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"So, do I go with the Chinese discs or try and track down a good second hand pair? I dont see why I should pay a vast premium for Brembo discs when they seem to warp so readily on this bike!"

Quality may be suspect on the Chinese but seriously , I doubt your discs are warped , try as Mark suggests , cleaning the bobbins. I put a long bolt through each one and secured with a nut then attached a cordless drill and sprayed with brake cleaner whilst spinning an the muck that came out was amazing...

If you look for SH discs in spec , what guarantee will you have that you dont just inherit the same problem ?

If you decide to replace any way try Galfer they are a bit cheaper once you include the pads (often sold as a discounted package). I have them and although I dont particularly like the 'feel/action' of the pads the disc quality is good.
 
Discussion starter · #24 ·
Oh, I'm pretty certain its the discs. As said above, I have 'spun' the bobbins to free them off which made no difference. I then cut out the star washers to convert the discs to full floating which made no difference. I then sanded the discs and removed all paint off the hub flanges which made no difference. Well, actually thats not true, the 'pulsing' through the lever at low speeds is now much more obvious. Pistons all clean and free and wheel bearings and headstock bearings are fine. If there is anything else to check then please let me know as I've reached the end of my list :)

Keith
 
Keith , seems you have checked all the normal likely culprits , and as Sherlock says "Once you have exluded every alternative possibility , what is left must be the answer"
So warped discs it is then :)
 
Oh, I'm pretty certain its the discs. As said above, I have 'spun' the bobbins to free them off which made no difference. I then cut out the star washers to convert the discs to full floating which made no difference. I then sanded the discs and removed all paint off the hub flanges which made no difference. Well, actually thats not true, the 'pulsing' through the lever at low speeds is now much more obvious. Pistons all clean and free and wheel bearings and headstock bearings are fine. If there is anything else to check then please let me know as I've reached the end of my list :)

Keith
Hi Keith,
I've been trying to sort out this problem for the last 2 months and i have done everything you mention above and the only thing left was the rotors.
Didn't wanted to believe it since it is a very expensive part but it needed to be done after all. (Mine weren't brembo)
After i have replaced rotors any vibrate/pulsing disappeared immediately.
Also i thing there there is no way to check discs if warped by spinning the wheel and using your eyes.
 
Keith, on the front end vibrations, i'd say recheck the steering head bearings when the bike has been running and the frame is hot !, ride along the road then wedge a finger from your left hand between the top yoke and the frame, then pull the front brake and see if you can feel any vibration/movement.

I found the normal static way to test the head bearings didn't show any play, but riding the bike and doing the above did, it's worth a try.
 
LOL it sounds more like one of those old fashioned motorcycle tips featuring tights, a detergent bottle and a boot lace. My tip for the STs carbide lamp is to use one of the wife's hair pins and some snuff.


Sent from my iPad using MO Free
 
Hey, hey, HEY! =P

That light, I mean candle, has gotten me through 4yrs of rainy commutes and short northern latitude days in the winter. It isn't great and I'm biding my time for an upgrade, but. . . ;)

Have a good one.
 
Discussion starter · #31 ·
Thats certainly an interesting tip for checking head races. I've still not made further progress mainly due to a 3 day working week and job uncertainty which is curtailing spending. If I was absolutely certain it was the discs I would spend the money but there is still that nagging doubt. Its no big deal if I dont get it sorted this year but I want to do at least one track day next year but not with those brakes :)

Keith
 
Discussion starter · #32 ·
I took a risk on some second hand discs. It was a bargain price as the listing was mis-spelt and when I got them I was delighted to see they were nearly mint. I slapped them straight on using the old pads and without bothering to free off the bobbins and straight away its clear that it brakes beautifully now :D Thus, confirming that my discs were the problem. I'm sure they were not warped and the micrometer suggests that slight variation in thickness was most likely the problem. I am assuming that they must have worn that way as there were certainly no deposits on the metal.

Unfortunately, the bad news is that near the end of a fun blast it started surging and firing back though the air box. It then completely dropped one cylinder :mad: I'm hoping its just a bad plug or loose connection but this bike is really making it hard for me to like it.....

Keith
 
Hello Keith,
Glad you sort this out.
Btw since the problem was not because of warped discs but because of bad wearing, can you see any weird wear pattern on the surface? What brake pads were you using? Don't you think you should replace them?
 
Discussion starter · #34 ·
The disc surfaces on the 'old' dics look fine and are clearly nearly new. I could see no warping when spinning them on the lathe and the full floater conversion should have coped with a certain amount of movement any way. I could measure a small thickness discrepancy around the disc with a micrometer(cannot remember how much) so that must have been the culprit and would certainly cause the pulsing through the lever. I have to assume they were fine from new so all I can think of is that the hardening process was not uniform around the discs and they have worn this way.

I agree I should fit new pads as best practice. However, its obviously also not best practice to fit second hand discs :) The pads are nearly new and the brakes are so much better so I'm going to stick with what I have.

Keith
 
Brake pulsing

I suspect your rotors are warped, but the warp only appears when the rotors are hot and the metal has expanded. It's likely caused by, or exacerbated by, the thinness of the rotor.

I have the same issue with my Toyota Tundra...

Best,
Kate
 
Truck equipment is heavier than cars, obviously, but modern automotive rotors depend on accurate lug nut torque for them to be true while mounted. Using a torque wrench on your lug nuts, esp after a shop has touched them (loosen and retorque), will usually true up rotors the rotors unless they have been warped for a while and worn into that pattern.

Have a good one.
 
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