Brake issues

JoelC said:

Hmm, this being the third master cylinder - the original one, then a bearmach one, and then an OEM one - they can't all be duff surely?

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It seems very unlikely, but then so is winning the lottery and someone does nearly every weekend.

If you check your brake fluid level carefully, noting it's height. Then spend a while repeatedly pushing the pedal to the floor, if the level doesn't drop then the fluid isn't leaking out anywhere. So, it's probably leaking past the seal.

Are any of your flexi hoses bulging? You really need someone there to help you.

JoelC said:

Ok, so I'm almost at a loss as to whats going on.

So far:

1. Replaced
   1. Calipers (Allmakes pattern part)
   2. Master Cylinder (OEM)
   3. Brake Servo (OEM)
   4. Front Brake lines and flexi's
2. Bled the system multiple times - cannot see any more air coming out of the system
3. Vacuum is good - enough to hold the pipe on the end of my finger.

The pedal travels about two inches before i get any brake bite, feels spongy even then. If i pump the pedal, it firms up, but keeping pressure on the pedal slowly moves the pedal downwards

If i clamp off the brake flexi's one at a time, there is no change, there is no weeping from any of the joints as far as I can tell.

Only other thing I am going to try is to reverse bleeding the calipers to see if that helps.

Anyone else have any suggestions?

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have you read post 34

When'd you last change the brake fluid?

Lionhound said:

When'd you last change the brake fluid?

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Have you read the whole thread?

Al2O3 said:

Have you read the whole thread?

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Obviously not. Was tired!!!

Al2O3 said:

It seems very unlikely, but then so is winning the lottery and someone does nearly every weekend.

If you check your brake fluid level carefully, noting it's height. Then spend a while repeatedly pushing the pedal to the floor, if the level doesn't drop then the fluid isn't leaking out anywhere. So, it's probably leaking past the seal.

Click to expand...

Done that, I've marked it up to the level, and then wedged the pedal down, so I will see if there is any fluid loss. I've ordered a master cylinder rebuild kit and I will rebuild the original MC and see if that makes a difference

nobber said:

Are any of your flexi hoses bulging? You really need someone there to help you.

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Flexi hoses are good, front two are new, rear is in good condition.

jamesmartin said:

have you read post 34

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I will try that tonight. I am also going to try blanking off the brake pipe connections to the MC and see if it firms up. Should at least rule out f the master cylinder is bad.

@JoelC
Any luck?

Ordered another master cylinder - i marked the reservoir and left the brake pedal wedged down for a week, checked today and the level had dropped, but once I unwedged and pumped the pedal a couple of times - the fluid level returned to normal. So i can only assume that the seals on the master cylinder have an issue. If a new master cylinder doesn't work then I might just take it to the local garage and see what they think.

JoelC said:

Ordered another master cylinder - i marked the reservoir and left the brake pedal wedged down for a week, checked today and the level had dropped, but once I unwedged and pumped the pedal a couple of times - the fluid level returned to normal. So i can only assume that the seals on the master cylinder have an issue. If a new master cylinder doesn't work then I might just take it to the local garage and see what they think.

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Fingers crossed. Sounds bloody frustrating.
On a positive note, you might win the lottery next weekend.
Good luck with the new MC

After changing my front calipers, I bled my system several times with a one man bleed kit and using the traditional 2 man method but got nowhere.
I bought one of these vacuum bleeders off ebay and it's one of the best tools I've bought. I bled the system in a few mins and without any mess and only using a tiny amount of fluid. So much easier than the pressure systems. I bet it would be decent for the clutch also. For some inexplicable reason, one of my calipers was full of air which never cleared with the other methods.

Just a further update, I've made some progress, but it still doesn't seem right. Pedal seems to be really low, and requires more force that i would expect, and there doesn't appear to be any gradual application of brakes, they appear to either be on or off. Although there is vacuum in the pipes, just about enough to hold on to the end of my finger, I don't feel the pedal go down when start the engine, so I'm still scratching my head.

I'm wondering it it might be vacuum pump related or a leak somewhere but can't locate it. I'm reluctant to throw more cash at it, so I think I'm going to take it to the local garage and get them to take a look, unless there is anyone in the rotherham area that might be able to take a gander for some beer tokens (or beer if you fancy cutting out the middleman)