I've done a quick search and cannot find an answer to this. Please forgive me if it has been covered before. I normally ride my MTS1200S 2010 every weekend, at least 80 miles frequently 200 or so. Due to work and other isses, such as the weather I've not been out for nearly a month. I found that the brakes require bleeding (especially the front). This was also an issue on my 998S over winter. Note the brakes work, albeit I have to grab a handful and the lever returns to the bar. Any ideas on how to prevent this? Perhaps using a better fluid etc? It's just a pain having to bleed the brakes everytime I leave it a few weeks. As always I would love to hear your advice (and ribbings).
I don't have this problem, although I do have a rear brake that does nearly bugger all I do though, have theory about how it occurs. You will all have heard of the trick of firming up your brakes by pulling in the lever and keeping it held there overnight with a bungy or cable tie. So where does the air go? And sooner or later the sponginess usually comes back again. It's my thought that at least some of any air trapped in the system dissolves in the brake fluid when held under pressure for an extended period. The CO2 and nitrogen content certainly will and probably the oxygen too. Over a period of time, especially if not used much, this air will come out of solution and re-create the spongy brake syndrome again. The only cure would be to make sure there is absolutely no air in the line in the first place. Unfortunately, as we all know, this is often easier said than done.
Does it live in damp or wet conditions when parked. Brake fluid is hygroscopic which means it absorbs and seeks water. Damp will cause the fluid to deteriorate and cause sponginess. Normally this takes much longer than the period of time you are quoting. The fact that it has happened to two of your bikes similarly would suggest it's an environmental issue or a problem or situation that is affecting them. Using a synthetic fluid might, help they do vary by composition, there is a table on the internet that lists the different types and how prone they are to be affected by conditions.
NO, the exact opposite. Air Conditioned garage. Note it takes the whole winter to make the 998 brakes go soft. Good point about the water and air dissolved in the fluid. I'm going to vacuum out the whole system, ensure it holds under 250mTorr and then introduce RBF600 fluid. This way I can guarrantee that there was no air or water in the system. If this works I'll document and put on this site.
It's not clear if you're using RBF already but it may make things worse, not better. It's a fantastic performer but goes off much faster than "lesser" fluids. Motul advise a 6-12 month change interval at the very most.
@AirConTechnical - how did you get on? Any particular reasons for going for the Motul RBF600 as against any other 'high spec' fluid? Thnx Brake fluid....what's everyone else's choice?
Aren't there issues mixing DOT5.1 with DOT4 i.e. a thorough system flush required? I think I'll stick with DOT4 as specified by Ducati
No. DOT3, DOT4 and DOT5.1 are fully miscible. The exception is DOT5 which is silicon based and must not be mixed with a gylcol based fluid. The newest fluids are 5.1 and are specifically aimed at use in ABS systems.
Thanks Derek....learnt two things there - that DOT3, 4 and 5.1 are miscible and after looking it up.....the meaning of the word miscible Apart from the increased boiling points are there any other benefits to 5.1?.......it's lower viscosity than DOT3/4 - is that an advantage? Don't appear to be any disadvantages that don't also apply to DOT3 and 4. So, why would Ducati not recommend DOT5.1? Cross reference, more useful info re brake fluid here: http://www.ducatiforum.co.uk/forum/threads/brakes.1433/#post-14395 Reference: http://www.opieoils.co.uk/pdfs/tech-articles/Brake-Fluid-Explained.pdf http://www.opieoils.co.uk/pdfs/MOTUL/RBF-600-Factory-Line-8069-(GB).pdf ......"Avoid mixing with polyglycols based brake fluid with lower performances"
It's more to do with the fact that the seals inflate with the pressure to tighten the seal against the bore in the cylinder, if a brake isn't used for a while the seals relax and the first part of the application only re inflates the seal, that's why the brakes feel spongy but if you clamp the lever overnight with a tie they are fine. That's why you sometimes find when you fit a new cylinder it is difficult to bleed out, when in fact it is bled out but the seals are relaxed and why a cable tie left overnight will fix it. I doubt if different fluid will have any effect on this, I would say that if it bothers you leave a little bit of pressure in the brake system by putting a piece of inner tube or wrapping buggy around the lever when you park it, you only need a little pressure though.
This trick of firming the lever up is not an air issue ......its lever travel , what happens when you tie the lever back is that the pistons 'creep' through the seals and get closer to the discs giving the effect of a firmer lever .....it just has less travel . once you ride the bike the discs expand a push the pistons back again putting travel back in the lever .
Its more about the shape of the seals when they are under pressure compared with when there is no pressure but I guess it amounts to the same thing pretty much. As per previous posts I would be very careful mixing fluids as this can thicken or do funny things to them that will not be obvious for a while, also make sure that any fluid you use is a direct replacement for the OEM fluid specification as the wrong fluid can destroy the seals over time. An example is to use Dot 4 in the place of Pentosin (which is a commonly used fluid on cars and Trucks) and the seals will swell to the point where nothing works over the next 6 months. I wouldn't waste my money on fancy fluids, just keep it fresh, use the correct one of a good quality and you will never exceed it's capabilities on a road or track bike unless your name is Marquez, Rossi or Lorenzo.....
