Back brake locking up

[Beau254]

Does anyone else notice that your back brake can lock up on you when coming to a stop? Like over sensitive? Can make the back end fishtail sideways if you’re not careful.

 

[Traumahawk]

Does anyone else notice that your back brake can lock up on you when coming to a stop? Like over sensitive? Can make the back end fishtail sideways if you’re not careful.

What year bike ( Gen 1 vs gen 2)?

 

[Beau254]

What year bike ( Gen 1 vs gen 2)?

Sorry, Gen-1. 1992. The one in my Avatar.

 

[marsmax85]

I had a bad spot in my rotor ... Rotor gone problem fixed

 

[Fire-medic]

If you just cannot accurately modulate your rear brake, an old trick racers used to do was to mill-out some of the pad/shoe material to give you less friction area. I suspect your brake action will become better-modulated, with time in the saddle.

 

[Traumahawk]

Sorry, Gen-1. 1992. The one in my Avatar.

You can go with the organic green pads, they are the recommended pads for the rear. Also, when was the fluid changed? If there is a build up of water, the fluid will boil faster under heavy use and lock up. Is the Rotor straight and true? Have the brake lines been changed? Steel braided lines will allow more fluid to go to the caliper, making it react quicker and lock up.

Are you trying to use the rear all of the time to stop the bike? Most of the braking (up to 90%) if I remember right is to be done from the front. When you brake hard ( with the front brakes), the weight will go forward, and put more weight on the front tire......allowing the brakes to be very effective. When the rear brake is applied the weight of the bike will still shift forward, and in reality trying to pick up the rear of the bike.

Here is my 07, I dont really ever use the rear. I have a spacer on on my caliper to where I can run a larger rotor on the rear, to match the front.

 

[Beau254]

You can go with the organic green pads, they are the recommended pads for the rear. Also, when was the fluid changed? If there is a build up of water, the fluid will boil faster under heavy use and lock up. Is the Rotor straight and true? Have the brake lines been changed? Steel braided lines will allow more fluid to go to the caliper, making it react quicker and lock up.

Are you trying to use the rear all of the time to stop the bike? Most of the braking (up to 90%) if I remember right is to be done from the front. When you brake hard ( with the front brakes), the weight will go forward, and put more weight on the front tire......allowing the brakes to be very effective. When the rear brake is applied the weight of the bike will still shift forward, and in reality trying to pick up the rear of the bike.

Here is my 07, I dont really ever use the rear. I have a spacer on on my caliper to where I can run a larger rotor on the rear, to match the front.

I’ll have to check my rotor but I don’t think it’s warped. I already have braided SS lines & fairly new pads. It does it more so when you solely try to use the back brake. But I usually brake 50/50. Front/back.

 

[MaxMidnight]

Check that the pivot and linkages are lubricated and moving freely and that the caliper pistons are not siezing.

 

[Fire-medic]

Plenty of the 'do-rag' crowd don't use the front brakes, "'cause using them will spit you over the front of the bike, like spittin' a watermelon seed, ya-know what I mean?"

I forget which of the American bike mags it was, who took three riders: a novice, an experienced long-time rider, and a pro racer. Three levels of experience, onto bikes. They all rode the same bikes. Braking exercises were run. Rear brake only, front brake only, combined f & r. Of-course the pro racer had the quickest stops in the shortest distance. What was surprising was how long it took the novice to come to a stop using only the rear brake. Their lack of experience and handling showed that in the event of an emergency situation, the rear-brake only novice was going to end-up like a Clint Eastwood/Dirty Harry movie: Sudden Impact.

Many novices are reluctant to use the front brakes much. Unfortunately, this greatly-increases their stopping distance, and the likelihood of an accident. That's where the MSF and the beginning and experienced rider courses help people to stay-alive. You may-not be doing Tom Cruise on a Triumph, Mission Impossible 2 stoppies, upon completion of the MSF course, but if you continue to practice what you learned, you're gonna have a better chance of survival when executing hard braking and maneuvering to avoid a collision. And if you cannot avoid a collision that's where your protective gear protects you from worse damage.

 

[[email protected]]

If the rotor is warped enough to cause issues, you can feel it in the brake pedal.
Chances are you just need to get used to modulating the pedal. Not much feel to it.

 

[MaxMidnight]

If the rotor is warped enough to cause issues, you can feel it in the brake pedal.
Chances are you just need to get used to modulating the pedal. Not much feel to it.

It would have to have a significant amount of warping before you would notice because as one piston is pushed in the other comes out and thus little brake fluid is displaced.
However, you need far less thickness variation to feel a pulsing as both pistons will go in and out at the same time which will displace fluid.

 

[Beau254]

If the rotor is warped enough to cause issues, you can feel it in the brake pedal.
Chances are you just need to get used to modulating the pedal. Not much feel to it.

Ya, it’s pretty touchy vs the front. But I’m sure that’s because the front has dual rotors vs single only pinching on one side.

 

[Beau254]

Plenty of the 'do-rag' crowd don't use the front brakes, "'cause using them will spit you over the front of the bike, like spittin' a watermelon seed, ya-know what I mean?"

I forget which of the American bike mags it was, who took three riders: a novice, an experienced long-time rider, and a pro racer. Three levels of experience, onto bikes. They all rode the same bikes. Braking exercises were run. Rear brake only, front brake only, combined f & r. Of-course the pro racer had the quickest stops in the shortest distance. What was surprising was how long it took the novice to come to a stop using only the rear brake. Their lack of experience and handling showed that in the event of an emergency situation, the rear-brake only novice was going to end-up like a Clint Eastwood/Dirty Harry movie: Sudden Impact.

