brake pedal pulsating
08-13-2018, 10:39 PM
#1
Instructor
Thread Starter
brake pedal pulsating
2003 Z06 - had a rear wheel bearing hub on its way out, so replaced both rear hubs with new GM. While it was apart, replaced all 4 shocks with C6 Z06 shocks. While all THIS was apart I replaced all 4 rotors and pad sets with a new aftermarket brake set. Everything went fine putting it all back together, took a test drive and I have horrible brake pulsations, enough to move my head back and forth. I checked the runout on the new rotors and was surprised to find the best one was about .002 and the worst one was about .010, new out of box. The real bad one was kind of hard to measure perfectly since it was bouncing my dial indicator, so I'm guessing that one. Hard to believe one could get brand new rotors that were that far off, but then I started thinking that I had also replaced the hub bearing assembly. Anyone ever gotten a bad hub assembly? The worst rotor was on one of the rears where I replaced the hub. I've already pulled the kit off and boxed it up to send back, got a different brand brake kit on the way. Planning on checking hub runout tomorrow, hopefully the hubs are ok. Also hoping this is not some freak issue with traction control or ABS or something. Any thoughts?
08-28-2018, 12:16 PM
#3
Instructor
Thread Starter
Update: my pedal vibration problem on my new brake install turned out to be some defective new rotors out of the box (excessive runout). Hub assemblies checked perfect, no runout. A new rotor set from another source fixed the issue, perfect brakes now. From now on I will be checking rotor runout on any new rotor I install prior to road testing the vehicle. Live and learn.....
Update: I did go with EBC rotors and pads this time. And I checked runout, which was within tolerance (almost zero runout).
Update: I did go with EBC rotors and pads this time. And I checked runout, which was within tolerance (almost zero runout).
Last edited by 50thz06; 08-29-2018 at 11:25 AM. Reason: additional info
08-29-2018, 12:07 AM
#4
Drifting
Used Centric/StopTech and Bosch disks on my daily drivers, both brands failed prematurely. One warped, the other had hollow voids in the casting as they aged. A little disappointed, thinking they were better than house brand disks. Unfortunately both are made in China, which might be the problem. Only the top of the line Stop Tech's are USA made. Using EBC disks and pads now, time will tell, but so far all good and not made in China.
08-29-2018, 12:39 AM
#5
Burning Brakes
Brake Rotors
Used Centric/StopTech and Bosch disks on my daily drivers, both brands failed prematurely. One warped, the other had hollow voids in the casting as they aged. A little disappointed, thinking they were better than house brand disks. Unfortunately both are made in China, which might be the problem. Only the top of the line Stop Tech's are USA made. Using EBC disks and pads now, time will tell, but so far all good and not made in China.
08-29-2018, 11:30 AM
#6
Team Owner
I’m retired from the auto parts business 40 years of it. When I first started all rotor and drums were USA made steel or composite and were made in the states. As time went by there was no American made rotors available. I was direct wth stop/tech. They were also Chinese rotors. Their top of the line were USA. Slowly American manufacturers are starting production again. The problem is people demanding low price. So we priced ourself’s out of the market. You would be surprised just how much auto parts are Chinese. Wagner brakes were the last to sell American made rotors and they were three times the price. The only difference is the warranty. If you purshase cheap rotors than maybe a 30 day warranty. Lifetime rotor were the same in the box just three times the price and had painted black hubs. I do not think very many manufacturers are doing lifetime anymore it’s up to the auto parts chain or vendor. We did lifetime rotor’s for are customers and just scraped the metal when there were “Defective”
………..and of course, the price of brake rotors went down.....along with the quality. With respect to drums, they're even worse! One shop we sold brake parts wouldn't even install new brake drums that tey got from us, without first putting them on a lathe, and giving them a clean-up cut.
