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How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 3:15 am
by Sibbo
and no, I'm not going to tell you how thin/ thick mine is ... but she stops just fine.
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 4:35 am
by ME 109
Sibbo wrote:and no, I'm not going to tell you how thin/ thick mine is ... but she stops just fine.
Manual says 4.5mm
4mm would pull it up for me.
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 7:17 am
by Sibbo
Well, mine is 4mm and it pulls me up pretty well but the price of a new one from Motobins is 250 quids ... $527 + postage !
Shudder !
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 7:20 am
by Kurt in S.A.
Yeah, that whole stopping safely thing is over rated!
Kurt in S.A.
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 2:00 pm
by Major Softie
The minimum thickness on a disc is for two reasons: stability of the disc material, and the dimensions of the caliper/pads.
On these old bikes, the disc starts out so thick that is is possible for the disc to become thin enough that, with severely worn pads, the caliper pistons may travel out too far, which could lead to them jamming (sudden violent stop), or catastrophic brake failure (sudden violent stop when you hit that thing in front of you because you have no brakes).
So, I personally would never run a disc past it's minimum spec with really worn pads, as I consider that to be suicidal. With nice new to 50% pads? Well, probably a terrible idea, but one which some crazy Aussie bastard could probably get away with.
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 2:15 pm
by Bamboo812
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 5:19 pm
by Sibbo
Thanks, that's much cheaper but it doesn't mention R80 ST which is my model. I'll email them and ask.
Bremsscheibe /6/7,RS,RT 1974-1985
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 5:24 pm
by Bamboo812
Yep, different part number; MaxBMW lists them for $377.36, but S.Meyer lists the correct one for 199 Euro:
http://www.meyer-bikes.de/index.php?pag ... 4111236005
Re: How thin can a single front disc be allowed to become ?
Posted: Thu Oct 15, 2015 5:46 pm
by Sibbo
Thanks, very much appreciated !
Now I just have to steel myself to another A$400 on top of the last $800. But this has to be done.
Re: How thin can a single front disc be allowed to become ?
Posted: Fri Oct 16, 2015 12:55 am
by Airbear
Mine measures 5.0mm, but I keep it well greased.
er, that's a joke, a very silly joke.
I've just ridden home from town with two new tyres (Lasertec and Pilot Activ) on beautifully balanced wheels, and a very wide grin. I love it when front and rear tyre replacements coincide. I had to keep telling the old dear to take it easy in corners for a while, but would she listen?
Sibbo, if you had a new bike you would be paying dollars like that for each service.