Brake Vibration?

[ashmostro]

Unless you're tracking laptimes on a track, I would venture any difference you'd feel from such a mod would be psychosomatic, at the very least not worth the price of entry. If you're doing it for looks, that's another story.

 

[Husky]

Unless you're tracking laptimes on a track, I would venture any difference you'd feel from such a mod would be psychosomatic, at the very least not worth the price of entry. If you're doing it for looks, that's another story.

I don't know. I certainly agree that there are plenty of mods that provide only an aesthetic or psychosomatic benefit. But losing 12 pounds on each front wheel might make a noticeable difference. Picture losing four 3lb sledges on each front wheel!

 

[joschneider]

I don't know. I certainly agree that there are plenty of mods that provide only an aesthetic or psychosomatic benefit. But losing 12 pounds on each front wheel might make a noticeable difference. Picture losing four 3lb sledges on each front wheel!

My last car I switched to lightweight enkei rims losing about 15 pounds per wheel. Didn’t notice a single difference, which was disappointing especially with how expensive they were. I would def recommend looking at this as more of a visual mod than anything else. I’m sure if I took it to the track I might notice a tenth or two off a laptime but on the street even driven hard as hell I didn’t notice any difference

 

[Husky]

The engineer in me is still not convinced that a reduction of over 30lbs of rotating, unsprung mass wouldn't be felt on the butt Dyno (in various ways). That's somewhere in the vicinity of a 15% reduction in unsprung weight. However I respect the fact that you've already done this with no notable improvement. I suppose maybe this discussion deserves it's own thread. It's interesting and involves plenty of physics.
I did some quick searching on this issue and came up with a couple of interesting comparison tests:

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=108

Are Lighter Wheels Really Better? | Articles | Grassroots Motorsports

Both of these tests found the weight reduction beneficial, although one can argue as to how much. The Tire Rack test seemed to find that there was a significant difference in the handling of the vehicle that was easily felt by the driver.

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[joschneider]

The engineer in me is still not convinced that a reduction of over 30lbs of rotating, unsprung mass wouldn't be felt on the butt Dyno (in various ways). That's somewhere in the vicinity of a 15% reduction in unsprung weight. However I respect the fact that you've already done this with no notable improvement. I suppose maybe this discussion deserves it's own thread. It's interesting and involves plenty of physics.
I did some quick searching on this issue and came up with a couple of interesting comparison tests:

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=108

Are Lighter Wheels Really Better? | Articles | Grassroots Motorsports

Both of these tests found the weight reduction beneficial, although one can argue as to how much. The Tire Rack test seemed to find that there was a significant difference in the handling of the vehicle that was easily felt by the driver.

I mean no one is arguing there won’t be a benefit, or at least I’m not. My argument is that unless you’re doing back to back tests, it’s not something you’ll easily be able to tell on the street, if at all. But mine is just anecdotal evidence and everyone’s butt dyno is calibrated differently so YMMV. For me, it wasn’t the difference I was expecting so prioritizing weight over looks in the future for my wheel choices won’t be the end all be all of my decisions

Edited to add that if you’re taking your car to a track or drag strip and really want to get your best times, then those tenths will be noticeable and weight is def important

 

[Husky]

I mean no one is arguing there won’t be a benefit, or at least I’m not. My argument is that unless you’re doing back to back tests, it’s not something you’ll easily be able to tell on the street, if at all. But mine is just anecdotal evidence and everyone’s butt dyno is calibrated differently so YMMV. For me, it wasn’t the difference I was expecting so prioritizing weight over looks in the future for my wheel choices won’t be the end all be all of my decisions

Edited to add that if you’re taking your car to a track or drag strip and really want to get your best times, then those tenths will be noticeable and weight is def important

For sure. No, I'm talking about street driving.

 

[PL718]

Thanks for the Stringer Forum article link. Very informative!

 

[ikonn]

Update: after rotor re-surfacing which seemed to work initially, the vibrations are back after 1000kms or so. Took the car in for regular service and the SA said that the rotors need changing. They’re on back order. Main part number is supposed to be the same however the new ones have a different suffix. SA said there’s a technical bulletin out on the rotors.

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[ashmostro]

Frustrating to hear this. I wish Hyundai/Kia would just get correct and admit they didn’t test the pad/rotor/vehicle weight/HP combo enough and do a TSB on the PADS... blaming the rotors is so old-school and not only that, it’s the more expensive (for the manufacturer) solution, let along the wrong one.

 

[ikonn]

Wonder if this is related?

https://www.procutusa.com/pdf/oem/18-01-005-G-Genesis-Brake-Pulsation.pdf

 

[ashmostro]

Yeah, looks like it. So old school.

 

[danygenesis]

Yep, blaming the rotors for this will cost more and won't solve anything. Same with Kia. What a shame.

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[Truck Norris]

SA said there’s a technical bulletin out on the rotors.

If anyone can find out the number on this that would be appreciated.

Edit: NVM I just clicked on the link above...

 

[Husky]

Update: after rotor re-surfacing which seemed to work initially, the vibrations are back after 1000kms or so. Took the car in for regular service and the SA said that the rotors need changing. They’re on back order. Main part number is supposed to be the same however the new ones have a different suffix. SA said there’s a technical bulletin out on the rotors.

Same thing happened to me, despite having paid for the HP Euro pads. I'm waiting for the dealer to install the new rotors as we speak. I hope this does it. They had been on back order also. If there is a new rotor part number, I doubt I'm getting it because the SA said he finally found them at the Kia dealer.

 

[ephone1]

Same thing happened to me, despite having paid for the HP Euro pads. I'm waiting for the dealer to install the new rotors as we speak. I hope this does it. They had been on back order also. If there is a new rotor part number, I doubt I'm getting it because the SA said he finally found them at the Kia dealer.

You put the Euro pads on and still got vibration? How many miles did you have when you replaced them? I replaced my pads at about 500 miles, hoping this would avoid the whole issue.

 

[ashmostro]

If there were pad deposits on the rotors already, switching to a new pad that isn’t terribly abrasive might not have removed the previous deposition layer and in that case the vibration wouldn’t have gone away. Now, if the rotors had been resurfaced before switching to the new pads and a new vibration was picked up, then that is a bit unexpected.

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[Husky]

If there were pad deposits on the rotors already, switching to a new pad that isn’t terribly abrasive might not have removed the previous deposition layer and in that case the vibration wouldn’t have gone away. Now, if the rotors had been resurfaced before switching to the new pads and a new vibration was picked up, then that is a bit unexpected.

Yes, in my case they resurfaced the rotors when they put my new Euro pads on (at about 7k miles). I thought that would do it, but I still had the vibration, and I measured .01" of run-out on one front rotor and .005" on the other. It may have been so bad that the resurface didn't fix it? I know, it's confusing.
At this point the vibration with the new rotors is totally gone. Hope it stays that way since I've got the better pads. Fingers crossed.

 

[ashmostro]

Good luck!

 

[danygenesis]

Looking at Hyundai parts there are two different rotors for the G70 Brembo brakes.
51712-J5500 Rotor for regular Brembo brakes
51712-J5550 Rotor for European pads Brembo brakes
@Husky could you please tell us which one did you get?

 

[Husky]

Looking at Hyundai parts there are two different rotors for the G70 Brembo brakes.
51712-J5500 Rotor for regular Brembo brakes
51712-J5550 Rotor for European pads Brembo brakes
@Husky could you please tell us which one did you get?

Oh boy, that's interesting, and news to me. The dealer got the rotors and installed them, so I would have to ask them. I'll let you know.
Any idea what the difference might be? They seem to fit and work properly.