Disappointed with new Shimano brakes

coursemyhorse

I got some brand new M675 SLX Shimano brakes with new SLX RT66 discs having read such good things and praise from every single review and post I think I have seen discussing them. Previously having problems with Avid I was hopeful these would be better. I went with SLX since there is no difference between them and XT I deem worthy of the extra cash.

In terms of bleeding. Great. Bleed not a problem. Easy. Lever feel good.
The pads are the standard SLX resin pads.

Ride 1: Awful. Not bed in yet. I thought resin bedded in quick but these weren't even good at the end of this ride, but got a tiny bit better.

Ride 2: Initially poor but by the end of the ride seemed to be bed in and good power, easily locking rear and stoppy-ing on the front. Fairly happy but didn't quite feel as good as my mate's XT ones.

Ride 3: Rear is consistently fine and locks the wheel. Front has started honking and squeaking and has lost bite. I can't stoppy any more.

Nothing was done to the bike between ride 2 and 3 at all. My friend said the only reason front would do that is contamination. How? It's been sat in the garage. I checked for leaks and cannot see anything. We took the pads out and put brake cleaner on them and cleaned and then put them back on the front. It improved it slightly. Then I put the bike away again and tried it again in the morning and it's honking and lost bite again. I checked the banjo bolt (as can be problematic apparently) and it does not look to be leaking.

I'm a bit miffed that I changed from Avids for "fit and forget" brakes and now I'm still chasing problems.

So last night I swapped the front pads with the rear ones and the performance generally did follow the pad. i.e. Slightly better on the front now than the rear. After really hammering them and getting them hot, they started to work well, but I'm just not happy with how hard I am having to pull them to get them to perform. My mate has XT and with his its a one finger pull, even sat down on the bike and you can stoppy easily on the front. It really snaps on with power. He has Sintered pads rather than my resin, but I thought resin were known for having more initial bite? His bike is a slightly smaller and lighter frame than mine so would that make them feel more powerful? He also runs older Avid discs so there is another difference, but mine are bigger than his. :?

Should I just get new pads? Could it be that the SLX RT66 discs are poor?

Another thing whilst I'm complaining, I dislike that the pad clearance on the Shimano is so fine. I can barely get a piece of paper between the pads and disc each side which contributes to disc rub more if not perfectly aligned.



I don't have much luck with brakes. I'd now happily pay for some that just work, well, all the time.

estampida

new sintered pads from superstar components.....

stubs

This doesnt sound like Shimanos new brakes. Shimano resin pads arent very good in my experience they bed in about a mile before they are worn out. As for the clearance somethings not right the Shimanos have masses of clearance, when you bled did you push the pistons right back.

Get some sintered pads clean the discs with meths or IPA and get them rebled using the proper Shimano instructions and bleed pot (or a syringe you can screw one into the M/cylinder port)

coursemyhorse

stubs wrote:

This doesnt sound like Shimanos new brakes. Shimano resin pads arent very good in my experience they bed in about a mile before they are worn out. As for the clearance somethings not right the Shimanos have masses of clearance, when you bled did you push the pistons right back.

Get some sintered pads clean the discs with meths or IPA and get them rebled using the proper Shimano instructions and bleed pot (or a syringe you can screw one into the M/cylinder port)

I guarantee you they are bled A1 following Shimano full procedure and using all Shimano flui and reservoir tool. I used the pad spacer that came with the brakes when I did it. The only reason I bled them was because of swapping/shortening hoses as they came from bike-discount Germany. The bleed I repeat, is A1. The pistons go fully back from what I can see. The clearance must just be like that? It's very, very minimal.

styxd

You've contaminated your pads I'd imagine. Get some new ones.

stubs

I have the XT a mate has the Deore and on both of ours the pad to disc clearance is very visible I would say at least a millimetere either side possibly a bit more. My back disc has a distinct wobble from when I smacked it against the bike carrier two weeks ago you can feel it pulse in the lever when your braking gently but it only just rubs the pads once a revolution. Somethings not right they shouldnt be so close to the disc thats the whole thing about the new Shimanos they dont (in my experience) rub.

stubs

Just been and had a look at my XTs and the clearance is 0.9mm either side of the disc measured using a feeler guage.

