bronco, once the valve lets the pressure off the line, the only way to repressure it is to pump the brakes again.

It DOES keep the rear from comming around the front, but it is not a true active abs system like the newer ones.

I've never had an ABS system that actually HELPED me in any way. I contest that if you know how to drive, they actually hurt you. I nearly lost my 99 Ranger because I needed a full wheel lock up, and that damn system was going to let me run right into a wall when I knew I had time to stop. The rear ABS on the Bronco is permenently disabled and will never be active again.

 

[SparkandFire]

I couldn't agree more! The tracloc/abs on my explorer does some really aweful stuff that makes it alot harder to drive.


I thought the mid to late 80's trucks had a weight proportional valve mounted above the rear diff. that decreased the amount of fluid that was allowed to flow into the rear brakes if the truck was unloaded?

 

[ericboutin]

I've never had an ABS system that actually HELPED me in any way. I contest that if you know how to drive, they actually hurt you. I nearly lost my 99 Ranger because I needed a full wheel lock up, and that damn system was going to let me run right into a wall when I knew I had time to stop. The rear ABS on the Bronco is permenently disabled and will never be active again.

While I agree with most of what you said "a full wheel lockup" will never stop you faster than "rolling friction" which is what ABS attempts to supply. Back in the day before ABS we were taught "threshold braking" which is human induced ABS or as you put it "knowing how to drive". Another reason you wouldn't want a full wheel lockup is you lose all ability to steer the vehicle...with rolling friction you still have the ability steer...with a full lockup your vehicle can only go in the direction of the vehicle's momentum which I've found in a "wreck scenario" is not usually the direction you want to go!

 

[rjjp]

I agree with Mel on this, my ABS dosent work and I like it that way... Had 4 trucks, 2 cars, and a suv all prove to me that ABS is just more automated bull sh** to go wrong with todays cars.

 

[Agnem]

Eric, in the specific case I'm thininking of, I was on a back road with a hairpin turn over a little creek with a stone wall along the bridge. I came up on it faster than I should have, and "locked em' up", but they didn't lock up of course. I could tell by the squeeling of the tires or the lack thereof, and I could feel the loss of breaking force as the ABS did it's thing. Problem was, I was in a situation where 3 feet was going to make the difference between an insurance claim, or driving to the car wash and enjoying a clean shine. I know if the ABS had been disabled I could have made it stop. With it cranking away though, and turning a 50 foot stop into a 60 plus foot stop, I had no choice. At the last millisecond when there was no more time to give the brakes, I cranked the wheel all the way over and let off the brakes completely. The front end came around and cleared the wall by just an inch or two. If I had normal non-ABS brakes, I may have even been able to get the rear end to come around which would have helped point me in the right direction as well. I realize that for every situation where ABS was a problem, there may be another situation that proves it saved someone or something, but I would like a panic switch to turn it off, because we all know that no system can be programed to perform the right actions 100% of the time. ABS was developed to help people who couldn't even get their VCR clocks to stop blinking, and I guess now Volvo and others are trying to get it to the point where your not even allowed to steer. This is a very dangerous direction the industry is trying to go.