Rotor Runout check?
Thread Starter
Racer
Joined: Nov 2005
Posts: 340
Likes: 0
From: Dublin
Rotor Runout check?
Hi
I'm after installing new front rotors and have a couple of questions regarding runout... Did a search but didnt find exactly what i'm looking for.
I have ordered a dial indicator from summit.
Where do I measure the runout from? the very edge of the rotor or the edge where the bolts are?
What amount is acceptable? The calipers have new O-rings installed.
thanks
I'm after installing new front rotors and have a couple of questions regarding runout... Did a search but didnt find exactly what i'm looking for.
I have ordered a dial indicator from summit.
Where do I measure the runout from? the very edge of the rotor or the edge where the bolts are?
What amount is acceptable? The calipers have new O-rings installed.
thanks
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
I'm surprised that you couldn't buy/borrow a dial indicator locally. Shipping from the US must be a killer, not to mention duty.
Measure the runout on the outer edge of the area swept by the brake pads. Try to get it below .005" although some say that .008" is OK.
Measure the runout on the outer edge of the area swept by the brake pads. Try to get it below .005" although some say that .008" is OK.
Melting Slicks
Joined: May 2006
Posts: 2,590
Likes: 403
From: Nashville TN
St. Jude Donor '09
I checked mine on the rotor surface that will contact the brake pads. Then I cut shims from a beer can and placed on the wheel studs between the spindle and rotor until I got within spec.
Thread Starter
Racer
Joined: Nov 2005
Posts: 340
Likes: 0
From: Dublin
thanks for the advice
luckily my brother in Boston is coming home for Christmas and bringing my summit order with him... no shipping tax or duty costs!
As in the picture posted: I should measure the run-out from the centre where the pad meets the surface?
Is it ok to use the coke can shims permanently?
thanks
luckily my brother in Boston is coming home for Christmas and bringing my summit order with him... no shipping tax or duty costs!
As in the picture posted: I should measure the run-out from the centre where the pad meets the surface?
Is it ok to use the coke can shims permanently?
thanks
Drifting
Joined: Nov 2002
Posts: 1,691
Likes: 203
From: Loveland, CO
Yes, you can use the "Coke" alum. can cut shims permanently. Mine have been in for years and still do their job. You may have to experiment by moving the shim material between various studs to get the measurement down to where you want it. I've aimed at .003.
Ralph.
Ralph.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Ah, yes, beer......the solution to (and the cause of) most of life's problems.........I used the beer can shims, too, thought I was being pretty clever, but I guess it turns out that quite a few folks have done exactly the same thing. I guess great minds DO think alike!!
My 2 cents worth is to make sure you put some sort of an index mark on the rotor and the spindle, so that when you are removing and replacing the rotor, you can be sure you are putting the same five holes on the same 5 studs. And measure the runout as close to the outer edge of the rotor as you can, it'll be more precise that way. See ya,
Scott
My 2 cents worth is to make sure you put some sort of an index mark on the rotor and the spindle, so that when you are removing and replacing the rotor, you can be sure you are putting the same five holes on the same 5 studs. And measure the runout as close to the outer edge of the rotor as you can, it'll be more precise that way. See ya,
Scott
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Le Mans Master
Joined: Mar 2008
Posts: 5,948
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From: Oxford MA-----You just lost the game!!!!
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
I can usually tell by just running the car on stands and watching the pads and rotor for movement. You can tell if it moves a lot. But, the axles need to be supported so the u-joints dont bind and cause shafts to jump around.
Safety Car
Joined: May 2008
Posts: 3,753
Likes: 721
From: Lafayette Louisiana
My 2 cents worth
I am sure it does not make a lot of difference, but I would suggest using steel shim stock, you can buy it in some different thicknesses and I would think steel is a little better for shims than aluminum too. Also agree put the rotors on the same way, lug nuts same way, tighten the same way, all repeatable the same way, otherwise you introduce another variable and you can chase your tail and drive yourself nuts (ask me how I know!!!!
)
Good luck and hope this helps!
(speaking of beer, you guys have the greatest Guiness on tap anywhere!!! ..............But hey, why should that be surprising!
)
)Good luck and hope this helps!
(speaking of beer, you guys have the greatest Guiness on tap anywhere!!! ..............But hey, why should that be surprising!
)
Last edited by 20mercury; Dec 9, 2011 at 09:23 PM.
