Post Number: 11
|Posted on Saturday, 02 July, 2016 - 08:24 pm: |
For twelve(?) years I have been using DOT5 silicone fluid in the hydraulics of my '71 Bentley T. Posted on various forums there were (are) dire warnings about the awful consequences, based on the ghastly experiences of a few folk. I tried the effects of DOT5 on a few examples of seals sold for RR363 ue and found no problems. I assumed that the seal material had been changed since the early days so that the problem no longer existed if all the seals were post 19XX (fill in your own guess). Someone will know about rubber materials, and they will enlighten us, yes/no.
Since then I have had one front brake piston seal failure and one accumulator diaphragm failure. The piston seal I can accept as a single incident in 12 years. The accumulator diaphragm could have been 45 years old, it was on the car when I bought it in 2002, so I don't put that down to DOT5 incompatibility.
When the diaphragm failed it flushed lots of black rubber residue around the rear hydraulic system - from the BACK of the diaphragm I guess. I compounded this problem by swapping the low-pressure returns from the regulators front-to-back when I reassembled the gubbins after fitting the new accumulator, so I had TWO lots of contaminated fluid to deal with. But this is almost indestructible silicone fluid so a filter made from a large bowl-shaped kitchen sieve lined with newspaper makes a very efficient (but slow) method of returning the fluid from black to the rather pleasant shade of blue. You can't do that with RR363.
During this time the car has driven about 22000 miles - some short wedding-type stuff and some tours of Scotland (John-0'-Groats), Cornwall (Lands End), Wales, Cumbria.... from our home in England, so it seems to work OK. The fluid has not been changed as part of routine maintenance.
I do NOT recommend it for other folk - see the other info on the net before you make your own decision - but I have saved time and money (I do my own maintenance). If anyone wants to try it I can give some hints to make the changeover easier.
Let the discussion begin.
Post Number: 19
|Posted on Saturday, 02 July, 2016 - 10:44 pm: |
On mine I rebuilt all the brakes and gear for possibly the first time in 35 years, I would like to never do it again, the correct fluid is not expensive if you change it every four years.
The black goo you found was probably dissolved rubber. The system works beautifully as designed from the factory with minimal maintainence and regular use. I know a lot of people try to save money on brakes, I think we would all sleep better at night if people didn't. I have a scar on my right hand from when I was a teenager and had four different types of tyre on the car I was running, I hit a diesel spill and spun out, with matching tyres I imagine the result would have been different.
Why would you recycle cheap brake fluid?
Each to their own I guess but we all share the road with others.
Post Number: 10
|Posted on Sunday, 03 July, 2016 - 12:32 am: |
Alan, thanks for doing this. You might be wrong you might be right but thanks for the real experience.
There are two brake fluids marked as DOT 5 now (seriously) and that probably makes a difference. Check the brand you are using and see if it is glycol based or silicone based.
Mercedes estates use a similar power steering suspension system with accumulators and spec a special oil. I have no idea if it would work. While it wouldn't be less expensive, it will likely be more readily available.
A lot of time finding alternative part numbers sounds like cheaping out, but proprietary numbers for common items just means spending extra money to wait a week with the car parked. Seriously toyota wanted $200 for a special order trans input shaft bearing that had the industry standard number printed on it. South shore bearing + $25 and the truck's running that afternoon.
On a regular basis I drive past a garage that has a Silver Shadow parked there getting serviced. It has been there quite a while. Did I mention that I drive past it on a regular basis.
To each their own.
Robert Noel Reddington
Post Number: 1010
|Posted on Sunday, 03 July, 2016 - 01:33 am: |
Silicon 5 rides again.
Dot 3/4 is and castor cheaper than the rest. As a said every 2 to 4 years is OK.
Silly cone still needs to be changed due to water.
My jeep has a special oil in the Rear lsd £9 from jeep or £8 from specialist. Every 3 years not worth the bother I just use the jeep one. Then I know it's exactly right. The local agent knows my jeep and even the various serial for axles etc.
Dot 5 is sil. And dot 5.1 is glycol.
My advice is no to dot 5 silicone and yes to Dot 3 RR 363 and dot with castor oil.
Probably overall LHM systems are better. But changing from dot to LHM is a lot of work, the biggy is the ACU diaphragms.
Some modern material will work on both LHM and Dot.
I don't get hydraulic trouble because of my constant beady eye on the bits so I shall carry on as Crewe intended.
Remember these cars are 40 years old so extra checking is needed, maybe twice as much.
I shall just pop into the man cave to polish my brake pipes and buff the calipers, vacuum the dust off floor etc.
Post Number: 13
|Posted on Sunday, 03 July, 2016 - 02:47 am: |
Like I said, I don't recommend it to others, I'm just recounting my experience. When I bought the car it had a leaky brake piston (rust), and before the change I had a few more, probably a hang-over from the ill-informed maintenance of the previous owner - or their garage. They are what spurred me to this effort.
1. Robert. "Silly cone" does not absorb water. The reservoir has remained spotless during the last 12 years. I had to remove it once to get at a cross-threaded plug about six years ago and it looked the same as when I first converted. I have considered switching to LHM. As you say the accumulator diaphragms are the big problem, but I might use an adapter to fit a standard Citroen acc. They are only 30 pounds or so and readily available, but I don't have any reason to switch again, though I suspect all the seals are compatible.
And I don't need a beady eye, 'cos this system seems to work for me, at least.
2. Ross. DOT5 is silicone based, DOT5.1 is glycol based. Someone in DOT just didn't think before acting.
3. Martin. "Why would you recycle cheap brake fluid?". It's not cheap, and because I can.
Thanks for all this input, chaps. It's not WW3 (yet).
