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Shimano Deore disk brakes not contacting rotor correctly?

14807 Views 19 Replies 11 Participants Last post by  OldMike
I recently upgraded from the stock tektro novella mechanical disk brakes on my bike to Shimano Deore M615 hydraulic brakes. The brakes work better but not as good as another bike I rode with the Deore brakes. After a few rides I can see the contact patch on the rotor doesn't look right. The pad doesn't seem to be touching the lower portion of the rotor. Anyone seen this before? The contact patch for the stock tektro brakes looked fine. The pads do seem like they have a little play between the hole and the cotter pin that hold the pads. Could this be the cause? Better brake systems use a bolt instead of the cotter pin.


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Different brake brands have pads with different surface areas. Looks like you're using your old Tektro rotors with the new Shimano calipers. I wouldn't expect the braking tracks to line up exactly.

As long as the pads are not overhanging the outer edge of the rotor, you'll be fine. If they are, then that's a problem. The angle on your front caliper picture makes it hard to tell, but it looks like the rear caliper probably is not overhanging.
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Looks like a shimming/alignment issue. What size rotors are you using? What adapter is that on the fork and if it's a 160mm rotor, did you try it without that adapter?

On the back rotor, no idea. Unless the stock rotor isn't the right size for the shimano calipers, but to my knowledge, they should both use the same (160mm)
That adapter on the fork is too big. You either need a smaller one or no adapter.
The stock tektro rotors were replaced. The sizes are stock, 180mm in the front and 160mm in the rear.

I originally had magura rotors but the brakes felt weaker than the other bike I rode with the standard shimano rotors. The shimano rotors were cheap so I bought a set to try. They work better than the maguras, but I think that's because there is less material at the OD of the magura rotors. I don't think this would be a problem if the pads were riding correctly on the rotors.

These are the magura rotors I tried.

Circle Fossil Drawing Gear
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You didn't address your pads overhanging or not. I see the same wear pattern on the outer edges of the Magura rotors, too.
Make sure that the Shimano rotors are not labeled "Resin Only". If they are, you will have to use Resin pads with those rotors.
The pads overhang the OD a little, but I can push them down then they don't overhang. It seems like there is too much play between the hole in the pad and the cotter pin and the pads are getting pushed up.

A friend of mine has the same bike (felt DD70) and he upgraded to the Shimano SLX with SLX rotors. His calipers come stock with a cotter pin holding the pads, but he was able to use the threaded pin from the XT brakes instead. His contact patch on the rotors looks normal.
Make sure that the Shimano rotors are not labeled "Resin Only". If they are, you will have to use Resin pads with those rotors.
The Shimano rotors are labeled resin only, but I have resin pads so were all good.
New Deore calipers use a narrower "track width" pad than the old Deore disks. Deore are now the same as pads as SLX. I think you will be OK, just that the inner part of the disc won't get used.

The difference between the disc rotors:

"old" Deore/M395 etc. on left, "new" Deore / SLX on right

Circle Visual arts Illustration Drawing Line art

New on top of old - you can see that with calipers matching the new disc rotor, there will be a section of the "old" rotor that will be un touched.

Pattern Circle Visual arts Silver Ceramic

Just make sure that your pads aren't overhanging the outer edge of the disc and wearing a 'step' in them. (I doubt they will be).

Non resin pads are ok on 'Resin Only' discs, but the discs will wear quicker.
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Cotter pin vs bolt, doesn't matter. The pads won't be in the outermost position every time you brake, so they won't wear a lip.
Even with bolt (pad axle) Y8JZ98010 the brake pads still move around just not as much with as with the cotter pin.
I think Misterg explained what is happening. I didn't even think about the different widths of surface area on the rotors RT-56 vs RT-66
Thanks for all the help guys. Didn't know there was a difference between the shimano rotors.

I ordered a set of the pins too, hopefully I can make them fit the deore calipers.
I installed the pad axels today. The thread is a 4mm x .7 and the hole in the caliper body was a couple thou under the tap drill size. It tapped fine by hand. There is quite a bit less play in the pads now.

Bicycle wheel rim Bicycle part Spoke Bicycle tire Rim

Wheel Bicycle tire Bicycle wheel rim Mode of transport Bicycle part
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I haven't gotten around to getting the bolts just yet, but my Zee's are already tapped for the bolts used in the Saint's. Common sense says they are the same casting, but I figured they would have omitted tapping the Zee's. Maybe they dropped the bolt for the pin after the calipers were machined.

Reason for swapping the pin for the bolt? Ease in removing the bolt. The pin is not a total pain, but I broke two cotters when I was installing just the front brake as I would swap between the caliper block and pads to bleed and test. Not planning on dealing with that during every service.
This an old post - but more pics! Works on the BR-M6100, BR-M6120, BR-MT520 as well


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What size Tap?
4mm by .7

and the part number for the pin and clip is Y8JZ98010 (Shimano).
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