Hope mini rubbing when it is hot
tjm
Posts: 190
Hi All,
I have a fairly old hope mini on the front. I've noticed recently that, when it gets hot, it starts to drag. Not just a slight contact, enough to slow the bike noticably and make a horrible howling noise. it is fine when cold.
I also noticed that the free travel at the level all but disappears when this happens - i.e. they bite as soon as the lever moves.
When I say hot, I can still touch the disc without burning myself so it is not getting hot enough to boil the fluid or anything like that.
the pistons don't appear to be stuck in that they pump out ok (without pads) and push back in ok. I did notice while doing this they don't look particularly clean, a few black "tide marks" round them.
I also noticed that, compared to the rear mono mini, they run pretty close to the disc when cold. No drag but I get over1/2" free lever movement before pad contact on the rear compared to 1/4" at the front.
I'm about to replace the disc and pads anyway and I guess it would be a good idea to pop out the pistons and clean and bleed them while I am at it but is there anything else I should look out for?
What about seals? Am I right in assuming that if they keep the fluid in they are ok?
What about the lever end? Anything there that would cause this?
TIA,
Toby
I have a fairly old hope mini on the front. I've noticed recently that, when it gets hot, it starts to drag. Not just a slight contact, enough to slow the bike noticably and make a horrible howling noise. it is fine when cold.
I also noticed that the free travel at the level all but disappears when this happens - i.e. they bite as soon as the lever moves.
When I say hot, I can still touch the disc without burning myself so it is not getting hot enough to boil the fluid or anything like that.
the pistons don't appear to be stuck in that they pump out ok (without pads) and push back in ok. I did notice while doing this they don't look particularly clean, a few black "tide marks" round them.
I also noticed that, compared to the rear mono mini, they run pretty close to the disc when cold. No drag but I get over1/2" free lever movement before pad contact on the rear compared to 1/4" at the front.
I'm about to replace the disc and pads anyway and I guess it would be a good idea to pop out the pistons and clean and bleed them while I am at it but is there anything else I should look out for?
What about seals? Am I right in assuming that if they keep the fluid in they are ok?
What about the lever end? Anything there that would cause this?
TIA,
Toby
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Comments
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is the disc catching on the caliper itself?
I had this when the caliper wasn't central, it made a really awful noise and heated up the rotor quite a bit.
just a thought
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No. I checked that already
It looks pretty central and no sign of rubbing.0 -
just give them a bleed. could be slightly overfilled with fluid."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
I did wonder about that but I can push the pistons back a lot further than they are when operatiing normally so I assumed that that meant there was enough expansion space.
They have been neglected for a while so I'll give them a good clean and bleed and see how things go.
Thanks for the comments, at least no one is saying I have forgotten something obvious! 0 -
Even when overfilled you can generally push them back further than they sit.0
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Ah, ok. I didn't know that.
Thanks.0
