A brake problem and a mystery

[Flypopa]

Because of the hard work that the vehicle does. Every year the cylinders are changed on its yearly overhaul. There are two on each wheel cost £336 approx. for just the front.
There is one on each rear wheel.
If I find as I said that the piston seal leaks too often, then the cylinder is changed again (under warranty).
The dirty fluid is caused from the wear of the piston rubbers.
On each piston there is the seal (a rubber ring) that has a taper (wide part to the top) and there is a dust cover over the top of the cylinder where the brake shoe fits into the slot on top of the piston.
But I expect you all know this.
The springs are good. A mole grip type tool has to be used to lift the shoe from the system Trust me when I tell you it is not easy to remove the shoe because of the strength of the springs.

In answer to JohnWR. If the hole was blocked in the master, this would be spotted when the brakes are bled. and would affect both wheels.
I have jacked up the front a few times to check to see if there is binding and the wheels run free.
Also if there was binding I would feel it in the brake pedal as it would go hard.

I feel sure that with the help and sugestions from you guys, we will solve this in the end.

 

[keyplayer]

The dirty fluid is caused from the wear of the piston rubbers.

This can't be right regardless of yearly use. If you've had any seals break down putting debris into the system this could cause your problem, and be the result of a dodgy batch. Yearly replacement of the cylinders seems like overkill to me, sleeping dogs and all that? Are you replacing the complete assemblies, or servicing the old? You could try pumping a load of fresh fluid through each pipe while the slaves are off and prior to final bleeding. Perhaps even blow them through with a compressor.

it is not easy to remove the shoe because of the strength of the springs.

This would still be the case even if the spring elasticity has reduced considerably. Could be worth trying a new set.

 

[Flypopa]

I am going to the garage in the morning for another session with the brakes. I have made notes of your suggestions which I shall mention. Pray for my vehicle and its braking system.
The saga continues...

 

[johnwr]

It was me that said about dirty brake fluid, I was talking about general wear not the seals breaking up, I have never seen it happen except on really old vehicles. The cost of the wheel cylinders seems a bit steep, is this for fitting aswell.

 

[Flypopa]

I had the cab booked in yesterday for another session. I had arranged for the adjusters on the front wheels to be changed as I had noticed that on a couple I could not feel the clicks.
When I arrived at the garage the foreman told me that he could not get any adjusters anywhere. I said that I would try on Monday a couple of places I knew.
On my way home I suddenly thought that I was sure that I had some in my box of bits. I did.
I returned to the garage and plonked them on the foreman’s desk.
The fitter that was going to do the job said that in the 20 years that he had been in the trade he had never had to fit adjusters. He did not seem happy with doing the job. I did mention the points that you guys had suggested. He was not very impressed or comment except for a shrugging and nodding.
He did make quite a meal of doing it as he stripped down the whole wheels to the back plate.
I could see that it was going to take some time so I walked home (about one mile). Later after lunch I cycled back and the job was done. Cost £102 for the labour.
As the wheels were stripped down, the brakes had to be bled and the fluid changed.
On the way home I drove around to get the brakes to warm up a bit….

Back to the think tank again. The offside is still getting warmer than the nearside.
£120 tax deductible.

The rest of the day I was deep in thought. What else could it be?
Early this morning when I woke up I had an idea. Eureka! and all that sort of thing. How can I check if both wheels/brakes are coming on at the same time? I know they are not sticking on as I had already tested this with the front jacked up and with a helper spinning the wheel and me braking.
No helper today. Some more thought. With a vice and some bits of timber I managed to get the brake pedal pressed by slowly opening the vice with the timber pushing down the brake pedal.

The adjustment was well out. With the brake just coming on the off side, the nearside was still free. I readjusted with the engine off, and then running for the servo to work. It seems it might have done the trick. I could not road test as it was getting late for I had other things to do. (She does nag).
Tomorrow…

I found out that the cylinders are not changed every year as I was led to believe. The cost I quoted was for one I had done recently X 4.

 

[johnwr]

I am surprised that one side is coming on before the other, you mentioned on an earlier posting that the brake system is split front / rear, so unless there is a blockage both brakes should come on at the same time. I would have a good look at the flexible hoses and brake pipes.

 

[Flypopa]

I am surprised that one side is coming on before the other, you mentioned on an earlier posting that the brake system is split front / rear, so unless there is a blockage both brakes should come on at the same time. I would have a good look at the flexible hoses and brake pipes.

This is the original problem. One side coming on before the other. If you recall from my original post. When I had a service and complete brake service. The position changed from the nearside to offside now coming on first.
As for a blockage. when the system was bled there was a good squirt from the bleed nipples.

I am going to do a road test first thing tomorrow. I shall head for the river, if it is not cured the cab could end up in there.

 

[Tarquin-F-Smythe-QJM]

Surely not 'Sarf ' of the river...i thought you guys dont go there.

 

[Flypopa]

Surely not 'Sarf ' of the river...i thought you guys dont go there.

I go where I am told to go up to 5pm. I like to go SOUTH of the river, just to see what I am not missing..

 

[Flypopa]

Reading though the posts again.
It is NOT one side coming on before the other. It is that one side is getting HOTTER than the other.
Although it would seem that one side is coming on first. If this was so then it would be pulling to that side.

 

[Flypopa]

To all those that have taken an interest in this problem of mine. I would tell you that I think I have cracked it.
After having the adjusters replaced, this allowed me to adjust the brakes better the way I told you earlier.
Over the last two days the brakes are more positive and the temperature of the fronts are even.

 

[Mick Leek]

sidecar_jon


GT750 i used to have one of those (KETTLE) back in the early eighties. What a beast of a bike that was... for its time

sorry totally off post but a fellow kettle rider, VERY rare breed of men

Mick

 

[Agile]

I have read this all for interest sake.

Half way through I was thinking " change the mechanic" in case he was doing anything idiosyncratic.

I then read he is reluctant to follow the owners instruction to change the adjusters.

I now read that adjustment by the owner seems to have solved the problem. My brain then blames the mechanic although its not clear what he has done wrong or not done.

After all this I am inclined to suggest the following distance is doubled and braking is less harsh. I also wonder why such an old "F" reg cab is being used for daily service when most are very much newer.

Tony

 

[Flypopa]

£30,000+ Is the answer. At my age and the amount of work that I do part time.
There are older cabs tham mine still working. (They don't make them like that anymore.)
by the way, The brakes are still OK.

 

[Agile]

Two interesting questions are still answered!

What is the conclusion about the mechanic?

Why dont cabies put cheap non-year specific number plates on cabs to hide their age?

Tony