M3 front control arms fitment

[rowsdower]

I've installed the TRW M3 arms on one side of my 128i but the straighter one was very difficult to get into its housing on the subframe. Like, beat it in there with a deadblow hammer and then lever it in with a screwdriver difficult. The stock one basically fell out of the housing. Is this normal? And if so does it need to be installed at the height you would expect the arm to be at under load or can it be installed without the strut under load? I did jack up the hub before tightening the bolt but the arm was pointed downward when I got it into the housing, and with it being so tight I'm not sure it would have rotated with the arm when I jacked up the hub. My concern is that the bushing is going to be flexed when just sitting there.

[gjm120]

I had the same fun with that arm.

I can't see where it will matter at what height you install it. Just make sure tighten the subframe end at ride height. (Steering knuckle end is tightened while the car is on stands) Ramps are the easiest way to do it. I used a Sharpie to mark the bolt to get the 90deg.

After I did mine I saw where a solution to the tight fit is to use a bolt and a couple of nuts to ever so slightly spread the housing for the arm.

[Suhb]

Same here, I had to beat it in. The arm you're referring to doesn't need to be torqued at ride height because it's a spherical bushing and isn't stressed not being at ride height. The thrust arm, the one that comes in at an angle, (which you should have also installed) does have a bushing that needs to be torqued at ride height.

[rowsdower]

Thanks guys, very helpful.

Can't wait to get this thing back on the road!

[gjm120]

Originally Posted by Suhb

Same here, I had to beat it in. The arm you're referring to doesn't need to be torqued at ride height because it's a spherical bushing and isn't stressed not being at ride height. The thrust arm, the one that comes in at an angle, (which you should have also installed) does have a bushing that needs to be torqued at ride height.

FWIW the Bentley manual says to tighten both arms "with car on ground and loaded". Maybe not really necessary but I do it that way to be sure.

[amg6975]

Originally Posted by gjm120

FWIW the Bentley manual says to tighten both arms "with car on ground and loaded". Maybe not really necessary but I do it that way to be sure.

The stock ones, yes. They have a rubber bushing that doesn't want to be twisted. The M3 arms have spherical bearings so they just spin into the position they want to be in.

Jack your car up and watch the arms as you lower it, you'll see the rubber dust boot rotate, instead of flex.

[gjm120]

Originally Posted by amg6975

The stock ones, yes. They have a rubber bushing that doesn't want to be twisted. The M3 arms have spherical bearings so they just spin into the position they want to be in.

Jack your car up and watch the arms as you lower it, you'll see the rubber dust boot rotate, instead of flex.

Oh. So only the tension strut has to be torqued at ride height? Makes sense.

I assume and hope the torque spec isn't different.

[Tommm]

Originally Posted by gjm120

I had the same fun with that arm.

...

After I did mine I saw where a solution to the tight fit is to use a bolt and a couple of nuts to ever so slightly spread the housing for the arm.

Why didn't I think of that. Would have saved so much time. It was a death match for me to get that arm in.

[gjm120]

Originally Posted by Tommm

Why didn't I think of that. Would have saved so much time. It was a death match for me to get that arm in.

It was in BabyBMW.net here

http://www.babybmw.net/forum/viewtopic.php?f=11&t=80611