Just Fitted Braided Hoses But All Is Not Well

[McDude 33]

I just fitted some of Miles' fine braided hoses (top quality kit by the way). I emptied/filled/bled the system with Racing DOT 4 but I fear i have overfilled it.

 

All is fine until I go out for a spirited drive, the pedal starts firming up until eventually there is almost no travel in the pedal at all. I also notice that the brakes are actually starting to bind with no pedal pressure applied. I get out the car and the pads are smoking. Leave it to cool and all is well again, pedal travel back to normal.

 

I filled up to the max level, but then when you put the cap on with the dibber it goes past max to essentially 'brimming'. DOH!!!

 

My theory is that as the brakes get a bit of heat, the fluid is expanding and has no where to go thanks to a fine braiding and expands the caliper pistons.

 

Can anyone confirm my theory? Or suggest another cause.

 

Next - if I'm right, how do I get the excess fluid out of the reservoir? Drinking straw and some ribena to wash it down with? I did that last time and it gave me a terrible headache

[Jrod 7]

Sounds like the servo is adjusted to far out which is applying the brakes slightly the whole time and when they get hot the sieze.

 

Did you by any chance change the master cylinder?

 

Just bleed a little bit of fluid out of a caliper or use a syringe.

Edited March 14, 2008 by Jrod

[McDude 33]

Yes I did change the master cylinder!!!

 

Is your advice still to bleed off a bit of fluid (I think that would be a good idea anyway as it really is brimming now everything has settled) and/or do I need to do anything to the master cylinder.

 

I thought that the master cylinder bolted to the bulkhead without adjustment - should I have adjusted anything prior to fitting?

 

By the way, brakes don't get hot on a motorway run (ie not using the brakes) - only on the back roads.

Edited March 14, 2008 by McDude

[Jrod 7]

I wouldnt worry about the fluid much but you can either bleed a bit off or syringe.

 

There is a rod in the servo which needs to be adjusted so it sits a certain distance from the master cylinder.

 

I'm not sure 100% on how this works so if you try a search you may have a bit more luck!

[v6Max 0]

What MC did you change to? If it's the 405 one the servo push rod is 2mm too long at the moment.

 

Unbolt the master cylinder and withdraw it from the servo and you'll clearly see the rod that actually engages in the piston. The rod is adjustable (it's threaded) and as I said above you need to make around 2mm shorter.

 

You'll find that when you turn the adjustment the whole rod will spin but apparently (do a search) you can actually remove the entire rod, clamp it in a vice, make the adjustment and then re-install it.

[McDude 33]

Old MC was a 20mm (not 20.6mm) so I put in a new 20mm.

[Miles 331 1 Cars]

Was it a pattern or OE one? But as said sounds like the rod needs adjusting which is unusal but I;ve heard of this a couple of time's, But it's odd only when getting hot on the back roads, Jack up a wheel and see if the front's or back's are binding.

If you do adjust the rod only do it by a small amount as it makes a huge difference.

 

Good to know the pipes got to you OK

[McDude 33]

Miles - it was a pattern part from GSF. Well I say pattern only because the box had no brand names on it!

 

Pipes are top quality, I would have fitted the pads at the same time, but was waiting for some new discs. I've now got them and wanted to fit them this weekend, but will have to wait until I've sorted out the MC.

 

I will bleed off some fluid as that is a 2 minute job then go for a drive. I wonder if the servo rod is only so fractionally out that at rest there is no binding, but after applying the brakes they stay applied for just a bit too long creating heat and expansion thus compounding the problem.

 

The fact that the fluid has nowhere to go can't help at all.

[Jrod 7]

I will bleed off some fluid as that is a 2 minute job then go for a drive. I wonder if the servo rod is only so fractionally out that at rest there is no binding, but after applying the brakes they stay applied for just a bit too long creating heat and expansion thus compounding the problem.

 

If you do a search then 90% of people had it exactly like this where they only start to bind once used and warm up a bit.

[Simes 248 2 Cars]

Another one for servo rod adjustment.

[Miles 331 1 Cars]

I would sent it back, The pattern one's I;ve found are rubbish (Not working out of the box) and for a few quid more you can get a OE Bendix one which will last 5 times as long,

[welshpug 1,657]

I'd try another one Like Miles said, the Bendix one isn't much more and is usually in stock as its the same as a Mk2 Golf one.

[McDude 33]

I didn't really think when I picked up the MC from GSF, in fact it wasn't until Miles said that I even gave it some thought. I usually steer well clear of pattern parts.

 

I'm going to have to take the damn thing off to adjust the servo anyway - so I'll see if I can get a Bendix unit to swap it out.

 

Thanks Dudes!

[kanyeost 0]

euro car parts claim to do bendix ones if gsf don't...

[welshpug 1,657]

GSF definitely do Bendix ones (usually in stock), we had to source one last year at llandow to fix Tim Faulkners 205!!

[McDude 33]

GSF definitely do Bendix ones (usually in stock), we had to source one last year at llandow to fix Tim Faulkners 205!!

GSF do stock them, £28.50 + VAT, I just picked up one tonight and I'm kicking myself for not getting one in the first place.

 

They were very good about it and seem to be open to the fact that the pattern part could be to blame. I'll try and get fitting it ASAP, fingers crossed the pattern part is to blame.

[McDude 33]

Update - Bendix part fitted and tested and no problems to report.

 

After further analysis this morning (before I swapped them over) I worked out what was going wrong. It wasn't the adjustment of the servo rod - if that had been the case then the brakes would ahve overheated on the motorway. The problem was that the MC was not returning back to its 'at rest' state. Maybe a crap return spring or a seal that was too tight. Either way, the pattern MC was 100% to blame.

 

Only niggle I now have (and had before I swapped anything out) is that there is quite a lot of pedal travel before the brakes get applied. Once applied the retardation and feel are excellent.

 

It's the frickin' servo rod isn't it!!! I can live with it if that needs adjusting!