Not the Real '89 VFR -a mild custom

I have handled a bunch of these as I have disassembled a lot of parts bikes and wheels, so I always seem to have plenty of extras when rebuilding a bike.

But if I needed some, it would absolutely be worth a try to source them alternatively (cheaper). The material doesn't feel that exotic or anything.

Heat, crush, water, chemicals (like wheel cleaners - light acid).

A real benefit would be to have a known good system where you could swap them out for comparison. Good luck and do report back.

 

Well - Yes! The Cure, all fixed and me somewhat wiser
Finally gave up after fitting new, home punched fibre washers and using the factory torque settings when fitting the discs back into place.

So, I removed the front wheel yet again, un-bolted the discs and measured them for the umpteenth time and concluded that there was a very minor thickness variation around the disc circumference -0.03mm, in and out, with no rational explanation that I could give.
Contacted a local manufacturer here in the Brisbane area (Metal Gear) and asked if he was prepared to take a look at them and give an opinion.
He said "Yes" and subsequently measured the discs to inform me he found the thickness variation to be as much as 0.06 on one disc, the other a bit less
and after placing both discs on his granite certified flat surface, one had a warp in it (He took me through into the factory and showed me this)
"These are cheap, no brand Chinese knock offs, only fit to be thrown away - take them back to where you got them and get your money back."
(I did, and they did give me a full refund!)
Metal Gear sold me a set of their own discs which I fitted, and straight away there was no longer any vibration and the bakes worked as I might have expected.
Incidentally the "no brand" discs were also 5mm thick (approx.) and were engraved with "minimum thickness 4mm" where Metal Gear say the factory thickness should be 4.5mm and minimum thickness 3.5mm.
Metal Gear say any thickness variation beyond 0.01mm will be felt through the brake lever and create vibration when stopping, and this cannot be compensated for by floating calipers, and will "not" bed in with time.
However, wheel mounting pad discrepancy, such as the existing 0.4mm (my measuring) on my bike can be compensated for by a properly operating "floating Caliper". In fact, this was one of the reasons floating calipers were used back in the days of early motorcycle disc brakes they told me. Higher precision machining on later manufactured bikes has subsequently permitted a number of variations to disc brake setup.

I have learned my lesson! Even though I was purchasing the discs from a company that has its base in the UK, and the stock was delivered from the UK I was informed, I now believe it originated in China.