2007 FJR Front Brake - only engaging right (linked) caliper

[Two-Wheeled Tourist]

So I'm a bit stumped about this front brake issue so I'm throwing it out here for some feedback.

I'm only getting braking from one side of my front wheel, as in the linked caliper (right side) is fully engaged when I pull the lever and the left side caliper isn't getting any pressure. When I feel the rotors after a ride, the left one is cold and the right one is hot.

What I've done already...

- Calipers have been rebuilt recently (less than 10k miles ago)

- New stainless steel lines have been connected (less than 10k miles ago)

- Brakes have been bled in this order - left front (non-linked), right front, front linked bleeder screw, rear brake

If there is any other information I need to provide to help with this, just let me know!

 

[audiowize]

Did you rebuild the brakes yourself, or have a shop do it? (Same with the bleeding)

Do you get stopping power on the front brake lever at all? (Just to confirm that the linked piston isn't the only moving piston)

I would recommend lifting the front end off the ground and removing the front wheel. Next, squeeze the front brake lever a little. When you see a piston moving freely, push it back into the caliper, then zip-tie it in place so it can't move anymore. Repeat until you see all the pistons moving; some may move a little more eaily than others.

If all the pistons are happily moving, I would rebleed brakes.

 

[Two-Wheeled Tourist]

Did you rebuild the brakes yourself, or have a shop do it? (Same with the bleeding)- Rebuild: done by shop

- Bleeding: done by shop then redone by me after about 3000 miles because brakes were getting squishy

Do you get stopping power on the front brake lever at all? (Just to confirm that the linked piston isn't the only moving piston)

Yes, I get stopping power and it's enough to stop the bike decently.

I would recommend lifting the front end off the ground and removing the front wheel. Next, squeeze the front brake lever a little. When you see a piston moving freely, push it back into the caliper, then zip-tie it in place so it can't move anymore. Repeat until you see all the pistons moving; some may move a little more eaily than others.

Going to have to try that. On the phone with one of my trusted mechanics to get more opinions.

If all the pistons are happily moving, I would rebleed brakes. I can only hope.

 

[HotRodZilla]

Sounds like you still have air in there. Getting all the air out can be a bear. Some people try holding the lever against the bar overnight to promote the bubbles sliding up the lines.

 

[odot]

The left calipers only get used once Abs kicks in. Thus the pulsating you feel.....left right left right etc.

 

[wfooshee]

Who let *him* back in????

 

[JamesK]

Can't add much beyond what's been said, but I know that when I rebuilt my calipers I made the stupid mistake of not pre-filling the calipers with brake fluid so took a long time and much pumping and mighty vac sucking to get the brakes to feel firm.

You mentioned that you upgraded to the stainless steel lines, just wondering which ones you went with.

 

[Denver_FJR]

You're actually riding? Ah, California.

That's pretty weird. I'm guessing when you bled the brakes it was passing fluid out of the left side caliper, yeah? Since all four pistons on the left side are activated by the front brake lever, it's seem unlikely that all four pistons are wedged up and if the caliper passes fluid during the bleed process it shouldn't be a blockage issue.

Will the wheel spin free when lifted off the ground? Rather then an issue with the left caliper could the problem be a stuck piston on the right side or possibly the an issue with the rear brake circuit engaging front system. Yeah, seems unlikely I know. Take a ride and don't use the front brakes at all then check front rotors for heat.

I don't think it's air in the line as that would affect both calipers, but re-bleeding is pretty cheap time and $$$ wise.

 

[HotRodZilla]

What?? The rear brake cannot engage the front as they are in no way connected. The "linked" system is only linked because the rear pedal activates the lower right front caliper.

Currently, both calipers are affected. The only thing working out front is the lower right piston, which is fed off the rear reservoir. All the front activated pistons are FUBAR if I read the OP correctly.

Edited to fix left/right because apparently I'm an idiot. Lol. Oops

 

[Denver_FJR]

We must be reading different posts!

Also, it's the right caliper that has front and rear circuits, the left is front only.