Chunkers1980

Why are you bleeding new brakes?

coursemyhorse

Chunkers1980 wrote:

Why are you bleeding new brakes?

Read above. Left and right hose lengths from Europe need swapping in UK. The bleed is fine. The levers are solid. The pistons fully retract.
Thanks Stubs, I will check with a feeler guage tonight what mine are. By eye and guessing, I would say maybe 0.5mm but I don't know. It's less on the rear than the front which I find odd.
Anyway, in terms of performance above saying pads are contaminated. This is why I posted this thread. Say they are contaminated. How does this happen? I don't want to keep buying pads if they just self contaminate within 3 weeks. Between ride 2 (when brakes seemed ok) and 3, the bike has sat, untouched, in a garage for a week. The brakes are not leaking. I did NOT contaminate them when I bled them before ride 1, and anyway, they were good on ride 2.

EDIT: Could I have not bedded them in hard enough? I basically just rode with them for a ride. Maybe this is the problem.

heez29

From what you've described I'm 99% sure its contamination. If the lever is firm and it doesn't stop you, there's no friction between disc and pad.

Could just be pick up from the trail. Rare when off road but it's not impossible.

Thewaylander

all sorts of ways to contaminate, I know you said you didnt when you bled but a small drop on the rotors or anything and your done.

My advise is get some new sintered pads in, clean the discs with some IPS and go from there no chance of carrying over then

coursemyhorse

When I bled them I was so careful. I am not 99% sure, I'm 100% sure I have not contaminated them myself, especially when bleeding. I know how important it is to not do this. The pads were not in the caliper when I bled them and the entire thing was cleaned with IPA before they went back in. Not that I spilt any fluid anyway.
Sorry, I'm just fed up with brake issues now.

supersonic

Did you clean the rotors before you installed them?

coursemyhorse

supersonic wrote:

Did you clean the rotors before you installed them?

I wiped them with a clean rag to get rid of any dust or anything obvious out of the packet, but no not an actual clean with any liquid. Should one have to do this?

supersonic

I usually do, as they can come covered in allsorts of gack.

pilch

Check the hose going in to the fitting on the calliper, my mate had a leak there a bit of fluid escapes... could possibly contaminate your pads?

coursemyhorse

pilch wrote:

Check the hose going in to the fitting on the calliper, my mate had a leak there a bit of fluid escapes... could possibly contaminate your pads?

Yep, looks all ok:

coursemyhorse wrote:

.... I checked the banjo bolt (as can be problematic apparently) and it does not look to be leaking.....

That's the bit I meant by the above. Sorry if I did not make clear. I see no leakage around this part where the hose is crimped at the caliper end, as I know these have been a problem for a batch of some of the Shimano stuff according to some people on forums.

supersonic wrote:

I usually do, as they can come covered in allsorts of gack.

Thanks. Ok. Maybe this is how they got contaminated. EDIT: But ride 2 was good performance.
I may buy some new Sintered pads. Now I need to decide whether to get the fins on them or not and whether to buy actual shimano ones. Recommendations welcome. Someone said superstar ones above. I have read mixed things on them.

stubs

I have superstar in my XTs and I cant tell any difference to the original Shimano pads

coursemyhorse

Ok thanks. So the sintered ones for "new XT/XTR non finned" that are £7 are the ones to get? £7? Is that it? I thought the official finned ones were like £50 a set?

EDIT: What about the Kevlar options?

coursemyhorse

Just for the record, I read of completely contrasting information as to which of the two compounds are meant to have the most initial bite and gradb. Is it sintered or resin?

cooldad

Resin. Sintered are harder.

*AJ*

Sintered are winter pads really!

Organic are softer and have more initial bite.

Kevlar have good bite and last longer.

