ean Posted March 23, 2017 Report Share Posted March 23, 2017 Vitesse Mk11 2L convertable I am sure that this has been discussed before but here goes, need some help. Am refurbishing/overhauling the clutch and brake cylinders as the car has been off the road for about three years and the fluid has not been changed for even longer than that. Which DOT fluid is considered to be the most appropriate? Link to comment Share on other sites More sharing options...
TomL Posted March 23, 2017 Report Share Posted March 23, 2017 Hi Ean, The cars would have had Dot 4 from new. Nothing wrong with it as long as you change it periodically as it is hygroscopic, meaning that it absorbs moisture from the air, therefore reducing its performance. A great deal has been discussed regarding the use of different fluids on this forum, and there is a clear division of opinion. I have used silicone fluid for over twenty years and been happy with it. Others not so. It's probably a good idea to have a chat to members at your local area meeting. Tom 1 Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 23, 2017 Report Share Posted March 23, 2017 Dot 5 is silicone and lasts indefinitely, it's 3 times the price of the others but will work out cheaper in the long run and it doesn't eat your paint work! Beware of dot 5.1, it's similar stuff to dot 3 & 4 and not silicone. Dot 3, 4 and 5.1 lubricate the rubber parts of the braking system and can cover up defects in the rubber. Dot 5 doesn't do this and some who have upgraded blame the new fluid for reduced braking performance. Here is a link to Buckeye Triumphs full and comprehensive study into brake fluids. http://buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm 1 Link to comment Share on other sites More sharing options...
Clive Posted March 23, 2017 Report Share Posted March 23, 2017 Simple answer is DOT4.... If you want to change to silicone fluid, I believe you really should change all the rubber seals in the system. I am sure people often don't, and get away with it. 1 Link to comment Share on other sites More sharing options...
Guest Posted March 23, 2017 Report Share Posted March 23, 2017 Clive. You are spot-on. Changing fluids requires a thorough flushing of the system and in addition all the rubber seals must be changed. This is the case if you going DOT4 to silicone and vice-versa. I run the Vitesse with DOT4 and the Alpine with silicone - both do the job and it's a personal choice. One useful benefit of silicone is that it does not damage the paintwork when making contact; which I found to my cost when the Vitesse clutch M/C decided to "throw-up" on the bulkhead, with DOT4 !! The club shop did an excellent deal on silicone recently and in fact it was one of the few offers that was repeated the following month - thanks Garth !! Ean, if you are using DOT4 I would stick with that and as Tom says, just be on top of it and you will not encounter any issues. Regards. Richard. Link to comment Share on other sites More sharing options...
Mjit Posted March 24, 2017 Report Share Posted March 24, 2017 Changing fluids requires a thorough flushing of the system and in addition all the rubber seals must be changed. This is the case if you going DOT4 to silicone and vice-versa. Says who? The "you need to flush the system and change the seals" statement always seems to come out when anyone mentions DoT5 fluid but it's not what it says on the side of a bottle of DoT5 fluid. In fact it states you DON'T need to flush/change seals*. The bottle does recommend flushing as the result will be a (generally safe) blend but the DoT4 bit will still be hydroscopic. Of course chances are your seals are getting on a bit and they're cheap as chips really so a bit of a false economy NOT to change them while you're faffinf around with them. * Or didn't last time I was bored-enough to read one. Link to comment Share on other sites More sharing options...
Guest Posted March 24, 2017 Report Share Posted March 24, 2017 I believe that statement comes from people who like to do the job properly, thoroughly and safely. One of those people, will be me. Regards. Richard. Link to comment Share on other sites More sharing options...
dave.vitesse Posted March 24, 2017 Report Share Posted March 24, 2017 Having been on the receiving end of someone not changing the seals or flushing out the system the answer is yes you have too. Otherwise the seals lose their form. Spongy foot pedal. It just like have air in the system. Dave Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 24, 2017 Report Share Posted March 24, 2017 Guys, I recommend you to read the Buckeye Triumphs piece I referred to earlier. This supports Mijit's view. You don't need to flush, dot 4 & 5 don't mix and if your rubbers are not ancient there won't be a problem. If there is a problem, change the rubbers! 1 Link to comment Share on other sites More sharing options...
ean Posted March 24, 2017 Author Report Share Posted March 24, 2017 Thanks you everyone for some interesting comments and advice. The brake and clutch systems have had DOT4 all their life and I will probably stick with that. As i stated at the beginning the car has been of the road for some time and the various cylinders looked very grotty so all are getting a good clean and the replacement of all rubbers, apart from the clutch slave on which I was unable to turn/remove the bleed nipple and eventually tore the exposed part of, a well known problem with different metals being in contact for long periods and not being exercised, so a new slave cylinder has been acquired (from the well known big R) Again thanks, greatly appreciated. Iain (real name) Link to comment Share on other sites More sharing options...
dave.vitesse Posted March 25, 2017 Report Share Posted March 25, 2017 Ian, I agree if the systems been running on DOT 4 and is not being rebuilt leave it on this. It is generally recommended that you change DOT4 every 2 years. One of the points that is always raised against using silicon is that it gives a spongy brake pedal. Having used it for over 20 years in a number of cars, after rebuilding their systems, in my case there is no spongy pedal! DOT4 against DOT5 can be a bit of a hot topic! Dave Link to comment Share on other sites More sharing options...
Darren Groves Posted March 25, 2017 Report Share Posted March 25, 2017 I'm in the silicone camp, my brakes are the best they've ever been and no spongy pedal. I suspect some blame a spongy pedal on the fluid when the problem lies elsewhere. 1 Link to comment Share on other sites More sharing options...
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