Brake Fluid Change

[mav2777]

The manual suggests I change my brake fluid every 80,000km. It says to use SAE J1703 or FMVSS116 DOT-3. I am going to flush it out using the old fashion way, depress brake pedal, loosen brake nipple at caliper, fluid comes out, tighten nipple, release brake pedal & repeat the same procedure. Does this method case any damage to master cylinder or seals ? Do I flush the entire contents of the old fluid or only bleed the brakes a few types while topping up with the new fluid. I have Castrol Response DOT 4 brake fluid which it states it is suitable for all DOT 3 applications.

[gslrallysport]

I am going to flush it out using the old fashion way, depress brake pedal, loosen brake nipple at caliper, fluid comes out, tighten nipple, release brake pedal & repeat the same procedure. Does this method case any damage to master cylinder or seals ?

Provided the piston in the master cylinder isn't traveling further than it would normally that's fine. Pushing the pedal down further than you usually would will push the piston seals into the 'dirty' area of the cylinder bore, and that can bugger the seals up. I've been doing it that for years with no problems.

Do I flush the entire contents of the old fluid or only bleed the brakes a few types while topping up with the new fluid.

Let as much of the old fluid out as possible before filling up with the new stuff.

I have Castrol Response DOT 4 brake fluid which it states it is suitable for all DOT 3 applications.

Yep that's correct, but just keep in mind that the Super Dot 4 is far from being a performance fluid, more just a heavy duty fluid for things like towing caravans. To be a performance fluid it really needs to be over the 300 degree mark dry. Super Dot 4 (or 5.1 as it's otherwise known) is around the 270-280 mark.

[mav2777]

"Provided the piston in the master cylinder isn't traveling further than it would normally that's fine. Pushing the pedal down further than you usually would will push the piston seals into the 'dirty' area of the cylinder bore, and that can bugger the seals up".

So I should place a block of timber behind the brake pedal so it won't go all the way to the floor & instead only be able to be pushed half way.

The car is a daily driver with short stints of some hard braking. Is the DOT 3 any better than the DOT 4.

Thanks very much for your advice.

[gslrallysport]

So I should place a block of timber behind the brake pedal so it won't go all the way to the floor & instead only be able to be pushed half way.

I wouldn't worry... just be aware of it and don't go pushing it as hard as you can. It's not that much of a problem.

The car is a daily driver with short stints of some hard braking. Is the DOT 3 any better than the DOT 4.

Dot 4 is better all round.

[Oldhead]

Advice and or recommendation.???

Gen 2 Mps 3 12mnths old.
Daily drive and has been on track once ,poss 12 hard laps.

Further track day to come .

Completely flushed fluid today and replaced with Dot 5.1.
Sequence used was L/H rear bled first until M/cylinder was below min,topped up with new fluid and continued L/R bleed until new fluid appeared.
Retopped M/cylinder
Proceeded to R/H rear and bled until new fluid .
Retopped M/cylinder
Proceeded to L/front and bled until new fluid.
retopped M/cylinder
Proceeded to R/Front and bled until new fluid.
Retopped M/cylinder.

Brake peddle now feels less hard and travel is lower to firm peddle .
???? Could this be the effect of Dot5.1 new fluid and was the sequence of bleed correct for front wheel drive with ABS.

[gslrallysport]

Hi mate,

Couple of things:

Further track day to come .

Completely flushed fluid today and replaced with Dot 5.1.

Dot 5.1 isn't really a track fluid. Good for heavy duty street use (like spirited driving or towing a caravan), but it will boil on the track, leaving pockets of air in your system, that can be a bugger to get out. To do track work you really need a fluid over the 300 degree mark, Dot 5.1 (or Super Dot 4 as it's sometimes called) is good for 270-280 odd. The stuff that we use and recommend is the TRW GP600 Dot 4 Racing Brake Fluid, which is good for 312 degrees, and $65 for a 1L bottle. If you've only just changed the fluid after the track day, then it's probably not going to be an issue in the short term while it's fresh and hasn't had a chance to absorb much moisture yet.

Sequence used was L/H rear bled first until M/cylinder was below min,topped up with new fluid and continued L/R bleed until new fluid appeared.
Retopped M/cylinder
Proceeded to R/H rear and bled until new fluid .
Retopped M/cylinder
Proceeded to L/front and bled until new fluid.
retopped M/cylinder
Proceeded to R/Front and bled until new fluid.
Retopped M/cylinder.

In the modern age of cars with 4 channel ABS, trac control, and some pretty funky ABS pumps (including ones that can cut off individual wheels if a brake lines burts...) it not really going to matter too much on which side of the car you start. So long as you go rear to front you'll be fine. Dot 5.1 (which is just fancy Dot 4) won't have had any bearing on the pedal feel.

How exactly did you 'bleed' each caliper?

[Oldhead]

Thanks heaps for advice. Much appreciated.
Each caliper was bled via tube on nipple and end into sealed jar with fluid and end bleeder hose below fluid level.
Crack,nipple and slowly push brake pedal to approx half travel,until new colored fluid was well through ,then hold pedal down and re tighten.
No air bubbles and end of bleed hose was always below fluid level.
Repeated for each wheel same proceedure .
2 people.
My thoughts where that the Dot5.1 was a synthetic and was causing a possible compression ,therfore a slightly less hard pedal(not spongy though).

[gslrallysport]

My thoughts where that the Dot5.1 was a synthetic

Nup, you're thinking of Dot 5. Dot 5.1 is polyethylene glycol-based fluid, same as Dot 3 or 4.

You've done nothing wrong with the above, only thing I like to do with bleeding is do the nipple crack under pressure, ie. person in drivers seat does 3 hard pumps and hold it down, then you crack the nipple while they hold it down, and very quickly shut the nipple off whist fluid is still coming out.