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What make of Brake/Clutch Fluid


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Hi Guys,

Well the TR has been stripped and shipped to a Bodyshop in Surrey, if it comes back looking great I will recommend the shop to you all. In the meantime I had stripped out the pedal box which will be blasted and powder coated and I intend to flush out the system when I renew the brakes on re-assembling.

Could someone please tell me what I should use to refill the reconditioned cylinders as I have no experience of synthetic ot whatever.

Many thanks

Charles

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Hi Charles,

to expand on Pete's reply.

DOT 5.1 is a polyethylene glycol-based fluid and was designed for modern cars with ABS. It has temp range simllar to its silcone counterpart.

 

DOT 5 is a silcone based fluid (SBF). It is generally accepted that it is not interchangeable or should not be mixed with the other fluids.

 

DOT 4 is the same as DOT 5.1 but with a lower temp range in its basic form, This is used for cars without ABS. It can be bought in various grades that encompass road going and racing.

 

DOT4 & 5.1 work very well BUT!! it can absorb water which reduces it effectivity and may cause rusting to Ferrous components. It should be changed every two years.

It is also a very useful paint stripper for most paints. Cellulose comes off a treat. 2 pack is more resistant but could be affected.

 

DOT 5 was designed to be used for long term storage and normal use in the military so it has a little compromise in it.

It does not absorb water BUT!! does not stop water getting into the system - so rust could still happen.

It will not strip your paint work but could contaminate it if you ever do touch ups to paint.

Many people swear by it, many people swear at it.

Not used by industry to any great extent.

 

I use Halfords DOT4 Super and it works fine. The idea is to keep the fluid in the pipes.

 

Roger

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Dot 4 Super, which has a significantly higher boiling point than traditional Dot 4, is probably the best bet.

 

On the other hand, many TR drivers these days are unlikely to get anywhere near the boiling point of Dot 3 never mind Dot 4 . . . .

 

Google brake fluids and the various Dot specs, there's lots of comment out there.

 

Cheers

 

Alec

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Hi Charles,

to expand on Pete's reply.

DOT 5.1 is a polyethylene glycol-based fluid and was designed for modern cars with ABS. It has temp range simllar to its silcone counterpart.

 

DOT 5 is a silcone based fluid (SBF). It is generally accepted that it is not interchangeable or should not be mixed with the other fluids.

 

DOT 4 is the same as DOT 5.1 but with a lower temp range in its basic form, This is used for cars without ABS. It can be bought in various grades that encompass road going and racing.

 

DOT4 & 5.1 work very well BUT!! it can absorb water which reduces it effectivity and may cause rusting to Ferrous components. It should be changed every two years.

It is also a very useful paint stripper for most paints. Cellulose comes off a treat. 2 pack is more resistant but could be affected.

 

DOT 5 was designed to be used for long term storage and normal use in the military so it has a little compromise in it.

It does not absorb water BUT!! does not stop water getting into the system - so rust could still happen.

It will not strip your paint work but could contaminate it if you ever do touch ups to paint.

Many people swear by it, many people swear at it.

Not used by industry to any great extent.

 

I use Halfords DOT4 Super and it works fine. The idea is to keep the fluid in the pipes.

 

Roger

Thanks Roger very detailed. Helps me decide what to look for when I flush the system in a month or so, ready for the spring.

Did I also read in a thread on the forum that silicone fluid can also cause the rubber seals to turn the fluid black, I can't find it now, but I'm sure I've read that somewhere.

 

Mark

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Hi Mark,

if you are going to flush the system with a view to changing the fluid type - from DOT4 to DOT5 you would be well advised to change ALL the rubber components.

It is quite a grey area as to what happens to the rubber when new fluid comes into contact with pre-soaked rubber of a different fluid.

 

I use DOT 4 in the brakes and clutch. My brake M/C fluid has always remained clear but the clutch turns black within days of fitting new seals.

I have no info on DOT 5 and the fluid changing colour.

 

Roger

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If you are changing from any one spec of brake fluid to any other then it makes sense to renew all the hydraulic seals, right the way through.

