I'm used to driving cars with 4-wheel antilock brakes and the grinding/pulsing sensation when the ABS kicks in is very obvious. But they have a hydraulic pump unit, too.

Today I hit a really slippery patch of dirt road covered with snow (and apparently a bit of ice) with my '93 F-250 diesel while in 4WD. I slid straight ahead and a bit sideways (intersecting road was slightly downhill in that direction). I didn't have time to look at the speedo. Friend behind me thinks my rear wheels were locked but isn't 100% sure.

I did not feel any indication that the RABS was operating. The light does come on for a few seconds when the ignition key is first turned on, then goes out.

I read on this site that the ABS doesn't operate when in 4WD: car.com/library/abs_kelseyhayes_rwal.htm
Is that correct for all the '87-up F-trucks?

Short of locking up the wheels, and either feeling pedal pulsations (or the rear not swinging around), or having someone watch all four wheels while I hit the brakes, is there a simple way to tell if the RABS is working?

thanks
Charles

Edit: I thought about this some more, and realized that if all four wheels are sliding and locked, the speedo (driven from the rear diff) will read zero so the RABS won't "know" to unlock the rear wheels.

Furthermore, in 4WD the front and rear diffs are locked together so if the front wheels are locked, so must the rear wheels. Definitely not as useful as a modern 4-wheel ABS...

 

the RABS on these trucks was marginal when new, i bet it has not worked in years.
the dealer disabled and deleted the RABS on my 88 when it was new because they could not get it to work. it would either throw you into the windshield, or you would run a red light 10 seconds after kissing the glass.
so i told them get rid of it, i never had a truck with abs and know how to drive.

the only vehicle i own that has working abs is the 2014, and as soon as that screws up it is getting disabled too, because i think the brakes on that truck suck.

 

Yeah there is no feedback with the RABS system on these trucks, the only indication that it is working is when the rear of your truck doesn't try to pass you in an emergency stop. So correct RABS operation would be.. slam on the brakes mid corner, the front tires will slide if they lockup but the back will just follow and not slide. If you slam on the brakes mid corner and spin out RABS isn't working.

 

best abs is a disabled abs. i cant believe they are putting it on motorcycles again!!! scary

 

I always disable the RABS on these trucks as well. One time of the pedal falling out from under your foot when in a panic stop will be enough to make you want to disable yours, too.

 

what years came with this rabs? do you think its on my 89 f350?

 

Thanks. I was going straight ahead and only have this one data point. The rear did not try and come around, but it may not have anyway...

I'll experiment a bit more when I can find a safer place to "lock 'em up" (and recover from the bad cold/moderate flu, AND get the truck back from the head gaskets replacement, too!)

Sure sounds like most people don't like it as-installed though!

 

The point of ABS is that locked wheels don't steer. Kind of important for the fronts on a car.

Not sure how that would work on a motorcycle - very little steering is done by the front, it's all "leaning". So you want (as in a pickup) to keep the rear wheel behind you. When I put mine down, I THINK the front locked up first but it all happened so fast there was no time to analyze it. That pavement is very very hard.

 

I think that is the deal with motorcycle ABS, keep the front wheel from locking up and sending you sliding on your lid. If the front wheel still rolls, then you can point the bike correctly. Yes, the rear can come around if it slides, but I think that is less of an issue then the front. Get in some pea gravel and it can get scary real quick like.

There again, most of this mandatory safety equipment is meant for people with less then marginal skills at operating a car/bike. Thus making it easier for them to do it. Personally I think they should ride the bus.

 

Then you have to ride that out until you come to a complete stop. Otherwise you risk causing a high side fall if you release the rear brake with the wheels unaligned. With ABS the rear will unlock before it has a chance to slide around.

Then why do I keep reading motorcycle reviews written by professional, or very experienced riders bemoan the fact that an Asian or European version of a bike comes with ABS, but the North American version doesn't?

 

The ABS on my 97 hasn't worked since I bought in 2010, and If it did work I would disable it asap. I was taught to drive in the snow/ice without ABS so I know how to handle it if it starts to go into a slide (Or better yet, prevent it from sliding in the first place).

Whenever I do drive a vehicle with ABS (like our 05 F-350) it scares the hell out of me when it kicks in since I can't even gently apply the brakes or steer. It has almost gotten me into several accidents, two of which were in the summer when there was just some loose gravel on the road.

 

Yeah not a fan of ABS here either, I'm sure I could stop a vehicle a lot quicker in winter without ABS, no it may not remain straight and in it's own lane but it will stop and sometimes that is all that matters.

ABS on a motorcycle is somewhat different as it also impacts stability in a positive way, I can see it being nice to have on wet roads. Combine it with traction control and any ham fisted idiot can pilot a superbike at much greater speeds than he could without all the electronic nanies, but that really isn't riding a superbike IMO.. what does one learn about smoothly rolling on the throttle out of a corner and the limits of braking traction if a computer is doing all the heavy lifting. This is why motorcycle journalists bemoan the lack of these features these days, they can put up impressive lap times on a bike that would put most of them in the hospital on the first lap if had to drive it with all the electronics removed.

 

yes Skip, your 89 came out of the factory with that useless RABS.
but i do not think it still works on your 89, it was probably disabled a long time ago.

 

We go through this fire drill every time someone has an issue with the RABS system on these trucks.

Plenty of arguments on both sides of the aisle. I learned to drive long before ABS was a common production feature. For the most part I like how it works on this vintage truck, i.e. rear only.

I fixed the broken pieces on my old 1992 F350 to ensure anybody could drive it and be safe. Both of my Gen 1 Lightnings had functioning RABS.

The simple test I used was to hit the brakes on a slick surface with nothing in the bed. When the RABS worked you could hear the hydraulic module under your left foot activate. Not much pedal feel that I recall.

YMMV

 

Thanks for the return to sanity I couldn't hear squat over the IDI grinding away, plus a 3" system (WITH muffler) from the Y to the bumper. Also over the sound of seat upholstery puckering up my butt as I slid out into the other road

I thought the RABS valve on my truck ('93 F-250) was in the right frame rail near the back?