Let's talk brake fluid! | GTAMotorcycle.com

Let's talk brake fluid!

42Seb

42Seb

Ride42 Trackdays
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So on my last track day I boiled fluid and lost the front brake while braking pretty deep into the turn. Stood the bike up and ran it off with luckily no damage other than the loss of trust on my R6's brakes :(

I'm going to be doing a full flush soon and was hoping to hear your feedback on what the "best" brake fluid would be. How important do you consider brake fluid to be and what are you using?
 
Sebi said:
So on my last track day I boiled fluid and lost the front brake while braking pretty deep into the turn. Stood the bike up and ran it off with luckily no damage other than the loss of trust on my R6's brakes :(

I'm going to be doing a full flush soon and was hoping to hear your feedback on what the "best" brake fluid would be. How important do you consider brake fluid to be and what are you using?
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I don't race but I would lean heavily on data to make a decision.....especially when it comes to brakes. I flush my street bike every year not that I'm hard on it....just cause it's so critical (to me). Glad you and the bike made it through that pucker factor experience unscathed.
Check for comparative data here..... https://www.lelandwest.com/brake-fluid-comparison-chart.cfm
 
I flush mine every couple weekends. Once the bottle of fluid is open it doesn’t last very long so you might as well use it up. On my street bike I flushed it every spring.

For me the boiling point is very important so I don’t end up with brake fade 15 laps into a race. It may not be necessary to spend big money on fluid depending on your pace. The motul rbf600 works well until you get moving at a good pace and then it will fade after 7-8 laps. The 660 has a higher resistance to fade/boiling but is also quite expensive. I wouldn’t just grab any old dot 4 off the shelf from Canadian tire and expect good results.
 
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Rbf660
 
I wonder if using a vacuume sealed bag would prevent that 1L bottle of SRF from being garbage after being opened.
 
I think brake fluid, and generally all components of the braking system, become more important to keep an eye on if you're taking your bike to the track on a regular basis.
My mechanic recommended ideally replacing the brake fluid after each track day --but I've gone up to 6 track days on the same fluid (Motul RBF600) with no issues. On the other hand, I've had to replace my front brake pads twice this season.
 
I think that as your brake pads wear down they transfer more heat to the caliper and ultimately the fluid. That's something to consider if you are experiencing brake fade and fluid boiling. Pads with half the material left might be ok for street use but not racing.
 
Sebi said:
So on my last track day I boiled fluid and lost the front brake while braking pretty deep into the turn. Stood the bike up and ran it off with luckily no damage other than the loss of trust on my R6's brakes :(

I'm going to be doing a full flush soon and was hoping to hear your feedback on what the "best" brake fluid would be. How important do you consider brake fluid to be and what are you using?
Click to expand...

No offence, but I'd be surprised if you're boiling fluid at your pace. I used normal Prestone DOT4 for along time and never had any issues with brake problems. Granted I'm not the hardest braker in the world, but I suspect I can out-brake you into most corners. Perhaps the fluid that was in your system was too old and had absorbed some moisture.

I would say that more important than the brand/boiling point of the fluid is just to make sure you change it at least each spring before the season starts.
 
doozerdave said:
No offence, but I'd be surprised if you're boiling fluid at your pace. I used normal Prestone DOT4 for along time and never had any issues with brake problems. Granted I'm not the hardest braker in the world, but I suspect I can out-brake you into most corners. Perhaps the fluid that was in your system was too old and had absorbed some moisture.

I would say that more important than the brand/boiling point of the fluid is just to make sure you change it at least each spring before the season starts.
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I've also used canadian tire dot4 before and never boiled it...

Anyway I use RBF

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dricked said:
I wonder if using a vacuume sealed bag would prevent that 1L bottle of SRF from being garbage after being opened.
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Why is it garbage after opening? After opening the stuff left in the bottle has seen just as much air/moisture as the stuff in the res

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dricked said:
I wonder if using a vacuume sealed bag would prevent that 1L bottle of SRF from being garbage after being opened.
Click to expand...

