First snow! Where are the rear antilock brakes

[bryanb]

Well, the first measurable snow arrived today!

Decided to see if the ABS works on the snow today. Hit the brakes hard, and the fronts lock, as they would, I assume. Not sure about the back brakes. I don't know if I can feel them locking. But in any case, the ABS does NOT activate. I don't have any lights, or other problems.

I do have an old story to add. Put new front pads and rotors on last spring. A month or two later went to put on new back brakes (drums and pads). Ended up having to put on new adjusters as well , since both little cables were broken, and the brakes hadn't been adjusting, and hence not working.

Last winter, I remember a couple times, I could hold the front brakes, and the back wheels would spin on the ice. Haven't noticed that so far, since I also have new tires, that have some traction.


What might I check for here? Of course I haven't taken the back wheels off yet, since its _cold_ out...

 

[satan]

First thing I'd check for is that the ABS light lights' up when you're first starting your truck.

 

[bryanb]

pretty sure the lights are there at start time, but I'll double check!

 

[bryanb]

yep, get an "rear antilock" light when I start it.

If I use the e-Brake, it feels like both the back wheels grab fine. I also tried to hit the brake pedal, and the gas at the same time, and looked out the window. The driver side rear seemed to spin awfully quickly, like at maybe 1100 rpm. (on a icy gravel driveway) I'd think the right wheel'd break loose first, being an open diff...

Anyway, Im going to get a free brake inspection at the local shop Wednesday, so I guess we'll know more then. Hopefully its not a $1000 brake job they want to do.

 

[Sasquatch_Ryda]

I bet you have no brake fluid going to your rear brakes. The rear antilock brake valve on the frame rail is known to gum and not let fluid get to the rear brakes.

 

[bryanb]

I bet you have no brake fluid going to your rear brakes. The rear antilock brake valve on the frame rail is known to gum and not let fluid get to the rear brakes.

Thats probably a good idea. I know the fluid is old, and dark colored. I know first off, the shop'll recommend a flush. Which I had been planning to have them do, when I get extra money. I'll be sure to ask what they charge for that.

 

[Sasquatch_Ryda]

When it gets bad enough that the rear brake don't work flushing the fluid won't do a damn thing.

You can either replace the valve or just bypass it. The RABS really doesn't work well enough to warrant keeping it on the truck....

 

[hondaxr650]

Pretty useless system. They aren't really designed to help you stop, just keep the rear of your truck from becoming the front if they locked up hard enough to slide the rear end around on ya.

 

[bryanb]

just got back from the shop today.

The guy there didn't seem receptive to the plugged hydraulic unit at all. he did pull the drums off, and took a look-see.

He claimed that the wheel cylinders are leaking, which is new, they were dry when i put new shoes and drums on last spring. He said that the different wear pattern from the old shoes to the new ones, (on the wheel cylinder shafts and seals) can make the wheel cylinders leak. Also said that the axle seals are leaking. This I did know about.

So the new wheel cylinder leaks are getting fluid on the shoes, and he wanted to replace the shoes, wheel cylinders, bearings, and axle seals. All of this I could handle in the spring, or possibly at a friends heated garage.

Any other thoughts?

 

[greenpus]

Pretty useless system. They aren't really designed to help you stop, just keep the rear of your truck from becoming the front if they locked up hard enough to slide the rear end around on ya.

yup, the rear abs is useless.

 

[bryanb]

Finally!

Bled the rear brakes today, after getting new wheel cylinders put in. Seemed to bleed alright, getting fluid right away. Had a helper hit the brakes after I spent a couple hours one day with a little hand pump / one man bleeder tool.

Both back wheels were getting fluid just fine as far as I can tell, and no air bubbles.

Didn't get a chance to bleed front brakes. The bleed screws are pretty well rusted onto the caliper. But in theory, I never broke the seals on the front brakes.

I did have the RABS valve off the truck as well (and sprayed it out with brake cleaner), before I did the wheel cylinders, so there should have been plenty of air in the lines. It really didn't seem like a lot of air when we did the pressure bleed. Maybe all the hand pump took care of most of that?

Anyway, went for a test drive, and the pedal feels more firm, but the back brakes haven't really improved much. Still got the fronts to stop me, and the back spinning on the ice. Went around the block, and backed up a few times, and it made a slight difference.

Are we still pinning this on the RABS valve? if so, how does it come apart, if at all, to clean more thoroughly? How can I seem to have good fluid to the rear brakes, but not a lot of 'breaking action?'

We also noticed that the master cylinder is leaking, slowly, or even seeping between it, and the vacuum booster. Could this be the cause somehow?