poor brakes

[jamcarr2]

Hi

I think I need to overall my brakes ,I went out yesterday and after about ten miles I noticed the pedal travelled a long way before having any effect :shock:. I would guess this is due to a worn master cylinder

(i have no loss of fluid and pads and shoes are new )so I intend to fit new master cylinder and whilst I am at it I will change the brake fluid ,the thing I am unsure of is what is the difference between the two fluids listed by rimmers and paddocks .one is obviously ordinary fluid but what is silicon brake fluid and is it worth four times the price of unipart

Also how do you get the vacuum pipe of the servo does it pull out or screw out or is there a clip on the back

John

[Stagdad]

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Hi John

I believe the silicon fluid is not hydroscopic (water absorbing)unlike normal fluid which is, and therefore has to be changed to stop internalcorrosion.

There may be other differences such as boiling point etc.




Good luck Steve

[seaside bill]

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Silicon fluid is not the wonder product that it's cracked up to be. It compresses more under load so you get longer pedal travel and spongier feel, it attacks rubber seals which can lead to brown trouser moments :? (you're advised to replace all rubber seals if swapping from glycol to silicon based fluid) and it's got a much higher viscosity so, although it won't absorb water, it will trap more air! I understand that Girling and AP Lockheed do not recommend Silicon fluid.
My advice is to use DOT 4 instead and change it every 3 years. You can buy a handy little device from Gunson that you stick in your reservoir and it will tell you what the moisture content is on a green/amber/red scale.

[Des N]

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Had that problem last year. Changed the brake master cylinder seals and the brakes were transformed! Try the seals first...lot cheaper than the whole unit.

[Gresley]

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I have silicon brake fluid in my PI estate. I have to say that the brakes are definately not as good as they were with DOT 4. Lots more pedal effort required for the same braking! I was going to use it in the Stag, but I think I'll stick to DOT 4 instead, and just change it regularly.

Brian

[Kevin Garrod]

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How old is your brake fluid? Maybe there is nothing wrong with your master cylinder and you just need to change your fluid:?I have fitted braided hoses all round and the brakes are much better now, also my old fluid was looking black and nasty.

[jamcarr2]

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Thanks for the advise i have just ordered a second hand master cylinder from les clake i will rebuild this and fit it also change fluid for dot 4 and will fit braided hoses whilst i am at it

john

[Bob Heritage]

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jamcarr2 wrote:

i have just ordered a second hand master cylinder from les clake

john

Was he the driver of the Skoda?

[Bob Heritage]

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Hi John

I have had silicone fluid in the Stag for about 8 years now. To be quite honest I can't think what it was like before. You do get a different feel on the braking but you don't have to change it so often and it is harmless to the paintwork. You have to flush out the dot 4 also as it doesn't mix. I changed mine when I replaced the brake pipes with copper. Your problem might be the seal where the servo joins the master cylinder, are you loosing fluid?

Bob

[jamcarr2]

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Hi Bob

No,i have no fluid loss at all just the pedal travels a lot further but it doesn't happen all the time, started after about 10 miles

and no he doesn't have a skoda but may be a relative of MR Kipling

john

[seaside bill]

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John

A simple & reliable test for the master cylinder is just to put your foot on the pedal and hold it there - if it doesn't hold pressure (progressively goes to the floor) it's time for some tlc.

[jamcarr2]

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seaside bill wrote:

John

A simple & reliable test for the master cylinder is just to put your foot on the pedal and hold it there - if it doesn't hold pressure (progressively goes to the floor) it's time for some tlc.

Bill

Just tried the above and the pedal slowly goes down not all the way to the floor but quite a long way . Looks like it is the master cylinder then .

John

[Bob Heritage]

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John

'Used Rubbers' should alwaysbe used withcaution. If you are going to fit a second hand master cylinder I would recommend that you buy a new kit and overhaul the cylinder first, check that the bore is are not scored. The only problem that takes time is getting the circlip out at the servo end. ( Servo pipes just pull off , in answer to you previous question)

Bob

[KOY 23]

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Never use "used rubbers"