Disc Rotors - out of true from the box?

[confusedcyclist]

I recently fitted BB7 MTB brakes to my new commuter. I wasn't heavy handed with the installation or anything, there's 2-3mm of lateral wobble toward the outer disc pads (on both sets) out of the box.

Is it unreasonable to expect the rotors to be true out of the box? I ask because I just can't seem to get them adjusted just right. I'm faced with either noisy brakes as the rotors strike the pads every rotation, or a larger amount of travel due to extra clearance required for quiet operation. The extra clearance means the brakes only bite 100% when the lever is touching the bars, I want a bit more tension than that, but it results in squeal.

I've been thinking about whipping the rotors off the wheels for a bit of DIY truing, or just replacing them, just curious if others have had similar problems with new rotors.

 

[DEFENDER01]

Doesn't seem right to me 2-3mm is quite a lot on rotors. i would get in touch with the supplier.
Certainly you should not need to fettle new parts to make them usable.

 

[confusedcyclist]

Yes, I thought it was odd, but having never fitted my own before, I wasn't sure if it was expected. 2mm wouldn't be an earth shattering movement for wheel truing for example.

 

[ianrauk]

Never had warped discs when I have bought.

I would send them back if they were.

 

[confusedcyclist]

I probably over egged it saying 2-3mm, it's more like 1-2mm looking at my ruler here on my desk.

 

[mythste]

I probably over egged it saying 2-3mm, it's more like 1-2mm looking at my ruler here on my desk.

Being curious of nature I would wonder what the chances are of 2 having the same issue like that.

Is there potentially any gunk under the mounting bolts that are stopping them being mounted evenly?

 

[dan_bo]

So the rotors don't lie flat on your desk?

 

[roadrash]

may seem a silly question but did you tighten the bolts doing one and then the next one to it or doing one and then the opposite one facing it like this
http://cycle.shimano.co.jp/media/te...SI-8KL0A-001-00-Eng_v1_m56577569830750014.pdf

 

[Drago]

My gut call is an error whilst fitting I'm afraid.

 

[confusedcyclist]

Is there potentially any gunk under the mounting bolts that are stopping them being mounted evenly?

I doubt it, both hubs and rotors were new.

may seem a silly question but did you tighten the bolts doing one and then the next one to it or doing one and then the opposite one facing it like this
http://cycle.shimano.co.jp/media/te...SI-8KL0A-001-00-Eng_v1_m56577569830750014.pdf

Ahh yes, I think this may be the problem. Although I did use a torque wrench to ensure all were equally tensioned...

Thanks for the tips. I'll whip them off tonight to double check if they lie flat. Glad I didn't take pliers to them in haste!

 

[Kajjal]

They should be flat if brand new, just get them replaced. My current bike was supplied with a warped rotor making it very hard to set the brakes properly without rubbing. Once swapped for a replacement the brakes now work very well with no rubbing etc.

 

[confusedcyclist]

I am a massive klutz. I somehow managed to round off one of the disc bolts and couldn't get the sodding thing off. Had to take a drill and screw removal kit to it. After 30 minutes of expletives then tears, the disc finally came off. Only after I managed to grind the bolt head down enough to get the molegrips in there. Likely now the hub bearings are contaminated with millions of metal shavings from the drill, but the disc came off at least.

Guess what, it was flat as a pancake, so definitely user installation error. There's nothing like learning the hard way.

I was meaning to install a dyno hub anyway and I'm not afraid of a wheel build these days, so good excuse for a weekend rebuild/fettle.

 

[dan_bo]

I am a massive klutz. I somehow managed to round off one of the disc bolts and couldn't get the sodding thing off. Had to take a drill and screw removal kit to it. After 30 minutes of expletives then tears, the disc finally came off. Only after I managed to grind the bolt head down enough to get the molegrips in there. Likely now the hub bearings are contaminated with millions of metal shavings from the drill, but the disc came off at least.

Guess what, it was flat as a pancake, so definitely user installation error. There's nothing like learning the hard way.

I was meaning to install a dyno hub anyway and I'm not afraid of a wheel build these days, so good excuse for a weekend rebuild/fettle.

Hahahahaha.


Not laughing.


We've all been there pal.

 

[raleighnut]

I am a massive klutz. I somehow managed to round off one of the disc bolts and couldn't get the sodding thing off. Had to take a drill and screw removal kit to it. After 30 minutes of expletives then tears, the disc finally came off. Only after I managed to grind the bolt head down enough to get the molegrips in there. Likely now the hub bearings are contaminated with millions of metal shavings from the drill, but the disc came off at least.

Guess what, it was flat as a pancake, so definitely user installation error. There's nothing like learning the hard way.

I was meaning to install a dyno hub anyway and I'm not afraid of a wheel build these days, so good excuse for a weekend rebuild/fettle.

Take the allen key that rounded the bolt off and throw it away, if it has done it once it will do it again.

 

[Yellow Saddle]

Take the allen key that rounded the bolt off and throw it away, if it has done it once it will do it again.

Or carefully grind it down (shorter past the rounded bits) whilst keeping it ultra cool by dipping frequently in water. We worked a lot with 1.3mm, 1.5mm and 2.0mm allen drivers when servicing forks and shocks. These obviously round very easily but are quite expensive in good quality. If we had to throw them away each time they rounded I'd never have made any money. Of course all ball-head allen keys were banned from the workshop or ground down on day 1. They are just tears waiting to happen.