Full Version: rear brake engages while rolling backwards
Last night I tried to push my car backwards out of the carport, and it seemed heavier than normal. Hmmm. Made sure the handbrake was off. Pushed it forward, no problem. Backwards, it goes maybe 3-4 feet, then stops. After repeating a few times, I could hear the right rear brake rubbing then engaging. Going forward releases it. Back when the engine was running, I never niticed any issues while backing up.
When I discovered this problem it was wet out and getting dark, so I didn't go under the car to investigate. I may have bumped something when I was working on the car earlier in the week (removed exhaust, driveshafts, shift bar).
1) Is this a known issue ? Cause ?
2) Anything quick 'n dirty I can do to make it easier to roll backwards ? I need to trailer it tomorrow AM, forward direction not an option.
TIA,
jeff
That is not normal. I'd guess that the pads are dragging anyway, that would allow them to grab and lock. Perhaps the pads are stuck in the calipers and not moving freely. Remove the pads and clean things up to free them up. I'd follow up by adjusting the venting clearance.
I have never had the experience. But i ask you a q.
When was the last time you adjusted your rear brake clearance?
Jack up the rear and spin each tire fwd & b/wrd (e-brake off...) & listen for anything abnormal. Notice a diff between one side and the other? Yes? Pull the wheels.
Try it again spinning the rotor fwd & b/wrd. Check your pads. Good?
Set the brake clearance. w/ the e-brake off...)
Gud Luck
When was the last time you adjusted your rear brake clearance?
Jack up the rear and spin each tire fwd & b/wrd (e-brake off...) & listen for anything abnormal. Notice a diff between one side and the other? Yes? Pull the wheels.
Try it again spinning the rotor fwd & b/wrd. Check your pads. Good?
Set the brake clearance. w/ the e-brake off...)
Gud Luck
Okay, I'll check into the venting clearance.
Thx.
QUOTE(jsteele22 @ Oct 20 2006, 09:18 AM) 
Last night I tried to push my car backwards out of the carport, and it seemed heavier than normal. Hmmm. Made sure the handbrake was off. Pushed it forward, no problem. Backwards, it goes maybe 3-4 feet, then stops. After repeating a few times, I could hear the right rear brake rubbing then engaging. Going forward releases it. Back when the engine was running, I never niticed any issues while backing up.
When I discovered this problem it was wet out and getting dark, so I didn't go under the car to investigate. I may have bumped something when I was working on the car earlier in the week (removed exhaust, driveshafts, shift bar).
1) Is this a known issue ? Cause ?
2) Anything quick 'n dirty I can do to make it easier to roll backwards ? I need to trailer it tomorrow AM, forward direction not an option.
TIA,
jeff
floor jack it out of the carport to turn it around [jack it up at the engine bar], it might take a couple of bodies to help.
QUOTE(messix @ Oct 20 2006, 10:49 AM)
floor jack it out of the carport to turn it around [jack it up at the engine bar], it might take a couple of bodies to help.
Well, it's gotta go over some gravel, so that won't be too practical.
These things get grungy fast.
Get some small wire brushes. Pull the caliper... just lift it up off the rotor. You can probably do this w/o pulling the hard line (be careful). Pull the clips and push out the pins. Chances are one of your pad springs is broken. Pull out your pads
Once you're there, like Dave says... clean everything out. Rust builds up on the edge of the pads and in the housing. Spiders absolutely love it in there... for the life of me I can't understand why. Get them outta there! LOL Take the little (toothbrush looking) wire brushes and get everything clean in there. You can try brake cleaner but, not too much, it can damage your rubber dust boots if it stays in contact with them for too long.
Then, as other have suggested, redo the venting clearance (while the calipers off, loosen the rear adjuster cover).
Get some small wire brushes. Pull the caliper... just lift it up off the rotor. You can probably do this w/o pulling the hard line (be careful). Pull the clips and push out the pins. Chances are one of your pad springs is broken. Pull out your pads
Once you're there, like Dave says... clean everything out. Rust builds up on the edge of the pads and in the housing. Spiders absolutely love it in there... for the life of me I can't understand why. Get them outta there! LOL Take the little (toothbrush looking) wire brushes and get everything clean in there. You can try brake cleaner but, not too much, it can damage your rubber dust boots if it stays in contact with them for too long.
Then, as other have suggested, redo the venting clearance (while the calipers off, loosen the rear adjuster cover).
Mystery Solved.
Brake pad return spring is fine.
Venting clearance is fine.
Calipers are fine.
E-brake cables fine.
Entire braking system is fine.
That's the good news, anyway. Anybody care to guesss what the idiot CO did wrong ? HINT : the answer is in the first post....
It was "Wet & dark out"
You had a little rock stopping you from oing backward.
You had a little rock stopping you from oing backward.
QUOTE(jsteele22 @ Oct 23 2006, 10:13 AM)
the answer is in the first post....
you left something lying in the driveway ...
Andy
You found your mute dog? 
Weeell, the mistake was the axles. I thought it would be okay to pull the axle shafts out of the hubs and leave them out. I mean, its not like I was gonna drive the car or anything. But apparently this is not the case.
On Friday night I went to look at the RR caliper, and as soon as I had the wheel off the ground it flopped around like the lug nuts were halfway out. So just the weight of the car plus maybe a few feet of rolling is enough to totally trash the wheel bearings. Since the wheels (and rotors) were free to flop around, the rotors were hitting the brake pads. I'm guessing there's something in the brake geometry to make forward rotation want to release the calipers (for obvious safety reasons) so backwards rotation has the opposite effect -- they grab harder.
Fortunately, the bearings are only a year old, so I at least I won't have to replace bearings that were old and worn out
I'm not sure you would trash the bearings that fast, but when they are not clamped by the hub & stub there will be a lot of free play. I know if you were to tow the car any distance you would do damage, but to roll it a few feet, I would not think so. Where is the Cap'n?
QUOTE(davep @ Oct 23 2006, 02:40 PM)
I'm not sure you would trash the bearings that fast, but when they are not clamped by the hub & stub there will be a lot of free play. I know if you were to tow the car any distance you would do damage, but to roll it a few feet, I would not think so. Where is the Cap'n?
Well, I'd be a very happy camper if they were still good. Is there a way to test ? If I put the stub axles in and torque down the nut, and if the wheel feels solid again, is that good enough ? Other thatn the sound of the brake rotors rubbing the pads, there aren't any unpleasant sounds when the car rolls.
I'd say the toal distance travelled so far is around 300 ft.
You're probably fine... actually you may not be fine but your car is probably fine.
Split bearings can be loose when not clamped down as Dave mentions. 300 ft. is a lot but probably not an issue.
Split bearings can be loose when not clamped down as Dave mentions. 300 ft. is a lot but probably not an issue.
When I read your first post in this thread I knew what was wrong (of course I just saw it 2 minutes ago). I also knew you'd figure it out. By the time I got to this end of the thread you had figured it out.
EDIT:
My guess is that the geometry of the caliper mounting vs. rotor coupled with the missing stub axle to keep the rotor on a stationary plane cause the rotors to "steer" slightly into the caliper when rolling the car backwards. I didn't do the best job of explaining that, but you're the physicist.
EDIT:
My guess is that the geometry of the caliper mounting vs. rotor coupled with the missing stub axle to keep the rotor on a stationary plane cause the rotors to "steer" slightly into the caliper when rolling the car backwards. I didn't do the best job of explaining that, but you're the physicist.
You are all wrong!!!!!!
Its gotta be gremlins bro. For real.
Its gotta be gremlins bro. For real.
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