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I know many that questions are here for this brake pad/rotor , but I have a different case.

I felt a medium steering wheel vibration when braking at high speeds (above 100 kph), no pedal shaking and I had some small noise (maybe cause the pads were dry)

So I checked the brake pads & found they still have maybe quarter of their life but they were dry (weather here is too hot), after replacing the pads , no noise except a very small sound (normal braking sound) but I still get some vibration from the steering wheel on braking.

On replacing the pads, the mechanic didn't replace the brake shims with the new ones & said the OEM (GM) shims are better than AC delco (that I got) but I have serious doubt on that.

The rotors look good, with very slight grooves (like small scratches) but I thought better not to resurface them to avoid ruining them soon.

The question here could this be from the shims ? do I need to wait for some time for the pads to match the rotors? since I got no pedal vibrations & rotors look good I feel I shouldn't resurface & maybe the shims are causing this.

Any advice please ?

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    Probably slightly warped rotors. BTW, GM "OEM" and AC Delco are the same parts and should have no difference in quality. – SteveRacer May 14 '18 at 22:50
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    Possible duplicate of Steering wheel shakes when braking at high speeds – Moab May 14 '18 at 23:44
  • Thanks @SteveRacer, I think maybe that is the case, however I think the new pads will bed in and then I shall not have this steering shuddering, what do you think? I don't want to surface the rotors and make them weaker unnecessarily – Ahmed Elkoussy May 15 '18 at 13:06
  • @Moab I have seen the other question & my case is different, he replaced the rotors & I didn't (only pads here), he has a very strong steering vibration mine is moderate – Ahmed Elkoussy May 15 '18 at 13:07
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    Does not mean they were turned correctly. – Moab May 15 '18 at 19:23
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Vibration through the steering wheel is generally caused by a defect in a rotating part or an imbalance in a rotating part. Note: neither pads nor shims rotate. If the problem is the same after you replaced the pads, I think that makes a pretty compelling case that it's not the pads/shims.

Likely sources of this vibration are in order of likelihood:

Warped rotors: You can't tell if they are warped by looking at them. You can check them for true with a dial indicator when you have the car on jack-stands. Or you can take them to a professional with the equipment to inspect and correct the defect if possible.

Pad Material bonded to the Rotor: This simulates a warped/imbalanced rotor and will have all the same symptoms and is also fixed by having a professional inspect and resurface the rotor if possible.

Bent Rim: If you have a bent rim it can cause symptoms similar to a warped rotor. Possible to not feel any wobble when driving without the brakes on, but lots of wobble when braking. A competent tire shop should be able to analyze this.

Bent Suspension parts: Difficult to ascertain without raising the care SAFELY and inspecting the suspension. Possibly involves removing parts and measuring against factory specs.

Rotors out of balance: This is rare but does happen, again an automotive professional can inspect the parts for true and balance. I've known people who swear that cutting and balancing the rotors on the car is the only way to go.

Hopefully your problem will be simple.

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    Thank you for your help, should I wait some time as maybe the new high quality pads will (sort of) resurface the rotors ? rotors look very good (the scratches seen cannot be felt), the mechanics here generally won't look too much what is the issue & will do unneeded work – Ahmed Elkoussy May 14 '18 at 22:10
  • Also from what I understood, if the rotors are warped & need resurfacing/replacing, I will feel pedal vibrations & will hear noise, which doesn't happen, suspension & rims are very good & balanced, I feel the old pads might have been too dry maybe but that is all , should I wait a week & check ? or would you recommend resurfacing rotors ? – Ahmed Elkoussy May 14 '18 at 22:13
  • @AhmedElkoussy In my experience, no magic "pad" is going to resurface a rotor and eliminate warp. The pad tends to wear the rotor evenly, and may even increase the warp over time, because the pad pressure changes along the surface, and the "high" spots will get even more heat. – SteveRacer May 14 '18 at 22:52
  • I am thinking pad material is bonded to rotor, especially if the rotors were not at least burnished during new pad install. – Pᴀᴜʟsᴛᴇʀ2 May 14 '18 at 23:00
  • Tim nice answer. I do know of one more root cause for braking shimmy. In some cases soft suspension bushings allow for the suspension arm to shift car rearward slightly during braking. This movement in steering geometry propagates as shimmy during braking. The fix = stiffer bushings. – zipzit May 15 '18 at 4:01
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In my case, it turned out to be the shims (I hadn't put the new shims with my new pads as the mechanic insisted that mine were GM so they are better than those of AC delco), when I read the parts manual that was with the shims (given with the pads actually) I found that the manual insisted that the shims must be put with the pads & that bad shims can cause these symptoms (braking sound & steering wheel vibration & sometimes a pull).

So I replaced the shims & now the problem is solved, it seems that the old shims were defective.

I want to thank everyone who tried to help me & I hope this answer would help someone else.

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