No return tension from spring on caliper
Matthewfalle
Posts: 17,380
Morning all
As the title suggests - two different calipers (one Ultegra, one Tektro) - squeeze them in and they don't spring out again - ie they stay compressed.
Both have been stripped, cleaned and reassembled, all lived up - makes no difference.
Any ideas?
Many thanks
M
As the title suggests - two different calipers (one Ultegra, one Tektro) - squeeze them in and they don't spring out again - ie they stay compressed.
Both have been stripped, cleaned and reassembled, all lived up - makes no difference.
Any ideas?
Many thanks
M
Postby team47b » Sun Jun 28, 2015 11:53 am
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honour
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honour
smithy21 wrote:
He's right you know.
0
Comments
-
mucky cables?0
-
Detached from bike completely and sitting on kitchen table.Postby team47b » Sun Jun 28, 2015 11:53 am
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honoursmithy21 wrote:
He's right you know.0 -
As you say no difference I presume they were the same before some numpty stripped and reassembled them? Can you unhook the spring from the peg and then get a feel for if they are binding without the spring tension on them. Did you get a feel for how free the pivots were whilst they were stripped? I'd think the pivots being gunked up would be the problem, I doubt the spring could lose tension, if it had you'd have felt it during reassembly. Centre bolt too tight?0
-
Yup - reason they were stripped was to clean them out and try to solve the problem.
No binding - they move smoothly but just don't return to shape - push them closed, they stay closed, pull them open they stay open.
Centre bolt loose enough to allow non binding movement but no lateral play.
Agree completely re spring not being able to lose tension.
Pivots felt pretty good.
Am now perplexed.....Postby team47b » Sun Jun 28, 2015 11:53 am
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honoursmithy21 wrote:
He's right you know.0 -
The primary pivot shaft, at least on Shimano brakes, is held in place by a grub screw that acts directly on the shaft. The secondary pivot also has a grub screw wound in from the other side to provide additional control over the pivot axial position.
What you have to do is adjust the position of the shaft to take out play in the caliper assembly without causing the brake to bind up, and then tighten the grub screw. Don't adjust the pivots without first loosening the grub screws, you'll damage the shaft surfaces.
It's a job that requires a fair bit of patience IME; the grub screw often causes the shaft to turn a little bit, and if you've adjusted it to within a gnat's crotchet of binding up then sometimes tightening the grubscrew takes it over the edge. The spring does not exert that much force; the caliper assy can feel smooth-ish but still be too tight for the spring to move. Both pivots need to be correctly adjusted.
Obv. all sliding surfaces should be greased (NOT anti-seize).
Bit difficult to describe without piccies but I hope that makes sense. Sorry if this is teaching you to suck eggs.- - - - - - - - - -
On Strava.{/url}0 -
^ That's a much more useful post.
I have a pair of unused black 105 calipers in my spares box if you get stuck. Came with the groupset when I built my bike and I haven't stuck them on the Bay yet.0 -
Problem solved - spring had slipped from mounting point (one straight end) so all it was doing was sliding rather than resisting.
Thank you very for help.Postby team47b » Sun Jun 28, 2015 11:53 am
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honoursmithy21 wrote:
He's right you know.0
