Brake Disc Bobbins

That really is the easiest way to do it, and you won't have any old stuff in there because the new will push the old ahead of it and out. If you drain everything you'll have completely bleed the whole system, and while it isn't as bad as it would first appear, it is no cakewalk.

Also if you're replacing the pads, it's a good idea to clean the gook and grime from the exposed portions of the brake pistons. That way you're less likely to have a sticking piston, or bad seal.

When I installed my stainless lines, including the clutch line, I bought a quart of brake fluid and didn't use but about half of it. But I got pretty lucky and everything went well. I've heard of guys going through a couple quarts trying to get the lines completely bled.

Also FWIW Speedbleeders are wonderful thing.

 

Blasted brake rotors bobbins with cleaner-surprise my brakes aren't sticking any more when the bobbins turn again when going though the calipers. When bobbins don't turn the brake pads are working un even. this makes the brakes grab weird and can upset the bike enough to actually upset your balance. I thought the calipers had junk in them-could be-but by really hitting the rotors with a lot of cleaner what ever crap is now gone. It might take half a can of cleaner to do this-that's a lot and mult times. If the rotors aren't warped-and the bobbins start turning again, you may not have to turn the bobbins manually, but I would do that too. the rubber lines may have not been the problem I was having.

 

Since the fluid in your brake system doesn't circulate, it just pushes out and then returns in tiny quantities, the dirty crap that sits in the lines and calipers can only be replaced by pulling it out the bleeders. It's a really good idea to do this every few years to get the old fluid with moisture in it out of your system. Oh and brake fluid absorbs moisture really well btw.

So suck the dirty stuff out of your master cylinder and top it up with fresh fluid, then attach a vacuum bleeder tool to the bleeder which is the furthest is the system from the master cylinder. Now suck the dirty fluid out through the bleeder until it comes clean and clear. Be careful to not completely empty the master cylinder!! Keep topping it up. It's a simple process really and it does wonders for how the brakes feel.

This is a great tip regarding the bobbins! I'll give that a shot to see if my little pulse disappears. Thanks Randy!

 

To play Devil's advocate here, a member on another forum posted this...(In regards to the use of the bolt to spin the bobbin).

Well, I was curious too and phoned EBC's technical support in the UK.

They have never heard of this, nor would they recommend doing it.

If you still want to go ahead, because neglect caused matters to corrode, be careful not to over tighten the bolt and nut because you do not want to compress the bobbin to a point it may damage or crack.

 

I guess if crank on it hard, there is no need to tighten the bolt that much. Just snug works good. It did make a difference on my bike. I used brake cleaner to flush the dirt out and a dry lube just for a non stick coating for a while.

 

Must say I never really thought about that. But it does make sense.

I guess if it is so tight that you have to reef on it, then that should be a sign that it needs a little more attention than a spray with brake cleaner. But if it does spin, and fairly freely, and does so with increased ease, then I think chances are you are doing yourself a favour. If you are in a situation where you have to use a lot of force on it, you should step back and re-consider what you are doing. Might be time for professional help.

 

If you first put the nut and bolt in by hand and turn only the bolt with a wrench in theory the bobbin should spin before the nut gets too tight. Only if the bobbin is frozen in place should it be possible to over tighten the nut. I would say use only a slight amount of pressure on the first try. If the bobbin is too tight soak it in brake cleaner for a while and try again.

If your bobbins are too tight and you wreck them you needed a new rotor anyway!

Great find Randy! Free advice that keeps us all safer! Gotta love it!

 

HellFire No. Its not free. You all owe me your mistresses but have to keep your wives.

 

I spoke to an EBC tech regarding the "bobbin" thang, and they really did not hear aboot it canada: speeling.) There was a date code that he gave me back when I phoned him which escapes my burned oot mind right now (date stamped on the actual bobbin.) This would corrolate to being able to re-build my rotors with different buttons "bobbins" I never really thought about them until I saw that vid from the UK. Thats what precipitated my phone conversation a while back. Nicest bang for the buck was over-hauling my calipers and cleaning oot the "mug" behind the seals, I then had titz brake lever action. This has nothing to do with ABS btw.

My 93 gen 3 bike has solid rotors and I do notice a difference in initial lever feel and brake dust (got organic blacks on it "blacks".) My 91 with the Pro-Lites, stops different, less progression, better intial bite, less brake dust too, (running EBC Greens me thinks.)

