Dot 5.1

[ghostbiker]

As allways there is a lot of conflicting advice on the net.
I have decided to change my front fluid to 5.1 as last track day I did I had a couple of brake fade "moments" LOL
Some say to drain and flush the system and others say just feed in the 5.1 untill it comes out the bleed nipple.

If I try to drain it will be a pain to bleed again (front on the gen 1 allways is)  and I doubt it will fully drain anyway. If I flush it what do I flush it with?  And if I just feed in 5.1 untill that comes out will the slight mix of 4.0 that will happen make any odds?
Feeding in seems the simplest way by far as long as I make sure it pushes plenty through.

Anyone know a bit more about it?
Only reason I'm changing is the track day next week. The fluid in there is 4 and less than 18 months old but did fade 2-3 times last track day. Never had fade on road at all.

[Chris]

Isn't fade more to do with the face of the pad glazing?  :o

Chris

[trudd]

As I understand it Dot 4.0 and 5.1 are compatible so you'll be fine feeding the 5.1 through.


My old race bike (SV650 Minitwin) had DOT 5.0 in which isn't compatible but I needed to do something with my brakes at Snetterton and the only thing available was DOT 4.0. I flushed the system with 0.5 litre of DOT 4.0 then bled it up. Never had a problem after that.

[Lawrence]

Iirc high temp DOT4 works at higher temperatures than 5.1, try some of that.

[ghostbiker]

Chris, I'm fairly sure it was fluid boil. Simply because the very next corner after it happened was after a long straight and I had the brakes return to fully working as soon as I touched them.

Instructor at the track and track tyre guy also thought it was fluid boil
That's not saying it wasn't pad related, but it seemed to fit symptoms more with fluid. Especially as it happened a few times and each time brakes came back as soon as I backed off and they cooled.

The "cause" as such is my riding, or should I say my lack of skill at riding i was way to gentle on the brakes so was lightly braking for much longer than I should.
If I had been more confident I would brake later and harder so on the brakes for less time = less heat build up.
Again the instructors thoughts. My thoughts were more .... Oh shit I'm gunna die.


Lawrence, 5.1 from everything I have read and been told by shops and guys at the track has a higher boil point than 4. But I notice you say high temp 4. I did see mention of this on google and was referred to as race spec dot 4. But there was little info and what there was, was a bit sketchy.
Not seen it widely available either.


Trud, that's my understanding to.

[Chris]

Ah right ok. Had heard of brake boil before but wasn't sure how it would effect the braking system.

Sounds like you're right though  8)

Hope you get it sorted, you're obviously making good progress before it's happening so keep up the good work! haha!

What course is it that you're doing if you don't mind me asking??

Chris

[Lawrence]

Bit more info here.

[Slaninar]

5.1 absorbs water quicker than dot 4 fluids, so should be changed before track day, for that track day. I believe "super" dot 4 hasn't got that problem and has a higher boiling point than 5.1. Do double check, however.

[ghostbiker]

Yup 5.1 absorbs water much faster and its only recomended for use on braided and sheathed hoses.
Much shorter shelf life to.

Very interesting about super dot 4 / or the many names it seems to go under. Not something I had ever heard of before. Just thought brake fluid was brake fluid.
I won a auction very cheap for 5.1 so I will be using this for the track day. (Brands hatch Indy) 2 x 500 ml for less than 4 quid posted LOL I love it when ppl spell stuff wrong and no one bids
But may look in to super 4 on my return as it seems to be better or at least as good as 5.1 without the draw backs.

Thx for the info guys.

[Chris]

Bit more info here.

Thanks for the info Lawrence  8)

Chris

[Chillum]

Trackday braking : If you aren't having trouble stopping yourself going over the handlebars you're braking too early

[Chris]

Trackday braking : If you aren't having trouble stopping yourself going over the handlebars you're braking too early

:eek  :lol

[ghostbiker]

Trackday braking : If you aren't having trouble stopping yourself going over the handlebars you're braking too early

I'm far from a fast rider on track, I tend to use it to have fun and expand skills. It's hard for me to get my mind from road riding to track. Especially where braking is concerned. I'm of the early, light and scrub the speed of with engine braking school LOL. On road its rare I touch the right leaver.