Put Rotors on the wrong direction + Other Brakes Q's

[Spetznaaz]

So i finally got around to doing my pads (EBC yellow Stuff) and rotors (Mtec). I drove about 15 miles and realised, i've put the bloody rotors on the wrong way. They are Mtec (U.K company) grooved and dimpled rotors and according to their website https://www.mtecbrakes.com/brake_dis...ing_bedding_in they are directional, so the grooves and dimples are going the wrong direction to what is apparently right. Interestingly the ones on before, drilled as standard, they were not directional meaning the drilled holes on one faced one way and the other the opposite way (when fitted).

Does anyone know if this really matters? I'm dreading having to take everything apart again and swap them over. I looked at the vents between either side of the rotor, thinking they might be directional and thus cooling would be affected however from what i can tell they are straight and don't go a certain direction.

Also perhaps someone could help me out with another thing. When braking it feels a little bit juddery / grindy, is this normal? Only done light braking so far. When i installed them i spun the wheel and there was scraping followed by no noise followed by scraping, suggesting the rotors were not on straight. After i tighten and torqued the wheel bolts the scraping was gone when i spun the wheel.

Another thing i just remembered, there is a slight chattering / ticking / clicking type sound when i go above 30mph. Kind of sounds like a stone stuck in a tyre but not as fast. Anyone know what it could possibly be?

Many thanks as always :)

[Jayz691]

Well, if theyre straight vanes, then ya usually go by direction of grooves. Pics would have helped. But the grooves should usually sweep up and back from the front of the car, if that makes sense. If they have directional vanes, then you go by that. Could be the reason for the juddering your feeling. Any directional rotors are usually labeled with a sticker too, L&R. Also, whenever ive run slotted rotirs, I always got a little bit of noise or slight grind feeling. Nothing much, but not as smooth as solid rotors.

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[Spetznaaz]

I never noticed any left/right marking but i was having a hell of a time getting the carrier bolts out (now i realise turning the steering wheel makes life 100x easier) i probably missed it.

The grooves sweep down and back so definitely wrong. Eurrgh this is going to be fun... And i'll need to buy 4 more carrier bolts as well. I damaged the old pads when taking them out, it was the only way to do it, really hope i don't damage my new ones.

Do you know if it matters if i drive about 50 more miles before swapping them? I really need to go out and get some parts before i do it tomorrow.

Thank you

[Audibot]

50 miles probably won't hurt if you're taking it easy. The directional vanes help with cooling, hence why they are important to get right!

[Charles.waite]

If the rotor was hitting the pads in one spot but not others then its possible you have debris between the rotor and the hub. Did you clean the hub surface really well with a wire brush before mounting them? Did your rotors use the retaining screws that the OEM rotors use?

Its common to have a slight "ticking" feel in the pedals from slotted rotors (grooved as you call them) but it shouldn't feel like the brakes are pulsing, if thats what it feels like then your rotors aren't mounted flat and you're going to need to sort that out.

As far as the vanes? I've yet to see rotors for our cars that have directional vanes. They're almost always straight which means they can go on either side. Maybe the expensive 2-piece specialty rotors could be directional but even then theres not really an advantage for a non-track car.

[Spetznaaz]

If the rotor was hitting the pads in one spot but not others then its possible you have debris between the rotor and the hub. Did you clean the hub surface really well with a wire brush before mounting them? Did your rotors use the retaining screws that the OEM rotors use?

Its common to have a slight "ticking" feel in the pedals from slotted rotors (grooved as you call them) but it shouldn't feel like the brakes are pulsing, if thats what it feels like then your rotors aren't mounted flat and you're going to need to sort that out.

As far as the vanes? I've yet to see rotors for our cars that have directional vanes. They're almost always straight which means they can go on either side. Maybe the expensive 2-piece specialty rotors could be directional but even then theres not really an advantage for a non-track car.

Yeah i cleaned it up with a hand wire brush and steel wool the best i could, the side i'm on about was completely smooth apart from a tiny bit that felt slightly rough, the other side had a few rough bits but i got them as smooth as i could with the tools i had. I did use the rotor retaining screw, although the hole wasn't as perfectly matched up as i would have liked, it went in fine but perhaps as it's only one screw, it didn't pull the rotor flat. As i say when i did the wheel bolts up (star pattern torqued to 120nm) the rubbing stopped so i'm thinking maybe doing so pulled the rotor nice and flat against the hub.

As for the pulsating - I couldn't say 100 percent if it's the ticking feel you mentioned due to the grooves or pulsating as i've never really had experience of either. I would say it isn't too bad but then again i've only performed very light braking and will do until 200miles when it's bed in time.

Pretty sure the veins aren't directional then but i think i should probably swap everything over. I think it will end up really bugging me knowing they aren't on the correct way.

[Theiceman]

well you know they are mounted wrong so fix that first. and make sure dust shield isnt bent and touching rotors.

[Spetznaaz]

So i switched the pads and discs around... The chattering noise has gone but now there's another noise. Hard to describe, like a grinding possibly, it comes from the left side and seems to come and go but gets louder and from both sides every time i apply the brakes.. I really don't understand what i could have done wrong as i was very careful to try and do everything by the book. Dust shield didn't seem to be touching the rotors.

Anyone got any ideas?

[Theiceman]

really hard to say on this without being there.. maybe time to pay a mechanic an hour time to put it on a lift and look at it .

[Jayz691]

From my past experience, slotted rotors always have a little noise and different pedal feel than drilled or blank rotors. Kinda why I don't run them anymore. It may be normal. Have you bed them in?

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[007J]

I have drilled and slotted rotors, and I paid my local Audi Dealership to re-install my brakes after I did them because of similar symptoms you are describing. They obviously did a better job than I did, but on light to medium braking you can feel a very slight frequency pulse difference on the slotted rotors slowing down. Every vehicle and motorcycle I've had with slotted rotors have had that similar brake feel. It's part of the compromise for the cooling, but worth not boiling your brakes out as fast if you enjoy track style driving on backroads and such. If you think the feeling is anything other than very slight, it could be every so slightly misaligned.