Tuesday, May 23, 2023

Brake Job

A slotted fastener? C'mon Shimano! Really?
 Not long ago I had a weird thing happen on a ride on the Noble GX5 where I applied the brakes hard to slowly descend a flood control dike. There was no issue there, but later into the ride I had the rear brake lever come all the way back to the bars with little braking power. While a brake bleed may be the initial diagnosis, it has been my experience as a mechanic working with Shimano hydraulic brakes that worn pads can cause this same effect. 

But all at once? I had great rear brake feel, then bad brake feel all in the same ride. Well, I decided to hedge my bets and I got both the brake bleed kit, mineral oil fluid, and a new set of organic pads. 

I figured on changing the pads first as that is the easiest fix. As I sat down to work on this, I discovered that the brake pad retention bolt had a slotted head. Not a hex interface, not a Torx interface, a slotted interface. What?!!

Warning! Rant Alert: As a mechanic it is my opinion that slotted interfaces should be banished from Planet Earth. There is no reason to use that anymore when superior technology exists and is extensively used in the industry. Why do I feel this way? Because a slotted interface fastener is super easy to damage, harder to work with, and .....well.....it just is not a good choice anymore. As stated above, better ideas exist and are readily available to any manufacturer. Okay....rant over. 

Once I had carefully selected the proper size flat blade screwdriver, the fastener came out undamaged. Whew! That was the worst of the job right there, and the rest was a breeze to finish up. I buttoned up everything and went out to bed in the pads to the rotor. 

And how did that go? Well, the brakes are better. But they are not what they were yet, so I may do a brake bleed anyway just to see if I can't bring the lever feel back to what it was. I mean, I can lock up the rear wheel and braking power, modulation, and all is just fine. It's the pad contact feel that is lacking and it seems to me that the lever travel is just a bit much yet. But here again, I've had Shimano road brakes on many bikes in my workstand where you couldn't get the rear to feel like the front no matter how much you bled the brakes.

And I had zero evidence of brake fluid leakage, which would indicate that the system is still sealed, but that doesn't necessarily mean anything here. It just points to the fact that it was mostly the pads that went away, but there may be something else going on here. 

Stay tuned. I may end up bleeding the brakes after all.


teamdarb said...

I like the choice of using a slot in this scenario. It's either that or cotter pin. The allen or six point sized for that head would just get lost once dropped on the ground.

Derek said...

I'm thinking they used to be like a 3mm hex head? Or smaller? Must be some reason Shimano spec'ed that bolt? I wouldn't think that they save much money on slotted vs hex vs star bit...... maybe they want to limit the torque people will apply, i.e. "ham fisted"?

Guitar Ted said...

@Derek - Shimano would typically use a 2mm hex head bolt in applications like this. I would have preferred to see a 3mm hex head or a Torx interface.

Derek said...

Ah, thanks, the tiny little 2mm! Maybe the slotted head is easier to clean packed clay dirt out of than a tiny recessed head like hex or Torx? That stuff gets to be almost like cement after it dries, and without a good pick you really struggle to clean it out.

Guitar Ted said...

@Derek - You are correct about dirt and debris 9in tiny fasteners like this that obviously would be exposed to a lot of dust, mud, dirt, moisture, etc. Are their MTB calipers like this though? It would be consistent with your suggestion if they were using a slotted pad holder bolt.

But you are right, hex and Torx bolts can and do get fouled by hard dirt and dust build up. I've battled that with the 4mm flat mount brake caliper bolts on the rear of some of my bikes. Amongst other places.....

I still say slotted fastener heads should be banished forever! :>)