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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 08-07-2011, 11:37 AM
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bluebee bluebee is offline
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Where is the published brake disk/disc lateral runout specification for the BMW E39?

In this thread today, the topic of the true effect of E39 lateral runout came up:
> Steering wheel shaking while braking (thrust arm bushings)

Quote:
Originally Posted by rdl View Post
I agree that one would not expect rotor runout to cause pedal pulsing, nor a variation in braking effect as the wheel rotates, which is what I assume you mean by "feel of the brakes."

But it seems to me that rotor runout could cause vibration and perhaps steering wheel shimmy under braking. Consider that with the caliper applied, any rotor runout would cause the caliper and pads to be moved side to side with each revolution. Moving the caliper side to side means an alternating force must be applied. Assuming
1 runout of 0.1 mm/0.004"
2 caliper and pad mass of 10 kg/22 lb - a SWAG
3 wheel speed 800 RPM, ~100 kph/60 MPH indicated on speedometer,
4 a flat rotor cocked on the hub slightly & therefore sinusoidal lateral runout
5 the caliper mass is 25 mm/1" inside the 324 mm OD of the rotor

I calculate ~ 1 Nm/0.75 lb-ft of alternating torque on the hub/strut/steering.

While this doesn't sound like much, it is close to what one would experience in straight driving (no braking) after losing a 1/4 oz balance weight on a 16x7 inch wheel. Loss of a 1/4 oz balance weight might not be so noticeable.
If runout is 0.2 mm (0.008") the result is equivalent to loss of a 1/2 oz weight which is noticeable.

I tried my version of TIS but couldn't find a rotor runout spec. FWIW, the service manual for my old Cadillac Catera (may it RIP) notes a maximum allowable runout of 0.1 mm/.004".
The topic of this thread is his penultimate sentence where RDL mentioned he couldn't find E39 lateral runout specifications:

Quote:
I tried my version of TIS but couldn't find a rotor runout spec. FWIW, the service manual for my old Cadillac Catera (may it RIP) notes a maximum allowable runout of 0.1 mm/.004".
As it is my wont to post specifications before running tests, I looked to my first bimmerfest thread, to see what I had posted for specs:
> How to check & replace your BMW front disc brakes and rotors

But, while every other spec imaginable was listed, there were no lateral runout specs listed anywhere in that thread.

Looking further to this thread, I find cn90 also tested his lateral runout:
- ATE Power Slot warped after 8 months and 3K miles, anyone?

But, he too, apparently, was unable to find the BMW runout specifications:

Quote:
Originally Posted by cn90 View Post
So, I also looked up my 1998 Volvo V70 spec because rotor runout and variation in thickness is pretty standard in many cars.

1998 Volvo V70

FRONT Rotor Runout....................0.04mm (0.0016")
FRONT Rotor Variation in Thickness ....0.008mm (0.0003")

REAR Rotor Runout............0.08mm (0.003")
REAR Rotor Variation in Thickness....0.008mm (0.0003")

So with my E39 0.003-inch runout, steering wheel vibration is expected. I will post an update after I have time to bring the rotors for re-surfacing.
So, the simple question is:
Q: Where is the published brake disk lateral runout specification for the BMW E39?


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Last edited by bluebee; 08-07-2011 at 01:37 PM. Reason: I'm not sure if it's 'disk' or 'disc' so I put both in the edited title (just in case).
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  #2  
Old 08-07-2011, 12:29 PM
edjack edjack is offline
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My '01 TIS calls out a max of 0.2 mm, at the outer edge of the disc, under Technical Data/Brakes.
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  #3  
Old 08-07-2011, 12:33 PM
JimLev JimLev is offline
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In the pic above is that jackstand bent? Sure looks like it to me.

The actual specs vary from 520's all the way up to 530's depending on the year.
No runout spec is given.

ALL rotors can be turned up to 0.8mm per side.
M car rotors are not recommended to be turned.

Edjack, I have 01/2005 TIS 3.4.1
I looked in the same place, it doesn't have runout, ugh

Last edited by JimLev; 08-07-2011 at 12:38 PM. Reason: Message to Edjack
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  #4  
Old 08-07-2011, 12:37 PM
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bmw_n00b13 bmw_n00b13 is offline
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Thanks, edjack. I'll make a note to check mine next time I have the wheels off. I know they need to be replaced, but it's always nice to know exactly how bad they are!

Nice clean workspace!

I'd be worried about those jack stands if I was working near that car. Perhaps an opportunity to try your hand at woodworking; some cribbing would certainly be safer than that :S
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  #5  
Old 08-07-2011, 01:25 PM
edjack edjack is offline
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JimLev,

When you got to "List of Subj.", did you have two entries? If so, the second one gives runout.
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  #6  
Old 04-06-2014, 05:26 AM
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bluebee bluebee is offline
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There is a nascent rotor runout discussion in this thread today:
> E39 (1997 - 2003) > Warped rotors again

I just searched for E39-only title-only threads with rotor "runout" in the title, and only these came up:
- Brake Rotor Runout (by Rjim)
- Wheel Shimmy; Brakes; Runout - CONFUSED! Please help! (by BEM3W9)
- Brake Rotor Runout?? (by fourwhls)

And, for tire runout:
- DIY: Quick way to measure Tire Runout (by cn90)
> E39 (1997 - 2003) > Uncomfortable vibrations
Quote:
Originally Posted by rdl View Post
E39 wheel runout specs are 0.012" radial & axial, tire 0.051" axial & 0.043" radial
See also:
> E39 (1997 - 2003) > Rotor Refinishing does that stuff work?
Quote:
Originally Posted by First time View Post
IIRC As a general rule of thumb, .002" of runout is enough to grant replacement.
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See also: E39 Bestlinks & How to easily find what you need

Last edited by bluebee; 05-15-2014 at 07:43 PM.
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  #7  
Old 05-15-2014, 06:43 PM
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bluebee bluebee is offline
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Today, this video was posted in the 'how to measure warp' thread:
> E39 (1997 - 2003) > PICTURES requested of the measurements of a permanently distorted "warped" E39 rotor

But I think the video more properly belongs in a 'how to measure runout' thread.

BTW, did we ever establish what the runout spec is for our E39s?

Quote:
Originally Posted by stigst3r View Post
I encounter warped rotors in the past, The rotors were brand new and the vender refused to replaced them even though i send them this video:



it was a little dangerous driving with them, i remember once having to brake from 70mph down to 50 and it was really unpleasant.
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  #8  
Old 07-20-2015, 12:04 PM
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bluebee bluebee is offline
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Just by way of cross reference, we're outlining the maximum radial and lateral runout specs for the BMW BBS alloy wheels over here today...
> E39 (1997 - 2003) > What home wheel measuring tools do you recommend for those who have measured a rim?
Quote:
Originally Posted by bluebee View Post
Running a few more searches, I find this related Bimmerfest thread:
- > E36/7 Z3 (1996-2002) > Tool to measure/check wheel roundness/trueness??

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And, on Bimmerforums, is this:
- How do you check a wheel for roundness?
- checking if wheel is bent - possible DIY?
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