APracing disc run-out tolerance

alpina527 · 10-10-2011, 01:06 PM

I would be amazed if they were warped. Can you get them checked off the car by a precision engineer?

Did you fit and tighten all 5 wheel bolts when you used the dial gauge?

BimmerRob08 · 10-10-2011, 03:42 PM

Quote:

Originally Posted by AMPowerJ

My OEM and Morr wheels (two different sets) are rock solid. I have Stoptech brakes by the way. On the track it isn't a problem and I have found that different road surfaces make it worse than others with the Apex/Hankook combo.

Do you think because the wheel/tire combo is lighter that is why we feel more vibrations?

Possible, but I had this vibe from day one with the AP BBK & 12mm spacers installed. BUT NOT the magnified vibe in the front end and steering wheel when braking at the time.

But I think a lighter wheel would not manifest a vibe if it's balanced and the tire(s) aren't bulged or something. I would think the opposite, that a heavier wheel combo would, if out of balance, create the vibe. The only way is process of illimination. But I can't put the stock brakes back on. Don't have them anymore and I'm sure not gonna go buy another $7,000 in brakes. Hope I'm not stuck with this issue.

But interesting that you have the issue with your Apex and not the other combo. Have you tried swoping the tires or new tires with the Apex? Road force balanced, etc.?

I'm currently getting my new tires and ARC-8's re-balanced at the dealer with the road force balancer in hopes that at least I can say it's not the front wheels. Guess we'll see what happens with the new rotors.

BimmerRob08 · 10-14-2011, 07:26 PM

Ok, so got my new front rotors in today and installed them. I trust as their brand new from APracing that these rotors are not going to have any flaws.

But to make sure I measured the surface run-out and the rotational run-out. I didn't take pictures (should have and will if need be), but I also measured the surface and rotational run-outs of the front axle hub's that the rotor mates to and the wheels lug nuts torque to. The hubs where .001" or less all around and very smooth rolling so there is no chance that the hubs could be causing my vibration issue.

I installed the rotors and measured the run out as I just explained. What I first found.

1. Left driver side disc rotor has a noticable wobble to it's rotation which I can see with my eye plainly as I rotate the rotor. Measured out to .034" on the left and .040" on the right rotor. I would think this would cause a out of balance issue with the rotor disc.

2. Left Rotor surface run-out was only .003" which is with in limits per APracing's direction from their surface run-out measurement sheet I have.

3. Right Rotor surface run-out measured out to .012" Low and high area was about 150 degrees out of each other. Well out of the .003" limit.

So, I'm pretty sure I am reading this correctly off the dial gauge. I've used such instruments and other micrometers when I was a jet engine technition and trained on how to use such instruments. So I hope I'm reading and taking these measurements incorrectly becasue I have a hard time believing that these brand new, zero miles, APracing rotors come already well out of limits and may cause further vibrations. Advice please! Damn things cost a butt load of $$.

If I'm taking these readings incorrectly, then someone please school me on this but I don't think I am.

RB

STALKER · 10-14-2011, 07:53 PM

Did you test them out on the road yet, at the end of the day, that is the real test for you.
Im on my second set of AP rotors and no vibrations.

BimmerRob08 · 10-14-2011, 09:36 PM

Quote:

Originally Posted by STALKER

Did you test them out on the road yet, at the end of the day, that is the real test for you.
Im on my second set of AP rotors and no vibrations.

Have not. I'm waiting for my calipers to come back from IND so it's still on jacks. I agree, it's the best way to tell but want to make sure I'm not putting new screwed up disc's on the road so I can send them back if AP replies that they are actually out of limits.

This entire AP thing has become the biggest fucking pain in the ass and cost me several thousand more than should have. Very fustrating because I can't pin-point the problem, nor can anyone else and I don't have the luxuary of buying shit and testing it all out either.

Should have gone with Brembo's. Would have cost me the same amount.

alpina527 · 10-15-2011, 03:30 AM

The runout of the outer diameter doesn't matter. The rotors are balanced at the factory.

The runout on the face doesn't matter either. If you had checked them before fitting, you will have found them to be almost perfect and within .0002"

Try tapping the rotor with a rubber mallet where the disc shows a high point and you will find they move due to the strap drive system. (assuming everything is clean)

Once the car is running, the rotors will self align.

