--- In st2_owners@yahoogroups.com, Colin Forster <ecol@...> wrote:
>
> I have had my ST4S for many years now and have NEVER truly sorted the shuddering front disc issue.
Commiserations, Colin. In your exhaustive list of checks, I see no mention of the calipers. I'm sure, as Eddy says, brake pulsing is a complex issue with many aspects to it. Basically, logic suggests there must be some out-of-true factor in the discs, but there are a number of design elements that seek to cancel or reduce the effects.
My experience concerns not my ST (thank goodness) but a Sachs b805 with twin Grimeca 4-piston calipers. The calipers are very similar to Brembos, but the discs are rather more primitive with fewer fixings to the (spoked) hubs. I got the discs running as true as possible using a dial indicator and cleaned their surfaces thoroughly, and of course I checked the carrier-buttons for free movement. I even modded the banjo-bolts. The only questionable factor left was the freedom of the pads to float within the calipers. The bike had had a very easy life of C3K miles, so I'm sure all was OEM, but those pistons were incredibly tight in the seals. Rather than struggle to find new seals for an obscure make, I bought some s/h Brembo calipers from an early Monster in which the pistons moved freely, and the problem was 95% solved. Just a tiny amount of pulsing remains, which I reckon must be the disc's fault, but at least the pistons are now able to track it and the braking effort is much more constant.
NickW, UK
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