[Closed] WTF, new brake pads destroyed my discs!

Seems a very odd rotor design to me. So little material in that middle section. Has to be promoting uneven wear surely.

I'm going to double up on the rotor design fault.

Me too!

I had a friend who's rotors (which are similar to yours, same design different brand's sticker) were munched by (surprise, surprise) Superstar's kevlar pads a couple of years ago.

Both the rotors and the pads are a bit dodgy.

[url= https://www.google.co.uk/search?client=opera&q=ashima+rotor&sourceid=opera&ie=utf-8&oe=utf-8&channel=suggest&gws_rd=ssl ]They're light weight Ashima rotors and I have been using these on my 29er for years without any issues, its only since trying these new pads that has caused the problem.[/url]

I made sure to check the website selling the pads, and there was nothing to mention not using them with specific discs.

yeah, very poor rotor design, much less material in the middle, the small amount of metal in the middle is going to have a correspondingly greater wear rate. Are they those crazy light ashima ones? I always cringe when I see people running those. Don't they come with a warning about rider weight and pad type to use? edit - yeah sintered pad only

Errrrrr........

Lightweight rotors wear quicker? It's not a huge surprise. Did you actually check the rotors when you switched pads? Not sure I'd necessarily have noticed them thinning like that in the centre unless I specifically checked.

All rotors seem to wear out in the middle of the track first, I'm sure there's some physics behind it, but even much more solid rotors wear like that.

And some manufacturers specifically say not to use sintered pads (Shimano do certainly) as it wears the rotors out, stands to reason anything harder will accelerate wear.

I'm slightly confused by the mileage, the bike is 7/8 months old, you got 1700miles from sintered pads, then 650 from each of the three ceramic pads?

Does the rotor manufacturer specify what sort of pads should be used with it?

What is the mechanism to get an even pad surface - are you relying on the material in between the two 'rails' to 'shave' it off rather than wear it down? In which case the hardness of the material comes into play?

Whilst I agree with the above comments on rotor design, I'm going to ask a question that goes against the grain.

Does or should the pad not contact both the circular hoops?? It looks like (and don't flame me for this) that the pad wear suggests they currently don't.

I had poor wear on a set of Hope rotors, similar to what you have above but not as bad. I sent them in and the rotor wasn't to fault the pads were. Seems the harder compound kevlar pad was to blame for the wear, because it was err.. too hard.

Looking at the rotor design you have very little metal in contact with the pads. Therefore you will need to have the pads exert far more pressure to generate the friction required that in turn changes to stopping power.

I would say that the pad compound wasn't that hard going by the wear shown on them also.

Cheap pads and cheap rotors. For the record I have used Superstar pads on hope ventilated discs for many years with issues.

Personally I wouldn't buy that type of rotor because you have more open sections than you do metal for the pads to contact.

These rotors are targeted at the seriously weight conscious or the competitive cross-country rider were every gram saving can make a huge difference on race day

A super lightweight rotor not lasting well is not exactly a surprise though is it. I appreciate that you have had not had issues before with a different material but I still think the design of the rotor had a lot to do with the issue. The compound is really hard so it has not worn down quickly in the centre as it is not doing much work (very little contact with metal in comparison with the edges) and has 'chased down' the centre areas as it wore.

I'd just put it down to a combination that don't play well together - super light rotors should maybe only used with softer pads.

The mechanism of failure here is over heated and warped discs, partly because they're so light duty.

Ceramic pads material, as you've found to your cost, is a very good insulator. This means your rotor can't dump heat into the brake and it build up in the rotor until it warps and fails.

It's well documented in motor sport if you do a bit of googling, and superstar carry exactly this warning on their website about their red kevlar pads and lightweight rotors.