BimmerRob08 · 10-15-2011, 04:09 PM

Quote:

Originally Posted by alpina527

The runout of the outer diameter doesn't matter. The rotors are balanced at the factory.

The runout on the face doesn't matter either. If you had checked them before fitting, you will have found them to be almost perfect and within .0002"

Try tapping the rotor with a rubber mallet where the disc shows a high point and you will find they move due to the strap drive system. (assuming everything is clean)

Once the car is running, the rotors will self align.

Yes, thank you for the inputs. I do agree. This is sort of a learning curve for me too as I'm trying to chase down a vibration issue and looking at all possabilities.

But the question remains then. If the old disc's and these new ones are actually all good and well within their limits, then what the hell is causing my vibrations? I have new wheels, freshly road force balanced, assuming the front AP rotors are ok, BMW tech checked everything up front, I'm not running spacers, etc. Everything should be as straight as an arrow. Yet, I have a vibration.

Stilen and AP uk are both working to resolve my issue, hopefully I'll hear more this week.

STALKER · 10-15-2011, 04:13 PM

Quote:

Originally Posted by BimmerRob08

Yes, thank you for the inputs. I do agree. This is sort of a learning curve for me too as I'm trying to chase down a vibration issue and looking at all possabilities.

But the question remains then. If the old disc's and these new ones are actually all good and well within their limits, then what the hell is causing my vibrations? I have new wheels, freshly road force balanced, assuming the front AP rotors are ok, BMW tech checked everything up front, I'm not running spacers, etc. Everything should be as straight as an arrow. Yet, I have a vibration.

Stilen and AP uk are both working to resolve my issue, hopefully I'll hear more this week.

Have you completely checked your suspension?
Are your tires round and seated on the wheel properly? A lot of times its the tires and not the wheels. I have first hand experience with bad tires, drove me nuts.

alpina527 · 10-15-2011, 04:43 PM

Try running the clock on the face of the alloy bell. It's possible but unlikely that the bell is badly machined. You could also check the runout at the rim edge.

As above, worn suspension bushes will give all sorts of vibration problems.

BimmerRob08 · 10-15-2011, 07:04 PM

Well, the BMW tech checked out all the front suspension parts. Ball joints, alignment, bushings, etc. Said everything looked ok and just as new.

I just picked up my front wheels (new PS2's and ARC-8) from the dealer and they re-balance them again. I have the spread sheet and the right wheel is balanced at 0g and 2grams. The left at 0g and 0g. Said their almost perfectly balanced with a road force balancer and the tires seem to not have any bulges or anything as such.

So at this point, as soon as I get my calipers back, I'll run it again and see. Hopefully it was just a wheel balance issue. Stilen did suggest the knock back spring/bar that AP has out for these calipers which is used to DD to keep the pads just slightly more off the disc surface and they suggest it helps with any groun/rubbing/ and uneven pad deposits. But if tracked, the mod needs to come off. So I may try that too.

What a pain in the ass!

BimmerRob08 · 10-24-2011, 12:40 AM

Update: New front AP disc rotors and another balance. Finally drives like it was ment to drive. Smooth and streight like an arrow. Not sure what it was at this point, either one wheel was out of balance or the disc's were warped but who cares. It's gone! Check out my post of "restoration" on the detailing forum for pictures. IND did a awesome job repainting my calipers. Thanks IND!

STALKER · 10-24-2011, 08:31 AM

Glad it worked out finally for you.