Foot note: I have an EBC Pro Lite rotor on a little chitter commuter and was unhappy the way brake lever felt even after re-building the master cylinder with oem stuff. I ended up buying a Suzuki "massa" cylinder for that bike and it cured my so-called problem. All my bikes have after market steel brake lines.

I may in time get some floating disks from EBC or a front wheel off an F3 (have a F3 front wheel on my 91) I do notice a slight pulse in my lever when I apply them binders on my 93, they are solid rotors remeber. Think a Penske Shock is in my future though, before a brake rotor upgrade. Cheers and Happy and Safe Riding. :vtr2:

Vaccum bleader is a luxury, but may be required for ABS linked brake systems. I have on and its kinda "titz" :stripper7:

 

You know, it's funny that you posted this. I remember seeing this when you first posted this and it was literally a day after I was searching Google for it. I actually found the same video too.

 

Thank's Randy,

Just watched the video, that that does make sense to me now.

 

I bought myself a used disc off eBay which was advertised as "straight", to replace a disc which I know has had a whack at some point in my ownership which caused the aluminium carrier to go out of true. I have straightened that in the past which solved 90% of the shudder, but a little bit remained, so I figured a new (old) disc would be a good fix. I've recently de-linked the brakes and fitted EBC HH pads to CBR600F4 brakes, and these are fierce, and probably exaggerate any shudder.

I visually inspected the new disc when it arrived and it was slightly less worn than mine, lacking the wear lip at the disc edge. I cleaned it (including a bobbin turn) and installed on the wheel and then checked run-out, which was basically zero. I gave the pads (1000km old) a light sand, then went for ride. Much to my surprise the shudder on the new disc was ten times worse. Bad enough to shake and indicator bulb out of its socket.

Assuming contamination of the surface was the cause, I attacked the disc with 220 grit paper, then finished off with brake cleaner. Result: no change, still horrible.

I've put my old disc back on, and I'm back to a tolerable shudder, so there's no doubt the disc is the source. So I took another look and noticed that it appears that the edge of one of the bobbins has been crimped (maybe in a vice) at some point:



This bobbin would turn, but only with a lot of effort. There was also no perceptible play moving the disc against the carrier at this point as well, unlike the other bobbins. Being the man of science that I am, I put a bolt and nut through the bobbin and spun it quickly with my battery drill. It squealed, worked free then started to seize up as friction warmed it. I did this a few times and now it will spin freely. I am interested to see if this has cured/reduced/amplified the shudder!

I don't fully understand why a sticky bobbin would cause the shudder?

 

In other words, that rotor at one time was bent, then straightened. I suggest that if that one bobbin is to tight and does not move freely in the socket as it is designed to do, maybe this causong the shudder because the rotor does not float enough to make up for minor imperfections in the trueness of the rotor

 

Actually Randy, based on the lack of runout I don't think the discs have been straightened, but someone has tried to crimp the bobbin tighter for some reason. The disc and carrier are unmarked and very true, the only sign of mistreatment is the bobbin.

My test ride after working the bobbin was disappointing, the shudder was as bad as ever. My fall back position is to reinstall the old disc, so I will next see about checking the gap between face of the disc and the bobbin using feeler gauges, and if the crimped one is tight, maybe prying gently with a chisel.

 

Makes me wonder if PO discovered the play in that bobbin, didn't understand tbe functionality of that play, and wrongly tried to tighten up the bobbin. I think you have found the cause of that shudder though.

 

replace with new part

 

Thanks SOW. I have ordered some of these just for you:




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Well more close inspection done, now I know where the shudder comes from. The disc is unevenly worn on the inner edge like it wasn't bolted up square on the original wheel. There's a reasonable lip at the edge of the swept area over half the rotation but not the other. The reverse is true on the other side. One for the bin.


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How are those wear marks in relation to those vise burrs? Does it look like PO had discovered that and tried to fix it? If so, that asshole should hang his head in shame for selling off damaged goods as vital as brake parts.

 

Not really much relationship. I doubt that the wrecker would have any idea the wear was there as the outer edge of the disc was true. I suspect the wheel had some imperfection that stopped the disc sitting true, so it wore unevenly. Probably not noticeable when used originally.


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