Im not sure if I made it clear enough.
I bought the bike new about 8 months ago, swapped the original discs for these about a month latter.
The original pads lasted (Avid DB-3) around 900-1000 miles and were then replaced with sintered pads.
I was always aware of how light the discs were, thats why I kept an eye on them for the first few months of using them and there were no issues whatsoever, and both the factory pads and the sintered pads wore evenly/flat.
Its just since I put these pads in 6 weeks ago, that is when the uneven wear has started, so the disc were 100% fine before I used these pads.

Glad I didnt recently buy those type of rotors.

I always periodically check pad wear to make sure it is even.

This is what it says on the site where I got the pads, no mention of rotor design at all;

Harder than ordinary pads. This is the highest density, hardest, ceramic compound for performance and longer lifetime. These organic disc brake pads contain a high amount of ceramic fiber, which insulate the brake system from friction heat up to 400oC.

Advantages: Better performing and longer lasting than medium pads
Details
Upgrade on original fitted pads
DIN 79100 Standard Approved
Organic Compound contains no metal material
Reduces damage to rotor
Carbonized compound reduces brake fading
Ceramic Fiber insulates brake system from friction heat

Ashima has an extensive Q &A section on it's [url= http://www.ashima.com.tw/index.html ]website[/url].

Er, no. It has nothing.

[i] they weren't cheap..[/i]

But they were nasty.

Sorry.

Actually I prefer Scienceofficer's response to mine!

Lightman - are these from superstar or another generic brand selling exactly the same thing?

If superstar :-

We do not recommend this compound for brake dragging alpine descents as they do not fade with heat [b]and will rapidly wear flimsy rotors which can't stand the heat.[/b]

Gone through rotors in <700 mostly road miles? Do you live on the Col Du Tourmalet?

Ran ashima lightweights for about 5 years - backwards! and not dead, though with sintered pads and I may be an outlier

OP, Ashima say sintered pads only, so your bad sadly.

Yeah it's still not the pad manufacturers fault that you decided to use them on a non-standard uber-light rotor though. As mentioned above, your previous softer pads probably would wear more evenly, now you have harder pads which are eating more into the disc (as you would expect) compounded with the fact that you're not letting the heat away from the rotor in the same way anymore.

Don't see the pad manufacturer being to blame here

As per legend, IMO there are no faulty parts here, just incompatible ones. That puts it as a mistake at your door OP.

Sorry.

I used similar Ashima rotors for a while with XT brakes and ss sintered pads. The wear rate on the rotor was noticeable and a distinct pulsing effect could be felt. I ditched the rotors soon after and have been fine since with; SS floating rotors, Hope floating, and Shimano (non Ice-tech) rotors.

To be honest, I think the problem would have started from the moment you ran sintered but only happened to become really obvious in the short time with kevlars.

...about 95% of that being on the road.

Never mind the knackered disk, I'm struggling with why you'd need anything other than bogo organic pads for road use.

Sintered pads can leave material behind on the disk when used, this means when swapping to a different compound this can be picked up by the new pads, in the case of organic pads it usually results in destroying pads quickly. Wondering if similar could happen with ceramic pads but being harder it's chewed the disk too.

Why would you use lightweight discs which have very little braking surface anyway? Brakes are one place I refuse to do any weight-saving as they're a safety-critical item!
I have had a Hope rotor wear excessively in the middle, caught it before it broke through. I blamed it on the cooling holes as the wear lined up with them. For my XC bike I wish someone made some near-solid braking surface discs as they rarely get at all hot so the extra cooling isn't necessary. These are the closest I've seen:

[img] ?w=1000&h=1000&a=7[/img]

Maybe someone can explain the whole obsession with cut-outs in the braking surface?

I'm not saying this is the problem but I wouldn't be happy running discs with so little metal and holes almost the size of the pads - will be a pad grater with no surface area to dissipated heat. If you want to save weight go smaller diameter but with more braking surface.

Okay, expensive lesson learned about pads and rotors. I still think there should be some sort of warning on the site about using hard pads with certain rotors though, not everyone is an expert.
Even in the Ashima manual, it does not mention pads which you shouldn't use, just what pads it recommends.

thestabiliser - Member

Gone through rotors in <700 mostly road miles? Do you live on the Col Du Tourmalet?

