Cycling UK Forum

Hi All
Not sure if this should be in another section.
I have an E Cargo trike, with the box and two wheels at the front. It has hydraulic disc brakes all round, with the front two operated by the same lever.
Its more noticeable in the wet, but when I brake the trike wants to turn to the right. I have looked at the brakes, they both seem to be working.
Any ideas of the problem?

Many thanks

Martin

possibly the disc brake on one side is ...

- contaminated
- caliper binding
-pads worn differently

Take a look at the pads; if they are worn unevenly then it may indicate a binding piston. If the pads are contaminated one side then swapping the left pads for the right may (temporarily) either move or cure the problem. However if contamination is the cause, you need to find its origin. A common cause of contamination is a tiny leak from a caliper; either in the transfer port seal or one of the main piston seals.

cheers

Since the only common component seems to be the lever / master cylinder i would recommend you reseal the master cylinder as you appear to be getting differential pressures at the wheel.

the way these systems are usually configured is with a single outlet from the MC and a splitter in the line. If so it is nigh-on impossible to get different pressures inside the two slave cylinders.

cheers

Brucey wrote:the way these systems are usually configured is with a single outlet from the MC and a splitter in the line. If so it is nigh-on impossible to get different pressures inside the two slave cylinders.

cheers

Not if one side has leaking seals and the other hasn't. BTW I think from what Landsurfer has said here about his business he's very knowledgeable about hydraulic systems.

I run a similar system on my ICE trike, single lever to twin brakes.
It was easy to get differential braking when I used cables, just needs one to be sticky/setup wrong.
Hard with hydraulics unless there's a fault in one of the calipers, the only time I've had it was when one froze in the cold.
I've found that anything going wrong in the brake lever tends to give you no brakes at all.

If there's a T in the system, then a leaking seal would only give you weaker brakes as you loose oil unless a pad gets contaminated.

pete75 wrote:

Brucey wrote:the way these systems are usually configured is with a single outlet from the MC and a splitter in the line. If so it is nigh-on impossible to get different pressures inside the two slave cylinders.

cheers

Not if one side has leaking seals and the other hasn't. BTW I think from what Landsurfer has said here about his business he's very knowledgeable about hydraulic systems.

It doesn't matter if there is a slight leak in the caliper seals or not, the pressure will still be equal in each caliper.

cheers

Brucey wrote:

pete75 wrote:

Brucey wrote:the way these systems are usually configured is with a single outlet from the MC and a splitter in the line. If so it is nigh-on impossible to get different pressures inside the two slave cylinders.

cheers

Not if one side has leaking seals and the other hasn't. BTW I think from what Landsurfer has said here about his business he's very knowledgeable about hydraulic systems.

It doesn't matter if there is a slight leak in the caliper seals or not, the pressure will still be equal in each caliper.

cheers

The important pressure is that which is supplied to the piston. If a leak is reducing that pressure then it does matter as does anything else which reduces brake effectiveness. Take a motorbike for an MOT with a leaking caliper seal and try to convince the tester it doesn't matter. You won't have much success.

My guess is corrosion/degredation of the left caliper affecting piston action. Possibly as a result of being closer to the kerb and muddy puddles.

Thanks for the advice, when I have time next week, I will have a better look.

Martin

pete75 wrote:

Brucey wrote:

pete75 wrote:Not if one side has leaking seals and the other hasn't. BTW I think from what Landsurfer has said here about his business he's very knowledgeable about hydraulic systems.

It doesn't matter if there is a slight leak in the caliper seals or not, the pressure will still be equal in each caliper.

cheers

The important pressure is that which is supplied to the piston. If a leak is reducing that pressure then it does matter as does anything else which reduces brake effectiveness. Take a motorbike for an MOT with a leaking caliper seal and try to convince the tester it doesn't matter. You won't have much success.

yes but my point is that if there is pressure in the system a small leak does not reduce the operating pressure on one piston from several, be the pistons in one caliper or several. Any leak is completely unacceptable for very many reasons..... none of which is that 'the pressure is reduced in only one of the calipers/pistons'.

Any advice that there is 'probably a fault with the MC' if there is a single piston MC driving a single circuit with two or more slave cylinders that are not working similarly when the system is pressurised is a complete red herring.

cheers

pete75 wrote:

Brucey wrote:

pete75 wrote:Not if one side has leaking seals and the other hasn't. BTW I think from what Landsurfer has said here about his business he's very knowledgeable about hydraulic systems.

It doesn't matter if there is a slight leak in the caliper seals or not, the pressure will still be equal in each caliper.

cheers

The important pressure is that which is supplied to the piston. If a leak is reducing that pressure then it does matter as does anything else which reduces brake effectiveness. Take a motorbike for an MOT with a leaking caliper seal and try to convince the tester it doesn't matter. You won't have much success.

With a very slight leak in the system you won't get a reduction in brakes until you either run out of oil or you pull air into the system.
In the first case the brakes work fine until the brake lever finally hits the handlebar, the you lose power.
In the second case the brake lever gets spongy and you loose braking power straight away.
I've had both happen to me due to main brake piston seal failure.
I've since resolved the issue causing that failure mode on my bent trike.
In both cases you stop in a straight lines as both brakes work the same.

^ correct.

cheers

Brucey wrote:

pete75 wrote:

Brucey wrote:
It doesn't matter if there is a slight leak in the caliper seals or not, the pressure will still be equal in each caliper.

cheers

The important pressure is that which is supplied to the piston. If a leak is reducing that pressure then it does matter as does anything else which reduces brake effectiveness. Take a motorbike for an MOT with a leaking caliper seal and try to convince the tester it doesn't matter. You won't have much success.

yes but my point is that if there is pressure in the system a small leak does not reduce the operating pressure on one piston from several, be the pistons in one caliper or several. Any leak is completely unacceptable for very many reasons..... none of which is that 'the pressure is reduced in only one of the calipers/pistons'.

Any advice that there is 'probably a fault with the MC' if there is a single piston MC driving a single circuit with two or more slave cylinders that are not working similarly when the system is pressurised is a complete red herring.

cheers

Any leak in a hydraulic system reduces it's working pressure and it can also suck air into the system which isn't a good idea either. A leak in one side will cause the caliper to work less effectively than a non leaking one on the other side. Only last weekend I fixed the front brakes on an 'Auntie' Rover 100 belonging to a friend. Braking caused a sharp pull to the right. The cause - leaking seals in the left hand caliper. You may claim that wasn't the cause but all I know is that after I fitted new seals it pulled up in a straight line.

pete75 wrote:
Any leak in a hydraulic system reduces it's working pressure.

but in a brake (that develops any appreciable pressure), NOT so that there is a different pressure in each slave cylinder on a single circuit.

cheers