Brake fluid cock-up

[oldtuckunder]

6 hours ago, PaulAA said:

... a litre. Sheet, this stuff ain't cheap.

 

The reason they do it in a litre bottle is so that after you have filled the system with it, you have some left over, so that when you need to top it up some Muppet doesn't do so with ordinary fluid as they didn't have any silcone stuff left! 

[TR5tar]

Hi Paul, 

Sorry to hear of your problems, but at least it looks like you are getting there. 

I did my first ever brake bleed about a year ago and it was quite a learning experience. I couldn't work out why after I got quite a bit of fluid out of the rear brakes I then only got air, and yet I was topping up the M/C. What I hadn't realised was that the M/C was divided, with the small compartment at the front of it feeding the rear brakes. Access to that compartment was through a narrow slit. Once I'd worked that out, it was easy.

It sounds the same as yours. 

Cheers, Darren  

[PaulAA]

12 hours ago, oldtuckunder said:

The reason they do it in a litre bottle is so that after you have filled the system with it, you have some left over, so that when you need to top it up some Muppet doesn't do so with ordinary fluid as they didn't have any silcone stuff left! 

Alan, you card...  thing is, I had the remains of a bottle of DOT5 from repairing the damage done after the last Cock-Up (different mechanic, lest rotund, same beaming smile: "I've gone one better than DOT 5 and topped it it with DOT5.1"), but could I find it?  I dismantled the whole cellar shelving, car boot, "my" corner of the utility room, etc... nothing, nado.  I'm going to buy one of those 'break glass in emergency' cabinets and mount it somewhere prominent.

Thanks, Darren - that's helpful.  Oddly, I'd assumed that it would be a diagonal split in the braking system, rather than fore-aft.  Time to break out the Haynes.  Which reminds me of a recurring observation when watching those car porn vids on YT - the ones where Elmer from Arseville dismantles the front end of a Mercedes SLS seemingly without the aid of instructions... does he instinctively know the car this well, or is there a greasy Haynes just out of camera shot..?

Paul

[JohnD]

Strictly, once you've broken the seal on a bottle of brake fluid, it starts to absorb water, so one that been on your shelf since the las time should go down the drain.

John

[PaulAA]

14 minutes ago, JohnD said:

Strictly, once you've broken the seal on a bottle of brake fluid, it starts to absorb water, so one that been on your shelf since the las time should go down the drain.

John

But not a problem with DOT 5 silicone, which is completely non-hygroscopic and has an almost indefinite service life.

[Nick Jones]

Older cars have front/rear split.  However, as the rear brakes tend to be rather less effective, more modern stuff has diagonal split giving one front and one rear - probably driven by legislation in the USA or Australia.  Of course, in the "normal" run of things this produces a fierce pull towards the side that is working at the front - dangerously so unless much more caster is dialled into the front suspension to reduce the effect.  This has the unfortunate side-effect of making the steering incredibly heavy, and suddenly PAS is needed...... which is why even little cars need PAS these days. 

Nick

[JohnD]

2 hours ago, PaulAA said:

But not a problem with DOT 5 silicone, which is completely non-hygroscopic and has an almost indefinite service life.

Ah!  I had forgotten which you were using!

j.

 

[Kev_tr6]

Hi Paul

It is a tandem master cylinder with the larger area of the reservoir for the front brakes and the smaller area for the rear brakes, when filling up the larger area it overflows into the smaller area.

Hope this helps.

Cheers Kev.

[PaulAA]

5 hours ago, Kev_tr6 said:

Hi Paul

It is a tandem master cylinder with the larger area of the reservoir for the front brakes and the smaller area for the rear brakes, when filling up the larger area it overflows into the smaller area.

Hope this helps.

Cheers Kev.

It does indeed - thanks, Kev.

Does anybody have an opinion about Bel-Ray DOT 5?  It seems to be the only stuff I can get hold of here - twenty-five quid for 2x 360ml.

Paul

[oldtuckunder]

MGB Hive are doing 1Ltr of Automec Silcone (which I use) on eBay for £28.95  in free UK postage, on their web-site its 23.29 + shipping, and they do ship to europe, might just be worth messaging them for EU shipment cost, As in the UK it has to go courier not post (because its a fluid) it may not be much more expensive. 

Here's their ebay add

https://www.ebay.co.uk/p/Automec-Dot-5-Silicone-Brake-Clutch-Fluid-1-Litre-1000ml-High-Performance/1810970327?iid=381628704505&chn=ps&adgroupid=52130532935&rlsatarget=pla-411617461420&abcId=1133946&adtype=pla&merchantid=7287744&poi=&googleloc=9045563&device=c&campaignid=1057748120&crdt=0

 

[2.5piman]

Hello Paul,

 

Auto Mec sell their brand of of DOT 5.

