SOHC.co.uk Forums > CB350/400
New to CB400 four and new here! Front brake improvement?
Mikep328:
Question...re the fixed pad/swingarm...
When the fixed pad is adjusted to have the minimum clearance is that spring on the adjusting bolt supposed to push the fixed pad/swingarm back to the established clearance?
This morning I found that even if I adjusted the bolt to provide far too much clearance, so I could move the caliper back/forth maybe 8-9mm by hand, once I applied the brakes and then released the lever, the swingarm/pad did not move back to the 8-9mm clearance. I had to push the caliper inward to re-establish the clearance. Is the spring supposed to be strong enough to do that? It doesn't seem to be very strong - easy to compress with my fingers.
Further... I pulled the caliper bolts to determine the type of pads. They appear to be sintered pads. No idea of the brand but "JB CR FF" is stamped on the backing plate. Don't know what that means. The pads are quite thick so appear to have very little mileage/use but there are grooves worn into the pads though the rotor is perfectly smooth.
Bryanj:
Sounds like that pivot pin is starting to sieze up, the bracket needs to be super free
McCabe-Thiele (Ted):
Bryan is correct about the pivot. plus the pads will be pushed away from the disc by a high spot to provide clearance.
Mikep328:
Thanks guys...
I checked and the pivot pin/swing arm is very free/moves with no effort at all if the adjusting bolt is loosened to provide some clearance and I physically push the caliper in which forces the active pad back into the caliper and creates the clearance. But it won't return to that clearance on its own once the brakes are applied/released. The spring cannot force the active pad back into the caliper to "open up" the clearance. I suppose it doesn't really matter - it's common for disc brake pads to JUST touch the rotor even when the brakes are not applied but if the 400's pads are supposed to stay in light contact with the rotor, what's the point of the spring?
Oddjob:
The spring is not there to force the active pad back into the caliper Mike, it's there to push the arm backwards so that when the active pad retracts the arm moves away from the disc allowing the clearance needed to stop the brake dragging. It's the piston seal that pulls the piston back into the caliper, as the piston moves out the seal distorts, it's this distortion that applies pressure to the piston and the seal trying to retain it's shape that pulls the piston back. It could be that the piston is pulling back but the pad is not, the pad should be just ever so slightly loose in order for the arm when it's being pushed back by the spring pushes the pad back into place.
If you remove the caliper and test the arm you'll find the spring is plenty strong enough to push any movement to the left back again, maybe test that and see if the spring has lost it's tension or maybe it's the wrong spring.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version