Front disc bobbins.

TWISTANDGO · Post by **TWISTANDGO** » Tue Jun 27, 2017 7:49 pm

Hi all, have a 1990 Exup, with blue spots and goodridge hoses, but orginal master cylinder, brakes work"ok" but take some pulling, and certainly wouldn't do a "stoppie". Having spoken to people, and read a post on here about the disc bobbins l checked mine, l can turn them all with pliars, but cant feel any real side movement of the disc, just before l buy the R1 caliper, would the bobbins being tight affect the braking performance, there is no judderingeven under heavy braking, thanks..

Post by **Stig** » Tue Jun 27, 2017 8:28 pm

If the bobbins aren't silly loose then they'll just be keeping the rotor on centre to its natural track
I'd say the poor performance would be down to the master cylinder being mismatched. It'll make a huge difference changing it

Post by **nugget** » Tue Jun 27, 2017 8:51 pm

Like stig says. Change the mc and you'll be going over the handlebars.

Jay762 · Post by **Jay762** » Tue Jun 27, 2017 9:22 pm

yup it should be proper 2 finger braking with the blue spots

TWISTANDGO · Post by **TWISTANDGO** » Tue Jun 27, 2017 9:41 pm

Thanks for the info, master cylinder it is then, is there a specific year R1 or thunder Ace master cylinder before l start searching for one??

Post by **Stig** » Tue Jun 27, 2017 9:43 pm

Any that comes from a bike with the same style calipers

I've got the later R1 radial type to try next

TWISTANDGO · Post by **TWISTANDGO** » Tue Jun 27, 2017 9:52 pm

Thanks Stig, the blue spots on the bike are the ones with the link pipe from one side to the other?

Post by **Stig** » Tue Jun 27, 2017 9:54 pm

They're from the Ace but it don't matter re:master cylinder
Same mc fitted to blue,silver and gold spots

TWISTANDGO · Post by **TWISTANDGO** » Tue Jun 27, 2017 10:05 pm

Cheers Stig, let the search begin, l managed to get my Exup valve sorted by the way, had a new outer bush made, much quiter now!! Will let you know how l get on with the brakes, thanks again to all.

TWISTANDGO · Post by **TWISTANDGO** » Sun Jul 23, 2017 10:05 pm

Hi, just an update on my front brake issues, well how right were you guys, thanks Stig, Nuggett, and Jay, got a mint Thunder Ace master cylinder off ebay, did the fork oil seals at the same time, and the brakes are now transformed, cannot believe the difference, big, big thanks to you all, bike is now ready for going to the Classic TT in August!!

Jay762 · Post by **Jay762** » Mon Jul 24, 2017 10:31 am

Great result!! easy fix we like those