Rear brakes do not work!

[SKIPNOMAD]

I went to go for a short ride on the T7 after it had sat for too long and realized my back brakes do not work. The pads are fine as I have about 3700 miles on them. And I have taken the extra brake fluid out so that it a little below the full mark. Not sure why they would not work. Any help would be much appreciated.

[sracer]

As I posted somewhere else: I changed pads to EBC, bled and adjusted, The biggest improvement was installing this rotor as someone else suggested: 

245mm Rear Brake Disc Rotor for Yamaha MT07 / ABS 14-21 MT-09 XSR 700 ABS XSR900

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Gold Front Rear Brake Rotor FZ09 MT-09 ABS 2014-2021 XSR900 ABS 16-21 For Yamaha. For YAMAHA 900cc XSR900 Abarth ABS 2018-and up. For YAMAHA 900cc XSR900 ABS (MTM850A)...

 

[mpatch]

I may have partially solved the rear brake issue. 
I used a old trick that worked on some KTM’s that would get a spongy front brake. On the KTMs all you’d have to do is tie the lever back and let it sit overnight and the brakes would be back to normal. 
I did the same with my T7’s rear brake, I hung some weight off the pedal overnight and it seems the have helped a ton. 
The issue I was having was way too much pedal travel with is much better now, the pedal actually feels firm now. 

[Simmons1]

4 hours ago, mpatch said:

I may have partially solved the rear brake issue. 
I used a old trick that worked on some KTM’s that would get a spongy front brake. On the KTMs all you’d have to do is tie the lever back and let it sit overnight and the brakes would be back to normal. 
I did the same with my T7’s rear brake, I hung some weight off the pedal overnight and it seems the have helped a ton. 
The issue I was having was way too much pedal travel with is much better now, the pedal actually feels firm now. 

I have been doing the same thing with mine, but the pedal gets soft again after a while with too much pedal travel.

[NeilW]

3 minutes ago, Simmons1 said:

I have been doing the same thing with mine, but the pedal gets soft again after a while with too much pedal travel.

Just saying that my issues is solid brake pedal and normal brake response for part of a ride and then the pedal goes to the ground with zero brake response. The rotor is always hot.  ( an no I am not riding the brake pedal)

 

[Hollybrook]

2 hours ago, NeilW said:

Just saying that my issues is solid brake pedal and normal brake response for part of a ride and then the pedal goes to the ground with zero brake response. The rotor is always hot.  ( an no I am not riding the brake pedal)

 

That sounds like your brake fluid is boiling.

[NeilW]

15 minutes ago, Hollybrook said:

That sounds like your brake fluid is boiling.

Agreed, but don't know why. I have stated on this and many threads. My foot is away from the pedal and I have to consciously move it to the pedal to use the rear brake. I am a front braker in the dirt and street. weird.

 

[Hollybrook]

Does sound weird.  Any chance moisture has accumulated in the brake fluid?  What type of fluid are you using? 

[NeilW]

7 minutes ago, Hollybrook said:

Does sound weird.  Any chance moisture has accumulated in the brake fluid?  What type of fluid are you using? 

Stock fluid. Remember it has only happened 3x in 3500 miles. goes away and doesn't come back on the same ride.  Only happened off road on several hour rides on gravel forest roads during an all day adventure of mixed street and dirt. 

[Hibobb]

Didn't you have the dealer looking into this?

Any response from them?

 

Keep your GoPro camera focused on your right foot next ride!

[NeilW]

2 minutes ago, Hibobb said:

Didn't you have the dealer looking into this?

Any response from them?

 

Keep your GoPro camera focused on your right foot next ride!

Others have had similar issue. overheating the rear brake when not "riding it" . You have to believe me that I know where my foot is. I am standing 100% of the time. I have to flex my ankle downward to push on the rear brake. I am not sitting down and with my boot angled down on the pedal.

 

[Hibobb]

Standing 100% of the time!!

Awesome, you must be 23 years old with legs like an oak tree....

 

Of course I trust you, but what the heck is going on???

 

Trust... but verify!

~Russian Proverb~

 

 

 

 

[Hollybrook]

I wonder if the stock fluid is hygroscopic.  I used to race sports cars and with the wrong fluid we used to have similar problems. 

[williestreet]

2 hours ago, NeilW said:

Others have had similar issue. overheating the rear brake when not "riding it" . You have to believe me that I know where my foot is. I am standing 100% of the time. I have to flex my ankle downward to push on the rear brake. I am not sitting down and with my boot angled down on the pedal.

 

There are a few other threads where it has been mentioned the bike comes with too much fluid in the reservoir.  The pads always lightly touch the rotor even if you are not using the brake and this heat causes expansion of the fluid.  If there is no space in the reservoir to accommodate this pressure will build and the situation compounds itself and it gets worse and worse until excessive pad wear happens among other things.  You probably already are aware of this , but it is the first thing that should be checked.  No need for any more than a 1/2 full rear reservoir.

 

The second thing you should do is remove and grease the brake lever pivot bolt.  The brake pivot, just like the shifter  pedal pivot is not greased from the factory and the friction in this joint can prevent the pedal from returning fully.  Pict below shows the bone dry brake pivot bolt.  

 

Also the return spring on  the brake is not very strong.  It only takes a little bit of road grime in the spring area to cause issues with the pedal not returning fully and causing the same issue as above.

I and a few others have fitted an extra return spring to the lever to help apply more return pressure and make sure the pedal retracts fully.

 

But most importantly remove the lever and grease the pivot bolt.  Every once and awhile spray the return spring with something to remove any buildup grime/dirt the may hinder pedal movement.