 

Alec

[PaulAA]

Reviving an old thread...

So, the seals on both rear brake cylinders seem finally to have given up the ghost and the passenger side one has disgorged a lavish amount of the silicon fluid onto the wheel, tyre and garage floor. It is impressive how far a small volume of the damned stuff will spread.

I'll replace the cylinder in both wheels, but the barely-worn brake shoes are visibly wet with the stuff and the question is whether it will be sufficient to wash them with soap and water, or whether they ought to be binned and replaced.

Cheers

Paul

[RogerH]

Hi Paul,

soapy water will be no use.

Something like brake cleaner  or the thinners that paint sprayers use to clean silicone contaminated paint. 

And then get it hot with a hot air gun.  Whatever you  end up with it needs to be thoroughly clean.

Now if it was DOT4 - that is easy peasy.

 

Roger

[PaulAA]

Hi Roger

Thank you... I have a small voodoo doll in a corner of the office, dedicated to the unknown turnip-head who decided to ditch the DOT4 in favour of the devil's purple semen.

I probably need to pluck up courage and dismantle the front callipers, to see whether there is any leakage there as well...

I see that Rimmers offer two bores for the rear brake cylinder, 0.7 and 0.75 - I assume they are interchangeable, but is there any difference between them?

Paul

[Nick Jones]

So, I hope the voodoo doll has been getting a serious poking with sharp object!

Not a Dot 5 fan me. 

Not sure on the cleaning question - it’s fairly evil stuff.

As to the 0.7 vs 0.75 question, the larger 0.75” ones will give more braking effort to the rear. I’m surprised there are two listed. Just possibly it’s a dual circuit vs single circuit thing but worth checking which is correct.

That wasn’t very helpful was it…. 
Sorry 

 

[Escadrille Ecosse]

Removing silicone fluid is a right pain. Lots of repeated cleaning with fresh cloths and alcohol.

I have mixed feelings about the stuff although still using it after best part of 40 years I am thinking of options.

Which car are the cylinders for (apologies for my memory)

[Nick Jones]

To improve on the above …..

https://www.triumphexp.com/forum/tr6-tech-forum.2/question-about-over-sized-rear-wheel.1459176/

….. have a read. Seems that 0.7 are the factory choice. Some prefer 0.75, some even go to 7/8”.  Some report premature locking of the rears with the bigger cylinders, which is not good. It will depend partly on the relative “bitiness” of front and rear friction material in reality. I d be sticking with 0.7

I’ve not come up with anything useful about cleaning the stuff off shoes.   I reckon the safe option is to bin the shoes; in general silicones are not afraid of anything and the very devil to shift. Nice to be able to stop!

I’d be very curious to know whether your brake cylinders have corroded inside, especially at the bottom. Water settling out at system low points is one of the suggested disadvantages of DOT5.

[Escadrille Ecosse]

24 minutes ago, Nick Jones said:

I’ve not come up with anything useful about cleaning the stuff off shoes.   I reckon the safe option is to bin the shoes; in general silicones are not afraid of anything and the very devil to shift. Nice to be able to stop!

My misunderstanding here. Sorry. Contaminated shoes go straight in the bin. Regardless of what contaminated them.

It's an perfect example of the difference between cost and value.

I have experimented at great length with alternative rear cylinder sizes on a couple of my Spitfires. Larger cylinders are perfect for the 4 cylinder car. Much better balance. Not so much with the 6 cylinder car.

I have no experience with TRs so can't comment directly but if you can cope with the faff then I think it is worth experimenting. With the caveat that you test the effect on maximal braking.

30 minutes ago, Nick Jones said:

I’d be very curious to know whether your brake cylinders have corroded inside, especially at the bottom. Water settling out at system low points is one of the suggested disadvantages of DOT5.

Never had an issue with this.

I have had to replace cylinders due to wear. Some have said this is because the silicon fluid is less lubricating. I suspect it's as much due to the fact that with silicon they last long enough to wear.

[RichardB]

Slightly off topic but another complaint against silicone fluid. Because its not hygroscopic, the water it would normally absorb has a tendency to sink to the bottom of the brake lines. Using the fluid doesn't eradicate the presence of water in the system.

Even when I was using the Spitfire as a daily driver, I had quite a bad issue with sticking pistons in the calipers. Upon disassembly I found that the sunken water had badly corroded them and they'd stuck. I replaced them with stainless pistons but it still begs the question how advantageous is DOT5 in practice, and that brakes still need regular bleeding.

