2014 Stelvio brake disk bobbin shims

[TimOz]

Hi All,
My "new to me" 2014 Stelvio NTX has a pusle from the front brakes as the bike slows to a stop.
I checked he front disk bobbins and almost all were bound up. I have cleaned them up and spun them and all but one seem much better. The the one bobbin that was loose seems to have lost the wave washer or shim. Flappin' around!

Are these replaceable?

If so, where are they available from?

[Markcarovilli]

Google search - there are several sources out of the UK and possibly ebay.  You may have to buy new complete sets....

Mark

[kballowe]

For the tough bobbins, I put a little bolt thru the hole and tighten a nut/washer and then use a drill,  or simply use a wrench.
Also and a bit of brake-clean.  Some of them will just be stiff, no matter what.

After taking many micrometer measurements and measuring runout - the issue (for me) appears to be brake pad material that has become deposited unevenly on the rotor surface.  Take some 220 grit sand paper and work the brake pad mating surface (both sides) on the rotors and then square the brake pads on a flat surface with some 180 grit paper.

This is a good opportunity to flush the old brake fluid, also.

[John Warner]

Pulsing Brakes are unlikely to be down to 'stiff' Bobbins.
I used to recommend cleaning them, until I saw a video where a guy explained that you shouldn't, he made a  lot of very good points, couldn't argue with anything he said, much as I wanted to.
Been trying to find it again.

Have a look here too . . .
http://blackshadow-uk.co.uk/Fitting.html

They sell Bobbins, and all related stuff.

[John Warner]

Found it.
He does go on a bit, but hear him out, see what you think.
https://www.youtube.com/watch?v=hOA5cOrvwRw&t=1s

[TimOz]

Thanks for the replies and Doc for the video link.

I can't seem to find a wave washer supplier. maybe not using the right search terms???

I watched the workshop video and I can't really agree entirely with his views. I agree with his basic physics and most of what he says but applying his views to every floating disk is a bit of a long stretch.

On my bike, one outer disk was not moveable at all. The other, (the one with the missing wave washer) had lateral movement on the section that hade the loose bobbin. The other parts of the disk were locked up.
I used brake cleaner on eack bobbin and now both disks move as they should. I assume that all this is due to road grime and brake dust "gumming up" the wave washers, preventing them from working properly.

Sure rotating the bobbins is probably not required except that it helps to move the crap out of the washer space. I did this using the bolt method thet Kballowe mentions.

In summary:
1. These are floating disck and are meant to float
2. Mine were not floating
3. Cleaned them and now they float again.

I will ride the bike today (37oC here today) and report back on the pulsing.

[Huzo]

A couple of observations..(mostly positive)
Yes he does pad out a bit but that’s because he’s not given that talk enough times.
If you knew nothing about your brakes and were keen to learn, it’d be a worthwhile view.
I soldiered through most of it and unless I missed it, he left out what I think is a salient point.
Machining tolerances being what they are, will mean there’ll be some inaccuracy in the machining of the mounting face of the hub/disc carrier interface.
A 300 mm disc of 150 mm radius mounted on a 80 mm hub surface of 40 mm radius will be about a 4:1 magnification of any machining anomaly at the hub/disc carrier interface.
I’ll suggest that as little as 0.5 thou’ inaccuracy at the hub, will translate to 2 or 3 thou’ at the disc.
If you look at the pad displacement for 1/4 lever travel on the front brake, you’ll see that the pad moves maybe 10 thou’.
So.
A 2 thou’ thrashing motion of your disc, will result in a pulsating motion at the lever 20% of available travel, akin to a cheap Fyshwick toy.....!
On that very topic..(which we weren’t)
Have a critical look at the shape and physical properties of a front brake lever.
I won’t elaborate unless asked to by a moderator...
Anyway...

The bobbins give a self aligning effect to a spinning disc.

[Markcarovilli]

http://blackshadow-uk.co.uk/index.html

Mark

[Huzo]

My Mum had a Singer sewing machine and it only had one bobbin.

[TimOz]

Thanks for the replies and Doc for the video link.

I can't seem to find a wave washer supplier. maybe not using the right search terms???

I watched the workshop video and I can't really agree entirely with his views. I agree with his basic physics and most of what he says but applying his views to every floating disk is a bit of a long stretch.

On my bike, one outer disk was not moveable at all. The other, (the one with the missing wave washer) had lateral movement on the section that hade the loose bobbin. The other parts of the disk were locked up.
I used brake cleaner on eack bobbin and now both disks move as they should. I assume that all this is due to road grime and brake dust "gumming up" the wave washers, preventing them from working properly.

Sure rotating the bobbins is probably not required except that it helps to move the crap out of the washer space. I did this using the bolt method thet Kballowe mentions.

In summary:
1. These are floating disck and are meant to float
2. Mine were not floating
3. Cleaned them and now they float again.

I will ride the bike today (37oC here today) and report back on the pulsing.

So I took it for a long ride (read that as a  hour traffic jam commute) and the pulsing has gone - almost. I would say that 90 % so it certainly did something. I might give the disks a clen and light sand next and see what happens.


On another topic - I know Stelvio engines tend to run cool but I really wanted a temp gauge on Tuesday. The dash thermometer was reading 44oC and I felt hotter than that stuck in traffic due to 2 broken down trucks in the Burnley Tunnel. The bike seemed not to care one bit.

Going to be a few degrees hotter than that today. 43oC in Melbourne usually means 45oC at my place.
Maybe MG dsigned this engine with global warming in mind 
 

[Huzo]

Go for a coffee at the Mt Dandenong summit.

[TimOz]

Go for a coffee at the Mt Dandenong summit.

Great idea. BoM say it will only be 38oC up there!   

[Huzo]

Great idea. BoM say it will only be 38oC up there!   

Try Mt Hotham..?

[John Warner]

I don't disagree with cleaning the Bobbins, but wouldn't spin them with a drill as some videos suggest.
I don't think it's a 'cure-all' by any means.

I think pulsing will quite often be due to the issue explained on the BlackShadow website, where the Rotor gets worn unevenly.
Only measuring thickness at many points, and checking run-out with a DTI will confirm either way.