Yes, the rear brake doesn't activate the front braking system, it activates the lower pads of the right front caliper. Thank you for the correction.

TWT says "left side caliper isn't getting any pressure". How do we know this? This sounds like an assumption based on the results of the right rotor getting hot and the left one staying cold. But she also says front braking appears to work normal.

 

[RossKean]

When you pull the (front) brake lever, is it firm or does it pull to the grip? If its firm, I don't think your problem is air in the system. If it's mushy, rebleed the brakes!

If the top right pistons engage when the lever is pulled but nothing is happening on the left side, the problem is blockage on the left. Crimped line or issue with your new SS lines. Messed up banjo fitting or the left-right splitter?

Note: If the bottom right pistons are engaging, that will only happen when the rear brake is applied. These do not engage with the front brakes at all (unless the plumbing was messed up when the new lines were installed). Any chance that the rotor heating was from application of the rear brake? If so, it is still possible that there is NO braking action from the front brake lever. If lever is firm, it isn't air but possibly master cylinder block.

Short of screwed up plumbing or a defective set of lines, I cannot imagine what could allow the top right piston to engage (firmly) with a solid brake lever and no action out of the left side. I can understand a blocked (or defective) master cylinder causing no braking action but getting normal response only out of the top right with "normal" brake lever feel...?

Perhaps we are not fully understanding the symptoms?

 

[Mihalis fjr]

Or the problem exists inside the ABS block,like Donal's problem..Was not exactly similar but... https://www.fjrforum.com/forum//index.php/topic/161927-abs-unit-blocked-on-front-brake-circuit/ . Ι Hope not!I don't know very well how the system works in the Gen2,but in the Gen1 there is one line for the front brakes.I believe that in the Gen2 is very different.Is a thought only.

Also here is the Donal's post with the diagram https://www.fjrforum.com/forum//index.php/topic/161927-abs-unit-blocked-on-front-brake-circuit/?p=1210357

 

[stealth1]

Just throwing this out because it happened to me once many years ago.

Check the left disc to make sure it is not warped or deformed.

If it is it will push the pistons away from the disc slightly as the wheel rotates.

Result is that when you squeeze the lever the pistons will all extend but the ones on the warped disc will not be exerting pressure on the disc as the right one is. When the bike is stationary and the wheel is not turning both will grip fine although you may have to pump it once to get the bad side to bight.This would also explain the left disc running cool.

Had this happen on a Suzuki many years ago when I had a front tire replaced at a shop and the installer somehow bent the disc slightly.

The shop bought me a new disc and that took care of it.

 

[Queensland Ken]

Try bleeding out the banjo's, esp if the lines have been replaced.

Also good to free up the bobbins on the semi-floating rotors

 

[wfooshee]

That ^^^^^ is NOT a good idea!!!! The rotors are free to float to prevent damage from heat expansion. Restricting the movement will mean that the heat expansion has to move something else, which will result in warped rotors.

 

[Queensland Ken]

You use a nut & bolt to FREE up the bobbins and allows the semi-floating rotors to work correctly.

As the bolt tightens, it loosens off the bobbins and is easily cleaned out with brake clean.

 

[Denver_FJR]

You use a nut & bolt to FREE up the bobbins and allows the semi-floating rotors to work correctly.As the bolt tightens, it loosens off the bobbins and is easily cleaned out with brake clean.

Am I the only one not following this?

 

[HotRodZilla]

You use a nut & bolt to FREE up the bobbins and allows the semi-floating rotors to work correctly.As the bolt tightens, it loosens off the bobbins and is easily cleaned out with brake clean.

Am I the only one not following this? :help:

No, I'm confused too.

You put a bolt through the bobbin thing and tighten it up to loosen the bobbin thing? How's that work? They get bound up?

 

[JamesK]

Try bleeding out the banjo's, esp if the lines have been replaced.
Also good to free up the bobbins on the semi-floating rotors

This is the weirdest thing I've ever seen

, could you pls explain.