Converting to DOT5/silicone brake fluid? Best choices for rubber suppliers?

[stillp]

No, an Eezibleed!

[Don H.]

So, we've had one report on the original topic -- the relative quality of brake rubber bits from the various suppliers -- and two dozen or so reports between the two camps of "love it" and "leave it" around DOT5. We all know the various pros and cons of silicone brake fluid, so we're really not adding much to our collective knowledge by going over that ground again (useful though it may be for newbies to our community).

 

Thanks Graeme, for your insight into the rubber parts you used. Anyone else have any opinions or experience in the quality rubber in master/slave/brake rebuild kits?

[RogerH]

Hi Don,

I believe Moss and TRshop supply the repair kits in Girling plastic bags - they certainly did a couple of years back.

 

Roger

[Alec Pringle]

Hi Don,

 

we should have a chat on the topic, specifically the seal components and potential contaminants thereof . . . . . bear in mind here that I utilise Dot 4 Super Glycol / Borate fluid for some applications, and Dot 5 Silicone fluid for others, as I consider appropriate.

 

Horses for courses . . . .

 

Changing from one specification to another is not necessarily quite as straightforward as some folks might like to have you believe, caveat emptor etc . . . . .

 

Cheers,

 

Alec

[Don H.]

Hi Don,

I believe Moss and TRshop supply the repair kits in Girling plastic bags - they certainly did a couple of years back.

 

Roger

 

Moss Motors (USA) tend to supply "Classic Gold" brake parts, which are sourced from India or China or somesuch dollar-a-day labor country. Not reassuring for brakes. Dunno about rebuild kits, but the Girling name would add some confidence.

 

TRF sell Girling-legacy wheel cylinders, now branded TRW as the corporate owner, but made in Italy. Better. Again, dunno about COO for rebuild kits. I may have one in my hydraulics box, so gotta check.

[Don H.]

Hi Don,

 

we should have a chat on the topic, specifically the seal components and potential contaminants thereof . . . . . bear in mind here that I utilise Dot 4 Super Glycol / Borate fluid for some applications, and Dot 5 Silicone fluid for others, as I consider appropriate.

 

Horses for courses . . . .

 

Changing from one specification to another is not necessarily quite as straightforward as some folks might like to have you believe, caveat emptor etc . . . . .

 

Cheers,

 

Alec

 

Yes, a good excuse to catch up, Alec. I'll give you a ring over the next few days.

 

The guidance I've always had is to put DOT5/silicone into an absolutely pristine system, with zero residual glycol ether fluid.

[Alec Pringle]

" but the Girling name would add some confidence "

 

You may very well think so . . . . . .

 

But consider some of the opinions which Girling have publically expressed re SBF in years gone by, and to the best of my knowledge have not subsequently retracted . . . .

 

Cheers,

 

Alec

[Don H.]

 

Moss Motors (USA) tend to supply "Classic Gold" brake parts, which are sourced from India or China or somesuch dollar-a-day labor country. Not reassuring for brakes. Dunno about rebuild kits, but the Girling name would add some confidence.

 

TRF sell Girling-legacy wheel cylinders, now branded TRW as the corporate owner, but made in Italy. Better. Again, dunno about COO for rebuild kits. I may have one in my hydraulics box, so gotta check.

 

As so often, assumptions are not to be made! Classic Gold reported from personal experience to be fine with DOT5. "Girling" branded... not so much.

 

Thinking about that, there was a time when Girling rubber was sensitive to all kinds of hydrocarbons. As in, use ONLY Girling grease on the seals or else. Probably due to some combination of natural rubber, which is still used surprisingly often in all kinds of products, frequently in combination with synthetics.

 

Have I said how much I like the collective wisdom of this group?

Edited November 21, 2017 by Don H.

[Peter Cobbold]

I read somewhere that old glycol can be flushed out of pipes with meths then blasted to dry with compressed air.

Peter

[Alec Pringle]

That is the most efficient method that I've come across Peter, but it isn't always 100% successful in terms of clearing historical residues . . . . largely dependent on the age of the brake hydraulic system.

 

Cheers,

 

Alec

[stuart]

"Pulls up comfy chair and opens bucket of popcorn" here we go again, this is going to be a long thread!

Stuart.

[RogerH]

.....and the 'B' movie is 'What type of OD oil'

 

 

Roger

[Guest ntc]

.....and the 'B' movie is 'What type of OD oil'

 

 

Roger

The internet knows it all

[Peter Cobbold]

I had two Moss Tech sites bookmarked from 2011 but they've killed them off. They gave chapter and verse.

