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zippy

Make solid disc a floater

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I would like to switch my 2003 Pro front disc from being a solid mount to a floater mount.

Is this as easy as just installing the bolts and collars that a floater disc uses?

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Do you really think anyone has really done this to that 14 year old POS bike that still remembers? Most have died off by now!

I think you would need a disc with bigger holes so the bolts just rattle like the rest of the bike!

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5 hours ago, copemech said:

Do you really think anyone has really done this to that 14 year old POS bike that still remembers? Most have died off by now!

I think you would need a disc with bigger holes so the bolts just rattle like the rest of the bike!

A simple " I think you will need to buy a new disc with bigger holes to accommodate the spacers" would have been enough.

If you are going to merely find my posts as an opportunity to either insult my bike or myself I would appreciate it if you would just keep scrolling and find something else to do with your time.

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I love  that Pro keeps a going. Probably has some of the most hours of any Pro. Keep making it better zippy.

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11 hours ago, lineaway said:

I love  that Pro keeps a going. Probably has some of the most hours of any Pro. Keep making it better zippy.

The Old BAGG is still fun to ride, her sister Big tiTTy ('86 TT350) sure is fun to play with also. :boobies:

Amazing difference in how that 2003 300 runs now that I have a Keihin carb and Carbontech reeds.

anyway back to the front brake.  so in theory if I buy a floaty disc and the spacers for a GasGas (and maybe new bolts) I should be able to make it a floaty.

About $100 for the upgrade, not bad

 

(I am basically buying a new bike...... $100 at a time HAHAH)

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15 hours ago, zippy said:

A simple " I think you will need to buy a new disc with bigger holes to accommodate the spacers" would have been enough.

If you are going to merely find my posts as an opportunity to either insult my bike or myself I would appreciate it if you would just keep scrolling and find something else to do with your time.

Don't be soo mean Zipperhead. I can make jokes about us old relics if I want to!:P

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3 hours ago, copemech said:

Don't be soo mean Zipperhead. I can make jokes about us old relics if I want to!:P

Yep you can make jokes, but after clicking on the "ignore" option I won't have to see them anymore.

Goodbye, have a nice life.

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Zippy I don't think there is a lot of performance difference between a floating disc and a fixed one. The floating disc will work a little better if both are equally damaged / bent I would think.

Let us know how you get on as I'm still learning. 

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The issue I am having is the front brake will engage with the lever at the exact spot I want it to, but during an event in the middle of a random section it will engage with the lever closer to the bars and I don't have the leverage/travel to get the front brake to bite the way it should.

Then later it works fine, almost like air in the system at just that point.

I have done the following:

Bled the system,

Replaced master cylinder

Rebuilt caliper (pistons and seals)

Discovered the pads were binding - ground the edges so the pad would slide in the caliper without touching the caliper and drilled the mounting holes 1 drill bit size larger to allow the pad to slide along the mounting pins.

Replaced front wheel bearings - which I may need to do again.

It is as though for some reason one brake pad contacts the fixed disc and pushes it towards the other pad, but being fixed the disc stays put.  then I am waiting for the other pad to come over and press on the disc as well or it never does and there is about half of the force on the disc.

My hope is that a floating disc will "slide over" that little bit, taking up slack from the different variables and allow pads to put pressure on both sides of the disc.

Is that clear as mud?

It will probably be a while before the keeper of the finances lets me try my theory.

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Here are some thoughts and suggestions to try before you spend money throwing parts at it.  I know from your posts that you have been riding along time and are pretty knowledgeable about bikes.  So, I offer my thoughts in hopes they will trigger you to consider something you already know but maybe skipped over in your diagnosis. 

 

Has the bike always done this?  If not, then consider what has changed?  In your case it sounds like several things have changed in an attempt to eliminate the problem.

 

There are 2 main potential types of issues that could be the cause: 1) Mechanical  2) Hydraulic.

 

Mechanical
Something is binding or forcing the pads apart differently sometimes.  Your efforts to drill the hotel and open the holes in the pads should take care of the binding.  Did you check for grooves or steps worn into the caliper?  I usually will put a very small amount of anti-seize on the sliding surface of the pads and pins. 

