steel vs. alum. control arms...............

[tim s]

we lifted the car to confirm that the thrust arm bushing arm cracked already & they are not even 1 year or 10k miles old.
so i am going to start pricing all the parts i would like to replace.
what are the pro's & con's of alum. control arms?
thanks
tim s.

[Johntee540]

Aluminum arms reduce the amount of unsprung weight in the suspension. Makes the car more handleable in rougher cornering situations.


I just changed out my 540 Controls for Aluminum arms. - JT

[632 Regal]

other than in all out performance applications the steel ones are just fine. There is NO noticable ride or handeling differences, just the unsprung weight of less than 1 lbs (a guess not measured as of yet).

[MTechnik540i]

we lifted the car to confirm that the thrust arm bushing arm cracked already & they are not even 1 year or 10k miles old.
so i am going to start pricing all the parts i would like to replace.
what are the pro's & con's of alum. control arms?
thanks
tim s.

Alum bends easier.

Wait savings is quite minimal.

[632 Regal]

the aluminum ones are an alloy and also quite a bit beefier than the steel ones. in comparison of the steel vs aluminum ones the car would usually be totaled to see which one is better under that circumstance.


Alum bends easier.

Wait savings is quite minimal.

[SharkmanBMW]

[QUOTE=MTechnik540i]Alum bends easier.


the last time this topic was discussed, I thought the theory was that the alu ones could not be bent.

[Interceptor]

the last time this topic was discussed, I thought the theory was that the alu ones could not be bent.
Under high stress aluminum tends to break rather than bend.

Sometimes it's harder to diagnose a slightly bent steel control arm than a broken aluminum one :)

[Jon K]

Under high stress aluminum tends to break rather than bend.

Sometimes it's harder to diagnose a slightly bent steel control arm than a broken aluminum one :)


Aluminum bends just as well as steel. It will crack BEFORE steel, but will bend every bit as much. Ever hit a pothole?

[Interceptor]

Aluminum bends just as well as steel. It will crack BEFORE steel, but will bend every bit as much. Ever hit a pothole?
I never had a case of bent/cracked control arm :)

[Hector]

http://www.bimmer.info/forum/showthread.php?t=9921&highlight=aluminum+control+arms

[Bill R.]

never seen one break thats steel. On the 7 series board someone had an aluminum one snap while his wife was driving. I'm sure it didn't just snap on its own, that something had to have been hit but never the less it broke and i've never seen a steel one do so.. The weight difference is less than 4 tenths of a kilo if you look them both up in the etk. This is unsprung weight but it doesn't have the same effect that lightening up wheels would do for handling. The control arm weight would have much less effect overal. I'd go for steel, can't see aluminum worth the additional cost to me.








we lifted the car to confirm that the thrust arm bushing arm cracked already & they are not even 1 year or 10k miles old.
so i am going to start pricing all the parts i would like to replace.
what are the pro's & con's of alum. control arms?
thanks
tim s.

[MTechnik540i]

I never had a case of bent/cracked control arm :)

Ah, this is just the impression i've been under the alum./alloy control arms...along with the E30 M3 ones. I think it's been mentioned before on Bimmerforums also, and i've heard something similar from Korman's shop...but, still...could be wrong.