Rainer Posted May 13, 2009 Report Share Posted May 13, 2009 I'm about to fit some Goodridge hoses to my SP1 and the reservoir cap says to use DOT4 fluid only. Is it safe to use DOT5.1? Link to comment Share on other sites More sharing options...
MonkeyJim Posted May 13, 2009 Report Share Posted May 13, 2009 I'm about to fit some Goodridge hoses to my SP1 and the reservoir cap says to use DOT4 fluid only. Is it safe to use DOT5.1? I believe so Rainer. 5.1 is an improvement on DOT4. Think I've got 5.1 in the R1, I'm pretty sure my garage has been using that for the last couple of years at least. but I'm sure someone that actually knows what they are on about will be along soon to help... Link to comment Share on other sites More sharing options...
Rainer Posted May 13, 2009 Author Report Share Posted May 13, 2009 Cheers Monkey. I used the 5.1 when I did the same job on my CBR (which is why I have half a bottle left in the shed), but just wanted to check before I fuck it all up! Link to comment Share on other sites More sharing options...
MonkeyJim Posted May 13, 2009 Report Share Posted May 13, 2009 Cheers Monkey. I used the 5.1 when I did the same job on my CBR (which is why I have half a bottle left in the shed), but just wanted to check before I fuck it all up! ahhh... well, be careful then. I think brake fluid is hygroscopic [sp?], well it attracts water, so if you've got half a bottle in the shed & it's been there for a while, then I would play it safe and get some fresh. Don't throw the old stuff away though, it can be mixed with vodka to make an excellent martini. Yesh, mish moneypenny. Link to comment Share on other sites More sharing options...
Rainer Posted May 13, 2009 Author Report Share Posted May 13, 2009 Bugger. Half a bottle of £16 brake fluid wasted Ah well, it wsa vrry tashty Martinurgh...... Link to comment Share on other sites More sharing options...
lorenzo Posted May 13, 2009 Report Share Posted May 13, 2009 Yep, 5.1 (not 5) is safe to mix with your old fluid dregs that'll be in the system and it has pretty decent characteristics in comparison to dot4 too. Its performance when freesh is fairly simialr to 4, slightly improved, but the key thing is that it doesn't deteriorate as much when it starts getting older and more water is absorbed. Link to comment Share on other sites More sharing options...
Rainer Posted May 13, 2009 Author Report Share Posted May 13, 2009 Yep, 5.1 (not 5) is safe to mix with your old fluid dregs that'll be in the system and it has pretty decent characteristics in comparison to dot4 too. Its performance when freesh is fairly simialr to 4, slightly improved, but the key thing is that it doesn't deteriorate as much when it starts getting older and more water is absorbed. Hmm... it's been two years since I last opened it. Link to comment Share on other sites More sharing options...
cagimaha Posted May 13, 2009 Report Share Posted May 13, 2009 As long as the lid was screwed onto the bottle properly after it was last used then it should be ok. The brake fluid can only absorb the small amount of moisture that is in the air gap in the bottle which is going to be pretty minimal unless you've been opening it loads. The other thing is you can try it and if the brakes bleed up ok then it's alright. If the lever is still slightly spongy then you might have to shell out for some fresh fluid. Hope this helps, Ben. Link to comment Share on other sites More sharing options...
lorenzo Posted May 13, 2009 Report Share Posted May 13, 2009 An easy way to tell is to have a look at it. The darker the fluid the more 'off' it is. Brand spanking new fluid is about the same shade as magnoila paint, except clear, obviously. Link to comment Share on other sites More sharing options...
sparx55 Posted May 13, 2009 Report Share Posted May 13, 2009 Like lorenzo says, mix n match, personally I d buy new, never save a tenner on brakes !!!!!!!!!!!! Mark 55 , ps , if you got a spare moment, what are the thicknessess for the dunlop look . cheers Link to comment Share on other sites More sharing options...
Agtrak100 Posted May 14, 2009 Report Share Posted May 14, 2009 DOT 5: the only real problem is that DOT5 is alot more "hydroscopic" than DOT4, so it will hold condesation alot more, especially from say a track day where brake fluid experiences higher operating temerarures, so you should chance the fluid more regularly.... SteveT RHRC ( CB 1187 ) Link to comment Share on other sites More sharing options...
lorenzo Posted May 15, 2009 Report Share Posted May 15, 2009 Also, don't get DOT 5 confused with DOT 5.1, they're completely different. Link to comment Share on other sites More sharing options...
buster Posted May 15, 2009 Report Share Posted May 15, 2009 Also, don't get DOT 5 confused with DOT 5.1, they're completely different. Glad about that as I've just bled my brakes with 5.1 Link to comment Share on other sites More sharing options...
MonkeyJim Posted May 15, 2009 Report Share Posted May 15, 2009 Also, don't get DOT 5 confused with DOT 5.1, they're completely different. indeed. DOT5 makes a fuckin' awful vodka martini Link to comment Share on other sites More sharing options...
matt_the_blat Posted May 15, 2009 Report Share Posted May 15, 2009 DOT5 is silicone based (I think) and I believe won't damage paintwork if spilled but can't be mixed with DOT 4 or 5.1 - only seen it once and as I recall it was a purple colour like meths DOT5.1 is similar to DOT4 but has a higher boiling point so is better suited to track use than DOT4. The downside of DOT5.1 is, as already pointed out, it is more hygroscopic (yes "hygro", not "hydro" - that would mean something else) i.e. it absorbs moisture more readily so needs changing more frequently. My riding is mainly on the road with the odd trackday now and then and I've used DOT5.1 for years in various bikes and never had a problem. Large and small bottles of DOT4 & 5.1 are available from Halfords for a few quid so no point messing around with old stuff - unless I know I needs loads I only buy a small bottle, use it up, then only get another one when I need it so it's always fresh. RFTR, Matt Link to comment Share on other sites More sharing options...
Rainer Posted May 16, 2009 Author Report Share Posted May 16, 2009 Job done. Lever pressure feels fine, but I think that (due to not using tubes on the bleed valves) the pads are nicely impregnated with DOT5.1 Link to comment Share on other sites More sharing options...
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