VW Caddy intermittent brake binding

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Fri 14 Jul 2023 20:09
VW Caddy intermittent brake binding - badbusdriver

For a while now have been having this intermittent problem of the o/s front brake binding. Seems no rhyme nor reason for it and doesn't seem to need the brakes being used for it to start happening. I say this because the other morning I could feel it starting to drag about 7 miles away from home, during which (through a combination of observation, care and luck!) I hadn't touched the brake pedal. Been to the garage a couple of times to try and get it fixed without any success. Mechanic now reckons something to do with ABS but I am starting to lose confidence with him.

Any thoughts?

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Fri 14 Jul 2023 20:39
VW Caddy intermittent brake binding - elekie&a/c doctor
I’m assuming the brake calliper and flexi hose have been checked. It could possibly be an abs unit fault. I would get the system flushed with new brake fluid.
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Sat 15 Jul 2023 06:10
VW Caddy intermittent brake binding - badbusdriver

Pardon my ignorance Doc, but is that two separate things?.

Buy a new abs unit and flush the brake fluid, or flushing the brake fluid will/could fix the abs fault? (and yes, it has all been stripped down, cleaned/lubricated, and put back together again).

Thanks.

Edited by badbusdriver on 15/07/2023 at 06:13

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Sat 15 Jul 2023 06:23
VW Caddy intermittent brake binding - paul 1963

Think Doc is suggesting flushing the system 'may' cure the fault? I know you had it looked at but to me it sounds like a sticky caliper.

As its you if you do need a caliper or even a abs module I'd be happy to get one for you and post it, doing what I do I get car parts at cost ( below trade price).

Edited by paul 1963 on 15/07/2023 at 06:37

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Sat 15 Jul 2023 08:56
VW Caddy intermittent brake binding - elekie&a/c doctor
Yes , full brake fluid flush before condemning the abs module. It’s possible that water in the fluid has caused corrosion on the abs hydraulic module valves and cause them to stick . These abs units are repairable. A new one would probably write off the vehicle.
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Sat 15 Jul 2023 16:21
VW Caddy intermittent brake binding - badbusdriver

Think Doc is suggesting flushing the system 'may' cure the fault? I know you had it looked at but to me it sounds like a sticky caliper.

But surely if it was a sticky calliper, the binding could only be triggered by using the brakes (and then the offending calliper doesn't release completely)?. As I mentioned, the other day it started binding several miles from home during which I (deliberately) had not used the brakes.

As its you if you do need a caliper or even a abs module I'd be happy to get one for you and post it, doing what I do I get car parts at cost ( below trade price).

That is very kind of you to offer Paul, but going by what Doc says about the abs unit cost, a replacement is still going to be very expensive with your discount!. The Caddy isn't going to be with me much longer, I'll get done what it needs (within reason) and sell it.

Yes , full brake fluid flush before condemning the abs module. It’s possible that water in the fluid has caused corrosion on the abs hydraulic module valves and cause them to stick . These abs units are repairable. A new one would probably write off the vehicle.

Thanks Doc, I'll look into getting the brake fluid flush done and also repair/refurbishment of the unit

Edited by badbusdriver on 15/07/2023 at 16:22

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Mon 17 Jul 2023 15:39
VW Caddy intermittent brake binding - John F

Any thoughts?

Sticky/seized caliper piston? How old are the pads? If quite worn, I would replace them, during which I would use the brake pedal and a large old screwdriver as a lever to make the caliper piston go back and forth along its full length of travel a few times. If fairly new, I would take the pads out and do the same thing, then check the pads can move freely in their mountings on reassembly.

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Mon 17 Jul 2023 16:16
VW Caddy intermittent brake binding - gordonbennet

I'm agreeing with JohnF, even if you arn't pressing the brake pedal if the caliper is sticking even slightly the pads and disc will get warm.

Part of my annual brake service routine is exercise the pistons as described by John, to do this i usually remove one pad (not the one nearest the piston) so when pushing the pistons fully out via repeated braking there's no danger of the piston actually falling out.

Its permissable to peel back the dust cover gently and wipe some of the correct red rubber grease onto the piston itself to help prolong caliper life but if its hard to push the pistons back then often its too late and time for either a rebuild or new caliper.

I have a huge pair of adjustable water pump pliers which prove invaluable for pushing pistons back in.

The other thing about brake servicing which gets missed too often, those stainless steel spring clips in the caliper that the pads sit and slide against, best to ping them off and with an old chisel and wire brush clean up the caliper well where the spring clips sit, crud builds up behind the things, do this and that pad you struggled to remove often slides back in easily and can slide as required in operation.

just out of interest, this exercising of pistons is why i dislike park brakes that operate on the rear pads, the adjusting mechanism used prevents you pushing the pistons in and out easily, probably the same issue but even more awkward with EPB's, thankfully i'm yet to have to deal with one of those and if i never have to own or work on a car so equipped that will suit me just fine...much prefer the vastly superior and trouble free drum inside disc park brake design.

Edited by gordonbennet on 17/07/2023 at 16:21

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Mon 17 Jul 2023 19:22
VW Caddy intermittent brake binding - paul 1963

Sort of agree with John about exercising the piston although I really wouldn't use a screw driver, you can buy quite cheaply a tool that winds back the piston, they really do need to move in and out squarely, it's oh so easy to score the bore and or damage the seals then it really is new caliper time.

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Tue 18 Jul 2023 03:44
VW Caddy intermittent brake binding - edlithgow

Its not THAT hard to strip them completely, as long as you avoid the prevailing Internyet advice to use air pressure to blow the pistons out, spectacularly daft when there is a brake pedal there specifically designed for the job.

(TBH it took me a day or two of messing about for this to dawn on me)

Mine were very bad after long neglect but cleaned up nicely.

Clean - up pistons and bores with aluminium foil, a gentle conformable abrasive with an anti-corrosion effect.

Calipers (and especially the slider surfaces under the stainless steel clips) abrade with a flattened beer can disk, finally using sunflower oil as a binder, so you get an aluminium paint.in intimate contact with the steel.

Dry lube only (or nothing) on the stainless clip surfaces and pad ears. I rub the clips with a soft "chippy" flat pencil, and wrap PTFE tape around the pad ears.

Caliper pins wrap with PTFE tape and apply silicone grease.

Cant really explain why the brakes bind spontaneously but intermittantly though, Could there be a little trapped air thats expanding when things get warm, perhaps in combination with a degraded hose or debris giving a non-return valve effect?

Edited by edlithgow on 18/07/2023 at 03:46

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Fri 28 Jul 2023 00:28
VW Caddy intermittent brake binding - edlithgow

Of course I have no experience of ABS, and don't much want any, but apparently they are extremely sensitive to the precise positioning of the magnetic speed sensor, and can start misbehaving with a very small amount of rust-jacking.

Relatively simply addressed here

www.youtube.com/channel/UCtAGzm9e_liY7ko1PBhzTHA

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Mon 17 Jul 2023 19:53
VW Caddy intermittent brake binding - bathtub tom
a large old screwdriver as a lever to make the caliper piston go back and forth along its full length of travel a few times.

But please don't lever against the disc, unless you want juddery brakes!

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