Lack of braking force!!

[Paul_Humphreys]

Right this has been getting worse for a while. I had not used my LC for a few month early on last year. Since using it again the brakes feel if the Servo was not working. There is a vacuum to the master unit. I have tried the "hold foot on the brake peddle and starting". It should drop a bit when starting (so I remember from years ago) but it does not. So is it time to chance the master cylinder unit or is there a common bit to change?

Boy do I hate working on brakes!!

Paul

 

[nivapilot]

If you pump the brakes before starting, and then the pedal doesn't drop as you start the engine, then it is the brake servo at fault Paul.

 

[clivehorridge]

Speaking straight from the top of my head, I'd suggest starting at the simple end... meaning vacuum pipes not blocked or kinked, any in-line valves not obstructed and the like.

On other cars, I've had servo diaphragms perish and split. It may be something simple before needing to worry about the master proper, if you get my drift.

 

[Chris]

Just for note - something that we have posted times many, is that on older cars, the seals in the MC get into a comfy position in the cyl . If you go pumping the brakes the seals get pushed further down the bore and this makes them very sad
Not saying they get ripped or anything, but it 'challenges' the seals in some way. Mine went like this as have many others. I took mine apart and ran my finger down the bore. You could feel where it had been polished and where it was roughened. If you have pushed the pedal all teh way down, there is a ery good chance that you have stuffed up the seals.

I went around mine for hours and hours pouring fluid in and bleeding the brakes, reading up on servos etc. This cured it - and I believe it has cured everyone else's who experienced the same thing. I tried all the tests you mentioned too and none of them seemed to give the results they should have given. Swapped the MC and I was away.

Just worth having at the back of your mind

Chris

 

[Paul_Humphreys]

The vacuum pipes are ok, tried them. Tried the pedal bit/thing. So I think it is the MC that needs changing. I was almost there Chris, just wanted thinking on the matter. Did you fit new of from Karl?

Its all my fault for not using it enough!!!

 

[Chris]

I fitted brand new genuine. I managed to blag a new one in a box for £50. Milners do them of course - but people are always so suspicious of after market MCs. It's a tube, with a piston and some seals. Sure, your life depends on it, but I think we'd hear if anything but genuine was that dangerous. Wouldn't we?

C

 

[Cptsideways]

I have a Milner MC & its been fine for 3 years. Just remember to bench bleed the thing before you fit it!!

 

[Chris]

You can do it on the vehicle actually. Procedure in the FSM. It worked for me. Done in seconds.

Chris

 

[Ben]

I have a Milner MC & its been fine for 3 years. Just remember to bench bleed the thing before you fit it!!

How do you bench bleed a master cylinder?

 

[Chris]

Well the MC is just a big syringe isn't it. But the problem is that there are places for air to hide. I guess you could fill it up on the bench to get rid of those pockets. These aren't cleared by the normal stroke of the piston. Easiest way though I think is to mount it all up, remove the delivery pipe, put your finger over it (with a cloth to catch the fluid) then have an assistant push down on the pedal. Then seal the outlet with your finger and allow the pedal back up slowly. This ensures that fluid is drawn into the cylinder from the reservoir rather then back up the delivery pipe. I dunno how, but it clears the bubbles in the toob pretty much in one go. Worked wonders for my brakes.

On the subject of brakes, I am running Milners new offerings. They gave me a set to try and I can honestly say they are the best pads in terms of stopping that I have had so far. Mine takes a lot of stopping. Anyone who has tried to lift one of my wheels will know this. So on normal wheels and set up, I'd imagine they'd be pretty good. Can't say what they're like on wear until I get into the front brakes again but I went through a set of OME pads in just over 1000 miles. Like I said, the beast takes some stopping.

Chris

 

[Paul_Humphreys]

Thanks for the info Gents.

 

[Cptsideways]

355192[/URL]]How do you bench bleed a master cylinder?

Youtube is your best friend on this one