Fully floating discs...identification.

[utopia]

I've always assumed that my discs are the semi-floating type, but I was wondering how one identifies the fully-floating type ....?
Mine have the spoked carrier rather than the ones with holes.
The bobbins have little washer/spring thingies to control the lateral slop.
Its a yr2000, M750 with twin discs from new.

[slob]

The bobbins is the difference, the spring washer makes them semi-floating (use on most modern production bikes). Yours will have likely peened over bobbins with a pain washer and a spring washer. The fully floating bobbins have no spring washer and usually have a groove that takes an e-clip to secure them. The clip will have a blob of epoxy to ensure it can't pop off.

http://www.biketorqueracing.co.uk/btr-tech-station/btr-tech-station-brake-systems/brake-discs/fixed-and-floating-brake-discs
http://motowheels.com/i-7579497-corse-dynamics-full-floating-rotor-button.html
https://www.youtube.com/watch?v=jJPCy2AsULo

Don't forget: your brakes are a safety critical component, if in doubt use a specialist!

[utopia]

Thanks, Rob.

The comparison of drag in your last link is a bit of an eye opener.
The difference between semi and fully floating is more marked than I had expected.

[alan s4]

Every day is a lesson!

Do any bikes come with fully floating discs (as per the vid) I've never come across discs that move around and make so much noise on any bike I've had. I always assumed my discs were "fully floating" - wrong again it seems:mand:

[Dukedesmo]

I have fully floating discs on both my Ducatis, they rattle like tambourines. The MOT tester always comments on them and once gave my 916 an advisory "brake discs worn".

Oddly, they gave me an 'exhaust a bit noisy' advisory on the Monster last year - I think the tester had a headache that day... :chuckle:

[Dookbob]

Some of the rubbish that MOT testers use for "advisories" is laughable. I have lost count how many times I have had to go back and "educate" them.

[slob]

Alan: some of the more exotic models eg 916SPS, 996R or SuperLight. Not seen any other manufacturers doing it and I don't think anything very recent does but I might be wrong.
I have them on my fancy bike, mine have distinctive alternate circles and triangles on the spider and use cast iron rotors, which aren't great in the wet as they take a fraction of a second to bite but have massive power and excellent feel in the dry. They also go orange at the first hint of moisture.
Min. rotor thickness is ultra important as cast iron has been known to shatter with horrendous consequences. Also they have lateral movement but should have almost no radial movement (side to side but not back and forward)
They sound like hell, especially on cattle grids. As Dukedesmo says: most MOT testers tend not to like them.
http://i109.photobucket.com/albums/n61/santav10/Ebay%20stuff/DSC_7038.jpg

[utopia]

Interesting that its possible to buy the full-float bobbins separately.
Though there's a lot of them on each disc so a conversion isn't actually going to be cheap.
But it would be interesting to see what difference they made on their own with all else remaining the same.

I'm not really looking for more braking power.
A little more would be nice but what I'm really after is better feel at ultra low speeds.
I miss the sort of control that I used to get from TLS drum brakes when just trundling through traffic.
The discs always seem less direct/more vague under those conditions (and any slight warping/pulsing is magnified at those speeds too).

[slob]

You can get Brembo floating discs, no problem, but a new set will make the bobbins look pretty cheap. Experimenting with different pad materials will probably give you what you want.

[Darkness]

Thanks, Rob.

The comparison of drag in your last link is a bit of an eye opener.
The difference between semi and fully floating is more marked than I had expected.

Me too, but to be directly comparable you'd need to reduce the number of possible variables, such as by swaping the rotors over a few times on the same bike to eliminate differences in wheel bearings and stiction of the pistons and pads in the callipers?

[utopia]

All the more intriguing to remove my semi-floating bobbins and fit fully-floating ones to my existing discs.
Its got to be worth a few quid of anyone's money just to do the experiment (with no other variables), never mind any improvement that it might bring.
I presume you just carefully grind off the swaging in the std rivets and remove/replace them one by one.
And the front wheel's coming out shortly anyway for a new tyre.

I do intend to experiment with different pads as well (and have to confess that I'm still on the originals .. after 20,000 miles :eek:).
My plan was to follow Zimbo's recommendation of Bendix pads.
But I was interested in the full-floating thing specifically here (thought I'd spotted some going cheap under the radar on ebay, but actually they're not full-floaters).

[slob]

I'd mark the disc and carrier with a sharpie (if you can't find another sure fire clue to orientation) and take the whole lot out together. That way you can give everything a really good clean (obviously taking care wipe your sharpie marks off). Crud in semi floating bobbins is often mis-diagnosed as a warped disc and the old favourite: spinning with a drill and dousing in brake cleaner, is less than ideal.

On a side note, I always warm the hub *gently* with a moving blow torch (so as not to damage paint), before taking out the disc bolts. This softens any thread-lock slightly. Particularly helpful if you've used Ti bolts, which can round off quite readily, since disc bolts often have half-height heads and less contact area for the allen/torx bit. Obviously clean out the threads and use suitable thread-lock when refitting.

