back brake became very poor yesterday after 2 days of riding. Cleaned the bike up tonight so thought i would check the back pads ( bike is only a few weeks old and done porb circa 80 miles. The brake pads were worn down to the metal pad spacer on one side but plenty of meat on the other side of the same pad. Whilst the other pad seems fine.

Why would one brake pad run flat on one half but fine on the other half, and the other pad is wearing evenly as you would expect?

Brakes are hope V2’s.

The inside will wear quicker I presume, due to the most pressure being exerted on that side of the caliper. Unless you design a perfect brake I can’t see how this won’t happen. Always seems to have happened to my brakes.

depth-junkie – Member

“Why would one brake pad run flat on one half but fine on the other half, and the other pad is wearing evenly as you would expect?”

Sticky piston, so more force is being applied on one side than the other, most likely.

caliper / pads not centralised, sticky piston all of them

If you centralise the caliper by putting the brakes on with the mount loose and then tightening the bolts you run the risk of it being off centre if the pistons are not moving equally. there is a very good video on the hope site for how to centralise properly

Was it original pads or cheap replacements?

djglover – Member

The inside will wear quicker I presume, due to the most pressure being exerted on that side of the caliper

Rubbish.

no, the same pad is worn very un-evenly. not the 2 seperate pads.

i.e half of the 1 pad is down to the metal whilst the other half of the same pad has plenty of meat left (and the amount you would expect for a bike only done 70-80miles)

Hmm – that is bizare. the leading edge will tend to wear a bit more quickly than the trailing edge.

Somepads can bind in the caliper causing them to tip out of true if they only bind on one side

The inside will wear quicker I presume, due to the most pressure being exerted on that side of the caliper

this might happen with cable discs but there no reason for it with hydraulic

i.e half of the 1 pad is down to the metal whilst the other half of the same pad has plenty of meat left

Sounds like the caliper is squint.

Except it’s only happening on one side.

I’m still going to go with with sticky pistons. TJ’s point about sticking pads makes sense with some aftermarket pads but not if they’re OEM Hopes which they should be with such new brakes, their pads are excellent and not likely to be jamming in the calipers. Not a Hope fan really but they don’t tend to screw up like that. But, sticking pistons from new can happen to anyone, or a seal could have got damaged in use, it’d be unlucky but feasible.

a sticky piston would cause one whole pad to wear more than the other – not one pad to wear unevenly while the other wore evenly

I’d consider the possibility of a twisted (and stuck) piston. The huge V2 pistons will gladly go in on the piss if one tries pushing them in from anywhere other than the dead-center. You should be able to visually determine if it is so, especially if it’s crooked enough to wear a pad in such a manner.

Caliper looks square, there is a line on the caliper and it is dead center inline with the disc edge. So all looks good, brakes were new and pads were original hope. How can i tell if a caliper is squeezing in offline(center)? It is only happening on the one pad as the other side is fine with the amount of wear you would expect on new brakes with a max of 80 miles on. If the caliper was offline would not the brake pad wear be uneven on both pads?

Twisted piston, not twisted caliper. Take the pads out; look at the pistons…does one look as though it isn’t sat square in the caliper? Could you remove the pads and take a picture looking down into the caliper?

Nothing looked out of place when i looked inside last night with the pads out. Will have another look tonight and take a photo.

have just noticed i’ve got the same problem with my xt front,one pad’s 80% other’s down to the metal,one of the pistons doesn’t seem to go back in properly and is very sticky,have just soaked it in gt85,will this cure?

No to GT 85!
Take the pads out and get some brake fuild (Shimano – Mineral Oil, Hope FOT brake fluid) and drip it aroung the piston, then GENTLY pump the piston in and push it back it, dripping more fluid onto it and cleaning every so often. This should help lubricate the piston seals and rinse out some of the crap / dirt out too. Might take a few go’s, but keep at it.

indeed – get the gt 85 off it now and hope its not buggered the seals. Shimano you might have got away with ‘cos its mineral oil

You must only use the correct lubes on seals – if youare not sure use the correct fluid for your brake

TandemJeremy – Member

“a sticky piston would cause one whole pad to wear more than the other – not one pad to wear unevenly while the other wore evenly “

Nah, not neccesarily, those brakes have pretty big pistons so if it’s sticking on one side it could easily be tilting the piston.

Hmmmmmmmm maybe but I would have though a piston that tiped would just jam. Could be tho I guess

It does sound weird… Just that’s the only thing I can see causing it, with OEM pads at least. Retracting slightly squint and dragging may be more likely than applying power unevenly I guess, I’ve had that on motorbikes but never on pushbikes.

Oh, Mr OP… On the pad with the weird wear, but on the side that doesn’t have the accelerated wear, does it have more or less material left on it than on the other pad that’s worn normally?

Right folks, i have taken some pics. I have put the bike on the work stand and have had a look at the pistons closing when the brake is applied. The pistons look to be equal until they close on the disc then they are going lobsided as they bite on the disc (the lobsided presure is going towards the thin pad side) however i changed the pads around and the lobsided happend again at bite point on the thin pad side however this time round it on the opposite piston and at the back as oppposed to the front on the opposite piston.

