Hope Trial Zone brake issues

[Bootstrapbob]

I have just picked up a used Hex fitted with Hope Tech3 brake levers, Hope Trial Zone calipers with red pads and Hope V2 discs but I am having some issues.

Firstly, can anyone tell me whether the calipers should have a spring to push back the pads or do they rely on reduced oil pressure to pull them back when releasing the levers?

Secondly I found when braking at above walking pace there was a brrrrr noise/vibration coming from the wheels.

I could see that the outside diameter of the discs (on the lobes) had obviously been rubbing as the steel was shiny in places as though it had been filed. See the photo. When removing the calipers I could also see that the aluminium anodising had been warn away at the base of the slot in the caliper where the disc had been touching it.

These are 180mm Hope discs fitted with Hope calipers on standard post mounts of an Inspired frame and fork with no spacers. According to the Hope site this is as it should be so why are the discs rubbing the calipers at the outer rim?

I can fix the problem with a washer on both post mounts to pack the calipers off but this just seams wrong, has anyone else had this problem?

Finally, it is also creating quite a challenge to centralise the discs in the calipers and partly why I asked the first question about a return spring as my pads do not appear to be retracting far when releasing the lever.

I have wound out the bite point adjuster as far as it will go but I suspect there may be too much brake fluid in the system. My next option would be to clean and bleed them as per the Hope instructions to see if the pistons are sticking.

 

This is my first trials bike and some of the answers may be "that's just what it is like on a trials bike" but I suspect the discs fouling the calipers is just wrong.

Looking for some guidance from the forum members.

[Daan]

No springs on the pads, the calliper pistons are magnetic. The top of the disc rubbing on the calliper itself sounds very trialsy, as in quality control, what's that? I'd just add a thin washer beneath both calliper tabs.

Calliper pistons don't retract too far on the Hope brakes, so they're pretty sensitive to disc wobble. If you can push the pistons/pads in a bit more and they stay there, they shouldn't be overfilled. If they don't stay out, just remove the lever top cap and again push the pistons back.

Before you do all that though, clean them up a bit first. Clearance to disc is dictated by the piston seals (bite point adjuster has nothing to do with it, as it only moves the position of the lever piston relative to the timing port), but it all must be clean to function optimally. If you then squeeze the lever a few times (with the disc between the pads obviously), the pistons will set themselves to their natural position.

Edited May 8 by Daan

[Bootstrapbob]

Thanks for the feedback Daan.

Good to know I'm not missing springs between pads, I did notice they were magnetic and retraction of the pistons would pull the pads back from the disc but it just didn't seem like much.

I did fit washers under the caliper lugs to give more clearance for the disc so I am happy this is something others do too.

Time to clean the pistons and bleed them I think, hopefully that will fix it.