Silicone brake fluid

Dear All,

I've just replaced almost the entire braking system on my Herald: calipers, wheel and master cylinders, hoses and some pipework. Now would therefore be a good time to change to silicone brake fluid, if I'm going to do it.

What do you all think? Worthwhile for a car which will be doing light summer duty only?

Ian

Reply to
Ian
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Ian (Ian ) gurgled happily, sounding much like they were saying:

I'd have said so. No chance for the moisture to settle into the fluid and just sit, gently rusting, over the winter.

Reply to
Adrian

Yes. I did the Vitesse a few years ago and have never found any reason to regret it. And if you buy it from Frost's, it gives you an excuse to make up the parcel with lots of other goodies.

Reply to
Willy Eckerslyke

I've heard the opposite argument, though - that normal brake fluid absorbs and dilutes and moisture, whereas silicone stuff just leaves it there to do its worst ...

Ian

Reply to
Ian

Ian (Ian ) gurgled happily, sounding much like they were saying:

If that was the case, wouldn't LHM systems have the same problem?

Reply to
Adrian

Yes, and then you find you are just a couple of quid under their free carriage limit so you buy something else you don't really need but might come in handy one day. After many months when you do actually need it, you've forgotten where you put it or even that you bought it at all.

BTDTGTTS

Ron Robinson

Reply to
R N Robinson

You've been screwfixed.

Incidentally, don't buy Frost's grooved pliers for bending brake pipes. They are crap.

Ian

Reply to
Ian

I have got Silicone fluid in my PI - the previous owner put it in and I carried on with it.

A couple of years ago, I needed to replace a seal in the Master cylinder, which went OK, but bleeding the system afterwards took a lot of effort. Silicone fluid gets what are called microbubbles as you bleed the air out, and I found the pedal didn't feel right even though there was no visible sign of air. But after leaving the car a couple of days, these microbubbles coalesce into proper bubbles and another go at bleeding got them out.

It was perfectly drivable after that, but the pedal still seemed a tiny bit soft. But after leaving the car standing a couple of weeks, a couple of bubbles came out in another bleed and then it was perfect, and has remained perfect.

So as far as the advantages of Silicone fluid are concerned, it doesn't age and it doesn't deteriorate during periods of non-use, so for a car you intend to keep and use occasionally for only part of the year, I would say it is worth it, particularly when you have already done all the hard work of replacing the brake hydraulics. But don't expect it to be as quick and easy to get the air out of the system as the normal fluid, but patience is eventually rewarded. Also, because the fluid doesn't deteriorate, you can let the stuff that comes out of the bleed tube settle long enough for the microbubbles to escape, and you can then use it to top up.

Just a tip though - put a label on the master cylinder to say it is silicone. You don't want some helpful MOT tester to top it up with the ordinary stuff if he thinks it is a tad low!

Jim

Reply to
Jim Warren

I don't think so. Just change the ordinary stuff every two years and you'll not have any corrosion problems. And a better pedal feel.

Reply to
Dave Plowman (News)

I when through that exercise and found the same thing. Not worth the effort or cost.

Flushing it on a regular basis keeps the system in good order. My MG has light use about 2000mls/year and have no problems. The whole system was overhauled about 8 years a go. The caliper pistons were replaced with stainless steel, rear cylinders resleeved stainless and the M/C resleeved stainless. The only problem is the sludge and film buildup within the system which needs cleaning. So the next step will be at 10 years to replace all the rubbers again as a regular maintenance item.

Regular maintenance is something that's neglected. Trying to step around it by using silicon fluid is not the answer.

There is some good reading on the web in regards to brake fluid from the manufactures - what to use and what effect it will have on the braking performance. Off hand silicon and blends (higher dot ratings) don't give a good pedal for road cars.

r
Reply to
Rob.

I suspect that few owners would really notice the difference unless making a direct comparison. As I said, I was more than happy with silicon fluid in my Vitesse. Thinking about it, I dispensed with the servo at the time I switched fluids, so the pedal feel was changing anyway. More critically, the brakes never felt unsafe after driving a modern car.

Reply to
Willy Eckerslyke

Hehe!

Have you told them? I may be wrong, but get the impression that they're a company who'd actually care.

Reply to
Willy Eckerslyke

One minor advantage if you're as clumsy as I am - it doesn't take the paint off when you spill it.

Geoff MacK

Reply to
Geoff Mackenzie

I haven't, but you're right. I should, and I will. The roblem is with these:

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The idea is nice: pliers with transverse grooves so you can bend brake pipes gently. Where it falls down is that the curved grooves are only on one side, and as a result the pipe invariably (yes, I tried several times, on several sizes of pipe) gets nicked, creased, buckled or kinked at the point where it emerges.

Ian

Reply to
Ian

... and just did, and they were interested and nice about it.

Ian

Reply to
Ian

And if you wash it off straight away it dosen't take the paint either.

Reply to
Rob.

Can we count that as a happy ending then?

Having followed your link on the item, I see what you mean that they look useful and would have been tempted myself if they actually worked.

Reply to
Willy Eckerslyke

There is a temptation after, say, a complete brake overhaul to want to use a fluid that will make things last for ever - but in practice the original system could already have lasted 20 years plus if looked after. With drum brakes they'll need a clean out every once in a while so a fluid change at the same time ain't that much of a chore if you have a pressure bleeder. Also a good time to inspect the hoses etc for damage. So aiming for maintenance free isn't necessarily a good idea.

Reply to
Dave Plowman (News)

Ian realised it was Tue, 22 Apr 2008

06:35:44 -0700 (PDT) and decided it was time to write:

The BIG difference is that silicone fluid isn't hygroscopic, like normal brake fluid. Therefore, there's no reason for moisture to get into the system in the first place.

Reply to
Yippee

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