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Discussion Starter · #1 ·
This has been extremely puzzling.

It started when i was riding, the rear brakes locked all the sudden, couldnt press the left brake lever at all. so i unscrewed the banjo bolt quickly just to let enough pressure out and it was operable again.

i bled the brakes later. while riding all day, the brake lever would be hard then soft normal, then hard, then normal. brakes are almost locked when the lever is hard but can still spin.

First i bought a new master cylinder. still same symptoms, all day it would get hard then soft..
I have now replaced both rear calipers , bled the lines. the lever is still hard sometimes and normal sometimes. Even when just parked. i would sometimes press the lever and its normal, then sometimes its hard nearly locked.

what the hell? replace the rubber hoses?
 

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Check that the foot brake pedal is moving freely. Have been reports of the pedal sticking. Lube the bushing or drill it out a little is the fix.
 

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If the foot pedal was stuck, wouldn't the hand lever be all loose and floppy?
When I have the foot brake down, the hand lever is really light until it reaches bottom, on both the 07 and the 16.

jrubicon, when it is hard, does the lever not want to move back at all, or does it go back most of the way super easy (way easier than normal), but then it gets hard when you finally do get resistance?

Also, would you please update your signature to include your year, model, and mods you've done?
 

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1. Jack it up so the wheels are off the ground, suspension is fully extended. What does it do?
2. Trace the line all the way from the cylinder to the calipers. Look for anything unusual.
3. Spin the wheels and watch the rotors. Are they warped?
4. Is everything clean or is there gunk getting jammed in there?
5. Remove the calipers from the hubs and let them hang. Put a piece of steel the same thickness as the rotor in each one to keep the pads apart. What does it do?
 

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Discussion Starter · #5 · (Edited)
If the foot pedal was stuck, wouldn't the hand lever be all loose and floppy?
When I have the foot brake down, the hand lever is really light until it reaches bottom, on both the 07 and the 16.

jrubicon, when it is hard, does the lever not want to move back at all, or does it go back most of the way super easy (way easier than normal), but then it gets hard when you finally do get resistance?

Also, would you please update your signature to include your year, model, and mods you've done?

whether riding all day or just sitting in the garage, the lever would randomly be hard to press, randomly normal easy to press. absolutely bizzare. i try to turn the wheel when its hard to press and it almost locked, i can still turn it but not as freewheeling as it should be.

all is clean, i mean its new rear calipers, line is perfect no kinks. i dont see the rubber lines to be expanding but i went ahead and ordered the one by the master cylinder.
 

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If the foot pedal was stuck, wouldn't the hand lever be all loose and floppy?
When I have the foot brake down, the hand lever is really light until it reaches bottom, on both the 07 and the 16.
The lever will have some free play.

I've seen this on two machines I ride with. A 14 and 15 Grizz 700.
On the 15 we did as the OP loosened the bolt to release the pressure.
The owner of the 14 discovered the foot brake problem. Since we have modified the 15.
Problem has never came back.
 

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Discussion Starter · #7 ·
THIS CONTINUES TO BE AN EXTREMELY MYSTERIOUS PROBLEM ON MY GRIZ

I have New: master cylinder complete assembly, left/right rear calipers complete, rear brake hose, While riding, the brake lever slowly gets too hard to brake, until the rear is completely locked later.

I have flushed and used new fluid and bled it twice. Lately, i have been relieving the pressure by quickly unscrewing the banjobolt, a quick open and close just to relieve the presure on the line, but will later lock up again.

I have also run the griz on a stand and the rear discs are not wobbling BUT, the left side is like slight oblong, it goes up and down a little.

any thoughts???
 

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It sounds like there is a one-way valve somewhere there shouldn't be.
This problem began before you replaced the master cylinder and the calipers?

So it was like this:
Problem began -> replaced that stuff -> still a problem

And it was NOT like this:
Replaced some stuff -> problem began -> stuff is new so probably isn't the problem

Right?
 

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Machine cold and sitting still it does this? So there is no chance of heat build up from a dragging pad or a bad wheel bearing. Correct?
All of the hydraulic parts have been change out with new parts. Correct?
 

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Discussion Starter · #10 ·
Thanks for trying to help. This is what happened.

Brand new 2013 Griz, put a HMF exhaust after 900 miles or so.
Was riding down a highway with buddies when i noticed it was slowing down, then later it stopped, the rear brakes was completely locked. couldnt even press the rear brake handle. i loosened the banjobolt on the master cylinder to relieve pressure and it unlocked.

later that day it would slowly lock again so i would release pressure whenever it happened.
i then got a master cylinder rebuild kit. new seals and piston. went for a ride same thing. even while the bike is sitting cold, i would press the handlebar and sometimes it would be hard sometimes soft.

