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The mkiv Supra Owners Club

Urgent Brake fluid!


Justin

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I just had a brake fluid change and the garage stuck in 4 DOT. Now brake fluid is p*ssing all over my passenger side front and the low fluid light is on.

 

Is 4 DOT not good for the Supe? I know it says 3 DOT on the lid of the reservoir but the garage said 'it is better stuff'. I'm just gonna take the wheel off now to check for burst pipe but.

 

A) Is 4 DOT bad?

B) What is the best make and DOT to put in?

 

Got a long and important journey 2morrow starting first thing so a bit concerned.

 

Ta.

J.:eek: :eek: :eek:

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You should really use either MOTUL RBF 600 or Castrol SRF.

 

If you are losing fluid they probably didn't tighten up the bleed valve properly.

 

Take it back and complain bitterly that they could have killed you :eek:

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I think DOT4 replaced DOT3 and is indeed an 'upgrade'. I think it's DOT4.1 that you SHOULD NOT USE (silicone based? or is it the other way round?). Then there's DOT5 which I think can also be used but was designed for higher temperatures or something?

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Dot 4 did indeed replace Dot 3, Dot 5 is a newer spec still.

 

The idea behind silicon brake fluid is that it will not absorb moisture from the air which 'standard' brake fluid does. That's why should change it totally every two years.

 

As regards whether Silicon fluid is 'bad' or not in the Supra I cannot say because I'm not an expert.

 

I am aware that silicates used in anti freeze should be avoided as this can cause long term damage to water pumps. Or so I am led to believe.

 

I would however get back to the garage that did the work asap.

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DOT 4 is absolutely fine.

It has a high er boiling point than DOT 3.

 

DOT 5 is the one that MUST NOT be used as it's silicone and does not mix with glycol-based brake fluids (DOT 3, DOT4, DOT 5.1).

You'd have to do a complete system flush with ether or something and even then you mustn't use it as it doesn't work properly with ABS brakes.

 

 

DOT5.1 is even better than than DOT 4. higher boiling point.

 

Yes, the best stuff is Motul 600 or Castrol SRF, but these are overkill unless you're doing serious track days.

 

 

Problem is like you said they've snapped off the bleed nipple which is easy to do, but it's 100% their fault and they must replace it at their cost. do not drive with brake fluid p1ssing out - super super dangerous. a small leak is tolerable for a limited distance but every time you press the brake pedal, it's squirting fluid out of the system. no brakes = no fun at all.

 

SO DOT4 or DOT5.1 are both fine. Motul600 and SRF both exceed DOT5.1 spec and have meg-high dry boiling points.

 

McLaren use Castrol SRF in their F1 cars. i know a Macca mechanic and that's what they use.

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Guest Martin F
Originally posted by Justin

Just taken the wheel off and seen that the bleed valve has been snapped off!

 

I really could have died!

 

Now I need a new flippin caliper! Smart!

 

:mad: :mad: :mad:

 

Take lots of pictures in case of dispute, get them to sort it and never use them again.

 

How can they let somebody drive away when they know they have broken such a vital component ?

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Pic 2. of the snapped off bleed valve and the housing that it screwed into.

 

To be fair I don't think the guys would have let me drive it if they knew what they had done. But I will have a little chat with them.

snapped valve.jpg

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I am sure Justin will post some pics,(opps he beat me to it) but I have never seen this before the nipple had been tightened so hard it had cracked the calliper fitting and the nipple housings had sheered off. Nothing left of the nipple or half the threaded part of the nipple housing.

 

Justin is very lucky to be alive, had it finally given way at speed he could not have maintained braking in a straight line.

 

The master cylinder still had a fair bit of fluid left and after fitting a new calliper and emptying the line of air the brakes appeared OK so we tried 30, 40,50 ,60 emergency stops and everything was fine. Scrubbing speed off at high leptons was also fine.

 

I have advised a complete fluid change with some new fluid, with larger braking distances until then. Without a complete bleed of all four callipers there is no way to be certain that there is not a small bubble in any of the other lines. Having said that the stopping power was not bad for JDM

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DOT4 is a higher boiling point than DOT3 (etc, etc), and therefore is better in terms of the brakes not fading under hard use BUT DOT 4 absorbs water more quickly than DOT3 (etc etc) and therefore goes off sooner

(boiling points plummet, and corrosion gets worse as water gets into the system) and the fluid needs changing more frequently.

 

On my motorbike I use DOT4 in the rear brake and clutch which is changed every 2 years, and DOT5.1 in the front brake which is changed every year at least.

 

On the subject of broken bleed nipples the most likely time to snap one is when loosening it at the start if it's "bound up", and if it was broken at that point the mechanic would notice. They only need tiny amounts of torque so it would take a real ape to break one when tightening it back up!

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in all fairness, it is very easy to break the bleed nipple, but garages must know this and you'd think they'd take extra care cos at the end of the day they'd have to sort it out.

 

to BREAK the bleed nipple and NOT TELL YOU is, in my humble opinion, negligence of the highest order and life-endangering.

 

water absoprption - yes brake fluid is highly hygroscopic (affinity for absorption of water, even water vapour from air) and therefore you shoulsn't open the can of brake fluid until you need to use it. even then, get it done, in the reservoir as quick as poss and get the cap back on.

 

yes, Castrol SRF (and all other brka efluids except silicone ons i.e DOT5) are hygroscopic, but this doesn't really matter for

race teams as they do complete brake fluid change very often. usually every meeting.

 

Brake fluid boiling temp. is quoted as "dry" and "wet". i.e the boiling temp. when "dry" (=new, with no water absorbed) and also when "wet" (with some water absorption). Water absorption obviously lowers the boiling point a lot, but even so these ultra-high-performance brake fluids would need mega-provocation to boil under track-conditions.

 

1 advantage of SRF is that it's boiling point when "wet" is a LOT closre to its' BP when dry than most fluids. perhaps explains why it costs £35 per litre (WTF??)

 

I actually have a litre of SRF available that i don't need. it's unopened, and it actually swiped from McLaren F1 team, so was (100% genuinely) gonna end up in Coulthards or Raikkonen's car, but you can have this once-in-a-lifetime chance to buy Team Macca fluid for a few quid.

 

offers pls before i stick it on Ebay..

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Terminator

 

it's yours.

SRF is like Beaujolais Nouveau - consume immediately !

 

name your meet and as if by magic, the shopkeeper will appear with a litre of ex-Raikkonen, ex-Coulthard brake fluid.

 

 

"Uzi 9mm??

- you sure know your guns pal

Phased plasma rifle in the 40watt range ?

- Hey just what you see pal..."

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