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jeffs64 (08-29-2018)
08-29-2018, 11:39 AM
#7
Instructor
Thread Starter
It's a shame that a person can't completely trust all "new" parts any more. Years ago, I can't remember ever buying any replacement parts that were defective out of the box. These days, a person has to check every new part first or risk having to re-do the job again. Rotors are particularly suspect, in my recent experience. I'm reluctant to name brands here, but I've stopped using some manufacturers products that I used to really trust years ago. When I'm shopping, I tend to stay away from "cheapest", if I don't know the manufacturer. Plus I try to lean toward forum member experiences in things I have no personal experience with. I'm sure we would all agree that while we enjoy working on our projects, no one likes redoing something simply because we installed a defective part. Even worse, would be premature failure of an inferior part down the road that causes additional damage or even life threatening situations, like brakes.
The following users liked this post:
jeffs64 (08-29-2018)
08-29-2018, 12:10 PM
#8
Burning Brakes
It's a shame that a person can't completely trust all "new" parts any more. Years ago, I can't remember ever buying any replacement parts that were defective out of the box. These days, a person has to check every new part first or risk having to re-do the job again. Rotors are particularly suspect, in my recent experience. I'm reluctant to name brands here, but I've stopped using some manufacturers products that I used to really trust years ago. When I'm shopping, I tend to stay away from "cheapest", if I don't know the manufacturer. Plus I try to lean toward forum member experiences in things I have no personal experience with. I'm sure we would all agree that while we enjoy working on our projects, no one likes redoing something simply because we installed a defective part. Even worse, would be premature failure of an inferior part down the road that causes additional damage or even life threatening situations, like brakes.
08-29-2018, 12:11 PM
#9
Burning Brakes
After I retired from the precision optics industry, I wound up working for Advance Auto Parts, for a few years, and I agree 100% with your sentiments, with 1 exception. The "green weenie tree huggers" also drove the foundries out of America with all of their draconian air pollution standards. And the real fallacy with their reasoning, is yes, the source of pollution under some controls, left America, but it then went to China, where there are little to NO controls. Bottom line, even more pollution is being produced, and pumped into the air. These "weenies" seem to think that there's a dome over the US, which shields us from foreign generated particulate.....
………..and of course, the price of brake rotors went down.....along with the quality. With respect to drums, they're even worse! One shop we sold brake parts wouldn't even install new brake drums that tey got from us, without first putting them on a lathe, and giving them a clean-up cut.
………..and of course, the price of brake rotors went down.....along with the quality. With respect to drums, they're even worse! One shop we sold brake parts wouldn't even install new brake drums that tey got from us, without first putting them on a lathe, and giving them a clean-up cut.
08-29-2018, 10:07 PM
#10
Burning Brakes
It’s the idiot US consumer who has demanded cheaper and cheaper prices. They have literally put their own industries out of business. It’s possible to make a foundry environmentally friendly, but it costs money. Money the cheap *** US consumer won’t pay, even to save their jobs.
After the election last year, I was at Harbor Freight, the only local store that stocks blast media. As I was walking to my truck, I noticed a ratty Nissan pickup in the parking lot next to me. It was covered with Trump stickers and “Buy American” and MAGA. The guy came out of HF with a shopping cart full of Chinese crap and I pointed to his truck and said “What gives?”
He looked at me with a stupid grin and said “What are you talking about?” I said, “ Your truck has Buy American stickers all over it, why are you shopping at Harbor Freight?” He shrugged and said, ‘It’s cheap.”
IDIOT
After the election last year, I was at Harbor Freight, the only local store that stocks blast media. As I was walking to my truck, I noticed a ratty Nissan pickup in the parking lot next to me. It was covered with Trump stickers and “Buy American” and MAGA. The guy came out of HF with a shopping cart full of Chinese crap and I pointed to his truck and said “What gives?”
He looked at me with a stupid grin and said “What are you talking about?” I said, “ Your truck has Buy American stickers all over it, why are you shopping at Harbor Freight?” He shrugged and said, ‘It’s cheap.”
IDIOT
08-31-2018, 04:45 AM
#11
Let's remember that rotors don't really warp. Not on cars. That piece of machined cast iron is really, really not going to bend. Cast iron is brittle, not particularly ductile, so if you heat the puppy up hot enough to cause structural damage, it's about 1000x more likely to crack than bend.
Not to mention that most folks aren't running the kind of pads, calipers, nor fluid that can withstand the temperatures required to get cast iron to bend.