Omar M. Shams
Post Number: 709
|Posted on Sunday, 03 July, 2016 - 04:04 am: |
This is a forum and views and points ought to be welcome by everyone. Everyone is free to choose - so thank you for your input. I am always interested to hear what others have experienced on this issue. If you get angry responses please understand that there are indeed some people who appreciate reading posts like yours. Those who don't like these posts can always respond, although I do wish they would do so with dignity and decorum.
It is good to note that being polite is a good sign of maturity.
Post Number: 411
|Posted on Sunday, 03 July, 2016 - 04:04 am: |
"3. Martin. "Why would you recycle cheap brake fluid?". It's not cheap, and because I can. "
It is cheap compared to the price of a funeral!
Post Number: 319
|Posted on Sunday, 03 July, 2016 - 05:58 am: |
Alan is the lubricity of DOT5 OK with the pumps ? Also do you have problems bleeding the brakes ? I used 5 in a Triumph Spitfire and had permanently Squidgy brake feel. Went back to DOT 4 , and problem cured.
gordon le feuvre
Post Number: 130
|Posted on Sunday, 03 July, 2016 - 06:04 am: |
It is interesting that before rr363was born the cars came from the factory with firstly castrol Crimson and then castrol Amber. Can't remember actually when 363 was born, but remember it was "sold" to dealer network as better lubricating qualities for various valves. As an aside it did take 15years to work out that the valves Citroen produced were more reliable and LHM does not affect paintwork and does not absorb moisture from atmosphere. I can't even think what the warranty cost was in the early days as the flexible pipes both in engine bay and under car had habit of chafing/coming off Union ends and spraying brake fluid all over the place, especially at motorway speeds. Hence the change to rigid pipes from the brake pumps to accumulator valves
Post Number: 14
|Posted on Sunday, 03 July, 2016 - 07:49 am: |
Mark, I suppose the lubrication of the pumps is OK - the pressure comes up from zero fast enough (I measured it after the burst accumulator incident, for curiosity). Pump ticking after firm brake pressing is for only a few seconds as it should be, so it seems the pumps are not worn.
I've read elsewhere about squidgyness, but with a power-operated system (not direct manual or power-assisted) any sponginess is overcome by the way the system works. This also masks air in the brake lines to some extent - a large amount of air shows up as a delay between pressing the pedal and braking action. I don't have that. I compare the braking with my Citroen CX25 - they are as superb as each other in "feel" and effect.
Regards from Alan D.
Post Number: 283
|Posted on Sunday, 03 July, 2016 - 08:20 am: |
This is a very interesting subject indeed gents.
I'm taking all this in.
Post Number: 1993
|Posted on Sunday, 03 July, 2016 - 01:27 pm: |
The reason one has to change out silicone fluid is not because the fluid itself absorbs water, it does not, but because the system is not sealed, and subject to condensation (however slight) during temperature changes, water will creep in to the system.
With silicone fluid water sinks, finding the lowest points it can find and then just sits there.
I guess if you have replaced all your mild steel with cunifer line, that would be largely irrelevant for a very long period of time.
When it comes down to it, if you ignore the pumps, any fluid with a sufficiently high boiling point could theoretically be used as hydraulic brake fluid. Fluids are incompressible, so as far as supplying pressure all (even water) would work were it not for a whole bunch of other factors (e.g. boiling at the caliper from braking heat generated) that rule a bunch of fluids out.
When it comes right down to it, all of the currently available DOT brake fluids, with the exception of DOT 5 silicone, are glycol based and the base is a lot bigger proportion of the total than the rest of the "tweaking additives."
Post Number: 13
|Posted on Sunday, 03 July, 2016 - 01:45 pm: |
This accumulator has a lot of black nasty goo inside it.
Post Number: 20
|Posted on Sunday, 03 July, 2016 - 06:02 pm: |
It is not just the pumps, the control valves and deceleration valve all move and share the same fluid.
It is a replicated system might even be triplicated but I've found the master cylinder circuit alone will not stop the car. Failures of high pressure lines are immediate and without warning, I've seen a few cars where the owners have thought it normal for brake warning lights to be on at startup, another car with the front caliper hooked up in series (bleed screw to input port)
The system works beautifully as designed, if you want to be cheap throw some caster oil in dot 3, it might be less risky
Post Number: 16
|Posted on Sunday, 03 July, 2016 - 06:37 pm: |
Brian, that's an interesting point about possible water contamination. I used a vacuum system via a big glass bottle (brewing) to empty both systems. I remove all the bleed nipples and suck through them each in turn, with a tap to turn it on after letting the bottle depressurise for a few seconds. It makes a satisfying slurping noise and removes 99.99999% (approx.) of the juice. I let it stand overnight to see if the black sludge settled. It did a little. Then it was decanted into plastic ex-milk bottles to make it manageable. There was no sign of water - no layer or "lumps" left in the bottom near the end. There was no residue after the filtering, either. I'm happy it seems not to be a concern. That's the same fluid for 12 years.
Martin, I've found cars like that, too. A Shadow MPW bought from a well-known London dealer had one side of the height-control inoperative. We traced the high-pressure supply pipe round the rear subframes and towards the front of the car where it ended in open air. "Dealer maintained from new" - quote. We re-piped it, it wasn't worth complaining, we are miles from London.
richard george yeaman
Post Number: 543
|Posted on Sunday, 03 July, 2016 - 07:11 pm: |
if you want to be cheap throw some castor oil in dot 3,it might be less risky.
In the five years that I have owned SRH19529 I have replaced the stuff that was in the car with RR363 this also involved cleaning out all the rubbish in the reservoirs, when it came to doing general maintenance on the brakes there was no RR363 then I had to use Dot 4 and castor oil which I still use mainly because it is always available and cost has nothing to do with it.