Floating disc that doesn't float

In my ongoing 'engine build prep' thread I asked for advice as I was struggling to bleed the 6 pot front caliper.

Then, even when I'd done it, and the ever felt great, as soon as I'd pushed the bike down the drive the brake had gone again!

Basically, the floating disc I'd fitted wasn't really floating. It was tight, and had become tight in a Positiion whereby it was not running true. as the wheel rotated, it pushed the pads back into the calipers? As they're 6 pot calipers, a lot of fluid needs to be moved to push all 6 all the way back out, taking 6-7 lever pumps.

Tis was because the retaining pins were a too tight fit. So I relieved the holes so all pins where a nice sliding fit, I numbered the so they all went back in the same place, and I replaced the curved 'E' clips that retained the pins with normal circlips.

The disc now floats freely and the brake works well.

Something other may wish to check when fitting new 'floating' discs'.

I think the the standard circlips are meant to hold the rivets hard against the disc carrier preventing the rivets from rattling - which they will do eventually as the whole assembly wears. Not the best of designs. Having said that I replaced my RGM disc because of radial play with a Hemmings Norvil disc last May. On the way to Cadwell Thursday evening, it became apparent the disc was not running true when suddenly there was severe pulsing at the lever under braking. Returned home to put the rattly RGM disc back on which solved the problem. Ended up with 4 hours sleep to leave at 4.30am to get to Cadwell for 7.30am for signing on for the track day....a bit tired.

Al-otment said:

I think the the standard circlips are meant to hold the rivets hard against the disc carrier preventing the rivets from rattling - which they will do eventually as the whole assembly wears. Not the best of designs. Having said that I replaced my RGM disc because of radial play with a Hemmings Norvil disc last May. On the way to Cadwell Thursday evening, it became apparent the disc was not running true when suddenly there was severe pulsing at the lever under braking. Returned home to put the rattly RGM disc back on which solved the problem. Ended up with 4 hours sleep to leave at 4.30am to get to Cadwell for 7.30am for signing on for the track day....a bit tired.

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I think you're correct Simon. The issue I have though, is that I'm not sure the carrier, or centre part of the disc, that would be pressed hard against the pins as you describe, are machined accurately enough to ensure that the disc will then run true. So, my thinking was / is to allow it to float freely.

I did do two things at once though, relieve the pin holes and change the circlips, so, I may try the original E clips again at some point.

More importantly though... How did the track day go?

Eddie, Norvil sell a wavy washer set to place behind the clip to stop the rattling, it's expensive for what they are but RGM are doing various sized wavy washers for 10pence each. I fitted them to stop my rattle and they worked a treat.

Hi Nige

The original Norvil floating discs had allen heads with alloy washers holding them on. You had to file your new fork legs because they would not allow the wheel to go round once you had fitted it! Even then you had to lock them up to get the clearance. (Carp!)

Chris

Chris said:

Hi Nige

The original Norvil floating discs had allen heads with alloy washers holding them on. You had to file your new fork legs because they would not allow the wheel to go round once you had fitted it! Even then you had to lock them up to get the clearance. (Carp!)

Chris

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I know Chris, been there! When all said and done though, the original Norvil set up works well I reckon.