[Nick Jones]

2 hours ago, RichardB said:

but it still begs the question how advantageous is DOT5 in practice, and that brakes still need regular bleeding.

Quite. And with the water settled to the bottom of calipers/cylinders you might not even get all the water out when bleeding. I suggest that the ONLY true advantage is that spills don’t damage paint. Quite a decent advantage I’ll admit, but there is a decent list of disadvantages. I’m sticking with the other stuff.

[Mark]

3 hours ago, RichardB said:

I had quite a bad issue with sticking pistons in the calipers. Upon disassembly I found that the sunken water had badly corroded them and they'd stuck.

Ah, Drove the Vitesse the other day, first time in a couple of months. After Braking hard I could feel severe knock back through the brake peddal. Pistons obviously stuck. I've used silicone fluid, mainly because it's kinder to rubber seals and paint work and hydrophobic. Was thinking moisture had got behind the piston seals, and corroded the sides of the piston, as usually happens. Hadn't considered water in the system sinking behind the calliper piston. How does water enter the system? is it caused by moisture condensing in the master/slave cylinders, brake pipes?

Edited January 26, 2023 by Mark

[Escadrille Ecosse]

Funny I have heard people complaining about water in silicone fluid but in the 40 odd years using it I have never experienced it myself. And I have some specific bits of kit that have been in use for 30+ years.

I found that it actually prevents the dreaded caliper piston corrosion under the seals. Mind you I always smeared these exposed side under the outer seals with silicone which keeps the water off. 

[RichardB]

Not sure how water enters to be honest, I guess that sounds logical Mark. Odd though isn't it because you wouldn't expect a plastic master cylinder reservoir to have much condensation and the rest of the system is submerged in fluid. You'd also think with the heat it would boil off and perhaps it does, but winter lay ups perhaps still prevent that happening some of the year.

My car had refurbed calipers fitted in 2003 by the previous owner and only silicone fluid used, by 2013 I'd started to have issues. Taking the calipers out showed corrosion at the back behind the seals rather than in front of them, so I guess it must be water in the pipes.

[JohnD]

May I recommend brake fluid to DoT 5.1 spec?

I fear that 'not many people know that', but 5.1 is NOT silicone, it's glycol based.  It has a higher spec than any DoT4 and just as good as DoT5.     I fear that for  manufacturers to claim longer (infinite?) change intervals, the rest of us can avoid worry about spilt fluid on coachwork, surely one that some care and a steady hand will avoid, but in exchange will have hidden corrosion on safety critical systems!    Surely not a  worthwhile swap?

This isn't the first "innovation" that has been foisted on us by the makers.    Multi-electrode plugs aren't "better" than those with a single electrode - the spark cannot jump more than one gap at a time!     But they can last a lot longer, when the one in use wears and shortens, the next longest will take its place.   So, four-times the plug service interval!    Quadruples all round at the service managers' Christmas Dinner!  (Sponsored, no doubt, by AC, Champion, KLG, NGK, Bosch and Denso etc etc)

John

 

 

[Escadrille Ecosse]

2 hours ago, JohnD said:

May I recommend brake fluid to DoT 5.1 spec?

I fear that 'not many people know that', but 5.1 is NOT silicone, it's glycol based.  It has a higher spec than any DoT4 and just as good as DoT5.     I fear that for  manufacturers to claim longer (infinite?) change intervals, the rest of us can avoid worry about spilt fluid on coachwork, surely one that some care and a steady hand will avoid, but in exchange will have hidden corrosion on safety critical systems!    Surely not a  worthwhile swap?

This isn't the first "innovation" that has been foisted on us by the makers.    Multi-electrode plugs aren't "better" than those with a single electrode - the spark cannot jump more than one gap at a time!     But they can last a lot longer, when the one in use wears and shortens, the next longest will take its place.   So, four-times the plug service interval!    Quadruples all round at the service managers' Christmas Dinner!  (Sponsored, no doubt, by AC, Champion, KLG, NGK, Bosch and Denso etc etc)

John

 

 

True for a lot of that.

However DOT5 wasn't really foisted. It was created for the military on the back of specific requirement because they didn't want the maintenance hassle associated with glycol based fluids. And there are only reason the military are moving away from it is because it isn't compatible with ABS systems that are becoming almost universal now.

As for damaging the paintwork. It's as much the tiny leaks (and occasional catastrophic seal failure, we've all had that wet foot moment surely) that cause damage no matter how careful you are about spills.