RRC Brakes sticking on

We’ve recently got my Soft Dash Classic moving again. However the brakes are sticking on. The brakes are off until the ABS pump pressurises the system, after which all 4 brakes lock on. After a leaving for a while the brakes are free again.

Has anyone come across this before?

Sticking Pistons in 2 or more calipers would get my vote.

I'd pull all the calipers and give them a going over/rebuild.

T-C said:

We’ve recently got my Soft Dash Classic moving again. However the brakes are sticking on. The brakes are off until the ABS pump pressurises the system, after which all 4 brakes lock on. After a leaving for a while the brakes are free again.

Has anyone come across this before?

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That would sound like valves in the modulator to me or a problem with the ABS ECU , if the brakes free off when the pressure goes I doubt it can be the callipers.

I would unplug the abs unit and try the brakes again. If there is no sticking, you onto a winner!
If there is still sticking. Remove each caliper (but not from the car or braking system)
and inspect and grease the guides. Failing that squeeze each piston with a clamp and look for resistance.
If the whole system still has resistance then go back to the distribution block!

Not had the exact same problem but have experienced one caliper sticking. I resolved it with a combination of bleeding the system - I know it is a PITA but it is the only way, also clean the calipers and push the pistons back and then CAREFULLY (with an assistant) operate the brakes to push the pistons out again to make sure they are free.
When you operate the brakes to push the pistons out, place a slim piece of timber or something between the pistons and the disc, you just need something in there that is thinner than your pads so the piston moves through a bigger range than previously. Check the piston seals while you're at it, the outer dust seals sometimes fall to bits.

HTH

+1 ^^

Mark Piercy said:

I would unplug the abs unit and try the brakes again. If there is no sticking, you onto a winner!
If there is still sticking. Remove each caliper (but not from the car or braking system)
and inspect and grease the guides. Failing that squeeze each piston with a clamp and look for resistance.
If the whole system still has resistance then go back to the distribution block!

Click to expand...

Which connected do I need to unplug the ABS unit? I unplugged the one on the top of the modulator next to the reservoir and it was no different.

I think my first action will be to do the bleeding again. We had a lot of issues so it might not have been done in the correct order.

A thorough bleed would rule out expanding warm air. If it's any thing like the 38' it has to be done to the T'!

@T-C ,how did you get on?

The connector on the top of reservoir is the level sensor.

Look for a round ball thing with connectors going to it similar to this -

Green is the level sensor for dash.
There’s a relay in the fusebox for it also

Mark Piercy said:

@T-C ,how did you get on?

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Haven’t done anything to it yet. Some of the brake pipes need replacing so will be replacing them before doing the bleeding again. I’ll definitely update this thread when I’ve found the time to do it.

Good luck with the repair and keep us in the loop.

Hopefully will get a chance to sort the pipes this weekend. In the meantime I have removed the ABS relay. The brakes are not stuck on with this removed so definitely something to do with the modulator I think.

Sounds like the pressure is leaking Into the brake system after it has pressurised.
Anybody got a diagram maybe?

Right. Finally got the pipes sorted. Re-bled the system which seemed to go as expected according to the instructions. However the brakes are still sticking on!

I might see if I can get some fault codes out of it. Other than that I don’t know what to do from here.

Brakes are now working!

For the benefit of those reading this in the future, I found someone else with the same problem on another forum. They had put the clevis pin on the brake pedal in the wrong hole. I suddenly remembered when I put mine back together, the brake lights were stuck on, so I assumed I’d got the wrong hole and changed it. Therefore my brakes were always slightly applied. With the pin in the correct hole the brakes are operating fine. Just need to adjust the brake light switch now.

T-C said:

Brakes are now working!

For the benefit of those reading this in the future, I found someone else with the same problem on another forum. They had put the clevis pin on the brake pedal in the wrong hole. I suddenly remembered when I put mine back together, the brake lights were stuck on, so I assumed I’d got the wrong hole and changed it. Therefore my brakes were always slightly applied. With the pin in the correct hole the brakes are operating fine. Just need to adjust the brake light switch now.

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Nice one