No, read again.
The rotors have done around 3000 problem free miles, its only the last 621 miles with the ceramic pads which have destroyed them.

friction is generally independent of surface area, but force isn't

teeny braking surface means more force on less material.

cut out rotors are a stupid idea.

[i]The rotors have done around 3000 [s]problem free[/s] miles during which time they were gradullay wearing, its only the last 621 miles with the ceramic pads [s]which have destroyed them.[/s]which have continued the wear leading to failure at the obvious weak point[/i]

ftfy

Unlucky combo of components that were never going to work together and poor info from pad mfrs - I'd be complaining to them I think.

IMO That looks like a huge % of cutout holes on the braking surface of the OP's rotors . 😯
Was it not Ashimas that sent an STW poster OTB ,when one collapsed on him?
He had put them on the wrong rotation,but the arrows weren't that obvious .

I think Stans Podium MMX rims are rated for 3000 miles after which you are supposed to bin them - some bike stuff can be too light outside of limited race use.

You're right OP. They don't tell anyone about this stuff.

Maybe someone can explain the whole obsession with cut-outs in the braking surface?

It lets the hot gas out of the disk/pad area, you seem them (or slots machined into the surface) on a lot of higher performance brakes. Off road it also gives the water/mud somewhere to go, so you'll occasionally see solid disks on road cars/bikes, but never on an MX bike or similar.

Bad luck, just swap them out. Deore rotors can be had for about £12 and they do the job.

Ashima reversed the direction of the arrow a while back, shortly after the first round of "holy shizzle, my rotor has turned into a slinky!" incidents.
I'm sure that it was entirely unconnected.

The arrows were wrong (it wasn't me but i had the same rotors)

Still find it hard to believe you get through that much material in 600 miles riding on the road regardless of the pad. the pads are worn unevenly top to bottom too, maybe the pistons are a bit sticky/pushing at the wrong point on the backing plate causing oblique wear?

When you take your car to a dealership they always recommend a change of disks with the pads. The disks are wear items and you will get nowhere trying to argue with their company that there is some fault.

Although as everyone has said, it'll be the combination that's caused this. Just write it off as a learning experience. Those disks look a very "race only" item.

he didn't thestabiliser - the rotors already had 2500 miles of wear from other pads before these ones were fitted.

tinas - I understand the purpose of small ones, especially for clearing dirt away, but why do some manufacturers go for extreme versions? They sometimes seem to be more style over substance.

I'd definitely send a polite email to both the pad and the rotor manufacturers, they may not be aware of the issue and may just be nice to you.

It does seem like a bad combination, but it's also a little unexpected to wear them out that fast.

If I read you right they were worn, by a mm or something before you pared them with those pads?

convert - Member
Seems a very odd rotor design to me. So little material in that middle section. Has to be promoting uneven wear surely.

POSTED 1 HOUR AGO # REPORT-POST
GregMay - Member
I'm going to double up on the rotor design fault.

POSTED 1 HOUR AGO # REPORT-POST
ads678 - Member
Me too!

Eerrrrr...

[img] [/img]

I know but he thinks they were brand spanking then Kerrr-blamm!! I was just trying to talk him round steadily. I can't be bothered now.

On the upside in couple of months I'll be back on here moaning in a similar vein 'cos I preplaced my ashima rotors with cheapo shimano discs that are organic only and am currently running sintered on! Yay!

Brake pads and rotors can be a bit of a minefield TBH, I've found (like the OP) to my cost. These days I stick to manufacturers pads and discs. (Hope Calipers, Hope discs, Hops Pads) At least I know they'll all play nicely together!

Eerrrrr...

Errrr meaning they sort of (if you squint) look like these avids so are find because the fine upstanding designers as Avid think it's Ok or Errrr Avid have screwed up too?