Motorcycle Racing Forum

Motorcycle Racing => Wrenching => Topic started by: tshort on August 22, 2007, 01:18:17 PM

Title: gixxer front-end: warped rotor
Post by: tshort on August 22, 2007, 01:18:17 PM
This is a real newb question.  I bought an 05 SV with an 01 gsxr 750 front end on it.  Had EBC pads, which I replaced with vesrah RJLs around four race weekends ago.  During this last weekend I had the bike up on its front stand and was checking out the front wheel, when I noticed a couple things:

1. the rotors (stock SV wheel and rotors) were a blue/black color, both sides
2. the wheel seemed harder to spin than I expected
3. giving the wheel a spin, it hung up at the same spot each time it went around
4. the vesrah pads appear to be pretty worn down.

Now - I'm no expert, but my guess is I've got one or both rotors warped.   :err:  And I'm guessing it could be due to one of two things:

1. when I put the pads in, I should have made sure the calipers were clean and the pistons were moving freely - maybe they were in need of a rebuild; and as a result, the pads weren't pushing back fully after letting off the brakes.  I've used these pads before and they lasted a whole season, so I'm guessing the current wear rate is not right.

2. when I remounted the front wheel, I didn't get the axle seated/aligned properly, and it is holding the wheel at an odd angle to the calipers/fork leg sliders (inverted forks).  I believe I snugged up the axle, then took it off the front stand, pumped the forks a few times, then tightened up the axle pinch bolts. 

Any thoughts/suggestions welcome. Regardless, would love to know what the correct procedure is for remounting the front wheel to make sure the axle/wheel/rotors/calipers are all properly aligned.

Thanks!

ps-  if you want to see some pix from the last AFM round out here at Infineon, there are some shots here: http://gotbluemilk.com/web070819/280/index.html 
Title: Re: gixxer front-end: warped rotor
Post by: Sobottka on August 22, 2007, 02:03:24 PM
not sure of the other stuff but vesrah's always turn your rotors blue. its not a problem though, if you change to another pad the blue disappears
Title: Re: gixxer front-end: warped rotor
Post by: tshort on August 22, 2007, 05:10:38 PM
No kidding?  Thanks, Rob - hadn't heard that before. 
Title: Re: gixxer front-end: warped rotor
Post by: resurection on September 15, 2007, 01:10:03 AM
The affect of the blue is still there ....
Tape a pencil to the fork as close to rotor as possible ,spin wheel you will see worp .
An indicator of sorts .Of course if you have dial indicator us it.
Title: Re: gixxer front-end: warped rotor
Post by: frskbm1 on November 22, 2007, 08:08:11 PM
blue/black is a sign of excess heat- one way to check the rotor/rotors is to use a 12 stell ruler/scale using it as a straight edge- clamp or have a pal hold it and measure with a feeler gauge and check against factory allowable tolerances- check thickness also at this time- you will need a micrometer or caliper gauge- too thin won't dissapate heat fast enough--is there too much brake fluid in the system-- heat expands it and with no place to go it makes for dragging brakes--using the rotor as a wedge so you don't let the piston/pistons come out too far check movement. should squeeze back with hand pressure. do the caliper ride freely on the pins-- check rubber brake lines for internal collapse with traps fluid not letting go of rotor.all this applies to cars also  mike lrrs517
Title: Re: gixxer front-end: warped rotor
Post by: Super Dave on November 23, 2007, 07:52:21 AM
Quote from: sobottka on August 22, 2007, 02:03:24 PM
not sure of the other stuff but vesrah's always turn your rotors blue.
I'll re direct.  Yes, this is true of some motorcycle pads.  The material that they deposit on the rotors is blue to black.  Still, you should be checking for heat issues.  Braking generates heat.
Title: Re: gixxer front-end: warped rotor
Post by: ahastings on November 23, 2007, 09:47:56 AM
Quote from: tshort on August 22, 2007, 01:18:17 PM
This is a real newb question.  I bought an 05 SV with an 01 gsxr 750 front end on it.  Had EBC pads, which I replaced with vesrah RJLs around four race weekends ago.  During this last weekend I had the bike up on its front stand and was checking out the front wheel, when I noticed a couple things:

1. the rotors (stock SV wheel and rotors) were a blue/black color, both sides
2. the wheel seemed harder to spin than I expected
3. giving the wheel a spin, it hung up at the same spot each time it went around
4. the vesrah pads appear to be pretty worn down.

Now - I'm no expert, but my guess is I've got one or both rotors warped.   :err:  And I'm guessing it could be due to one of two things:

1. when I put the pads in, I should have made sure the calipers were clean and the pistons were moving freely - maybe they were in need of a rebuild; and as a result, the pads weren't pushing back fully after letting off the brakes.  I've used these pads before and they lasted a whole season, so I'm guessing the current wear rate is not right.

2. when I remounted the front wheel, I didn't get the axle seated/aligned properly, and it is holding the wheel at an odd angle to the calipers/fork leg sliders (inverted forks).  I believe I snugged up the axle, then took it off the front stand, pumped the forks a few times, then tightened up the axle pinch bolts. 

Any thoughts/suggestions welcome. Regardless, would love to know what the correct procedure is for remounting the front wheel to make sure the axle/wheel/rotors/calipers are all properly aligned.

Thanks!

ps-  if you want to see some pix from the last AFM round out here at Infineon, there are some shots here: http://gotbluemilk.com/web070819/280/index.html 
.How is it possible to get the axle misaligned so that the wheel isn't square to the calipers and forks? Something sounds strange there? Are you sure it is an SV wheel and rotors ? That is odd with a GSXR 750 front end as you would have to have adapters made for the brakes as the SV rotors are like 30mm smaller and it would require some special spacers and bearings becasue the SV axle is about half the daimeter of the GSXR axle. I had the same front end on my SV superbike but with a gsxr front wheel.
Title: Re: gixxer front-end: warped rotor
Post by: GSXR RACER MIKE on November 23, 2007, 11:54:59 AM
So Tom, since this was 3 months ago, did you ever come to a conclusion?