However the soft organic pads don't exactly wear fast! My commuter only requires them once a year! Obviously off road riding wears them quicker, but even so! At the price superstar ask its not an issue!

benpinnick

Dont confuse shimano resin pads with other options like organic. The resin pads on Shimanos are pretty nasty OEM money savers, and really only designed to use with softer steel discs (They even make the discs extra wide too they are so soft). Ditch them for Sintered or something else ASAP.

cooldad

Superstar organics work lovely in this weather. Only lasted two descents of the Wall in appalling conditions though.
Although I probably use my brakes way too much, being a pussy.

coursemyhorse

benpinnick wrote:

Dont confuse shimano resin pads with other options like organic. The resin pads on Shimanos are pretty nasty OEM money savers, and really only designed to use with softer steel discs (They even make the discs extra wide too they are so soft). Ditch them for Sintered or something else ASAP.

I thought organic pads and resin were the same thing? Like metallic are the same as sintered. Just different names?

You say about the discs being wider, maybe that is why I am having pad clearance issues... I went with the SLX RT66 Discs but they do not say that I must only use resin. As far as I am aware, they can take Sintered as well.

My mate has standard Shimano Sintered with fins, and they stop incredibly well. I basically just want that and I'll be happy forever. I can't imagine anything being more powerful than his setup. It just grabs so hard.

cooldad

Rotors make so little difference as to be immaterial. And brakes are self adjusting, or you'd need to fiddle as the pads wear.
Clean the rotors, stick new pads in and try again.

step83

I had resin ones with my deore brakes, they were aweful swapped to some orgainic ones and noticed a marked improvement.
Resin pads are just that as resin pressed into a pad shaped mould. Organic tends to be a mix of things like glass and rubber with a bit or kevlar and resin to hold it all together. Sintered are a metallic mix of materials tend to be a very hard compound so slightly less braking capacity but last far longer. Kevlar im not too sure on myself someone who rides with them would be able to explain better.

YeehaaMcgee

coursemyhorse wrote:

Chunkers1980 wrote:

Why are you bleeding new brakes?

Read above. Left and right hose lengths from Europe need swapping in UK. The bleed is fine.

Who says the bleed is fine?
There's a knack to bleeding brakes, which unfortunately requires a bit more than just following the steps.
However, the honking sounds like contaminated pads, but the clearance issue sounds like there's other problems too.

benpinnick

coursemyhorse wrote:

benpinnick wrote:

Dont confuse shimano resin pads with other options like organic. The resin pads on Shimanos are pretty nasty OEM money savers, and really only designed to use with softer steel discs (They even make the discs extra wide too they are so soft). Ditch them for Sintered or something else ASAP.

I thought organic pads and resin were the same thing? Like metallic are the same as sintered. Just different names?

You say about the discs being wider, maybe that is why I am having pad clearance issues... I went with the SLX RT66 Discs but they do not say that I must only use resin. As far as I am aware, they can take Sintered as well.

My mate has standard Shimano Sintered with fins, and they stop incredibly well. I basically just want that and I'll be happy forever. I can't imagine anything being more powerful than his setup. It just grabs so hard.

Thats my point - Shimano Resin (OEM) are cheap and nasty... doesnt mean all resins are. Saves nearly 10% on the cost of the brakes when buying them OEM though, so you can understand why the grey market guys get resin over the sintered option... the poor buyer at the other end doesnt know that they are getting a seriously inferior product.

Your discs arent fat ones BTW - thats only the low end steel ones that are resin pads only, sounds like you just need to play with the bite point.

coursemyhorse

Ok thanks for advice I will check the brakes out as soon as I get a chance and post my findings.

DodgeT

Had a funny one with mine this week. Got m675 on both my bikes, havent rode the enduro for 2 months and the session for a month. Both were perfect when last ridden, enduro with shimano pads, session with ss kevlar.
Tuesday took the enduro out, brakes were honking unbelievably loud and there was no stopping power at all. I even had a nice otb courtesy of it, steep dh sections with switchbacks are not good with no brakes.
I rode around a bit dragging the brakes then chucked some water on them, few times doing this improved them a lot.

Tonight ive been prepping the session for the race this weekend, thought id try the brakes... loud honking and hardly any power! Had the pads out and sanded them, cleaned the discs, rode around the garden dragging them, again a lot better.

Bikes have been stored in the garage, under several sheets, so no chance of anything getting on them etc. No leaks at all.
Is it the bikes way of telling me I need to ride them more often?