Brakes

[Slowcoach]

I have braided hoses on my braking system, I read somewhere that these should be replaced every year - is that being a little over zealous or in your experience is it really neccesary ?

[Adam43]

Who told you, a hose manufacture?

Actually I have never heard that. Obviously, as with everything we make sure they are in tip-top condition, but I've not heard this before. I'll be interested to hear what others say.

One thing is clear decent hoses do improve the braking performance as there is no expansion in the hose. The only expansion comes at the calliper where it is needed!

[Slowcoach]

Ha ha , no I read it somewhere - just another racer I think, but he said that the little metal strands do break over time and the can cut into the rubber or teflon or whatever is inside and so can cause a small leak or at least somewhere that air could get into the system. The reason I ask is, I have just had a new super fandango front system fitted (including master cylinders and it has been bled properly) but still I get a spongey pedal and frankly I am not stopping anything nearly like I should be - the fluid isnt boiling - its the best you can get- so I can only think perhaps there is a tiny bit of air getting in somewhere - that only leaves the braided hoses which have not been replaced during my 3 years of ownership........

[Adam43]

It does sound like it could be the hoses. As you have a some lovely new bits it is probably worth investing. Even if they are not 'worn' it could be they are not up to the standard of the rest of your system. Maybe your new bits are exposing a weakness you already had (?). More expense.

The explanation you were given seems reasonable, I know ours have been on a couple of seasons now...

[Tim Falce]

Are they stainless steel braided and are they rubber or teflon pipes?
I have had stainless steel covered teflon for 6 years on my car with no problems.
The thing you need to check is if the steel isn't worn as the pipes won't take much pressure without the covering intact.

[Red Dog]

Slowcoach, if you can get air into the system then you will certainly get fluid coming out!!! The -3 aeroquip pipes last for years and years. You have to really abuse them to ruin them. Spongy pedal is most likely to be air. Some cal;ipers are really hard to bleed all the air out. Might need to remove them and wiggle them a bit to get the air out, but usually thumping the pedal with the bleed nipple closed works.

[Red Dog]

I should have added that you then carry on the bleeding process as before, holding the pedal under a bit of pressure while you open the nipple.

[zefarelly]

I've just built my brakes . . . .all new aeroquip hoses, fresjh pistons, new seals . . . .and had a spongey pedal . . . .mos annoying, its got better, by basically, adjusting the rears, more bleeding and letting the pads bed in . . . its still not rock hard like my old set up . . .but I'm convinced its the padds as we've used a pressure bleeder and tweaked everything.

anyway, in response to your question, Ive never had any problems with SS braided hoses, they should last years

[JimW]

Have a look at a thread in the Technology forum: http://tentenths.com/forum/showthrea...hreadid=50830. It gives some interesting information about why a particular fluid tends to give a spongey pedal.

Regards

Jim

[Slowcoach]

Thanks everybody. I think I am going to replace all the braided hoses with kunifer pipes and new braided joiners. Many people I have spoken to have expressed great surprise that the whole system is braided, some of these lengths must be 10 or 12 ft and I estimate they could be 8 years old. It certainly shouldn't make things worse and it will eliminate another question mark from my mind. Then the whole system will be new from top to bottom and then it is all down to fluid and bleeding or should that be bleeding fluid. The cost of replacing the pipe work is relatively low compared to the price of the new discs, calipers etc. (A roll of the kunifer pipe is £20 for 7.5 metres if anyone is interested to know.)

[Dave Brand]

Originally posted by Slowcoach
Many people I have spoken to have expressed great surprise that the whole system is braided, some of these lengths must be 10 or 12 ft and I estimate they could be 8 years old.

Amazing! Add me to that list! I just can't understand why anybody would go to all that expense to end up with an inferior system.

[Red Dog]

Its quite usual to find only Aeroquip braided hoses on formula cars and absolutely no rigid pipes. The system is not inferior. The only fault that braided has is that it rubs through almost anything unless you sleeve it with heatshrink tubing. Kunifer 10 can and will fracture if vibed enough. New brake shoes can make a pedal feel spongy but unless you have a very rough disc or pad face then new pads should not feel bad although they certainly improve slightly when they are bedded in.

