Rear Brake Super Soft After Wheel Removal & Brake Work

[Motogiro]

After watching that video, I agree there is something amiss on the caliper after watching that video. There is too much movement of the piston and the entire caliper assembly. I would pull the rear wheel and start from the beginning, making sure the anti rotation arm on the caliper is where it's supposed to be on the swing arm.

 

[FinalImpact]

X3! mine does not move at all.

I keep going back to too much grease in the slide. Grease in excess does not compress. I know my caliper moves with slight hand pressure (pads out). I am guessing that one does not.

 

[durty3]

Hey guys,
Finally got back to the bike and I have a mixed bag of news and lots of videos!

Here is the quick playlist I made, the fun really starts at video 4: https://www.youtube.com/playlist?list=PLw8IDKp6i5hYMAd0waZL7VDqpzuawfbqk

I do a complete removal of the caliper and overview of everything that is going on back there.

Good news is that my rear master cylinder seems to be in great shape! Bad news is that when the caliper is fully assembled and mounted, the pedal is still super soft.

Any ideas as to why that front caliper slide bolt might be locking things up? Where else should I focus my attention?

Thanks for watching and all of the guidance!

 

[Motogiro]

I keep thinking the aluminum casting that you are mounting your caliper to is not installed correctly. There should be a slot where it slides into a key way on the swing arm and must stay aligned on that key way as the axle is inserted when assembly of the wheel is performed. I think that cast aluminum assembly is c0cked and when you install the bolts they are aligning the caliper to the cast aluminum assembly but it is c0cked which is causing the caliper to be out of square with the rotor. when you loosen the bolts you are not forcing the alignment to the casting and the caliper can float and be square to the rotor. Disassemble the wheel and look carefully at how that casting has an anti rotation arm that must be assembled in a key way on the inside of the swing arm.

Look at Scott's post #4 http://www.600riders.com/forum/fz6-...fter-wheel-removal-brake-work.html#post624821

That's what I'm referring to. See that lower slot in the casting. Is that slot mounted on the key way on the inside of the swing arm? You may have lost the alignment when you where reinserting the axle and now that assembly is c0cked and out of alignment.

 

[durty3]

Thanks for the reply Motogiro!

I think you must be right! Everything else looks happy with the caliper, so that has to be the next area to address.

I need a second set of hands, but hopefully will have an update by Sunday.

Thanks!


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[TownsendsFJR1300]

Great video's!!!

Couple things. I just looked at my main brake bracket and it looks the same as yours- I'm pretty sure your good there.

Those accordion "rubbers" need grease in them, both of them.(later once the issue is found is fine)

What I did (or didn't see), two things:

Is the FRONT boot. If its partially in the hole or if you look closely, there's a slight lip on that bolt JUST FOR the boot.
Make sure that boot isn't crooked and NOT allowing the the caliper to sit / seat correctly.
The video, when you tighten up that bolt confirms the issue is there...I believe that boot isn't
seated correctly.

Also, when you put the INNER brake pad on, for me, I had to hold up the rear of it, to keep it from falling as I installed the caliper, YOU didn't (at least one time)
Is it possible the front of that pad moved and is sitting incorrectly in the caliper??


Just to confirm, make sure that front boot is properly seated, not jambed up in the hole (as that boot DOES HELP CENTER the caliper-
And just double check the pads are fully in their resting spot. The front anti rattle spring could have moved when the pad dropped and then jambed up
once everything was assembled.

 

[durty3]

Hey Townsend,
Thanks for the great info! Here are my thoughts:

1) In my videos, specifically, the last video #5, at about 15 seconds in, I show I remounted the caliper without the front accordion boot in place. The issue occurs as soon as I slide the front bolt into the hole, without even tightening it. Maybe the bolt is bent or the hole it goes into is bent? The bolt I have looks good, but I did notice longitudinal grooves on the length of it, they do look machined? If the boot is seated in the caliper mounting bracket (it fits into a lip), when you slide the bolt through the caliper, there is no good way to have the outboard part of the boot fall precisely into the cylindrical groove, any thoughts on that?

2) Anything is possible about the pad fitment! However, I did notice that I had the inboard pad fall once, as you mention, so I have become quite conscious of seating it on the proper spot in the caliper mounting bracket. I will certainly double check this too!

Thanks so much and really excited to hopefully have the "ah, ha" moment next trip to the garage!

 

[TownsendsFJR1300]

I don't remember any longitudinal grooves but its very possible, just to hold grease in there. And if the grooves look machined in there, they most likely are.

That front bolt if bent would cause issues. You can roll it on a flat surface and should be able to see anything bent. A straight edge checked on a couple of sides would confirm as well.

I would make sure the pads are fully seated with the anti rattle springs. The issue is definitely in the area of that bolt , possible pad not fully in place...

BTW, how easy does that forward bolt screw in with THE CALIPER OFF the bike? You should be able to see as well if that bolt is bent and you thread it in. I don't know how it would get bent. I would also, as you assemble(and hold the inner pad in place, START the forward bolt(just a couple of threads), then the rear, then the pad holding pin.