 

Damn sight more important than the paint finish or the pedal box . . . . .

 

Cheers

 

Alec

Edited by Alec Pringle
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HI, No I'd planned to keep away from Silicone, I'm sure its wonderful stuff and possibly more of a polish than a stripper on the paint. Choice was dot 4 or 5.1 and it looks like they are basically the same stuff, just a with higher boiling points, Although I've never boiled brake fluid in my life, clearly I'm not driving my cars hard enough :D

 

Mark

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In which case buy a decent Dot 4 - our cars were designed for Dot 3, and Dot 4 will do the job nicely, or Dot 4 Super for an enhanced margin.

 

Dot 5.1 is good stuff, but designed for later systems, and personally I'd rather not use it on a system that has previously contained older spec fluids . . . .

 

4 Super wouldn't have been developed if 5.1 was invariably an instant answer for our old cars . . . .

 

Cheers

 

Alec

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Put silicone into my system when I restored the car and it had a tendancy to lock the brakes on! Turned out the servo was not too keen on the stuff, so that is now bypassed and I just use a heavy boot to stop.

 

The seals in the master cylinder decided to let go during winter lay-up a few years ago, even though there was fluid all over the pedals and floor of the car it was easily cleaned up and no adverse affects, except for the slippery pedals for a while.

 

Changed the fluid in the brakes recently and was supprised at how it held it's colour, even though it was clear in the master cylinder, and no sign of any water, unless that's still sitting in the bottom of the brake cylinders :unsure:

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Hi Justin,

the servo is another area for possible problem when using DOT5.

If your servo fails and the engine starts sucking brake fluid into the combustion area it could degrade the silcon fluid in crystals (sand) which wouldn't do things too good.

Not sure if this could actually happen but it has been discussed on here.

 

Roger

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I used silicone fluid, from Namrick. 26 years on, there's no change to the (purplish) colour in the brake master cylinder, but the clutch fluid has gone blackish, although it works fine.

 

One reason I chose SBF was that when I was stripping the car, I found the boot lid had been painted with a high-build primer, that Nitromors wouldn't touch. Moving on to other tasks, I left a rag soaked with 'ordinary' brake fluid lying on the boot lid. When I picked up the rag a few days later, all the paint came with it, down to bare metal.

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Just watching a prog on BBC4 about the Mary Rose.

 

Guess what !!

 

they are using Polyetheylene glycol (DOT 4 brake fluid) to displace the water in the wooden items in order to preserve them.

The PEG floods through the wood following anywhere that the water is.

 

Roger

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The issue with servos sticking on when using silicone fluid can be got round by greasing the seals with "Molykote" silicone o-ring grease.

 

Had my mot-a-vac rebuilt 6 years ago and have used silicone fluid since the car was restored. Works fine (had sticking problem with a lockheed unit prior to mot-a-vac being fitted)

 

Cheers

ade

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no sign of any water, unless that's still sitting in the bottom of the brake cylinders :unsure:

Which is precisely where it will be.

Stuart.

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Excellent comments thanks all.
I think DOT 4 Super wll be OK for my use (unless I can identify the existing fluid which has been in the system since 1996). I see servos on sale for circa £100 so will probably fit one while I am at it.
Cheers
Charles

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Hi Charles,

if you still have some of your old fluid in the system pour it into a glass jar and add some water.

If it is SBF then the water will sink to the bottom and will not mix. It may also have a purple hue to it (but not always)

If it is EG then it will mix easily with the water and have a yellowish/golden hue to it (however some SBF was coloured yellow)

 

As for a servo - unless you have a problem pushing the pedal (age/knackered etc - join the club) then the brakes can work very well without.

 

Last year my front brakes worked so well that I broke a wishbone bracket doing a rapid stop :o

 

Roger

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Last question, I think I should clean out the brake pipes before re-assembling any ideas out there as to what I should use?

How about soapy water followed by my Henry (a vacum cleaner) sucking it dry for a few minutes (rubber tape over spout to pipe should do it).

Thanks

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  • 2 years later...

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