I then got a new master cylinder assembly complete. still same issue. (excerpt here)

later, crashed the grizz on a boulder, removed EVERYTHING and put in a brand new frame, brand new bumper etc etc. while i had the metal brake line off the griz, i blew compresed air in it, then installed it on new frame. got new calipers left and right complete assemblies. got new rear brake line hose also.

while riding again, it locked and brakes smoking this time, cuz i rode fast , back to camp. put on stand, run it and its not warped or wobbling but the left is wobble up and down not left right. so the caliper isnt like moving with the disc.

its frustrating, i love my griz.
 

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Sitting still the rotation is not present.
And you have all new hydraulic parts.
It has to be mechanical. Since you now indicated that you replaced the frame there is a better chance of problem along these lines.
Check the operation of the hand brake lever. Besides it operating the master cylinder there is the foot brake cable connect to it.
Check that the cable from the hand brake to the foot brake is sliding freely. A very tight zip tie can restrict the movement of a cable in the sheath.
As I posted above check the that every part of the foot brake is moving freely.
 

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Discussion Starter · #12 ·
heath.
As I posted above check the that every part of the foot brake is moving freely.[/QUOTE]

Thanks geo,

remember i was having this issue before frame swap. the frame swap only allowed me to redo everything, lube everything, and its still doing the same thing. it is absolutely bizzarre
 

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You say that you have replaced and serviced every part of the braking system..all of the hydraulic and mechanical parts. The brake locks up with the engine off and just sitting still (not moving).

That leaves nothing else..It is time to bring out the secret weapon....Get yourself a Ouija board.
 

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You say that you have replaced and serviced every part of the braking system..all of the hydraulic and mechanical parts. The brake locks up with the engine off and just sitting still (not moving).

That leaves nothing else..It is time to bring out the secret weapon....Get yourself a Ouija board.
Ouija, couldn't find it at partszilla. How about a link shheesssh a little help
 

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I was thinking of two other possible problems before I went to my dark place.

1.)Have you replace all of the brake fluid? If not try flush the lines and replacing all the fluid with DOT4 fluid.
2.) Do you have the brake hose banjo fittings in the proper positions. On the calipers the pipe must be against the stops and at the master cylinder it must be 60 degrees below the horizon (horizontal).
 

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Never been here, but just wondering, problem started after muffler change, makes me wonder if some heat is changing the dynamics of your braking system, might explain why it locks up sitting, the heat causing a problem shortly after the ride.

If you still have the original muffler, maybe check there, or at least make sure your motor is not running in an extreme lean condition that is causing the entire motor to run hotter than usual.

My half a penny of thoughts.

My other half penny of thoughts, verify the brake line routing, you did a complete frame off and on, maybe you missed the original route and incidentally enhanced a heat expansion issue.

Ok, one more thought, can you have over filled the brake caliper reservoir and has no room for fluid expansion?

Been awhile since I read on proper level of fluid, maybe somebody can post up.
 

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Never been here, but just wondering, problem started after muffler change, makes me wonder if some heat is changing the dynamics of your braking system, might explain why it locks up sitting, the heat causing a problem shortly after the ride.

If you still have the original muffler, maybe check there, or at least make sure your motor is not running in an extreme lean condition that is causing the entire motor to run hotter than usual.

My half a penny of thoughts.

My other half penny of thoughts, verify the brake line routing, you did a complete frame off and on, maybe you missed the original route and incidentally enhanced a heat expansion issue.

Ok, one more thought, can you have over filled the brake caliper reservoir and has no room for fluid expansion?

Been awhile since I read on proper level of fluid, maybe somebody can post up.
X2 overfill. Try running fluid on the low side, have similar issue with my wolverine and it helped
 

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Might be a longshot, but you did mention (iirc) that the brake rotor disc was going up and down, not turning concentricly. Two possibilities come to mind. Is it possible the brake rotor is expanding from brake heat and binding on the caliper? Second possibility is the bearing may not be good and allowing for movement that should not be there.
You have checked all the hydraulics, so check the mechanics of the movement of the wheel. Check for wobble in the wheel itself. Take a look at the bearings themselves.
If the rotor is striking the caliper in a wobble, would it not cause backfeed pressure issues?
 

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I realize that this is an old string but I read it to see if anyone had anything to say about the rear brake cable routing. I removed the headlight from a Kodiak 450 to wire in the switch for the winch and saw that the headlight height adjuster was cross threaded half way through the nylon nut and the cable and wire routings are doomed for failure, right from the factory and dealer PDI. The brake cable is jammed between parts that will kink or wear through it. Any chance that your brake problems could be an intermittent cable problem? If you had the machine torn down to the frame you probably would notice a bad cable though.
 
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