Control Arm Bushing Question

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nj325ci
Posts: 170
Joined: Wed May 21, 2008 9:38 am

Control Arm Bushing Question

Post by nj325ci »

I'm replacing the front lower control arm bushings on my 2006 Z4 Coupe. One of them called it quits at Thunderbolt. It's essentially an E46 front suspension. My question is should I replace and not reuse the two bolts on each side that mount the bushing/bracket assembly? Bentley manual says never reuse and I've read that elsewhere but the parts guy at the BMW dealer said I didn't need to replace them.

While I'm asking I've also read not to reuse the 8 bolts that secure the aluminum tray that covers most of the front underside. Is this true also?

One more while I'm at it, if these are "throw away" are they stretch bolts or are those just found on engines?

Thanks very much, Bill

victory1auto
Posts: 643
Joined: Wed Nov 10, 2004 1:37 pm

Post by victory1auto »

Replace both bushings. Have the front toe checked/reset.

BMW prescribes that the bracket bolts and underbody-brace bolts be replaced.

I am unsure why they want the bracket bolts replaced, as the bolts are not locktited or torque-to-yield. I replace them.

The brace bolts are angle-tightened [and I believe torque-to-yield] and should be replaced.

nj325ci
Posts: 170
Joined: Wed May 21, 2008 9:38 am

Post by nj325ci »

Perfect! Thanks as always Vic!

mmarv
Posts: 522
Joined: Tue Nov 13, 2007 8:07 am

Post by mmarv »

victory1auto wrote:Replace both bushings. Have the front toe checked/reset.

BMW prescribes that the bracket bolts and underbody-brace bolts be replaced.

I am unsure why they want the bracket bolts replaced, as the bolts are not locktited or torque-to-yield. I replace them.

The brace bolts are angle-tightened [and I believe torque-to-yield] and should be replaced.
This. Anything that is torque+angle is generally replaced with new ones after removing.


Edited. You a funny funny man :P
Last edited by mmarv on Fri Jun 07, 2013 1:47 pm, edited 3 times in total.
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2017 BMW M2

RealM3E30
Posts: 979
Joined: Fri Jan 14, 2005 7:55 pm

Bolts

Post by RealM3E30 »

I have "used" bolts on my E46 for about 20K, no problems. 8)
91 E30 M//3 GQ
88 E30 M//3 TR
07 E91 328XIT
12 E70 X5D
16 F31 MSport Wagon
71 2002 Vintage Race Car

victory1auto
Posts: 643
Joined: Wed Nov 10, 2004 1:37 pm

Post by victory1auto »

There is a difference between plain torque + angle [eg: M10 cylinder-head bolts, which can be reused], and torque-to-yield [which is also torque + angle but uses bolts designed to be stressed beyond the yield point], which should be replaced.

The bolts that attach the control-arm-bushing bracket are neither, yet on the E46 chassis BMW says to change them, yet on the E30 and E36 chassis, with a similar design, the bolts can be reused. Perhaps on the E46 there is a fear of corrosion of the bolts with the aluminum bracket.

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