Your close!

 

[FinalImpact]

Assuming the bracket is in the grove, maybe its bent... But that only happens if its out of the grove and the axle is torqued to spec.

Again, remove the pads and assemble it. Measure from the inner pad stop to rotor on the leading and trailing edge of the caliper. I bet the values are not equal. As Cliff implied, something is wrong w the alignment.

 

[chunkygoat]

I'm not sure I can be of too much help here, but I'm wondering a few things....

Is it possible you over torqued the caliper pins and bent the bracket?

Maybe measure your pads if you've got a pair of calipers laying around and compare against OEM pads? Verify you've got the right ones on there?

Double check rear wheel alignment?

Does the keyed caliper notch that slides into the swingarm sleeve look damaged or bent? Was it forced on?

Any wiggle room side to side of the caliper when torqued?

 

[TownsendsFJR1300]

Any updates???

 

[durty3]

Sorry guys, I worked a 12 hour day yesterday! Will be getting to the bike later this morning!


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[durty3]

Hey guys,
So I went to the bike and had a look!

Here are the videos from this round: https://www.youtube.com/playlist?list=PLw8IDKp6i5haw5StWbkvRyBchy8frT1T5

When disassembled, everything appeared to have been installed correctly. As you will see from the videos, it is only when the front mounting bolt goes in that I have a problem (if installed on the bike).

I am pretty stumped, so look forward to your comments.

 

[TownsendsFJR1300]

Two things,

On the swing arm, the rectangular tab, that holds the main brake bracket, when I freeze the video, it appears to maybe have a "ledge on it"?

I also thought (it was kinda quick) the main brake bracket was not dead nuts parrallel to the the surface you held in on, ie, possibly slightly bent from that rectangular tab?

Can you confirm the condition of that tab AND how well does the bracket FULLY SEAT in there. What I'm after is if that bracket is hanging up on the edge of that tab, c0cking it. If its not FULLY "LOOSE" in that slot, IE, there's absolutely no ridges pushing the bracket inward.

*****If that's all ok, assemble everything but do NOT tighten the axle beyond snug. Tighten the two brake caliper bolts fully and see what happens.
I'm suspecting it won't drag and once you start to tighten the axle, IF the main bracket is bent, or not seated fully, its going to bind up and you loose pedal.

Now the PO,(or mechanic) may have bent that bracket but they got it to seat screwing with it. Please look real close around the bracket, BY THE TAB for any marks, that it was installed and tightening incorrectly. I'm suspecting at this point it was..

 

[Zealot]

I know that when I replaced my rotors, to re-seat the brake pads and alignments (much the same as you'd do following pad replacement) there was a step to squeeze the lever really hard and set everything evenly. My lever very quickly went from zero to being solid like a rock - and then I think I tightened everything up. Was there (or did you do) a step like that?

You have enough fluid I assume, since you said you bled the lines?

 

[Motogiro]

If the bushings on the wheel are different you may have the bushings swapped which would put the rotor in the wrong location with respect to your caliper. Swap those bushings and reassemble to see if the rotor and caliper then align.

 

[TownsendsFJR1300]

If the bushings on the wheel are different you may have the bushings swapped which would put the rotor in the wrong location with respect to your caliper. Swap those bushings and reassemble to see if the rotor and caliper then align.

The bushings are the same on both sides Cliff.

Did you notice the swing arm, rectangular tab looked "mis-shapened"? IE, not completely square?

One other thing for the OP to check and probably not it, the rubber cushions inside the sprocket carrier.
Check and make sure one didn't pop out slightly, etc. They do fit pretty tight, I usually spray em with silicone.
upon assembly. That WOULD cause some improper spacing..

 

[durty3]

I'm at the bike now and the tab looks good to me.

Also, the bracket looks true, just held it to a piece of glass.

This all looks happy too:

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[durty3]

What you will see in the video below is the caliper mounted, while the axle is just snug. Give me a slight twist to the caliper by hand creates the soft pedal.

https://vimeo.com/167660295


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[TownsendsFJR1300]

Thanks for the clarification and yes, the tab looks fine.

When you twist the caliper, your pushing the piston back in and the fluid as well.

Getting no petal doing that is normal till you pump it up and get the piston back out.

What I meant about the brake bracket, is when you hold the axle mount / flange on a straight surface, can you measure or rule out that the distance across the whole
lenth is egual between the surface and bracket, IE, trying to make sure that's not bent..


Re the rotor, you can check that pretty easily for run out.

Assemble without the caliper, all spacers, bracket, etc, snugged down, preferably if you can, keep the chain off to the side would be even better.

Then take say a wire coat hanger (or anything long with a sharp point) and clamp it to say a stool, chair, etc right next to the rotor.
Put the point just touching the rotor. Now slowly spin the rotor /wheel and watch for any run out, spaces/gaps/pushes your pointer away...

I don't remember what the run out spec's are but you really shouldn't see anything...

See what you come up with... Fingers crossed for ya..


Being it started with a tire change, it does happen, someone lets a wheel fall over and bend a rotor and doesn't say anything.