10-10-2011, 01:06 PM	#23
alpina527 Banned 60 Rep 638 Posts Drives: 2008 E92 M3 DCT JZB/FR Join Date: Jan 2010 Location: London, England iTrader: (1)	I would be amazed if they were warped. Can you get them checked off the car by a precision engineer? Did you fit and tighten all 5 wheel bolts when you used the dial gauge?
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10-14-2011, 07:26 PM	#25
BimmerRob08 Major 110 Rep 1,311 Posts Drives: 2008 M3, Space Gray Join Date: Mar 2008 Location: KIKR (ABQ), NM iTrader: (0)	Ok, so got my new front rotors in today and installed them. I trust as their brand new from APracing that these rotors are not going to have any flaws. But to make sure I measured the surface run-out and the rotational run-out. I didn't take pictures (should have and will if need be), but I also measured the surface and rotational run-outs of the front axle hub's that the rotor mates to and the wheels lug nuts torque to. The hubs where .001" or less all around and very smooth rolling so there is no chance that the hubs could be causing my vibration issue. I installed the rotors and measured the run out as I just explained. What I first found. 1. Left driver side disc rotor has a noticable wobble to it's rotation which I can see with my eye plainly as I rotate the rotor. Measured out to .034" on the left and .040" on the right rotor. I would think this would cause a out of balance issue with the rotor disc. 2. Left Rotor surface run-out was only .003" which is with in limits per APracing's direction from their surface run-out measurement sheet I have. 3. Right Rotor surface run-out measured out to .012" Low and high area was about 150 degrees out of each other. Well out of the .003" limit. So, I'm pretty sure I am reading this correctly off the dial gauge. I've used such instruments and other micrometers when I was a jet engine technition and trained on how to use such instruments. So I hope I'm reading and taking these measurements incorrectly becasue I have a hard time believing that these brand new, zero miles, APracing rotors come already well out of limits and may cause further vibrations. Advice please! Damn things cost a butt load of $$. If I'm taking these readings incorrectly, then someone please school me on this but I don't think I am. RB Attached Images
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10-14-2011, 07:53 PM	#26
STALKER Brigadier General 169 Rep 3,831 Posts Drives: 997.2 GT3, Golf R Join Date: Feb 2009 Location: Toronto, ON iTrader: (5)	Did you test them out on the road yet, at the end of the day, that is the real test for you. Im on my second set of AP rotors and no vibrations. __________________
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10-15-2011, 03:30 AM	#28
alpina527 Banned 60 Rep 638 Posts Drives: 2008 E92 M3 DCT JZB/FR Join Date: Jan 2010 Location: London, England iTrader: (1)	The runout of the outer diameter doesn't matter. The rotors are balanced at the factory. The runout on the face doesn't matter either. If you had checked them before fitting, you will have found them to be almost perfect and within .0002" Try tapping the rotor with a rubber mallet where the disc shows a high point and you will find they move due to the strap drive system. (assuming everything is clean) Once the car is running, the rotors will self align.
	Appreciate 0 Quote

10-15-2011, 04:43 PM	#31
alpina527 Banned 60 Rep 638 Posts Drives: 2008 E92 M3 DCT JZB/FR Join Date: Jan 2010 Location: London, England iTrader: (1)	Try running the clock on the face of the alloy bell. It's possible but unlikely that the bell is badly machined. You could also check the runout at the rim edge. As above, worn suspension bushes will give all sorts of vibration problems.
	Appreciate 0 Quote

10-15-2011, 07:04 PM	#32
BimmerRob08 Major 110 Rep 1,311 Posts Drives: 2008 M3, Space Gray Join Date: Mar 2008 Location: KIKR (ABQ), NM iTrader: (0)	Well, the BMW tech checked out all the front suspension parts. Ball joints, alignment, bushings, etc. Said everything looked ok and just as new. I just picked up my front wheels (new PS2's and ARC-8) from the dealer and they re-balance them again. I have the spread sheet and the right wheel is balanced at 0g and 2grams. The left at 0g and 0g. Said their almost perfectly balanced with a road force balancer and the tires seem to not have any bulges or anything as such. So at this point, as soon as I get my calipers back, I'll run it again and see. Hopefully it was just a wheel balance issue. Stilen did suggest the knock back spring/bar that AP has out for these calipers which is used to DD to keep the pads just slightly more off the disc surface and they suggest it helps with any groun/rubbing/ and uneven pad deposits. But if tracked, the mod needs to come off. So I may try that too. What a pain in the ass!
	Appreciate 0 Quote

10-24-2011, 12:40 AM	#33
BimmerRob08 Major 110 Rep 1,311 Posts Drives: 2008 M3, Space Gray Join Date: Mar 2008 Location: KIKR (ABQ), NM iTrader: (0)	Update: New front AP disc rotors and another balance. Finally drives like it was ment to drive. Smooth and streight like an arrow. Not sure what it was at this point, either one wheel was out of balance or the disc's were warped but who cares. It's gone! Check out my post of "restoration" on the detailing forum for pictures. IND did a awesome job repainting my calipers. Thanks IND!
	Appreciate 0 Quote

10-24-2011, 08:31 AM	#34
STALKER Brigadier General 169 Rep 3,831 Posts Drives: 997.2 GT3, Golf R Join Date: Feb 2009 Location: Toronto, ON iTrader: (5)	Glad it worked out finally for you. __________________
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