Peter

[dingle]

Ok, just to keep the pot boiling, here is Nelson Riedel's treatise on brake fluid posted on the Buckeye site- http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm

I have used DOT 5 for brake&clutch systems for 30 years without a problem, including pedal softness.

Berry

[Ian Vincent]

One of the problems with converting a TR3 to silicone is that if all the seals have to be changed then there is one in each of the front brake callipers between the two halves. Nobody seems to supply them.

 

Rgds Ian

[pinky]

 

hi,

 

I have used silicone for two years no problem, I replaced all the rubbers,

and the rubber pipes, washed all the pipes out

and blew them out with compressed air, I don't have a soft peddle,

I think it is great, the big thing with me is it isn't a paint stripper

 

I no people who have had problems, I can only presume the preparation wasn't

carried out to a high standard,

 

pink

[RogerH]

One of the problems with converting a TR3 to silicone is that if all the seals have to be changed then there is one in each of the front brake callipers between the two halves. Nobody seems to supply them.

 

Rgds Ian

Hi Ian,

the rubber seals used for DOT4 (EG) are the same as for DOT5 (SBF).

The concern in changing from on DOT to the other is what affect will the different chemistry do to a seal that is soaked in one then the other.

The chemicals working on new rubber does what it does but it is unknown when mixed.

Excess swelling is the often claimed issue

 

The small O ring between the caliper halves would have little problem in my mind as they are simply contained between the two halves.

Any adverse swelling would be restricted by its position. Unlike the other seals where they need a sliding fit.

 

Roger

[stillp]

I read somewhere that old glycol can be flushed out of pipes with meths then blasted to dry with compressed air.

Peter

From the pipes, yes, but that wont get it all out of the cylinders.

[Don H.]

From the pipes, yes, but that wont get it all out of the cylinders.

 

Yes, hence the original point of this thread -- are there differences in quality in the rubber kits when all the cylinders are rebuilt during the conversion?

[Don H.]

hi,

 

I have used silicone for two years no problem, I replaced all the rubbers,

and the rubber pipes, washed all the pipes out

and blew them out with compressed air, I don't have a soft peddle,

I think it is great, the big thing with me is it isn't a paint stripper

 

I no people who have had problems, I can only presume the preparation wasn't

carried out to a high standard,

 

pink

 

That's helpful, pink -- thanks. Another correspondent reminded me as well to change all the flexible hoses too as part of a conversion.

[Alec Pringle]

" are there differences in quality in the rubber kits "

 

I wouldn't describe the differences as issues of quality . . . . . there is no reason under the appropriate technical standards for the seals to perform properly with anything other than the specified brake (or clutch) fluid for the particular application.

 

If a seal performs 100% when exposed to the fluid for which it was designed, that it might offer less than 100% performance when exposed to a fluid for which it was not designed is hardly a lack of quality . . . . .

 

From past researches and discussions with major UK and European brake component and system manufacturers, not one of them recommended the useage of SBF, and in more than one instance explained precisely why their particular seals might prove unsatisfactory.

 

That is not to suggest, may I emphasise, that reproduction hydraulic components might give similar problems . . . . . indeed, I have good reason to believe that some are specifically designed to accommodate silicone, glycol and borate fluids with equal satisfaction.

 

Under no circumstances would I be utilising nos or existing used OE hydraulic seals manufactured back in the day, which as far as I'm concerned are a recipe for possible disaster.

 

Cheers,

 

Alec

[Don H.]

Thanks, Alec. Most useful.

 

It's common for formulators of many automotive fluids to add partial solvents for rubber seals as swelling agents. These soften the seals and help ensure a good fit to the bore. Swelling agents are common in automatic transmission fluids and power steering fluids. Dunno about brake fluid, but I'd expect something along those lines (as if brake fluid itself wasn't swelling enough!) This swelling mechanism could be one of the reasons why silicones aren't recommended by some producers. They're not likely to have any effect on synthetic or natural rubber.

 

(I intended the word quality more in the sense of "a distinctive attribute or characteristic possessed by someone or something" rather than "excellence" in my previous post.)

[ed_h]

Since Don (the OP) is in the US, I'll offer this.

 

Under US Federal regulation, a "brake fluid" is defined thus:

 

"Brake fluid means a liquid designed for use in a motor vehicle hydraulic brake system in which it will contact elastomeric components made of styrene and butadiene rubber (SBR), ethylene and propylene rubber (EPR), polychloroprene (CR) brake hose inner tube stock or natural rubber (NR)." [49 CFR 571.116]

 

So it appears that any maker of brake fluid who wants to claim compliance with US Federal standards (and every bottle I've seen does) will have to ensure compatibility with those rubber compounds. On the other side of the coin, any maker of brake parts for new or old cars would be crazy to use any rubber component not on that list.