 

Is the rotor bent?  That would wobble and push the pads apart, making for more travel needed to contact the pads.  Test with the bike on the stand, front wheel up. Hold a pencil or marker close to the rotor on something solid like a jack stand.  Spin the wheel and look at the gap between the rotor and pencil tip.  It should be pretty consistent as it spins.  

 

Worn wheel bearings would cause the same sort of wobble.  Loose axle bolt could also allow this.   Test with bike on stand, brakes off, grab the wheel top and bottom, try to push the top left while pulling the bottom right and repeat. If you feel any looseness or clicking the bearings or axle are probably the culprit.

 

Lever and perch.   Check for wear in the holes.  Out of round holes can cause inconsistent movement.  Lube them.

 

Hydraulic

You changed the caliper seals and pistons.  Did they move smoothly in the bores?  Was there any corrosion or pitting?

 

Is the lever consistently firm or is it mushy sometimes?  If it’s mushy, there is still some air in the system.  Bleeding these things can be challenging.  One trick is to park the bike with the master cylinder being the highest part of the hydraulic system (Bike on the stand, front wheel high, bars full lock left).  Apply the front brake and clamp the lever to the bars with a bungie cord to hold brake pressure overnight.  This will force any bubble to the top of the master cylinder bore.  In the morning, take the cover off and watch as you release the lever.  If there was air, you will see it escape through the return port.

 

Speaking of the return port, you know that when the lever is pulled, the spool inside the master cylinder blocks the return port so the pressure is transferred to the wheel cylinder applying the brakes.  When the lever is released, the return port is uncovered to allow the pressure and fluid to flow back into the master cylinder reservoir.  If this port is not open, the pressure holds and the brake pads can’t move back from the rotor.  The hole could be blocked by some crud or the spool might not be returning fully when the lever is released.  With the cover off the M/C, squeeze the brake lever, then release it.  You should see a miniature geyser of brake fluid.  If it is blocked with crud you can use a thin wire to clear the hole (this is best done with the spool removed otherwise you are pushing crud further into your brake system).  If the hole is still covered by the spool, it is not retracting full.  This could be caused by

Foreign material between the end of the spool and that little C-clip, or because there is not enough free play in the lever adjustment. 

 

Floating disc.

If you still want to try a floating disc, you can simulate that by putting some small o-rings on the bolts each side of the disc but not tightening them too much.  This would allow the o-rings to squish, so the rotor can move a little.  I would suggest using some sort of removable thread lock so the bolts don’t unscrew while riding.

 

 

Keep us posted on what you find.

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3 hours ago, thats_a_five said:

Here are some thoughts and suggestions to try before you spend money throwing parts at it.  I know from your posts that you have been riding along time and are pretty knowledgeable about bikes.  So, I offer my thoughts in hopes they will trigger you to consider something you already know but maybe skipped over in your diagnosis. 

Sometimes even the most knowledgeable person will overlook the simple.  yep.

Beginning of this riding season I had the front brake working exactly how I want it to work.  this past weekend I started having issues again.

I think I found the issue today, but I will save that for last to force you to read my answers below.  :D

Has the bike always done this?  If not, then consider what has changed?  In your case it sounds like several things have changed in an attempt to eliminate the problem.

when first purchased the lever would pull super easy until brakes engaged then it was almost like an on/off switch.  but that on/off point would vary.

Now the lever pull is a little more "progressive", firms up proportional to lever position.

There are 2 main potential types of issues that could be the cause: 1) Mechanical  2) Hydraulic.

 

 

 

Mechanical
Something is binding or forcing the pads apart differently sometimes.  Your efforts to drill the hotel (ha) and open the holes in the pads should take care of the binding.  Did you check for grooves or steps worn into the caliper?  I usually will put a very small amount of anti-seize on the sliding surface of the pads and pins. 

when I changed the pistons and seals I noticed grooves in the caliper and used a file, etc.. to smooth these out.

After drilling the holes just a hair larger and grinding the width of the pads skinnier both pads will "float" freely in the caliper.