 

 

 

 

[NeilW]

1 hour ago, williestreet said:

There are a few other threads where it has been mentioned the bike comes with too much fluid in the reservoir.  The pads always lightly touch the rotor even if you are not using the brake and this heat causes expansion of the fluid.  If there is no space in the reservoir to accommodate this pressure will build and the situation compounds itself and it gets worse and worse until excessive pad wear happens among other things.  You probably already are aware of this , but it is the first thing that should be checked.  No need for any more than a 1/2 full rear reservoir.

 

The second thing you should do is remove and grease the brake lever pivot bolt.  The brake pivot, just like the shifter  pedal pivot is not greased from the factory and the friction in this joint can prevent the pedal from returning fully.  Pict below shows the bone dry brake pivot bolt.  

 

Also the return spring on  the brake is not very strong.  It only takes a little bit of road grime in the spring area to cause issues with the pedal not returning fully and causing the same issue as above.

I and a few others have fitted an extra return spring to the lever to help apply more return pressure and make sure the pedal retracts fully.

 

But most importantly remove the lever and grease the pivot bolt.  Every once and awhile spray the return spring with something to remove any buildup grime/dirt the may hinder pedal movement.

 

 

 

 

This is great info. Thanks 

[NeilW]

6 hours ago, Hibobb said:

Standing 100% of the time!!

Awesome, you must be 23 years old with legs like an oak tree....

 

Of course I trust you, but what the heck is going on???

 

Trust... but verify!

~Russian Proverb~

 

 

 

 

Really if I am riding under 50 mph I stand. I have been playing ice hockey since  1994. I am 70 years old. I have always been a standing “dirt bike “ rider. I am very comfortable standing and simply do not get tired standing. I picked up my T7 about 1000 miles from my house. The first day was 140 miles of seated torture in the stock seat. The second day was 320 miles of which about 280 was standing. The third day was over 500 miles and I started out at 6:30 am and got home at 8:30pm. I stood for all but the last 90 minutes that were over 60mph. I have independent references of people I have ridden with that   Will vouch for me being a stander. I love the view and control. Enough??

[Buggy Nate]

It will almost definitely be a problem with the rear brake master cylinder. Brembo make great components but their assembly leaves much to be desired. I have pulled hundreds of Brembo master cylinders and calipers apart over the years. Usually it is swarf or poor/careless assembly damaging the outer most master cylinder seal. The seal suck air in over multiple uses and eventually leaves you a soggy pedal.

My brand new Xtz660 did it around 5000k’s and my prior Fz6 also did the same thing. 

[Simmons1]

9 hours ago, Buggy Nate said:

It will almost definitely be a problem with the rear brake master cylinder. Brembo make great components but their assembly leaves much to be desired. I have pulled hundreds of Brembo master cylinders and calipers apart over the years. Usually it is swarf or poor/careless assembly damaging the outer most master cylinder seal. The seal suck air in over multiple uses and eventually leaves you a soggy pedal.

My brand new Xtz660 did it around 5000k’s and my prior Fz6 also did the same thing. 

So is the fix to replace the master cylinder with another Brembo that could have the same problem, or fit a different manufacturers master cylinder?

[Dougie]

2 hours ago, Simmons1 said:

So is the fix to replace the master cylinder with another Brembo that could have the same problem, or fit a different manufacturers master cylinder?

I reckon he’s saying strip, flush, clean and re fit any new seals. 

[Buggy Nate]

5 hours ago, Simmons1 said:

So is the fix to replace the master cylinder with another Brembo that could have the same problem, or fit a different manufacturers master cylinder?

One of the bikes I was able to removed the swarf refit and bleed with nil issues. The other required a master cylinder kit. Fairly inexpensive.

[Redneckj]

Consider changing to Motul brake fluid.  I am going to install the galfer rear pads and change the fluid.  

 

Wet boiling point 185.0 °C / 365.0 °F

[Simmons1]

The dealer just replaced the Master Cylinder on my buddies bike.  My buddy told me the dealer said they have 3 more bikes in the shop with the same problem.

[NeilW]

19 minutes ago, Simmons1 said:

The dealer just replaced the Master Cylinder on my buddies bike.  My buddy told me the dealer said they have 3 more bikes in the shop with the same problem.

as in T7 with Master Cylinders that suck air?

 

[Simmons1]

T7s with soft rear brake pedals, so mostly likely yes sucking air.

[Hollybrook]

47 minutes ago, Redneckj said:

Consider changing to Motul brake fluid.  I am going to install the galfer rear pads and change the fluid.  

 

Wet boiling point 185.0 °C / 365.0 °F

 

Or ATE TYP 200 DOT4 with a dry boiling point of 388°F and a wet boiling point of 388°F.  We used it in my race car with solid rotors that was abusive to brake components.

 

I looked into the Yamalube brake fluid and now better understand why some folks are having problems with it.  First of all, its a DOT4 fluid which are typically somewhat hygroscopic.  Combined with low boiling points (400°F dry and 311°F wet) that is a recipe for heat related problems.  Any hard use or dragging the brake once the fluid has absorbed some moisture and the brakes will fade quickly.

[jetdr21]

On 7/7/2022 at 4:56 PM, Simmons1 said:

The dealer just replaced the Master Cylinder on my buddies bike.  My buddy told me the dealer said they have 3 more bikes in the shop with the same problem.

An update, I just picked the bike up and the MC was replaced last week and the brake feels better than it ever has before..  BTW when it went in it had zero brakes and the dealer then bled it and let it sit for few days, and it repeated, zero brakes so they witnessed the issue..  Now to see if Yamaha will warranty, it is almost  2 years old.   They are waiting on a answer from Yamaha.  Like Rich said,  they have seen 3 with the same issue..