Front Disc Bobbins

Beeroclock · Aug 22, 2025 at 8:00 AM

Hi all, my Sprint ST has just failed its CT (MOT) on excessive radial movement on the front disc. I know the bobbins are there to allow a little axial movement but not radial.
I have looked at the cost of a new disc and when I had recovered from my light headed moment I started searching for another fix.
I found that BMW and some others do a bobbin replacement kit.
Apparently, the bobbins are made from softer stuff than the disc and therefore wear first.
Has anybody heard about this or have experience?
I am going to remove the disc and drill out a bobbin and have a look later, will keep you posted

Adie P · Aug 22, 2025 at 8:20 AM

Beeroclock said: ↑

Hi all, my Sprint ST has just failed its CT (MOT) on excessive radial movement on the front disc. I know the bobbins are there to allow a little axial movement but not radial.
I have looked at the cost of a new disc and when I had recovered from my light headed moment I started searching for another fix.
I found that BMW and some others do a bobbin replacement kit.
Apparently, the bobbins are made from softer stuff than the disc and therefore wear first.
Has anybody heard about this or have experience?
I am going to remove the disc and drill out a bobbin and have a look later, will keep you posted
Click to expand...

Am I missing something here? Why drill out the bobbins - don't they unscrew?

I replaced discs on a recent Daytona purchase and bought new titanium bobbins - no rust, no fuss. Just hope that blue loctite is OK on titanium.

Beeroclock · Aug 22, 2025 at 9:02 AM

Hi and thanks for your reply.
No they dont unscrew they are riveted together in the factory

Adie P · Aug 22, 2025 at 1:05 PM

Ah, apologies, OK - my mistake ... I thought you meant the disc to hub carrier bolts but now realise you mean the rotor to centre/hub carriers which, as you say, are factory pressed. No cheap and/or easy answer for you, I fear.

I'd guess your best bet will be to keep an eye on ebay for good used. Wish you luck.