Update on the Ducati600ss brake problem

Thanks once again for all your help!

I have finally discovered the problem by removing the caliper and refitting;
the brake disk isn't central between the pads, it is pressing against one
pad continually while the other pad is a mile away from it. Leaving the
caliper mounting bolts loose, I get a very firm brake lever, but tighten the
bolts and the lever is loose again. The disk is in good condition, not
warped or bent and I have double-checked that the caliper is the correct
one. Main thing is, I have no air in the system LOL.

According to Ducati, I can adjust the front wheel which may have been
mis-aligned to begin with, or maybe even mis-installed, causing one fork leg
to bend inwards and cause the problem. Typically, the caliper needs to come
further away from the wheel, which means I can't stick a spacer or shim on
it anywhere. Apparently it's a case of slackening the fork pinch bolts,
tapping the wheel with a (rubber) hammer until the disk lines up correctly,
then tighten bolts, without actually having to loosen or remove the axle.

Yes, I should have thought to check the positioning of the disk and pads,
but I'll put it down to experience and once again, many thanks for the help
guys. By far the best advice I've had on usenet on any subject, and always
useful for the future.

Tomorrow's subject - "please help, my wheel fell off" haha.

 

You can't mis-align a front wheel. You just can't. You *can* get the
forks slightly twisted in the yokes but as the caliper would turn with
the twist...

This sounds possible. I would suggest that you may have left out a vital
spacer or something.

 

You can, but only if the threaded axle insert in the left-hand fork leg
has not been installed properly I think.

Chances are that the left-hand fork's axle pinch bolts were undone
when the axle was taken out, and it has moved inwards slightly -
this would throw everything over to the right and hence the caliper
needs spacing over.

Undo the left-hand fork pinch bolts at the bottom and make sure
that the threaded insert is fully pushed home - you may want to
insert the axle (without wheel is fine) and then tap it through.
Once that's done, tighten the left-hand pinch bolts only to the
right torque then remove the axle. Now you can refit everything
and see if it lines up.

Remember that you only need to undo the right-hand fork's
axle pinch bolts to get the wheel out. The left-hand ones never
need to be touched.

 

The Older Gentleman said...

It's fucked, I'll give him a tenner for it.

Paging AntonyE, could you email me details of regs etc for next season's
Desmo Due series please.

 

Yes. What he said.

 

Unless you like shearing bolts off when you least need it. Be a good
idea to loosen them at least once and apply coppashit.
--
Dave
GS850x2 XS650 SE6a
Every post contains Nutri-Ceramide-R and Pre-Biotics
for your reading pleasure.
Folding@Home Team UKRM
http://vspx27.stanford.edu/cgi-bin/main.py?qtype=teampage&teamnum=47957

 

Heh, I've got a spare pair of straight forks sitting in my garage
that are doing nothing if they're needed. In fact I'm only missing
a frame to make another complete bike...

 

Tbh, you should never need to take those out as they only hold
the threaded insert into the fork bottom, and there's really no
reason to take that out!

 

Did the old caliper have the same problem ? Did you have the
wheel out when you swapped the calipers ? Are the pistons
on both sides of the caliper moving freely or is one side
hung up and not moving ?

My first bet is that the piston(s) on one side may be frozen. I'd also
do a serious comparison of the old and new calipers before I did
anything else.

Is the distance between the disk and the caliper body the
same or different on the two sides ? (Not the pads or
pistons, but the caliper body).

That doesn't sound right. My bet would be a frozen piston and/or
a misplaced spacer on the axle or possibly a difference in the
caliper bodies themselves. Go easy on any hammering when
you're feeling tired and frustrated.

BTW, it's quite possible to machine a small amount off the
mount points on the caliper body if there's a real mismatch
between caliper and fork. I swapped in a different front caliper
on my bike and the cost of machining the mounts was trivial.

Like I said, know when to put down the hammer and walk away
for a while.

 

And I *still* have a rear wheel with your name on it.

 

I know, I know. I will get round to collecting it at some
point, honest!

 

IF the threads never get damaged on it...

I take it there's no nut, just this insert performing the nut function?
--
Dave
GS850x2 XS650 SE6a
Every post contains Nutri-Ceramide-R and Pre-Biotics
for your reading pleasure.
Folding@Home Team UKRM
http://vspx27.stanford.edu/cgi-bin/main.py?qtype=teampage&teamnum=47957

 

Yes, it's just an insert held in place by the pinch bolts.