 

Is the rotor bent?  That would wobble and push the pads apart, making for more travel needed to contact the pads.  Test with the bike on the stand, front wheel up. Hold a pencil or marker close to the rotor on something solid like a jack stand.  Spin the wheel and look at the gap between the rotor and pencil tip.  It should be pretty consistent as it spins.  

Rotor be straight.

 

 

Worn wheel bearings would cause the same sort of wobble.  Loose axle bolt could also allow this.   Test with bike on stand, brakes off, grab the wheel top and bottom, try to push the top left while pulling the bottom right and repeat. If you feel any looseness or clicking the bearings or axle are probably the culprit.

We will discuss this in a little bit...............there is a hint

 

 

Lever and perch.   Check for wear in the holes.  Out of round holes can cause inconsistent movement.  Lube them.

Actually had never thought about this.  Lever and master cylinder about a year old, without looking at it, I am just going to say "yeah should be good"....  but I will probably take a look at this later.

 

Hydraulic

 

You changed the caliper seals and pistons.  Did they move smoothly in the bores?  Was there any corrosion or pitting?

Free moving pistons with no caliper not attached to bike and brake pads removed.  (4 pot caliper)

 

 

Is the lever consistently firm or is it mushy sometimes?  If it’s mushy, there is still some air in the system.  Bleeding these things can be challenging.  One trick is to park the bike with the master cylinder being the highest part of the hydraulic system (Bike on the stand, front wheel high, bars full lock left).  Apply the front brake and clamp the lever to the bars with a bungie cord to hold brake pressure overnight.  This will force any bubble to the top of the master cylinder bore.  In the morning, take the cover off and watch as you release the lever.  If there was air, you will see it escape through the return port.

consistently firm, used many bleeding techniques, including the brake pressure overnight thing.  At this time I am 98% sure there is no air.  I don't want to say 100% just in case I am wrong.

 

 

Speaking of the return port, you know that when the lever is pulled, the spool inside the master cylinder blocks the return port so the pressure is transferred to the wheel cylinder applying the brakes.  When the lever is released, the return port is uncovered to allow the pressure and fluid to flow back into the master cylinder reservoir.  If this port is not open, the pressure holds and the brake pads can’t move back from the rotor.  The hole could be blocked by some crud or the spool might not be returning fully when the lever is released.  With the cover off the M/C, squeeze the brake lever, then release it.  You should see a miniature geyser of brake fluid.  If it is blocked with crud you can use a thin wire to clear the hole (this is best done with the spool removed otherwise you are pushing crud further into your brake system).  If the hole is still covered by the spool, it is not retracting full.  This could be caused by

 

Foreign material between the end of the spool and that little C-clip, or because there is not enough free play in the lever adjustment. 

return port is clear, much fluid squirt happens.  and there is free play at the lever adjustment, I can wiggle lever without the pin touching the plunger (spool)

 

 

Floating disc.

 

If you still want to try a floating disc, you can simulate that by putting some small o-rings on the bolts each side of the disc but not tightening them too much.  This would allow the o-rings to squish, so the rotor can move a little.  I would suggest using some sort of removable thread lock so the bolts don’t unscrew while riding.

 

That is an interesting idea,  might be worthwhile just as a test.  I don't think I would want to run it that way forever, but could be useful as a test. 

 

 

 

Keep us posted on what you find.

 

So today I thought maybe the front wheel bearings were bad and causing a wobble that transferred into bad front brake.

I popped off the front wheel and to my surprise the wheel bearings were not loose at all.

The wheel bearings so tight they did not roll.  Not just hard to roll or notchy.  The damn things (both sides) will NOT move.

SO new wheel bearings later and run around yard a bit and I think we are all good again.

Edited by zippy

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My old 03 TXT Pro had a floating front rotor, I thought it was standard.

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4 hours ago, glynn said:

My old 03 TXT Pro had a floating front rotor, I thought it was standard.

you making me jealous.  HA

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On ‎7‎/‎14‎/‎2017 at 11:04 PM, zippy said:

Yep you can make jokes, but after clicking on the "ignore" option I won't have to see them anymore.

Goodbye, have a nice life.

Geeze I am sorry man. I knew you were from up north, but after all the years I never knew you were a snowflake!

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