brake fluid

[ChrisCrashTM]

the brake fluid in my favorit has gone very very thin, like water, im assuming it needs changing.. but is it something to worry about when the fluid gone a dark shade of like a bluey grey? its a weird colour but its deffinetly not clean.

and out of curiosity if i was to put in brake fluid with a boiling pint of 500 degrees as a pose to 230, would this help stop brake fade? or is the fade down to the pads?

thanks

oh and thanks to everyone who posted helping about the pug 106 a week or so ago as the problem are all solved (Y)

[anewman]

It goes that colour due to age, and as you describe it I'd say it's best replaced. MFR's recommend every 2 years I think. I'm beginning to hate brakes as everything seems to be going wrong with them on mine If you have brake fade now it's likely to be due to the brake fluid absorbing water.

I recommend going to a garage to get the fluid changed properly with a vacuum bleed thingy as I knackered the seals in my master cylinder pumping the pedal.

The other option is to use an eezibleed, but none of the caps supplied fit so you either need to buy one of the universal caps. Or the other option is to pull one off a favorit in a scrappie, remove the float level switch (just pulls out) and drill an appropriate sized hole. You then need to seal it up to stop it leaking and pi$$ing brake fluid all over your engine bay. I used bathroom silicone sealant in a number of layers on the outside and a bit on the inside - here's the result. Managed to bleed the system with it with a new master cylinder but then the rear cylinder let go but the nipple snapped off anyway.

While doing the job make sure the float switch brings the light up on the dash. If it doesn't, remove the white plastic cap on the top and give the contacts inside a good sanding and a little spray of electrical contact cleaner. Also sand the male spade terminals on the cap and give them a spray of cleaner, and also give the female spade connectors a good spray too. That should get it working again.

[ChrisCrashTM]

Cheers il leave it now untill the pads wear out they are well on there way towards the end of their life, and what about the more expensive fluid with high boiling temprature? any good? considering its only a few quid more is it worth trying?

[Captain Sisko]

Probably. It depends on your driving style.

I try to avoid harsh braking where possible.

But otherwise if the proce difference is negligible go for DOT4 is it?

I think I only have DOT3 fluid but my brakes are ok, will have to check the pads again soon.

[anewman]

If the brake fluid has been in there for 2 years or longer I think there will be a noticeable improvement anyway just using standard dot 4. Here's a short guide to the different types in another thread http://briskoda.net/maintenance-performance/brake-fluids-hopefully-definitive-thread/65339/

[Cepheuz]

the brake fluid in my favorit has gone very very thin, like water, im assuming it needs changing.. but is it something to worry about when the fluid gone a dark shade of like a bluey grey? its a weird colour but its deffinetly not clean.

and out of curiosity if i was to put in brake fluid with a boiling pint of 500 degrees as a pose to 230, would this help stop brake fade? or is the fade down to the pads?

thanks

oh and thanks to everyone who posted helping about the pug 106 a week or so ago as the problem are all solved (Y)

Brake fluid does turn dark, even black, and at that time, it better to be replaced.

Brake fade is due to a air bubble in the syste, water mixed with the brake fluid, or brake pads (usualy the ones in the back) wearing out.

as far as brake fluid i use DOT4, why cus is almost the same price as DOT3, but both work perfectly for any small car, even mid sie cars

[KenONeill]

Go for DOT 4, unless you do a lot of track days!!

Brake fade is due to either water in the fluid boiling, and giving you gas bubbles in the lines, or seriously overheated friction material (back to the track days, or trailing brakes down long hils in top).

[TeflonTom]

also, don't mix brake fluid types, certain types of fluid will damage the seals

[ChrisCrashTM]

just standard dot 4 brake fluid then, anyone have any experience with green stuff brake pads?

