Jersey Royal Posted March 15, 2007 Report Share Posted March 15, 2007 Hi Chaps, I have read up on brake and clutch fluid, and am aware that dot 3, 4, 5.1 are glycerol based and dot 5 is silicon based and you cannot mix dot 5 with the others. I am aware of the benefits of dot 5, however i prefer a firmer feel and a more available fluid should i need it . My car vcurrently has dot 5 silicon runiing through her veins and i would like to put dot 5.1 in instead. Is it the case that all i need to do is .. drain old fluid , refill and bleed. Or should i fill with dot 5.1 bleed and flush through and refill.? Your thoughts would be appreciated. Reagrds Guy Quote Link to post Share on other sites
jonlar Posted March 15, 2007 Report Share Posted March 15, 2007 Hi Guy, a lot of people recommend changing all seals before switching between mineral and silicone based fluids (either way), I've never done this and have never had any problems, I've never noticed any difference in the feel of the different types of fluid. If pedal is spongy, it could be a little bit of air in the system. Also, mineral fluid is hygroscopic and needs regular changing. Personally, if you insist on changing, I'd let gravity drain the system, run some of the new fluid through, drain and allow stand for a couple of days, if there's a lot of separation (pour off and re-use), fill and drain a couple of times, until there's no separation, then refill with brand new fluid. Quote Link to post Share on other sites
stuart Posted March 15, 2007 Report Share Posted March 15, 2007 Guy Having been through this situation once before with a MK2 Jaguar my personal recommendation is to strip the whole system out and re rubber everything and flush all the pipes out as well with methylated spirts. The two types of fluid will not mix at all and its impossible to get all the old fluid out by flushing insitu. Also the major brake part suppliers usually say that the guarantee is void if silicon fluid is used. Stuart. Quote Link to post Share on other sites
Guest ron Posted March 15, 2007 Report Share Posted March 15, 2007 Hi Guy I would recommend you stick with silicone fluid, I think it is much better for classic cars that don't get a lot of use, like Jonlar I've never noticed any difference with different fluids so if your pedal is spongy I would look for problems elsewhere. If I was going to change to a different type of fluid I would at least flush the whole system through but I would prefer to change all the seals as well. Ron Quote Link to post Share on other sites
Jersey Royal Posted March 15, 2007 Author Report Share Posted March 15, 2007 Thanks Ron and Stuart, Jonlar Well i have changed my mind, have ordered Automec Dot 5 fluids. I have new seals for master and slave cylinder on the clutch and will sort that when fluid and rubber grease arrive. With regards to brakes going to replace fluid with Dot 5 bleed . and check through complete system. Thanks for your guidance Guy Quote Link to post Share on other sites
67_gt6 Posted March 15, 2007 Report Share Posted March 15, 2007 On my GT6 I had Automec silicone fluid and stainless braided hoses front and back. Pedal felt fine and wheels would lock with ease. I think steel braided hoses and a proper bleed make for as firm a pedal as you would want irrespective of mineral or silicon fluid Quote Link to post Share on other sites
JohnC Posted March 15, 2007 Report Share Posted March 15, 2007 If you need to change the fluid (whether to a different type or not), I've always believed that flushing with white spirits to be the safest course. I may be wrong, but doesn't Meths attack some kinds of rubber? I have swapped to silicone fluid and back. Going to silicone I needed to change the m/c seals as they were badly worn; going the other way several years ago I just flushed with white spirit. I don't have braided hoses, but I do second the observation that a good bleed firms up the brakes no end. I use the Gunsons Ezi-Bleed system (pressurised from a tyre), and reckon it's the dog's b*ll*cks. Cheers, John Quote Link to post Share on other sites
Jersey Royal Posted March 15, 2007 Author Report Share Posted March 15, 2007 (edited) [ I don't have braided hoses, but I do second the observation that a good bleed firms up the brakes no end. I use the Gunsons Ezi-Bleed system (pressurised from a tyre), and reckon it's the dog's b*ll*cks. Cheers, John Thanks chaps, Going to get one of those bleeders too. Could anyone tell the capacity of fluid in the brake system and also the clutch, need to check i have ordered sufficient. Tar Muchly Again Guy Edited March 15, 2007 by Jersey Royal Quote Link to post Share on other sites
JohnC Posted March 16, 2007 Report Share Posted March 16, 2007 I'll bow to practical experience any day, especially when it goes back (ahem) a few years like Alec's! My advice came from a marine engineer a couple of decades ago, and I've never had reason to challenge it. Consider it challenged Incidentally, I doubt there's a difference in formulation between UK & Oz. Not so it appears for modern gear oils, where Penrite assure me their GLwhatever doesn't attack yellow metal, which I keep seeing raised in this forum as an issue in the UK. Meths it is. Hic Cheers, John Quote Link to post Share on other sites
Guest ron Posted March 17, 2007 Report Share Posted March 17, 2007 Guy I couldn't tell you exactly how much fluid the braking system holds but it's less than 1/2 litre, but you would be better to order a litre to allow for bleeding, spillage and future top ups, Ron Quote Link to post Share on other sites
Jersey Royal Posted March 17, 2007 Author Report Share Posted March 17, 2007 GuyI couldn't tell you exactly how much fluid the braking system holds but it's less than 1/2 litre, but you would be better to order a litre to allow for bleeding, spillage and future top ups, Ron Thanks Ron, I ended up ordering 2.5 litres as will do clutch and brakes and will have plenty left for future top ups etc. Cheers Guy Quote Link to post Share on other sites
jonlar Posted March 17, 2007 Report Share Posted March 17, 2007 Hi Guy, what did you have to pay for it. The last time I bought 1L one, I got stung for £28 (local factor). Quote Link to post Share on other sites
Jersey Royal Posted March 17, 2007 Author Report Share Posted March 17, 2007 Hi Guy, what did you have to pay for it. The last time I bought 1L one, I got stung for £28 (local factor). Hi Jonlar, I litre automech cost me about £18.00 from Rimmer (thats the less vat price, as is export) but in my case would have to add shipping. I had one retailer over here trying to tell me dot 5.1 was the same as dot 5 and they are all compatable, the mind boggles( oh and she had been in the business for twenty years) others never heard of SBF Cheers Guy Quote Link to post Share on other sites
jonlar Posted March 17, 2007 Report Share Posted March 17, 2007 Thanks for that Guy, be sure that you let the container stand for a couple of days, and fill M/C very gently to avoid creating any microscopic air bubbles. Quote Link to post Share on other sites
Roger H Posted March 19, 2007 Report Share Posted March 19, 2007 (edited) I ended up ordering 2.5 litres as will do clutch and brakes and will have plenty left for future top ups etc. As Jonlar pointed out, mineral brake fluid is hygroscopic. It is unwise to use fluid from containers that have been opened and then stored for more than a few months. (Sorry - just re-read the post and realised you are staying with Dot 5 in which case the above is n/a - rather than 'pull the post', it may benefit someone else!) Edited March 19, 2007 by Roger H Quote Link to post Share on other sites
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