[Darren69]

They Brembo clubman ones I have are stainless rotors and billet carriers, I'm not sure if the more common cast iron type are similar. Is there any guidance on how much float is ok? I have some that I intend to fit sometime soon they're not new but very low mileage but I'm debating checking and replacing the buttons/shims first.

Just how noisy are they?

[Dukedesmo]

The discs on my Monster are Ducati/Brembo on which I fitted the full-floating buttons, made by STM, IIRC cost around £80 from PDQ but it was some years ago.

I found it easier to remove the old ones with a grinder fitted with a 'soft' pad as they are a bitch to drill because they're hard and tend to rotate...

[slob]

If you want STM stuff, have a chat with Pompone

[Mr Gazza]

Those cast iron fully floating discs like Slob posted, were fitted to the late M900S (carbie)

I missed out on those by a year with my M900Sie...They just got the standard discs.

I had to replace the originals as they warped. I fitted Arashi wavy discs and EBC organic pads. The brake has just got better and better, with immense power and feel.

I know what you mean about the slow speed feel though Jeff. As the speed gets lower a great deal more sensitivity is needed on the lever...If I nip the new ones too hard at the give way line, it's literally like hitting a brick wall, and can unsettle me to the point of unseating sometimes...Not cool!
Those last few yards before coming to a halt, were when I felt the warped discs too.

You mention the nice feel of a cable TLS...I managed to reproduce that with discs and also have huge power, on an OIF Triumph. I fitted Lockheed racing calipers on standard solid iron discs with the chrome skimmed off, and used EBC "Greenstuff" pads....That was the power part. The feel part was down to little springs that placed over the pad retaining pins, between the pads.
This had the effect of pushing the pads apart....Just a little...They were only very weak springs and could not push the pads much off the disc (I think they might have been from Biro pens?).
It stopped the pads jangling in the calipers, removed any drag and gave a brilliant familliar "Cable" feel to the lever as the miniscule slack was taken up...Much nicer than the woody feel without the springs.
I was worried that the clearance of the pads would allow water to build on the discs in the rain, but that never appeared to happen...The feel and power was just the same in the wet.

Probably the best all round brake I ever had. Not sure if it is possible to fit springs on the Brembo calipers, but I bet more than one would throw thier hands up in terror at the idea anyway?

And finally getting back to the idea of fitting fully floating bobbins to your (presumably) slightly warped discs...Sounds like a bad idea, and the wrong fix...You need straight discs.

[Mark64]

All the more intriguing to remove my semi-floating bobbins and fit fully-floating ones to my existing discs.
Its got to be worth a few quid of anyone's money just to do the experiment (with no other variables), never mind any improvement that it might bring.
I presume you just carefully gring off the swaging in the std rivets and remove/replace them one by one.
And the front wheel's coming out shortly anyway for a new tyre.

I do intend to experiment with different pads as well (and have to confess that I'm still on the originals .. after 20,000 miles :eek:).
My plan was to follow Zimbo's recommendation of Bendix pads.
But I was interested in the full-floating thing specifically here (thought I'd spotted some going cheap under the radar on ebay, but actually they're not full-floaters).

+1 for the bendix pads, reccomended to me by Cornerspeed, I used them on my 900 monster and found them to be great at all speeds.

[utopia]

I like the biro springs idea .. I think.
I might even like it a lot, but will reserve judgement until I've had a close squint at the calipers.

I don't think my discs are warped actually.
They do exhibit the familiar pulsing at very slow speeds often attributed to warping, but ...
I've lived with them now for 4 or 5 yrs (with mot advisories most years) and my persistence has mostly been because I want to solve the problem.
Well that and the fact that its completely unnoticeable above 5 or 10 mph.
I've measured the discs in every conceivable way and they are well within the tolerances for thickness at all points and for truth, inside and out, top and bottom, while fitted on the bike.
I've also cleaned out the bobbins (which have been confirmed to be free) and I've given the disc surfaces a mildly aggressive scouring.
Nothing has made much difference, but ....
I strongly believe that simply using the brakes has slowly but surely improved their performance, and the harder I use them the better they become.
Yeah I know we get used to stuff and compensate, but it isn't that.
I first noticed it after the Mallory trackday in 2011, when they had obviously had a fairly serious seeing to.
This seems to point towards the pulsing problem being possibly linked with some kind of surface "tempering" or "conditioning" of the discs.
The bike began its life with two lady owners, neither of whom rode it more than a few hundred miles ... I suspect that the brakes were never properly conditioned in the first place. (no veiled sexist comment there .. they both just didn't ride it enough to get to know it ... clearly, or they would never have sold it :))
Another possibility that I think is likely is that the bike has been parked up and left for a long period/s with wet pads, which have caused a pad-shaped corrosion on the discs, leading to the pulsing.
And on that subject, I have recently heard of a monster which required new discs after such an event.

