braking on ball-bearings

well, that's what it feels like.

on the 7R, no handling problems, no problems with braking at speed, no
steering funnies at any speed.

no, what I've got is, when (softly) braking in the last bit between
5mph and rest, it sometimes - maybe 20% of the time - feels like I'm
riding over ball-bearings or a series of small ridges on the ground.
Sort of a notch-ity feeling through the bars.

What's that going to be then - head race bearings? Brake calipers need
sorting?

Yours, clueless of Enfield.

 

Could be warped disks.

 

I've had warped disks before, this feels completely different - a
really quick series of light judders through the bars.

 

Is a regular pulsing, cos that would mean the disks. It would also be worth
checking out your head bearings and examing the road for ball bearings.

 

bearings.

it's not regular pulsing - more like a sort of ratta-tatta-tat random
notchiness. And it doesn't happen most of the time, which is why I
don't think it's warped disks.

And as for examining the road for ball bearings, that was the first
thing I checked.

 

err, don't think so, but I'll check.

what, what?

Sorry, NT, I'll try not to make a habit of it.

 

Try taking your hands off the bars - but not very far off - when going along
and see if the bike shakes its head.

 

It's an odd one. I too would suspect warped disks, but as you say,
that ought to show up at higher speeds too.

I'd try a couple of things - unfortunately, both require the front
wheel off the ground. Do you have a front paddock stand? If not,
you'll have to put it on the rear stand and block the front up
somehow.

1. Check the headraces for loseness. This would be my first guess as
to the cause. With the front wheel off the ground, grab the bottom of
a fork leg with each hand and pull backwards and forwards - can you
hear/feel any movement? [1] If so, you need to tighten them up

2. Spin the wheel and check it spins freely without binding. If
there is a small amount of binding, it may be this only shows up when
the momentum of the bike is mostly gone. If it binds, or there's any
untoward noise, take the calipers off and check the pads are ok, and
that all the pistons are moving.

Those 6 piston calipers are a bit prone to getting un-balanced, in
that if dirt/corrosion stops one piston moving properly, the other 5
carry on, causing un-even pad and disk wear.

[1] I know you may already know how to do this, but I've typed it out
in full for the hoards of newbie lurkers out there.

 

Get a man in. (Simian, ideally)

 

Champ has posted how to check for loose head races, down below
somewhere. To check for notchy ones, just prop the front wheel off the
deck, and turn the bars with your fingertips, and see if you find a
notch in the dead central position.

Really fecked races have more than one notch!

Other than that - the usual. Tyre wear, presure, and just have a llok
at the pads to see they're OK.

 

Worn/loose head bearings can do exactly that. When you're braking from
higher speed or harder, the extra force takes up any slack in the
bearings & holds it there until the brake pressure is released. When
you brake at slow speed or gently, the slack is initially taken up, but
then the weight of the bike pulls it back again. If you're slowing at
just the right rate, you get the two alternating, leading to that ball
bearing feeling.

 

Drum & Bass?

 

I only have a rear stand (which the RGV sits on permanently) I'll work
something out.

I'll check.

uh - that looks like something I'd rather pay someone else to do.

I did, but it's one of the few things I know how to check.

 

Does it make any noise?

Not that I'm claiming to be an expert or anything but when I bought the
Gixer the brake seals were knackered and one of the pads used to rattle
against the disk. Is it possible you might feel this?

Possibly I'd have thought.

 

Champ wrote

The leading/trailing edge of the holes arriving/leaving the pads?

I've ridden dozens of bikes but most of them had drum brakes. The
stopping power of disks is imho such a gift from the heavens that it
shall not be questioned or examined, merely worshipped.

I believe you are right.

 

No. Bollocks.

 

darsy says...

Loose brake caliper bolts?

 

steve auvache says...

Tell that to the **** who writes the bike reviews in UMG then.

 

Bear says...

Done exactley the same myself, that's why I suggested it.

 

AOL, except it was,

"OW! WTF just hit my foot?!"

<grind, grind, crunch, scrape...>

Side stand down... Get off bike.

"I say. I seem to have one less brake caliper than would seem to be the norm
for two front disks".

<looks down>

"...and a brake pad embedded in my boot".

"... and a warranty that runs out in three weeks"

<two days later>

and a free pair of front discs, calipers, pads and a free service throw in
by way of "please don't sue us".