With the last bottle I had, I tried squeezing it so there was almost no air at the top then closing it tight, but the bottle doesn't seal 100% and after a few days it had sucked in air and gone back to normal shape.
 
One factor is the temperature that the brake fluid will withstand but the other factor is how much heat is getting into the calipers to begin with.

If your brake calipers had insulators in the pistons between the pistons and the back of the brake pads, make sure they are there and in decent shape.

Don't do anything that disrupts or partially blocks airflow around the brake rotors and calipers.

If the issue is that your lever is coming back to the bar, make sure the real issue isn't that accumulated dirt and crap on the caliper pistons is stopping the pistons from moving properly or is causing them to be pulled back too far. Eventually those seals get buggered up. This past season I got fed up with having this issue on my race bike and I ordered a new set of seals and rebuilt the calipers (carefully cleaning ALL dirt off the pistons in the process). This made a world of difference. Most caliper designs don't allow full access to the pistons to clean them all the way around unless you take the calipers apart and take the pistons completely out.

I use ordinary prestone DOT4 from Canadian Tire. But my bike doesn't have enough power to really cook the brakes. I get a couple of seasons out of a set of brake pads.
 
kellen said:
Why is it garbage after opening? After opening the stuff left in the bottle has seen just as much air/moisture as the stuff in the res

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doozerdave said:
With the last bottle I had, I tried squeezing it so there was almost no air at the top then closing it tight, but the bottle doesn't seal 100% and after a few days it had sucked in air and gone back to normal shape.
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It’s absorbing water the second the bottle is opened. I’ve bled my brakes with fluid that’s been opened for the whole season to get terrible brake fade within a few laps. To spend the kind of money that the SRF costs and only get the maximum performance from it for a short while it’s crazy that it’s only sold in 1L bottles. A 250ml bottle is perfect. Buy 4 of those and you’ve got me sold.

I change my brake pads every third weekend as well so my pass have lots of life and material to keep the fluid from boiling but slowing down a
 
dricked said:
It’s absorbing water the second the bottle is opened. I’ve bled my brakes with fluid that’s been opened for the whole season to get terrible brake fade within a few laps. To spend the kind of money that the SRF costs and only get the maximum performance from it for a short while it’s crazy that it’s only sold in 1L bottles. A 250ml bottle is perfect. Buy 4 of those and you’ve got me sold.

I change my brake pads every third weekend as well so my pass have lots of life and material to keep the fluid from boiling but slowing down a
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Right, but what I'm saying is that the brake res is likely no more air tight than the bottle is once it's opened. How often to you have to change out the brake fluid?

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kellen said:
Right, but what I'm saying is that the brake res is likely no more air tight than the bottle is once it's opened. How often to you have to change out the brake fluid?

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I bleed mine every weekend or two. Before I was using the same bottle or two of fluid all season which didn’t get rid of brake fade. Maybe slightly but not long term and by Sunday I’d have fade. Remember I’m doing 22 laps, those brakes get hot.
 
dricked said:
It’s absorbing water the second the bottle is opened. I’ve bled my brakes with fluid that’s been opened for the whole season to get terrible brake fade within a few laps. To spend the kind of money that the SRF costs and only get the maximum performance from it for a short while it’s crazy that it’s only sold in 1L bottles. A 250ml bottle is perfect. Buy 4 of those and you’ve got me sold.

I change my brake pads every third weekend as well so my pass have lots of life and material to keep the fluid from boiling but slowing down a
Click to expand...

Yes, I know. It absorbs that moisture from the air, so my point was to reduce the amount of air the fluid was exposed to, which failed because their bottles don't seal well enough. I agree that 250ml would be perfect, and I though exactly the same thing the first time I used RBF660. At least it comes in 500ml bottles, but still twice as expensive of a job as it needs to be.
 
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