Sooooo ....
I think it might actually teach me something if I try the full-floater bobbins with my existing discs.
If they still pulse after that, then its a surface problem ... and I can fix that anyway ... I still have the swirly thing with the wet 'n dry held in reserve.
Or I could just continue waiting while it improves itself.

There is another reason that I'm considering the new bobbins, but that really deserves a separate post of its own.
Which will be a bit later on, when I'm back from the shops.
See if you can guess what it is before I get back.

[utopia]

I see you're all bursting with curiosity and alive with guesses then ....:biggrin:

Its the weight.

Those ally bobbins in Slobs link can save .... half a pound per wheel.
That's a total of getting on for half a kilo (for two discs) of prime, unsprung, front wheel weight, rotating at a decent radius with all its inertial and gyroscopic consequences.
I could fancy a bit of that.
The price doesn't seem that bad at all, considering.
And with an experimental interest on the side too.
Not to mention the potential for an improvement in braking.
And the reduction in drag ... that's totally free bhp, you know !
In fact, they pay you to take it away, via longer pad and disc life and such.

I'm arguing myself into a corner here, aren't I ?
Group buy, anyone ? :dizzy:

[Mr Gazza]

I see you're all bursting with curiosity and alive with guesses then ....:biggrin:

I've been working on it while you were away...Honest.

I figured that it would be about wieght in some way, but though that maybe you had a plan to spin up some Titanium carriers or something like that.....Doh!!....What have I said..:confused:

[Dukedesmo]

Those ally bobbins in Slobs link can save .... half a pound per wheel.


The weight reduction is noticeable as is the reduction in friction (wheel will spin for ages).

Some MOT testers might not like the wording on the STM bobbins though;

http://ducatiforum.co.uk/data/photos/l/2/2262-1382873769-e2923fa49562f96e073803a0515467ab.jpg

[utopia]

Correction .....
The weight saving from the alloy bobbins is not as great as I quoted earlier.
The aforementioned "half a pound per wheel" was a direct quote from the Corse Dynamics specs but I think this is an error.
On their own scales the bobbins actually each weigh 6g less than std, which is a 60g saving on each of my 10-bobbin discs.
That's more like 1/8 lb per disc in total, or 1/4 lb per wheel.
.......which is much more believable.
In fact now that I've clocked the error, the 1/2lb figure sounds completely ridiculous.
I guess I was easily seduced by the attraction of such massive improvements.
Still, its rotating and unsprung so even 1/8lb for each disc is worth saving .... but the relative cost per gram saved is doubled.
And to date, the only prices that I've found are on the prohibitive side for lightweight bobbins.
Fully floating stainless bobbins with no weight advantage are available at a cheaper price though (but may actually be slightly heavier than the std bobbins).

http://www.ebay.co.uk/itm/Motorcycle-floating-front-brake-disc-Bobbins-Circlip-sets-Blackshadow-Uk-/301838079450?hash=item4646f395da:g:Q3wAAOxy4t1SfLv L

[utopia]

Well, I might actually have found a cheaper supplier of lightweight fully floating bobbins.
But there is one dimension that I need to verify and I can't measure my bobbins without first removing them.
So, does anyone have an old bobbin that they could measure for me ? .....Tim ?
I just need the main/effective dia.
I expect and hope that its 13.85mm ... which is available from this supplier.
The alternative is 12.85mm apparently ... which he says is 99.9% unlikely, but they don't do those.

I'll post more details once I know that they're suitable.
Hopefully, that won't require me to drill out my own bobbins to measure.

[Dukedesmo]

So, does anyone have an old bobbin that they could measure for me ? .....Tim ?
I just need the main/effective dia.
I expect and hope that its 13.85mm ... which is available from this supplier.


Using a dial vernier it measures 13.8mm and as a double check (vernier might have 'bounced' a few times!) with an imperial micrometer I get 0.547" = 13.8938mm.

So, yes you want the 13.85. :thumbsup:

[Dirty]

http://media.moddb.com/images/mods/1/13/12122/floatingdiscUI_skinned.1.png

[Darkness]

Some MOT testers might not like the wording on the STM bobbins though;

http://ducatiforum.co.uk/data/photos/l/2/2262-1382873769-e2923fa49562f96e073803a0515467ab.jpg

You would have to be very careful not to lose the wording in use: it looks like it may fade or disappear completely if you keep your brakes polished. :biggrin::biggrin:

[Darren69]

Interesting that the ebay seller says this:-

They can be used either as SEMI-Floating with the anti-rattle washer or FULLY- Floating without the Anti-rattle washer but you may need to fit extra flat washers depending on the thickness of the disc (at an extra charge).
Fully floating is only really suitable for racing as firstly they will rattle and second if you take it for an MOT it will almost certainly fail.

I have heard some MOT testers don't like them but it shouldn't really be a problem since:-
a) There is nothing wrong with the disk, you can buy them like that.
b) Some of the higher spec models already have them fitted as standard.