Many novices are reluctant to use the front brakes much. Unfortunately, this greatly-increases their stopping distance, and the likelihood of an accident. That's where the MSF and the beginning and experienced rider courses help people to stay-alive. You may-not be doing Tom Cruise on a Triumph, Mission Impossible 2 stoppies, upon completion of the MSF course, but if you continue to practice what you learned, you're gonna have a better chance of survival when executing hard braking and maneuvering to avoid a collision. And if you cannot avoid a collision that's where your protective gear protects you from worse damage.

View attachment 77372

I usually use both front & rear. But the other day I had a scenario where I had to make a sudden quick turn & stop @ the same time. So a front brake grab would not have been wise. I woulda went over the front like in your pic. That was when I notice the back fish tail around when it grabbed. Which is the reason for my post.

 

[MaxMidnight]

Ya, it’s pretty touchy vs the front. But I’m sure that’s because the front has dual rotors vs single only pinching on one side.

The rear is a dual piston caliper so the pads will still exert pressureon both side.
If it was a single piston type then the caliper would (should) slide on the mounting pin so both pads would still be pressing onto the disc.

 

[02GF74]

Going back to the original post, surely it depends how hard the brake pedal is pressed?

Without a pressure sensor fitted to the pedal, it is going to be hard to compare as it is very subjective. One person's hard is another person's soft.

I usually brake 50/50. Front/back.

BTW how to you measure that?

In my case for regular stopping (straight line on tarmac) it is more like 80/20 - of course like I'm asking above, how do I quantify that? Basically what I'm saying is vast majority of braking effort is front.

 

[Fire-medic]

The rear is a dual piston caliper so the pads will still exert pressureon both side.
If it was a single piston type then the caliper would (should) slide on the mounting pin so both pads would still be pressing onto the disc.

MaxMidnight, I believe that you thought he was referring-to a single piston, fixed caliper, when he was referring to the rear only has one rotor. The front has two calipers/rotors, one-each on either side of the longitudinal bike centerline. His thought being that with retarding brake drag on one-side only of the rear wheel, that would result in some dynamic imbalance at the rear of the bike upon rear brake application, with a heavy foot (or a heavy thumb, in the case of your Australian 'cousin' Mick Doohan, and the later adopters).
Mick’s secret | Tips | Brembo Motorcycle Configurator



Bikes with longer wheelbases, like cruisers, 'power-cruisers' or otherwise, actually brake better for f-r modulation with their less weight-transfer to the front, in the event of a vigorous application of the brakes. Whereas sportbikes with their short wheelbases by comparison tend to be able to have all their weight go to the front, resulting in a 'stoppie,' rarely would a cruiser be able to generate sufficient front braking force to lift the rear wheel off the ground. For cruisers, the rear brake actually does-something. The center of gravity also comes into play, as sportbikes have higher ground clearance/higher centers of gravity, compared to low seat height/low center of gravity cruisers.

 

[desert_max]

Rarely would a cruiser be able to generate sufficient front braking force to lift the rear wheel off the ground.

...I dunno, man. I could swear I've felt the rear end get pretty light on my '86 after converting to Hayabusa brakes on the front. There are definitely some advantages to having that capability:

 

[JMax92]

Here is a possibility for you. I had problems with my front brake not coming on smoothly, then grabbing and not releasing as soon as the lever was released. I stripped the whole system down and found corrosion in the brake cylinders. The corrosion was preventing smooth movement of the pistons, and when they did move they would not slide back/off properly. I would suggest getting a servicing kit and strip down, clean/ rebuild of the rear slave system. I would also recommend if you are not confident with front braking, doing a training course or get some good tutoring on emergency braking. Stay upright!

 

[Beau254]

MaxMidnight, I believe that you thought he was referring-to a single piston, fixed caliper, when he was referring to the rear only has one rotor. The front has two calipers/rotors, one-each on either side of the longitudinal bike centerline. His thought being that with retarding brake drag on one-side only of the rear wheel, that would result in some dynamic imbalance at the rear of the bike upon rear brake application, with a heavy foot (or a heavy thumb, in the case of your Australian 'cousin' Mick Doohan, and the later adopters).
Mick’s secret | Tips | Brembo Motorcycle Configurator

View attachment 77391

Bikes with longer wheelbases, like cruisers, 'power-cruisers' or otherwise, actually brake better for f-r modulation with their less weight-transfer to the front, in the event of a vigorous application of the brakes. Whereas sportbikes with their short wheelbases by comparison tend to be able to have all their weight go to the front, resulting in a 'stoppie,' rarely would a cruiser be able to generate sufficient front braking force to lift the rear wheel off the ground. For cruisers, the rear brake actually does-something. The center of gravity also comes into play, as sportbikes have higher ground clearance/higher centers of gravity, compared to low seat height/low center of gravity cruisers.

You are correct. I meant 1 rotor vs 2.

 

[Beau254]

Going back to the original post, surely it depends how hard the brake pedal is pressed?

Without a pressure sensor fitted to the pedal, it is going to be hard to compare as it is very subjective. One person's hard is another person's soft.



BTW how to you measure that?

In my case for regular stopping (straight line on tarmac) it is more like 80/20 - of course like I'm asking above, how do I quantify that? Basically what I'm saying is vast majority of braking effort is front.

I just press both @ the same time lightly. I’ve also seen YouTube videos of other Vmax riders coming to a stop & the back end locking & fishtailing a little @ stop. So I know it’s not just me experiencing this. That’s why I posted about it.