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Front Brake Rotors - not warped just not floating

Campagman

Cruisin' Guzzisti
GT Contributor
Joined
Dec 1, 2009
Messages
346
Location
Manchester, UK
Seen a few threads on warped rotors over the years.

I believe my front discs were slightly warped, showing up as a pulsing on the lever during low speed braking, this became worse more recently. Mentioned it locally and it was suggested that I clean and power wash the floating fixings on the rotors as they can stick. Just trying then on the bike suggested very little float.

So I dropped the wheel out, took of the rotors, then used some biodegradable cleaning fluid (MuckOff), a light brass wire brush and following up with high pressure jet blast. Finally, I carefully lubed the fixings with WD40.

Cleaned up (making sure no WD on the braking surfaces) and refitted, taking the opportunity to clean the hub and spokes and a very brief walking pace test ride showed no pulsing, problem solved. :D :D :D Should improve my low speed handling.

Also gave the bike a generally clean up and polish, doesn't happen that often, but it does look good now. :D
Some ideas for next winter to maintain the appearance - Corrocoat the headers and link pipes, maybe powdercoat the rocker covers (black) , the sump guard, the engine bars and pannier frames.
 
WD 40 isn't a good lubricant. Also any lubricant used there will attract dust and cause the initial symptoms to reappear in short order. I'd recommend removal all traces of WD40 (denatured alcohol comes to mind) and either keep the area dry, or locate a dry film lubricant. Really I don't think any lubricant could survive in the rotor button environment with all the forces applied.
 
Thanks John, accept that WD40 isn't a lubricant as such but its good at getting stuck thing freed up ;which is exactly what it did, then cleaned off to avoid getting on the friction surfaces.
Correct the best prevention from now is to clean the rotors more often (maybe should clean the bike in general more often anyway).
Main purpose of the post was to reflect upon the lack of float and the impact on braking action that can be remedied by a simple cleaning process.

Also took a look at the WD40 web site - I now know what it stands for (be a good pub quiz question :D )

Here it is http://wd40.com/faqs/
 
Having been an aprilia rider for over 8 years I am used to this problem. If they are the same fixings that have a petal shaped washer on the inside of the disc/rotor, we used to use a flat sharp knife to slide under and lift either every petal or every other one to take the pressure off and allow the disc/rotor to float easier.

windy
 
The non floating issue is a common one with the Brembo design. Here's a way to get them to float without taking the whole thing apart: Use a 6mm allen head cap screw that is about 1/2" longer than the width of the bobbin. Run the screw through the bobbin and lock it in place with a lock nut. Chuck the appropriate allen socket in an electric drill and use the drill to spin the bobbin. You might need to tap the bobbin with a small hammer to break it free but when you get it to spin you will dislodge the crud that is holding everything in place and keeping from floating. I could do the fronts on my Ducati in about 30 minutes, good for a year or so.

Peter Y.
 
Or when you're done dealing with them and ready or in need to replace them, I highly recommend the new Brembo "T-Drive" per below. I have them in my Store here; https://www.guzzitech.com/store/produc ... pathway-10 (use the drop-down menu to select)

brembo-tdrive.jpg
 
The buttons were lubed originally with a very light coat of a moly paste. I have replaced the bobbins with full floaters many times on many different bikes. The full floater buttons come out with a clip, and allow you to take them out clean and re-lube(I have used honda moly 60 many years now). Most of the time the pulsing is caused by un-even build up of deposited brake pad material, and a good scrubbing of the rotors (outer rings) and a re-seat of the pads cure the problem.

cleaning
method 1: bead blast with fine (clean fresh glass beads) do not re-use old contaminated dirty beads...some folks say this is not a good way to clean rotors, but we have done the race bikes for years like this and never had issues...but the beads were 1 USE and CLEAN

method 2: use grey (gray) scotchbrite pads and then wash the rotors

both require a re-bed of the pads.

Note: you will have to drill out the old spools but this is a 20min trivial job.

Use very little lube on the new spools.