Have you fitted calipers with bigger pistons or a smaller diameter master cylinder? Either will give you more travel. The fluid should be the lowest tech that you can get away with - Dot 4 is fine for most small race cars. If you boil your fluid then you will have no brakes for sure! Get some temperature strips to be certain.

[zefarelly]

something I havent checked yet is that my car is an early one and has different rear wheel cylinders than the later cars . . . .as theyre 2 piston affairs I think they require more pedal travel than the later 1 piston type . . although they have the better manual adjusters . .I think I'll see how they go and more than likely swap them over !

[Jedi088]

I can see that the hoses might need replacing after years of use but air in will mean fluid out . I found a porous master cylinder on a friends car which had a tell tale spot of fluid dripping after being sat in the garage for a week

[Dave Brand]

Originally posted by zefarelly
something I havent checked yet is that my car is an early one and has different rear wheel cylinders than the later cars . . . .as theyre 2 piston affairs I think they require more pedal travel than the later 1 piston type . . although they have the better manual adjusters . .I think I'll see how they go and more than likely swap them over !

The pedal travel is determined by how far you need to move the shoes to bring them into contact with the drums. Say you need to move each shoe half a millimetre to contact the drums; in a twin piston cylinder each piston maves half a millimetre, while in a single piston cylinder the piston moves a millimetre relative to the cylinder & the cylinder slides half a millimetre in the backplate to equalise the movement between the shoes - given equal cylinder bores, the amount of fluid dislaced is the same, so pedal movement is equal.

I'd stick with the rears you've got - for my money, one of the best drum brakes ever made!

Don't confuse pedal travel with sponginess - you can have long travel but still have a firm pedal when all the friction materials finally contact the disc/drum surfaces.

If you've fitted new rear shoes it's possible that they have not yet bedded in properly - shoes are normally supplied with a lining radius .030" less than the nominal drum radius to avoid 'heel & toe' contact, which can make the brakes grab or squeal. What this can mean is that, especially if the drums have been resurfaced, the ends of the shoes are clear of the drum; when pressure is applied to the brakes, the shoe flexes giving a 'springy' feel to the pedal. It might be worth taking a drum off & checking just how much of the lining is contacting the drum.

It may, as you say, be the pads. The 'feel' of the system will vary with different pad materials.

[Goran Malmberg]

Originally posted by Slowcoach
I read somewhere that these should be replaced every year ?

Steel braided hoses dont like twisting motions.
If routed the wrong way this may occure at the front wheels as they both turn and moves vertically. This may hurt the end attachment.
Goran Malmberg

[zefarelly]

Dave . . .absolutely spot on . . .thanks . . . .the pads wherent making full contact, and theyre getting better by the corner . . . . .the fronts are fine . . .as a huge black streak at Donington prooves just before the chicane . . .several infact as I was bedding in the tyres !

[ChironWSC]

We have found that the brake caliper piston seals will cause a soft pedal if worn even though they where NOT worn to the extent that they where leaking or air was getting in. These where on AP 4 pot calipers one and a half seasons old.

[Peter Mallett]

Originally posted by zefarelly
as a huge black streak at Donington prooves just before the chicane . . .several infact as I was bedding in the tyres !

That'll be the offside front. It goes light and if your brakes are less than perfect it locks. I was lying third lat time there and on the very last lap the wheel locked (yet again) but this time the tyre blew. Having gathered it all up I crawled across the line in tenth!

I've now got AP four pots.

[zefarelly]

I was still going in a straight line so it was both . . . .totally outbraked the imp I was overtaking, then outbraked myself and virtually freewheels through, behind the imp! all new seals on mine and new pistons up front, I will be examining shoes pads this week to see how much theyve settled down after a proper work out

[Peter Mallett]

Exactly. Its caused by a bump in the track on the straight bit just before the chicane.