front brake upgrade: post-mortem
Posted: Tue Jan 30, 2007 2:17 pm
I posted last week about the problem I had upgrading to a 320mm front
rotor.
Apparently Blake ran into the same snag with his install, which was
stripping out the threads in the aluminum caliper relocation bracket
that came with the new rotor. I had originally blamed cross-threading
but I think he nailed the actual problem, which is that we had both
tried to torque the mounting bolts to stock spec (18 ft-lbs if I
recall correctly). The soft aluminum wants substantially lower
torque, which seems obvious now, but in the rush to farkle, one
doesn't think ...
I ordered an M8 thread insert kit off eBay ("PermaCoil" - $15 shipped
for a dozen inserts, tap, and insertion tool) and it took about 10
minutes last night to drill out the receiving hole, tap it, screw in
the insert, and grind it flush (that portion of the bracket is a lot
narrower than an insert is long). I doused the insert with blue
threadlock and put it all together with the original M8 bolts. Seems
rock solid now, I'd venture moreso than the hole I DIDN'T mangle.
The 320mm rotor with Galfer Green pads (had EBC pads before) has
completely transformed the braking experience of the bike, though I
haven't tried anything like a radical stop as the pads are bedding
in. I think I'll consider this an essential first safety upgrade for
future KLRs in my life.
The rotor upgrade kit (from klr650.com) also came with a stainless
steel brake line, which I installed before the mangled thread stopped
the rest of the operation. So I got to experience that particular
upgrade in isolation for a few weeks. I have to say I didn't notice a
significant improvement in braking performance from the ss line
alone. I guess as a result I would recommend that as more of a
preventive maintenance farkle for old bikes like mine (88) whose
stock rubber lines are probably on their way to being pretty
degraded, rather than as something you ought to rush off to do at
first opportunity. YMMV.
Tim
Los Gatos, CA