After one extreme hard breaking breaks become dangerously soft

[tsmith154]

Hello everyone,


I have to admit I was on a track drag racing a Vmax and at the end of the track I braked as hard and stopped as fast as I can. Almost riding an endo slowing down from 110 mph. After that I went to pull off of the track and found my front break handle pulling all the way down to the grip. I left the bike stand for over an hour and my breaks were fine again. It's installed but I do not use the anti lock break system. I have a 2015 R1200Rt with 13,000 miles on it in mint condition. Always garage kept.


Any thoughts with my problem?

[David.]

Sounds like the brake fluid has been boiled.

"During periods of increased braking such as high-speed stops, heat can be transferred to the brake caliper, dramatically increasing the brake fluid temperature. Brake fluid naturally attracts and absorbs water. If the fluid has absorbed water, the boiling point is reduced dramatically. Between the dramatic increase in temperature and the lower boiling point, the brake fluid can easily boil. This boiling can create air bubbles in the brake system. Unlike the brake fluid, the air bubbles will easily compress during braking, and when it does, it can cause the brake handle to go straight to the grip without the bike slowing."

Once the brakes & fluid have cooled down, normal service may return. Having boiled the brakes, it would be good practice to change the brake fluid. Was the brake fluid changed at year one, then every two years after that. I know someone who prepares his bike for a track day by changing the brake fluid beforehand.

[Peter Baker]

Sounds like the brake fluid has been boiled.

Once the brakes & fluid have cooled down, normal service may return. Having boiled the brakes, it would be good practice to change the brake fluid. Was the brake fluid changed at year one, then every two years after that. I know someone who prepares his bike for a track day by changing the brake fluid beforehand.

 


This would be my conclusion too and regardless of how long ago it was changed I might be tempted to change it again before the next track day:-) Peter

[Talisker]

If there are no brake fluid leaks the boiled fluid would be the most obvious answer.  And I agree change it ASAP.


More importantly, clever technical stuff aside, did you beat the V Max?

[tsmith154]

I greatly appreciate this information. This all makes sense. It's winter now so right before I start riding again I will change that fluid. And It seems like changing it any time I have this problem is the best solution. I like changing the oil after one or two, well beating up the engine. It may be 500 to 1000 miles but why not. It's cheap compared to buying a new bike. I might as well throw in the break fluid while I'm at it.


Any break pads recommended? I would rather wear out the pads vs. the rotors.

[David.]

Any brake pads recommended.

Although not model specific, this "Poll of Brake Pads", viewtopic.php?p=47398#p47398 indicates that most folks are using BMW OEM pads.

I would rather wear out the pads vs. the rotors.

After 13,000 miles, are the pads and rotors (discs) still the original OEM (Brembo) fitment. The rotors should be stamped with a minimum thickness, likely to be 4.5mm.
Typically, the rotors may be 0.5mm thicker when new. Measuring the thickness will give an indication of wear vs. mileage.

If able to do an endo, (front end stoppie) from 110 mph, there isn't much wrong with the current set up.

[tsmith154]

Yep. This are the original everything on the bike. I'll measure the break pads and rotors with a set of calipers. At first glance there not ridges or slots in the rotors. Completely smooth still.


A change of habit I did after going through the first set of tires is to use my rear break for every day breaking with slow decelerations for stop signs and lights. I made the change because every bike I've owned I ended up with humps on my front tire. I finally searched the internet and one person explained in detail why that happens and said the answer is to start using more rear breaks while being less aggressive. The results are phenomenal. After 8000 miles my tires just started to get that flat spot in the middle from driving straight for long periods of time. Maybe that's helping my rotor and break pad wear.


I've been riding for 35 years and I would like to share my experience with these tires I've changed to for my last set I've used for 9000 miles. First time trying these. Amazing. I can lean farther than ever before with confidence like I'm on rails. When I do slide a bit they give me so much warning I would have to be blind not to notice. Their lasting like I've never experienced before. I've always burned through a set by now or at least it would be time to change. But this experience is mostly derived from other bikes I've owned and only one set on this bike before these new ones I have on now.  I've loaded my bike up with everything including the kitchen sink (lot's of weight) but did have to bring the tire pressure up to 43 psi to decrease the excessive wear on an extremely hot day (I was getting rolls of rubber just under 100 miles and the tire rubber was very soft. my finger nail could press into the center of the tread). That's when I noticed the flat spot forming and very quick. Went from perfectly round to flat spot in a 100 miles. Once I increased the pressure and the road cooled down that evening the rolls of rubber stopped and the center part of the tire became hard again. I covered around 1400 miles in two days. Philadelphia through Chicago up to Wisconsin and back. But so I'm not exaggerating. Half of the trip was 700 going to none stop and 700 coming back not stop from a family visit.  Road Pilot 5 tires. After taking some aggressive corners I press my thumb into the rubber on the edges and when pulling away my thumb actually sticks to the tire like pulling away from that blue painters tape. Not duck tape affect. Wet weather riding with extreme down pores are impressive as well. Some of that 700 miles was with that rain on the way home. Almost constant rain with some down pores on the way back. Only 2 hrs. on the way back was with no rain. But even with the rain I was smiling ear to ear feeling confident going through some mountains with long turns. Yep going though the turns faster than a person should be with some fear not knowing the tires 100% yet. To my opinion going from my old flat tires to these center / top narrow hard rubber well, the first couple of turns were OH CRUD! Am I on the bike still? But quickly turned into, turns are extremely easy to lean into and desired to find out can I scrap the pegs and what does the bike feel like in that condition. Yep I'm old but I still like to play as long as I never place anyone else at risk other than myself. And Yep I always ride with full textile from head to toe even on hot days. And I'm fortunate I do that. I've tested how far textile can last on a constant slide. Pretty good I can tell ya. But when I play no cars are ever around. But trees can be a...


Thank you for letting me share a bit of my experience and thank you for all the advice. Always enjoy getting others advice.

[tsmith154]

OH! SORRY. To the question I over looked to answer. YEP! My top end speed was faster and surprisingly we pulled out at the same speed. But he did say he messed up changing gears. I really did like looking at him face to face after the race and after he was braging about the VMax being a great drag bike. But he didn't know have owned a VMax with a Sassy installed. (Sassy, can over ride when the V-Boost kicks in. With a pre-programed rpm setting or press the button at any time. Below 3000 rpm just bogs the bike but in first gear over 3000 rpm HOLD ON tight. That's if the tire sticks. Most of the time the tire doesn't stick. The rubber compound is so hard. The tire options are so limited for that bike due to sizing unless the bike is modified.).


Yea! us BMW R1200RT stock bike has bragging rights over a V-max 1200 stock. Of course that's if he didn't miss a gear, he says.  lol. He could have though. Not really sure. :))

[tsmith154]

If there are no brake fluid leaks the boiled fluid would be the most obvious answer.  And I agree change it ASAP.


More importantly, clever technical stuff aside, did you beat the V Max?

YEP!  :))