Both front brakes dragging after Disc and Pad change
Discussion
Hi guys,
I recently did a full pad and disc change on my 997, pistons moved back with ease and new pads dropped in along with the new discs. Everything moved freely and life was good. Drove the car to the MOT the next day where it passed without any problems. Now 100 odd miles later both front brakes are binding with the usual signs of hot discs, poor MPG and car not moving on a light slope etc.
The calipers are a 4 piston design and I can't see any obvious signs that any of them are sticking and I can push the pads back with my thumbs which then gives them more than enough clearance from the disc (until you hit the brakes and they don't move back far enough).
Any thoughts on what to check? I've just taken the pads out and made sure the back of them and the pistons are free from dirt etc but I can't see anything obviously wrong.
I recently did a full pad and disc change on my 997, pistons moved back with ease and new pads dropped in along with the new discs. Everything moved freely and life was good. Drove the car to the MOT the next day where it passed without any problems. Now 100 odd miles later both front brakes are binding with the usual signs of hot discs, poor MPG and car not moving on a light slope etc.
The calipers are a 4 piston design and I can't see any obvious signs that any of them are sticking and I can push the pads back with my thumbs which then gives them more than enough clearance from the disc (until you hit the brakes and they don't move back far enough).
Any thoughts on what to check? I've just taken the pads out and made sure the back of them and the pistons are free from dirt etc but I can't see anything obviously wrong.
Daston said:
Hi guys,
I recently did a full pad and disc change on my 997, pistons moved back with ease and new pads dropped in along with the new discs. Everything moved freely and life was good. Drove the car to the MOT the next day where it passed without any problems. Now 100 odd miles later both front brakes are binding with the usual signs of hot discs, poor MPG and car not moving on a light slope etc.
The calipers are a 4 piston design and I can't see any obvious signs that any of them are sticking and I can push the pads back with my thumbs which then gives them more than enough clearance from the disc (until you hit the brakes and they don't move back far enough).
Any thoughts on what to check? I've just taken the pads out and made sure the back of them and the pistons are free from dirt etc but I can't see anything obviously wrong.
Obviously, get the car in the air and look.I recently did a full pad and disc change on my 997, pistons moved back with ease and new pads dropped in along with the new discs. Everything moved freely and life was good. Drove the car to the MOT the next day where it passed without any problems. Now 100 odd miles later both front brakes are binding with the usual signs of hot discs, poor MPG and car not moving on a light slope etc.
The calipers are a 4 piston design and I can't see any obvious signs that any of them are sticking and I can push the pads back with my thumbs which then gives them more than enough clearance from the disc (until you hit the brakes and they don't move back far enough).
Any thoughts on what to check? I've just taken the pads out and made sure the back of them and the pistons are free from dirt etc but I can't see anything obviously wrong.
Were the wheels free or tight to rotate when you had the car in the air ? Is it just the fronts ? or rear also ?
stevieturbo said:
Obviously, get the car in the air and look.
Were the wheels free or tight to rotate when you had the car in the air ? Is it just the fronts ? or rear also ?
Yeah both fronts are tight when in the air. Not checked the rears as I hadn't touched those, will take a look at them. Were the wheels free or tight to rotate when you had the car in the air ? Is it just the fronts ? or rear also ?
stevieturbo said:
Obviously, get the car in the air and look.
Were the wheels free or tight to rotate when you had the car in the air ? Is it just the fronts ? or rear also ?
Yeah both fronts are tight when in the air. Not checked the rears as I hadn't touched those, will take a look at them. Were the wheels free or tight to rotate when you had the car in the air ? Is it just the fronts ? or rear also ?
Quick update,
Drove the car out of the garage onto the drive and got it in the air. Rear wheel has very small resistance (more likely the drivetrain) yet the fronts are both very stiff to move. With the wheel removed I need both hands to shift the Disc it is that tight.
In terms of fault finding I am thinking of removing the caliper from the hub and getting the wife to gently press the brakes and then identify the piston or pistons that are not retracting.
Drove the car out of the garage onto the drive and got it in the air. Rear wheel has very small resistance (more likely the drivetrain) yet the fronts are both very stiff to move. With the wheel removed I need both hands to shift the Disc it is that tight.
In terms of fault finding I am thinking of removing the caliper from the hub and getting the wife to gently press the brakes and then identify the piston or pistons that are not retracting.
Daston said:
Quick update,
Drove the car out of the garage onto the drive and got it in the air. Rear wheel has very small resistance (more likely the drivetrain) yet the fronts are both very stiff to move. With the wheel removed I need both hands to shift the Disc it is that tight.