Warped rotors are, in the majority of cases, simply pad deposits. Re-bed in the rotors and the pad deposits go away.
Excessive runout can happen. Rare but it happens.
Y'all know why people make rotors in china and not the US? Because a basic iron rotor - like the kind that sits on almost any corvette not running a carbon rotor - a basic iron rotor is a trivial piece of machinery. Iron is cast into a mold, the proper holes are machined, the rotor surface is machined smooth. That's about it. You probably get a painted hat and if you're lucky, a painted side to prevent rust. This is some really basic stuff that even most foundries in countries that don't care a lot about quality can still accomplish. Nice rotors don't really help you stop faster, not unless you're reducing weight by going to a two-piece setup, and even then most of the limit anywhere except the track (with repeated hard braking) is the tires. Pretty much any bottom-of-the-barrel brake rotor and ceramic pad will bite harder than your tires can support. And before you worry about rotor upgrades for the track, worry about brake fluid, pads, and then do your rotors when you get better lighter bigger calipers to support bigger rotors too. Till then, do what the track rats do: buy the cheapest rotors that don't seem to crack, and carry spares. Or, since most aren't hitting the track, just don't worry too much.
So that's why people buy cheap rotors: less than 1% of cars need anything more than the cheapest rotors that don't break when you look at them funny. And, yeah, that does mean lower quality control, but statistically it's a lot cheaper to occasionally (maybe one in ten thousand?) have a crap rotor, and pay for the issues it causes, than to put in the effort to make them 10x less likely (one in a hundred thousand?) to have a defect.
Oh, and if y'all aren't sure how pollution works, some of the stuff in the air immediately impacts us all, some of it takes a long time to float over the pacific and becomes quite dilute by the time it does, and most (but not all) of the crap leeching into the soil and water is so diluted by the time it reaches us here in the states. Not great - nobody's advocating for pollution from factories in china - but to pretend that it makes no difference whether factories are putting run-off into your well water or not is lunacy.
Not to mention that most folks aren't running the kind of pads, calipers, nor fluid that can withstand the temperatures required to get cast iron to bend.
Warped rotors are, in the majority of cases, simply pad deposits. Re-bed in the rotors and the pad deposits go away.
Excessive runout can happen. Rare but it happens.
Y'all know why people make rotors in china and not the US? Because a basic iron rotor - like the kind that sits on almost any corvette not running a carbon rotor - a basic iron rotor is a trivial piece of machinery. Iron is cast into a mold, the proper holes are machined, the rotor surface is machined smooth. That's about it. You probably get a painted hat and if you're lucky, a painted side to prevent rust. This is some really basic stuff that even most foundries in countries that don't care a lot about quality can still accomplish. Nice rotors don't really help you stop faster, not unless you're reducing weight by going to a two-piece setup, and even then most of the limit anywhere except the track (with repeated hard braking) is the tires. Pretty much any bottom-of-the-barrel brake rotor and ceramic pad will bite harder than your tires can support. And before you worry about rotor upgrades for the track, worry about brake fluid, pads, and then do your rotors when you get better lighter bigger calipers to support bigger rotors too. Till then, do what the track rats do: buy the cheapest rotors that don't seem to crack, and carry spares. Or, since most aren't hitting the track, just don't worry too much.
So that's why people buy cheap rotors: less than 1% of cars need anything more than the cheapest rotors that don't break when you look at them funny. And, yeah, that does mean lower quality control, but statistically it's a lot cheaper to occasionally (maybe one in ten thousand?) have a crap rotor, and pay for the issues it causes, than to put in the effort to make them 10x less likely (one in a hundred thousand?) to have a defect.
Oh, and if y'all aren't sure how pollution works, some of the stuff in the air immediately impacts us all, some of it takes a long time to float over the pacific and becomes quite dilute by the time it does, and most (but not all) of the crap leeching into the soil and water is so diluted by the time it reaches us here in the states. Not great - nobody's advocating for pollution from factories in china - but to pretend that it makes no difference whether factories are putting run-off into your well water or not is lunacy.
Last edited by gimp; 08-31-2018 at 04:47 AM.