P.S. coming to a full screaming stop from high speed or down a long grade under heavy braking...then keeping the calipers clamped hard after the stop is a easy way to induce pulsing (but the rotors are almost never warped) just locally (were the pads were on the rotor) dirty

Bedding is putting an even deposited film of pad material on the rotor surface
 
Would you believe it..... Ever since I got my Stelvio the front has 'pulsed' at walking pace but nothing above 15. Mph... Thought the disc was warped , like you do, and sourced a used replacement from guzzibits ..... Which turned out to be worse than the one I was replacing.... Then I saw this thread.... I gave each bobbin a light tap with a soft faced mallet and the problem has completely gone.... Just as I was about to buy a pair of Brembo discs from eBay for £400.... Thank you all who contributed... A pint to all when I see you.
Glenn
 
Glenn.1 said:
I gave each bobbin a light tap with a soft faced mallet

that's part of my annual scheduled maintenance, in addition a blast of compressed air to each side of the bobbin is done. As a static test. I tap the rotor lightly with the plastic end of a screw driver and listen to the sound - a stuck bobbin sounds duller.(?) - at least different.
 
Wellll y'all just fixed my 2011 Cali on the cheap. 12,500 miles and the pulse just started. Supposed to be a rainy weekend here in Florida so I guess I'll swat deer flies and skeeters and fix rotors.
 
Looks like I may have replaced my "Warped" rotors for no good reason. Redline originally told me they were warped and I just assumed they knew what they were talking about. Got some very nice Duc rotors on there now and no more wobble. So they either were or weren't. But, I'll never know now.
 
Toadride said:
So they either were or weren't. But, I'll never know now.
They're warped, else I wouldn't have replaced them for you. :pinch:
 
Oh sorry Todd. I didn't know if I had actually asked you if oyu could see the warp. No offense. :oops:
 
Toadride said:
Oh sorry Todd. I didn't know if I had actually asked you if oyu could see the warp. No offense. :oops:
None taken, the runout was horrible with loose buttons and the thickness was below the minimum. You got some good life out of them, what was is 24k KM?
 
On thinking about it you know.... Although i accept that the floating rotor has ceased to float .. It seems incredible that a bit of crud in the bobbins lock so tightly that it causes the whole front end to wobble.... Surely , you would have thought, if the disc was sat crucked on the rotor, as soon as the brake is pulled , it would true up the disc and break the crudded seal on the bobbins as opposed to making the whole front end vibrate....... Just saying!!
 
My 2V norge has done 95000 km and there has been no sign of disc problems. Stil original discs and only third set of pads. I dont ride like a grandma would possibly ride and Im happy with the brakes. A friend has a 2V norge with only two consecutive frame numbers from mine and he has had no end of problems there. Often also is is detirmined that discs can have a different grain structure on one part of the disc causing a different friction coeficient, caused by the cooling process when manufactured."BMW late 80s tech info".
 
Glenn.1 said:
On thinking about it you know.... Although i accept that the floating rotor has ceased to float .. It seems incredible that a bit of crud in the bobbins lock so tightly that it causes the whole front end to wobble.... Surely , you would have thought, if the disc was sat crucked on the rotor, as soon as the brake is pulled , it would true up the disc and break the crudded seal on the bobbins as opposed to making the whole front end vibrate....... Just saying!!

Check out apriliaforum.com tuono or rsv section and search discs, or bobbins, you'll find loads of info and "how to" on freeing up the petals on the spring washers. You are, of course, right it shouldn't happen, if it is this problem the wobble is usually felt at low speed for some odd reason..

BTW, I lived up your way for a few years, Drighlington and worked in Bradford in the early nineties :D just thought I'd mention that.. :whistle:

windy
 
Glenn.1 said:
On thinking about it you know.... Although i accept that the floating rotor has ceased to float .. It seems incredible that a bit of crud in the bobbins lock so tightly that it causes the whole front end to wobble.... Surely , you would have thought, if the disc was sat crucked on the rotor, as soon as the brake is pulled , it would true up the disc and break the crudded seal on the bobbins as opposed to making the whole front end vibrate....... Just saying!!

Truly 'warped' rotors are very rare IMHO.
Often, as mentioned a few posts back, you get a bit of pad material baked on a single spot after a hard stop. That will grab the rotor as it goes by and really shake the bike.
I use 3M Rolok disks in an angle grinder to clean the rotor surface. They come in various grits. They make versions of these just for this purpose, because it is so common.
 
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