SeboAmp

Well, today i adjusted my M416 Shimano mechanical front disc brake, the lever is now really tight, and the pads barely touch the rotor, then i wanted to set it up doing some braking on a soft hill, but then i noticed that it lacks power, it is tight, but it doesnt brake as i want it to brake...could be that the rotor heated up too much? or is the brake not ready to deliver its maximum performance?
Im using a 160mm rotor, SM RT54 S specifically, with resin pads, the caliper itself is new, and so are the pads, i bought it 4 days ago.
Thanks

coupster

Did you bed the pads? New pads and rotors will not stop very well for the first couple of stops. In a safe area, get the bike rolling and brake hard 3 or 4 times in a row. The braking force should improve with use.

pierce

what brake levers are you using with that?

mountain disk brakes require 'long pull' aka v-brake levers, while the newest cyclocross disks use short pull (as do most caliber brakes and cantilevers). I note on the instruction sheet for those M416's, it says...

also says some stuff about which disks and pad types to use.
https://techdocs.shimano.com/media/te...9830696761.pdf

SeboAmp

Im actually using these:

The rotor and pads are the adequate ones for the caliper.

pierce

fun fun, there's multiple versions of those EF51 shift/brake controls. like, the one you posted looks like a 4-finger lever, while this one, https://www.amazon.com/Shimano-Acera-.../dp/B003ZMFO06 is a 2-finger.



and extra fun, I'm not finding these on Shimano's tech site so I can't even say what all possible combinations of versions they have, but just poking around amazon, I'm seeing 7 and 8 speed versions, and 2 and 4 finger versions, ALL called ST-EF51. some of them say they are for v-brakes, so should work for those disks, but others dont say what they are for.

so... when you pull hard on the handles, are they bottoming out into the bars, or are you feeling hard brake, but its just not stopping ?

did you degrease the rotors ? I would have hit them with some brakleen (nasty auto disk brake cleaner in a spray can, a really potent degreaser) before assembling them, and avoided touching the braking surfaces after. you might pull the pads out and buff them a bit with some medium sandpaper to take the glaze off, then do some repeated braking to break the brakes in.

SeboAmp

Well, i just took a look to the levers, and it says exactly ST-EF51-L, 7 speed.
And no, when i got the rotors and calipers , i didnt degrease them.. I just read that, to clean the rotors i could use isopropyl alcohool, and thats what i did.
Also i forgot to say that the rear caliper does brake properly, the wheel locks and no 100% pressure on the lever is required to do that.

oldbobcat

I'll bet the fixed inner pad is retracted so it isn't hitting the rotor. Your outer pad is pressing the rotor against the caliper instead of the inner pad. Here's what to do.

First, loosen the cable pinch bolt and the bolts that align the caliper with the rotor. You want everything loose at this point.

Second, check that you can see the inner pad protruding from the inside edge of the caliper. If it isn't, you need to tighten the pad adjusting bolt. This is the Allen fitting on the wheel side of the caliper. It takes a 4 or 5 mm Allen wrench. Tighten this until you see 1-2 mm of pad

Third, Adjust your cable tension so the brake lever pulls about parallel with the handlebar when the brake is fully applied. Then center the caliper.

That should do it.

SeboAmp

The inner pad is fully retracted as you say, but im pretty sure that when pressing the lever, the outer pad makes pressure on the inner pad and not the caliper.

cobba

Is the rotor centred in the brake calliper.

fietsbob

Pads Out , carborundum paper cleans off glazing , then you put them back in,again..

osco53

Once you get the brake adjusted Get one of these,,,

Retro Grouch 

What are you using for cable housing?

Compressionless brake housing, like Jagwire Rip Cord, costs about double but makes an enormous difference in the operation of mechanical disc brakes. It's hard to describe how much difference it can make.

SeboAmp

Im using the ones which came with the brake itself, i think its a Shimano housing

SeboAmp

Well, i double checked it and you were kinda right, when braking, the rotor was making a little bit of contact with the caliper itself, now i did what you told me to do, and the braking performance improved.

fietsbob

Back to bedding in the pads.. if that was not done right, they stay glazed,,
take the pads out, sand off the surface glazing and put them back in.