I presume the lobsided bite point is purely at this stage down to the fact there is virtualy no pad left on that side, hence the piston keep pushing that pad at that point till it bites (i.e it is the last point to bite as the meat side and the pad have already bit)

i am stumped at the min as i looking at the caliper and pistons i cant see anything out of the norm.

forgot to say, ive orderd some new pads so i can see how i go with the next set. But i do need to find out why its happening because it will be an expensive system if i need to keep putting fresh pads in every 80 miles or so.

From that 1st photo it looks like the caliiper is not sitting square, so either needs shimming or the mounts need facing to get it back in line.

The point of most wear is where that pad is hitting first, do you drag the brakes a lot though, because I’d have thought that the other pad should exhibit the same wear but the other way around if full pressure is applied.

Possibly get the frame mounts faced, if you haven’t already.

How about a bit of a bleed/top up fluid??

From that 1st photo it looks like the caliiper is not sitting square, so either needs shimming or the mounts need facing to get it back in line.

The point of most wear is where that pad is hitting first, do you drag the brakes a lot though, because I’d have thought that the other pad should exhibit the same wear but the other way around if full pressure is applied.

No, i dont drag the brakes & this bike is brand new (only done 80miles)

I am not using the brakes any different to my old bike’s Avid elixer 5’s and ive got over 600miles out of that bike with a change of pads at 300 odd miles and they still had a bit of meat left on them.

on the new bike 1 pad is still like new (wear you would expect for 80 miles) the other is worn down to the metal on oneside, and the other half is still a lot less than the other pad.

I can assure you the caliper is straight inline with the disc, you can see that from the marking line on the caliper inline with the rotor. I am really at a loss with this. Think i will try the new pads out and check for wear in a few miles and if its still doing it take it back to the shop. And they can sought it ad i ait paying for new pads every 70-80miles

Sorry, can’t offer any solutions to your problem, but thought i’d let you know i’ve running Tech V2’s on my five for the last year and a half and only just replaced the original pads last week.

Hope you get it sorted out mate… Actually I’d give hope a bell (not read all of above, so apologies if you’ve already done that).

Cheers.

From that 1st photo it looks like the caliiper is not sitting square, so either needs shimming or the mounts need facing to get it back in line.

It’s a PM caliper on a mount. If the wear on the pads was top to bottom then I would agree that the brake spots needed facing. As it is, the wear is front to back, which would indicate that the caliper needs to be rotated on the mount.

Although the rotor lines up with the line on the caliper at the back, it doesn’t appear to do so at the front. The outboard piston also appears barely extended in comparison to the inboard one. Which side of the caliper was the badly worn pad fitted?

My feeling is that the caliper is not properly aligned and that the outboard piston is not working properly. The pads, clearly, are ruined and are completely useless to a working brake. Make sure that the pistons are both moving freely (check the first paragraph of this guide to see how I do it) and then double check the alignment. You can’t just line the rotor up with the line at the back; you also need to make sure that the spacing for the rotor is identical at the front slot. Have you seen the set-up videos on Hope’s website? Here’s the caliper set-up and here’s the piston set-up.

With new pads, and assuming that there is no manufacturing defect, it’s a ten minute fix to get that brake running properly.

It sounds very much as if you have a lazy piston. This is caused, as mentioned above, by dry seals or a piston that’s in on the wonk. Either can be the cause of the uneven front-to rear pad wear. Basically, the piston with the unworn pad on it is not extending, while the one with the worn pad is popping in and out quite happily.

For dry seals (and this is always worth the first try) I’d suggest the following.

1) find a spanner which will comfortably hold the piston into the caliper, if one edge is on the piston, and the other clamps the back of the caliper. Put a bit of tape ’round the inside of the spanner’s crescent to avoid scratching the finish on the caliper.

2) Fit the spanner to the caliper half / piston that’s working. you want to stop this moving, basically.

3) *Carefully* pull the brake lever. The lazy piston will (hopefully) move out. You don’t want to pop it completely out of the caliper, remember, just get it moving a couple of millimetres.

4) Get a few drops of brake fluid – DOT 4 or DOT 5.1, depending on what’s in the brake – and run them around the edge of the piston and seal where it comes out of the caliper. I find a feeding syringe works a treat – most chemists find them. You’re looking to lubricate the seal between the piston and the caliper.

5) use a tyre lever or other non-scratchy lever to push the piston back in to the caliper.

6) Repeat a few times until the caliper is moving freely.

7) reset both pistons back into the caliper half, clean off excess brake fluid with meths or similar, and fit new pads. Carefully bed in, then go for a short ride.

8) Check pad wear every ride for the first couple of weeks.

9) If that doesn’t work, send ’em back.

Bear in mind that Hope’s web site has tons of really good advice on it, and if that doesn’t work, the staff are excellent and very helpful.

This is repeating a lot of very good advice above, so apologies if redundant.

HTH