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Rob Wilsher_2958

Which brake fluid?

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My brakes have recently become very hard and useless so I have replaced the:

1) master cylinder

2) servo

3) rear cylinder units

4) offside front calliper (nearside was replaced a couple of years ago)

I have drawn off the fluid from the pipework using a vacuum pump at each wheel and then connecting my air compressor to the two pipes that would normally connect to the master cylinder.

(I have been advised not to pedal pump it out)

Which fluid should I use? I understand that Dot 5 is not corrosive but is hard to bleed and has a spongey feel?

Having replaced so many parts, I now want to make the right choice.

Cheers, Rob

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What was in it before?

I suggest you use Dot 5.1

Jerry

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Jerry,

If you are considering going to SBF (or back to normal), you have to remove ALL old brake fluid. Blowing clear may not be enough. I did this many years ago on an Jaguar XK (I removed the conventional and went to SBF). The little relief hole in the MC got blocked and the brackes seized.

I have SBF in my TR, but only after I replaced every seal and cleaned every individual line /component. I contacted 2 suppliers for compatibility of the rubbers with SBF, both did not object.

Waldi

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As has been said above, you need to be very careful about using Dot 5 .... whereas 5.1 is compatible with everything (apart from 5). 

5 does look pretty though :)

Edited by Hawk

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Thanks fellas...

I thought using compressed air through the front and rear circuits would have cleared the pipe work ... is there a better way to do it our some sort of fluid that could prepare the lines for silicone dot5 fluid... I will need to dismantle the 2 year old calliper and clean it out manually but otherwise, all the other components will be new.

Rob

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Why use silicon???? There is no added benefit. I drive with Dot 4 Typ 200. no problems at all. 

Jochem

Edited by JochemsTR

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DOT5's benign attitude toward paint was the deciding factor for me.

It's not a matter of if, but when, you eventually get a little leak somewhere.

Ed

Edited by ed_h

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2 hours ago, Rob Wilsher_2958 said:

is there a better way to do it our some sort of fluid that could prepare the lines for silicone dot5 fluid...

Rob

Hi Rob,

I blew mine with brake cleaner (rattle can) until a white cloth remained white. 

Same for brake cylinders.

I would replace the seals that have contacted the conventional brake fluid and also the rubber hoses.

FWIW: my SBF was supplied by Moss.

Waldi

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Rob, you haven't said what brake fluid you were previously using.

Don't get confused with Dot 5 which is silicone and many on here would not recommend.

Dot 5.1 is conventional, but higher boiling point than Dot 3 or 4 (come to think of it, not sure I've come across Dot 4 in the UK).

I've used both Dot 5 (silicone) and 5.1. I stick to Dot 5.1 and risk the paintwork.  Do you want working brakes or shiny paint?

Jerry

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It was very confusing when I purged the system.... there was a label tagged to the master cylinder which stated Dot5...the fluid that came out the other day is a gold/brown colour which I assume is not Dot 5 (usually purple?).  I had topped up with Dot5 when I changed the near side calliper 2 years ago on the basis of the tag and maybe I caused the problem then... The master cylinder has been leaking and damaged the metalwork underneath which I have now renovated.

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If you join yours with some new brake fluid, you can easily see what you have.

If it does not mix, it is “the other one”, if it looks like one fluid, not 2 layers, it is what you compared with.

Waldi

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Dot 5, Silicone, isn't a paint stripper so you will preserve the engine bay paint. Yes it is a bit harder to bleed and in my TR2 it feels a bit different but it is fine and the paint protection makes it all worthwhile.

I believe you need to replace all rubber in the systems, not just flush it through.

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15 hours ago, jerrytr5 said:

Dot 5.1 is conventional, but higher boiling point than Dot 3 or 4 (come to think of it, not sure I've come across Dot 4 in the UK).

I've used both Dot 5 (silicone) and 5.1. I stick to Dot 5.1 and risk the paintwork.  Do you want working brakes or shiny paint?

+1

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23 hours ago, jerrytr5 said:

Rob, you haven't said what brake fluid you were previously using.

Don't get confused with Dot 5 which is silicone and many on here would not recommend.

Dot 5.1 is conventional, but higher boiling point than Dot 3 or 4 (come to think of it, not sure I've come across Dot 4 in the UK).