[Cepheuz]

also, don't mix brake fluid types, certain types of fluid will damage the seals

Agree with TeflonTom, this is actualy the most important thing to bear in mind, you can mix DOT 3 with DOT 4, or even some DOT 5.1, but since one is never realy sure is better to be on the safe side and not to mix brake fluids, i use DOT4 from a specific brand wich you can get here anywhere, is not faked and is of very good quality, (and cheap, wich is always a plus)

[oldskool]

You can mix brake fluids of differnet grades but if you do remember that the boilng point will ony be as good as the lower spec. I.e if you put dot 4 in with dot 3 it will only be as good as dot3. You can go as high as a super dot 4 which i believe is 350 degree centigrade. Any higher and your getting into the realms of silicone based fluids which definately will not mix,and will even req. changing all the seals in the system and flushing through to remove any trace of mineral fluids. Super dot 4 should be as good as you'll ever need on a road car with some track days.

Fitting vented or cross drilled discs and fitting green stuff pads is a good idea as they don't actually improve the braking (if a wheel locks up which they will in standard form thats the maximum efficiency for that wheel) but they transfer and dissipate heat better so reducing the risk of the fluid boiling for repeated heavy braking.

[TeflonTom]

:iagree: you mustn't use Dot 5 fluid in road cars, although it has many magic properties like not being hydroscopic like dot 4 fluid and hence stops corroding the brake pipes, it is silicon based and WILL ruin your master cylinder seals and brake calipers..

dot 5.1 seems to be the fluid of choice but it is expensive.

[ChrisCrashTM]

ok its all becoming more clear now, so better brakes are simply down to servo and calipers? well.. if the wheels where wider with a good set of tyres maybe? well anyway if i switched to green stuff with dot 5.1 fluid brake fade will reduce and in time a set of drilled and grooved brake disks will help more. will this change improve the brakes in the sense that they may be more sensative/sharper to the touch? or am i still making big mistakes?

[TeflonTom]

the actual size of the disc plays a bigger part in the equation, basically bigger diameter = more leverage, also don't overlook the possible gains by improving the cooling to the discs.. also stiffer suspension springs can reduce braking distances dramatically...

without going into the pro's and con's of wider tyres, basically more rubber on the road will give you more grip so you would be less likely to lock up the front brakes in heavy braking. but don't over-do it because if they are too wide you will compromise handling in the wet... in my opinion don't go any wider than 195mm tyre width

don't bother with drilled discs, they are an absolute menace.

[FelRace]

don't bother with drilled discs, they are an absolute menace.

I have to ask what you mean by this? Fellies and Favorits own brakes are very good and in rally they are usually in use as original (only Fedoro etc. pads added). Still I´ve thought that drilled discs could be good when thinking about cooling during special stages with heavy use of brakes. What is problem with these?

"Real" (=thicker) ventilated discs are issue of wider modification of brakes and that is something outside of my plans.

[FelRace]

ok its all becoming more clear now, so better brakes are simply down to servo and calipers?

If you like to have better and exact braking touch will steel braided brake tubes (or whaterver is the right expression for native English speakers...), make difference, original rubber tubes are always distending a bit when braking and it makes brakes "soft". Steel braided tubes prevent this.

With stiffer spring mentioned by Tom also stiffer bushes in chassis makes braking clearly sharper when all flexibility is removed and slowdown starts immediately when pads takes grip to discs. But it is also then question about big change in general driving touch.

[TeflonTom]

it depends on how much you are willing to pay for the discs... drilling holes through the disc causes a stress point, and having a stress point is not good news for something that goes through many heating and cooling cycles, eventually it will crack and possibly shatter.. in fact, in some countries they have been banned from use on the roads..

ok, now i hear everybody saying "yeah but porsche and merc use them as original equipment on thier cars", which is true, but then when you need to replace them every 20k they cost about £650 for the set, this is because they are made of higher grade materials which are heat treated or even ceramic, and these aren't exactly in the same league as 'black widow':O or green **** discs...

[FelRace]

drilling holes through the disc causes a stress point, and having a stress point is not good news for something that goes through many heating and cooling cycles, eventually it will crack and possibly shatter.. in fact, in some countries they have been banned from use on the roads..

Thanks Tom, I got your point. I´m sure there is a risk just like you told and in rally use those heating and cooling cycles are extremely numerous during stages. On the other hand, total kilometres driven are quite low so if discs are checked after every race and on service breaks I think there is no big risk of losing disc and then brake during SS.