In terms of fault finding I am thinking of removing the caliper from the hub and getting the wife to gently press the brakes and then identify the piston or pistons that are not retracting.
Jack car up etc, when this tightness is occurring, and crack open a bleed nipple to see what happensDrove the car out of the garage onto the drive and got it in the air. Rear wheel has very small resistance (more likely the drivetrain) yet the fronts are both very stiff to move. With the wheel removed I need both hands to shift the Disc it is that tight.
In terms of fault finding I am thinking of removing the caliper from the hub and getting the wife to gently press the brakes and then identify the piston or pistons that are not retracting.
So the OP can push the pads back easily but the brakes are binding. Is that right?
I don't see any clear explanation of the wheels being able to spin more freely after the pads have been pushed back by the OP. But lets assume they can.
I am therefore pretty stumped. If OP can push the pads back easily and then the wheels spin freely then why doesn't this happen naturally and prevent the binding.
I don't see any clear explanation of the wheels being able to spin more freely after the pads have been pushed back by the OP. But lets assume they can.
I am therefore pretty stumped. If OP can push the pads back easily and then the wheels spin freely then why doesn't this happen naturally and prevent the binding.
Landcruisers have similar 4 piston calipers on the front, they are prone to one piston only of the 4 starting to seize, on those its usually the inner lower.
To check on your car, remove one pad at a time so you can check the opposite pistons, as you push one piston home the other should slide out by the same amount, probably the most ideal caliper arrangement for exercising the pistons in their bores, you can do this multiple times before having to press the brake pedal to put a bit more fluid into the caliper.
If you can push one piston home without the other sliding out you've found the culprit.
Another couple of thoughts.
Do your calipers have those stainless sprung steel clips that the pads sit in, crud builds up under those clips so it pays to remove them every brake service, wire brush the clips and scrape the clip seats with an old chisel or sharp screwdriver and wire brush to finish., surprising how easily new pads slot in when you've done this.
You can put a light wipe of your chosen lube under the clips to help prevent corrosion if that's an issue.
Did you clean up and lightly lube the locking pins that go through and locate the pad backing plates?
You refitted the sprung tensioner correctly? Not suggesting you've messed up but now and again i try to refit the thing the wrong way which could jam the pad or disc scrape the spring if left unnoticed.
To check on your car, remove one pad at a time so you can check the opposite pistons, as you push one piston home the other should slide out by the same amount, probably the most ideal caliper arrangement for exercising the pistons in their bores, you can do this multiple times before having to press the brake pedal to put a bit more fluid into the caliper.
If you can push one piston home without the other sliding out you've found the culprit.
Another couple of thoughts.
Do your calipers have those stainless sprung steel clips that the pads sit in, crud builds up under those clips so it pays to remove them every brake service, wire brush the clips and scrape the clip seats with an old chisel or sharp screwdriver and wire brush to finish., surprising how easily new pads slot in when you've done this.
You can put a light wipe of your chosen lube under the clips to help prevent corrosion if that's an issue.
Did you clean up and lightly lube the locking pins that go through and locate the pad backing plates?
You refitted the sprung tensioner correctly? Not suggesting you've messed up but now and again i try to refit the thing the wrong way which could jam the pad or disc scrape the spring if left unnoticed.
Right I think I have found this issue.
Took the pads out and placed a bit of thin wood between the disc and pistons. As soon as the brakes were released the wood is free to move about.
So I think it's safe to say the calipers are okay, with the pads in there is a little resitance but it frees up once the disc is spinning a few times.
However, as soon as I torque the Caliper bolts up to the hub the outside pad is binding hard to the disc surface on both sides of the car. Going to wire brush the hubs down tonight after work to see if it's as stupid as a build up of brake dust etc.
Took the pads out and placed a bit of thin wood between the disc and pistons. As soon as the brakes were released the wood is free to move about.
So I think it's safe to say the calipers are okay, with the pads in there is a little resitance but it frees up once the disc is spinning a few times.
However, as soon as I torque the Caliper bolts up to the hub the outside pad is binding hard to the disc surface on both sides of the car. Going to wire brush the hubs down tonight after work to see if it's as stupid as a build up of brake dust etc.
I've had that before ... turned out the pads were the tiniest bit bigger than they should be (not the pad material but the hard bit at the back shaped to locate the pad in the caliper - sorry, not aware of the proper name for it). They fitted tight, but fine, by hand, but bound up when torqued down correctly. Maybe the QC guy was on lunch break when these ones came down the line? 
A quick tickle with the angle grinder and a light dab of grease and they were hunky dorey.
A quick tickle with the angle grinder and a light dab of grease and they were hunky dorey.
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