Alex Posted June 18, 2011 Posted June 18, 2011 Can anyone advise me the easiest way to get all the brake fluid out of the clutch and brake system?I'm thinking that I'd like to replace it with silicone fluid after its painted so as not to risk damage to the paint again if it leaks.....thoughts?Obviously if I drain the system I can get the master cylinders and brake pipes right out of the way.Ideally I'd remove the engine as well but thats not gooing to happen(I'm thinking I could shrink wrap it to reduce chances of things being white that shouldnt be.....).
Billy Boy Bailey Posted June 18, 2011 Posted June 18, 2011 Hi Alex, you can't take risks with brakes but the clutch doesn't matter so much. Brake fluid damages paint and is hydroscopic, so it absorbs water and corrodes things. You will have to disconnect all the pipes and blow out all the old fluid. I sucked up thinners in the pipes to clean them out and blew them dry. The master and slave cylinders need to be taken appart and cleaned of all old fuid. The rubbers can be lubricated with silicone and reassembled. It's worth doing properly once and then enjoy maintenance free hydraulic systems for a long time.regards Bill Boy
Alex Posted June 18, 2011 Author Posted June 18, 2011 Is there an issue with the seals using silicone in a system that previously had normal brake fluid?Also I've read somewhere that if going to silicone then you dont have to be as vigorous cleaning the system out but if going back to normal fluid then you have to be 100% sure its all clear.....why would/could this be?
jms700 Posted June 19, 2011 Posted June 19, 2011 not certain about why its ok to change one way with out as thourogh a cleaning. my best bet is that silicon effects the normal hydrolic fluid adversly. so if changing to silicon, it gets rid of the old fluid, but if changing back to regular the left over silicon damages the new fluid ?
CAE DAN Posted June 22, 2011 Posted June 22, 2011 Alex wrote:Is there an issue with the seals using silicone in a system that previously had normal brake fluid?Also I've read somewhere that if going to silicone then you dont have to be as vigorous cleaning the system out but if going back to normal fluid then you have to be 100% sure its all clear.....why would/could this be?Yes, they are not compatible. You will need to get synthetic seals to go with the conversion. The synthetic brake fluid will react and swell the original seals and you will be replacing everything!I did it! I know! TBH, with a car that only does 95mph tops, (and you won't be doing that often in an old car) the benefits will not be felt, as the fluid won't overheat too much.
Alex Posted June 22, 2011 Author Posted June 22, 2011 3629 wrote:TBH, with a car that only does 95mph tops, (and you won't be doing that often in an old car) the benefits will not be felt, as the fluid won't overheat too much.My reasoning is not to stop the fluid boiling....its to prevent any damage to the paintwork should a leak occur.95mph tops.....are you sure,I dont think you've ever seen me drive my spitfire ;D
smithy Posted June 22, 2011 Posted June 22, 2011 Alex wrote:95mph tops.....are you sure,I dont think you've ever seen me drive my spitfire ;DAlex, no really (and with the greatest of respect), do you go over a lot of cliffs? ;D :X
Alex Posted June 22, 2011 Author Posted June 22, 2011 smithy wrote:Alex, no really (and with the greatest of respect), do you go over a lot of cliffs? ;D :XYou cheeky......... ;D
Nick Jones Posted June 22, 2011 Posted June 22, 2011 I'd avoid silicone fluid. It may not damage paintwork and it may not be hygroscopic but it has other issues.It is more viscous, which makes it harder to bleed as it tends to trap small air bubbles which take ages to escape.It is more compressible which gives a nasty squashy/springy pedal feel.Any water that does find its way into the system (and it will) sits at the low points and causes corrosion, made worse because people don't change it because they have heard it doesn't absorb water...... This is one of the reasons why some hydraulic components suppliers specifically state that warranty is void if used with silicone. Also, a little pocket of water sitting in your brake calipers will boil real easy..... brake fade anyone :-/Stick with good quality DOT 4 or DOT 5.1 and change it every couple of years. You'll have better feeling brakes and don't have to worry about compatibility. :)Nick
Alex Posted June 22, 2011 Author Posted June 22, 2011 Ok Nick thanks I'll just have to be more careful ;D
heraldcoupe Posted June 23, 2011 Posted June 23, 2011 3629 wrote:Yes, they are not compatible. You will need to get synthetic seals to go with the conversion. The synthetic brake fluid will react and swell the original seals and you will be replacing everything!It's not quite as simple as that.The seals specified for DOT3 fluid are not compatible with DOT4. I'm not sure you'll find those DOT3 seals anywhere now.ALL seals swell in brake systems. That swelling is very small though, it's all considered in the design. What differs though is the mechanism by which the seals swell, between DOT4 and Silicone fluids, so seals exposed to both fluids can swell to different dimensions to those intended. This is theoretical, it may or may not be a problem in the real world, but I would change all seals and thoroughly purge the system when changing fluid types.Like Nick though, I won't use silicone fluid. There are as many negatives as there are positives,Cheers,Bill.
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