When driving rally by FWD car the holding makes big stress for brakes, so they are all the time quite hot. That´s why I planned drilled discs. For example Speedpro sells those with very sufficient price, I´m sure those are not special material but brand new anyway and so cheap that can be replaced even couple times a year

[KenONeill]

Chris, the usual "weapons of choice" for VAG cars friction material are Mintex or Pagid fast road or Ferodo? DS2500 pads.

On the general point, I agree with Tom. Cross-drilled discs are pretty much pointless for road work, and I'm not convinced either way about grooved discs either.

[KenONeill]

Thanks Tom, I got your point. I´m sure there is a risk just like you told and in rally use those heating and cooling cycles are extremely numerous during stages. On the other hand, total kilometres driven are quite low so if discs are checked after every race and on service breaks I think there is no big risk of losing disc and then brake during SS.

When driving rally by FWD car the holding makes big stress for brakes, so they are all the time quite hot. That´s why I planned drilled discs. For example Speedpro sells those with very sufficient price, I´m sure those are not special material but brand new anyway and so cheap that can be replaced even couple times a year

AFAICS cross-drilling reduces unsprung mass, which will actually tend to increase disc temperature, and possibly reduce water film formation, but that should be less of a problem with hot discs anyway.

What is certainly worthwhile for competition use is grooved discs, which reduce pad gas buildup and hence fade.

[Glen_scim_feli]

When driving rally by FWD car the holding makes big stress for brakes, so they are all the time quite hot. That´s why I planned drilled discs. For example Speedpro sells those with very sufficient price, I´m sure those are not special material but brand new anyway and so cheap that can be replaced even couple times a year

Can you get EBC "Green Stuff" pads for a Felicia? They worked wonders on my scimitar as the original spec were not really up to the job on a 3-litre engined car! Only faded when very very hot and lasted a bit longer too.

[ChrisCrashTM]

Can you get EBC "Green Stuff" pads for a Felicia? They worked wonders on my scimitar as the original spec were not really up to the job on a 3-litre engined car! Only faded when very very hot and lasted a bit longer too.

]

there are green stuff available for the favorit, i beleive they are the same in the felicia but im not 100%

either way there are green stuff pads available for both cars.

[ChrisCrashTM]

Chris, the usual "weapons of choice" for VAG cars friction material are Mintex or Pagid fast road or Ferodo? DS2500 pads.

On the general point, I agree with Tom. Cross-drilled discs are pretty much pointless for road work, and I'm not convinced either way about grooved discs either.

and what is your opinion on braided hoses? i can see the principle with stopping the pipes expanding under load, but do they work?

[Richard Black]

I've got Green Stuff pads on my Fav, fitted them quite recently (like a lot of little upgrades, motivated as much by curiosity as anything else) and they definitely reduce the brake pedal pressure needed to pull the car up, though as someone else pointed out they don't reduce the minimum stopping distance because that's a function of tyres and suspension.

As for souped-up discs etc. - how fast are you planning to drive, for how long? Felly and Fav are quite light cars with a top speed of less than a ton and not much acceleration, so you're frankly not going to need to worry about losing loads of heat from the discs. I drive my Fav damned hard sometimes and brake fade is one thing I've never noticed except VERY slightly on really long inclines where I was just experimenting - normally I would do the sensible thing and use more engine braking, but for test purposes I was coasting in neutral. And even there the brakes held up adequately to stop the car. The heat you are dumping into a disc is proportional to the weight of the car times the square of its speed, so in a 19cwt Felly doing 80mph you've got a heck of a lot less heat to dump than in 2 tons of Jag doing 140! That why big and/or fast cars have big, ventilated, grooved discs.

[ChrisCrashTM]

just as you said, im interested and want to give it a go. the mk3 clio is a light car and the 1.5 dci does 115 without any slipstream yet the brakes on that are good enough to snap your neck compared to a skoda fav or felly. i know thats a newer car and all that jazz but theres no harm in and allways room for improvement.