I've used both Dot 5 (silicone) and 5.1. I stick to Dot 5.1 and risk the paintwork.  Do you want working brakes or shiny paint?

Jerry

Utter nonsense.

DoT 5 is 100% safe and effective in car braking systems.

the clues in ‘DoT’ aka Department of Transport

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23 hours ago, jerrytr5 said:

Do you want working brakes or shiny paint?

That, of course, is a false choice.

Ed

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2 hours ago, Yojimbo said:

Utter nonsense.

DoT 5 is 100% safe and effective in car braking systems.

the clues in ‘DoT’ aka Department of Transport

That is not quite a correct statement for this thread.

Any automotive fluid can gain a DoT number if submitted for testing (and paid for).  But that fluid may not be particularly useful for brakes etc.

The DoT 5 silicon fluid was developed for military long term storage. These military vehicles generally have huge brakes and have whole battle fields to stop in (only joking)

It was not developed for delicate small car systems.

So it has a DoT number but it is quite meaningless.

 

Indeed there are many aged cars out there that use it successfully.

 

Roger

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Let’s agree to disagree.

There are two streams on this forum (not camps): pro and anti SBF.

Each of us can make a balanced decision based on the facts and what others say/feel/write (and that includes me).

Cheers,

Waldi

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1 minute ago, Waldi said:

Let’s agree to disagree.

There are two streams on this forum (not camps): pro and anti SBF.

Each of us can make a balanced decision based on the facts and what others say/feel/write (and that includes me).

Cheers,

Waldi

+1

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SBF, what to put in trunions, to modify or not to modify.  All a basis for great discussions. 

The fact that they are good discussion subjects probably indicates that there is no one correct answer!

For the record my position on each of the 3 questions is:

SBF (and I have swapped without a complete rebuild and the brakes worked fine!)

Oil

It is entirely up to you

Cheers

Tim

 

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Hi All

I'm just about to get my brake system up and running, some of you may have seen my post on engine bay brake pipe routing.

So i have this question, SBF or not.

I've no experience of silicone fluid or old braking systems come to that, well not recently anyway.

I can absolutely see the attraction of silicone, no paint damage due to a leak or spillage and with my new(ish) paint thats hugely attractive.

But what are the downsides? I've read it harder to bleed, ok how har? as i don't intend bleeding my brakes that often. Secondly the brakes apparently feel more spongy, but again how much. Is it barely noticable or like presing on a rotting potato, and how much of that sponginess (if any) is that due to bleeding dificulties and air getting in at that stage.

Now bear in mind that my whole system is new so no residue of old fluid at all.

Cheers

Keith

 

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Not had problem with bleeding.  Not noticed significant changes in feel.  Having bad brake pads or old flexible pipe probably makes more difference. 

Tim

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8 minutes ago, Tim D. said:

Not had problem with bleeding.  Not noticed significant changes in feel.  Having bad brake pads or old flexible pipe probably makes more difference. 

Tim

Agree, have used dot5 for 20+ years, nearly 30 years ( ouch) starting with a rebuilt system all-new seals and hoses.

Peter

Edited by Peter Cobbold

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Not sure where these claims about DOT5 bleeding and sponginess come from, but they are certainly amplified by the Internet echo chamber.  I didn't notice either malady with my new DOT5 system.

Ed

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My came with dot5 sbf from automec, so i have stuck with it.

i did some research and the compressability of sbf IS greater than that of dry dot4, but in reality it doesnt make a huge difference.

I dont think there is any difference with bleeding

what is different is the way air bubbles behave in sbf, micro bubbles stay in suspension longer.

so two tips, avoid getting air in the fluid by pouring it in smoothly from a non agitated container, and deploy Stuart’s pateneted broomstick trick

this is to wedge the brake pedal down for 24hours plus with a broomstick after filling/bleeding the system

this compresses any air in the fluid system encouraging it to form larger bubbles which can then flow to the top of the system, the reservoir.

all in all i’m happy with the automec

steve

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Mine also came with Dot 5 Automec and bills show that TRGB did the conversion  in 2014 with new MC/wheel cyl and upgraded Goodridge Hoses. I have had no problems  with a firm pedal and nice clear purple fluid after 5 years.

Roger

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