Brake rotor vibration

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bigdoug
Posts: 80
Joined: Thu Jul 21, 2016 5:36 pm
Location: Detroit Area, Michigan

Brake rotor vibration

Post by bigdoug »

I'm going to post two threads because I have two separate issues. Along with many others that I'm dealing with.

I've had this problem in the past. I step on the brakes, usually at higher speeds, and the steering wheel vibrates. It's probably brake rotors. I had the same problem with my Focus. I always wondered why this happens. I do a lot of slow and stop and go driving in urban locations, although I try to be easy on the brakes and don't hit them hard unless it's absolutely necessary. I wondered if that's the issue, or if it's just because of crap, badly made rotors using inferior materials. Or possibly because of frozen calipers. A friend mechanic claims it's because of me braking hard, but I don't brake hard, and he never drives with me so I don't know where he got that idea.

The brake pads themselves are about 1/4" pad left left, I don't know how thick a full pad is but if I have to replace them I will live. The question is, how to prevent this from happening again. Is it because of bad calipers and should I replace the calipers (even though that will add to the cost?). Should I spend $40-50+ on premium rotors which will push total cost quite a bit over $100? With my focus, a year before I got rid of it I had replaced the rotors with AC-Delco's economy/bargain rotors and never had a pulse problem again, so I could try that, but I want to prevent this from happening again.
jolt
Posts: 945
Joined: Sun Mar 02, 2014 2:07 am
Location: Twin Cities, Minnesota

Re: Brake rotor vibration

Post by jolt »

The problem can be caused by all of the above that you have talked about. At this forum others have stated that the rotors that lasted the longest for them were the Toyota OEM rotors at about $80.00 per rotor and that the cheap rotors are not worth buying because they will warp.

Also make sure that the hub surface is free of rust where the rotor makes contact with the hub and that the wheel surface is also free of rust where the rim makes contact with the rotor. Torque all your wheel nuts in a cross pattern going in steps like 30 ft-lbs, then repeat at 50 ft-lbs, and then the final of 70 ft-lbs. Doing this will distribute the clamping load on the rotor so that you are not stressing the rotor on one side before the other nuts are tighten as that could lead to warping the rotor. Rotors are a casting and all castings have stress in them when they cool. The stress will be relieved over time and with added temperature. When this happens, it can lead to warping of the casting. A good casting will have a slower cooling time and may even be heat treated to reduce the internal stress which makes the casting more stable and less likely to warp. It adds to the cost of manufacturing the part but is a better quality part when done.
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vibrologist
Posts: 1598
Joined: Sat May 10, 2014 8:24 am
Location: Iowa

Re: Brake rotor vibration

Post by vibrologist »

My 2 cents to this topic:
That vibration is most likely caused by thickness variation. Most people assume the rotors are warped. It does not matter. Either way you get that vibration.
Make sure the calipers can retract easily on the sliders. Even a little drag means that the pads will touch the rotors when parked. That means the rotors will rust over night just slightly uneven and that can give rise tot he thickness variation as the rust gets rubbed off when braking.
Beyond that you can only improve the situation by buying quality products. I've been generally satisfied with Wagner rotors and dissatisfied with store brands.
Vibrologist
'05 Vibe

"It is important to know the difference between 'accurate' and 'precise' even if you are neither!"

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bigdoug
Posts: 80
Joined: Thu Jul 21, 2016 5:36 pm
Location: Detroit Area, Michigan

Re: Brake rotor vibration

Post by bigdoug »

I think I have a reason for the rotor vibration.

Back in Feb I bought a pair of tires from Walmart, then bought another pair again. $350 for cheap but decent tires. It wasn't the tires that were the problem though. When trying to remove the front wheels in the past couple weeks I noticed the lugnuts felt way too tight, and some of them were bigger than the 21mm socket. Seems some were having the problem listed in this thread: viewtopic.php?f=20&t=45885&p=518429#p518429

What I think happened is the idiots at walmart overtightened them or hit them with an impact wrench, and that might have very well warped the rotors as well. Not only do I have to replace some lug nuts, which might have been their fault or just because I live in Michigan, I now have to replace a stud, because when I was trying to spin it off it was stiff, creaking, and then it snapped. Nice.
broken.jpg
broken.jpg (28.44 KiB) Viewed 1956 times
Makes me rather reluctant to buy any tires from walmart ever again.

Found these while looking for rotors. Seems like a good price... maybe too good of a price for slotted/drilled. In any case I'm not a performance driver and don't need slotted/drilled, just ones that dissipate heat decently and don't warp.
jolt
Posts: 945
Joined: Sun Mar 02, 2014 2:07 am
Location: Twin Cities, Minnesota

Re: Brake rotor vibration

Post by jolt »

bigdoug, did you notice in your picture that the ends of the wheel studs are not rusty like the rest of the bare metal is in your picture. That because the wheel studs are zinc plated. The zinc platting keeps the studs from rusting and is a lubricant for the threads. Zinc is a very soft metal and will wear away from the threads under pressure. This can be seen if you look at the threads of your studs. You are down to bare steel on the threads. Steel on steel with no lubrication will wear faster and can cause the threads to gall. More info about this here: https://www.boltdepot.com/fastener-info ... lling.aspx
Back before they started zinc platting the studs, the manufactures recommended putting light oil on the stud threads before torquing the wheel nuts. Guess what a quality anti-seize is made of.....zinc! By using this, you are replacing the dry zinc lubricant that has wore away from repeated wheel nut removal and installs with the zinc that is in the anti-seize. Does this change the clamping load when torqued....yes. It gets the clamping load of the fastener back to were it should be with a lubricant of zinc that was there from the factory. If you read the link above in this post, see "Slow Down Installation Speed", which is the opposite of using an air gun to spin the nuts on like the wheel shops do. The nuts should go on by hand and tightened by hand. Take the torque up in steps in a cross pattern on the wheel studs like I said in my first post above, and when it comes to anti-seize, a little goes a long ways. Use it sparingly.
bigdoug
Posts: 80
Joined: Thu Jul 21, 2016 5:36 pm
Location: Detroit Area, Michigan

Re: Brake rotor vibration

Post by bigdoug »

Do any of you guys know the size of the small holes in the rotor where you can stick bolts to get the rotor unstuck from the hub?
ehoff121
Posts: 756
Joined: Mon Feb 26, 2007 12:19 am
Location: Conn.

Re: Brake rotor vibration

Post by ehoff121 »

bigdoug wrote:Do any of you guys know the size of the small holes in the rotor where you can stick bolts to get the rotor unstuck from the hub?
8 mm x 1.25 mm threaded bolts. They only need to be like 1 1/2 inches long. Be sure to put them in hand tight at first (use a little anti-seize on the threads if you need a lubricant) and alternate giving them a 1/2 turn. You'll probably still need to smack the rotor, as the bolts alone won't be enough.
2005 Pontiac Vibe AWD - Platinum
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