E39-front control arm swap/150Lb x 3 weights/subframe bolt torque/ride height

[aajs]

Greetings Bimmer Forums,

I want to start out by saying thank you. Your website has been a GREAT resource for me the past 5 years since I bought my E39(2003 530i). I do all my own wrenching; anytime I need guidance your website is my go-to source for information. That being said, here is my question...

I just replaced my front lower control arms(straight). As I read, the procedure is to torque the ball joint studs to spec, leaving the attachment bolts to the sub-frame only snug. Lower the vehicle onto the tires and wait 30 minutes for the struts to "relax" and return to "normal" ride height. Add 150Lbs. to each front seat and 150Lbs. to the center of rear seats along with a full tank of gas to preload the suspension. Drive the vehicle onto wooden 2x8 "ramps" and creep under the car to torque the control arm to sub-frame bolts. This all makes perfect sense to me and is relatively straight forward. Due to the serrations or "knurling" on the inner control arm bushings you want the car at true ride height before tightening the bolts and locking them in place. This leads me to my main concerns:

One day while standing in front of the car with no passengers or loads I noticed that the front ride height on the drivers side was slightly higher than the passenger side. I took a tape measure and verified this to be true; the driver side front wheel arch gap was in fact about 8mm higher than the passenger side. I went on the forum and did a search for crooked ride height. What I read was that BMW engineers figured that 90% of the time the car would be occupied by just the driver. Therefore the drivers side ride height is just a bit higher so that when the driver gets in the car sits at a level stance. This made perfect sense to me! I would like to maintain this slight difference in ride height so when I get in the car it sits level. Here is where my concern comes into play. If I load the car as instructed with 150Lbs left, right, and rear and torque the sub-frame bolts wouldn't the car sit level without the driver? In addition to that, I am a large man 6' 2" and 250 Lbs. Should the weight in the drivers seat be adjusted to compensate for this? My goal is for the car to have a level stance with me in it. I drive 99% of the time by myself and don't want the car sagging on the drivers side when I enter the vehicle. Perhaps I am being overly concerned with this? I am a machinist and perfectionist by nature; perhaps this is why I love BMW's!!

Thank you in advance for any feedback/advice...

[Hova]

Follow BMW's recommendation.


The arms you're referring to do NOT affect ride height. The springs, shocks, perch placement etc that affects ride height. The recommendation from BMW to pre-load the suspension for bushings is so they are in a neutral position when parked/driving on a smooth road and don't wear out prematurely.

I normally try to shake the car to force it to settle, or if you have the ability to get under it, put the 2 bolts back in and roll the car slightly (they MUST have a nut on them) to get the car all the way settled.


Not to mention, a few mm will not change the look of the car. The entire car will drop front and rear with weight in the back seat and a full tank of gas.


Go load 150lbs and 150 in the back seat with a full tank of gas, measure it. Then 250lbs on the seat. You'll notice the difference in the ride height is negligible.


BTW sold my E39 a few years ago, 530i as well. Real soft spot in my heart. Drove her cross country multiple times, awesome cars.

[aajs]

Hova,

Thank you very much for your feedback!! After you explain things I completely understand what needs to be done. I do have the 2 bolts inserted joining the control arms to the subframe; I ran the nuts down finger tight and then backed them each off a 1/4 turn. I am going to construct some stacked and screwed wooden ramps using 2 x 8 lumber as I have seen others do on this forum. I can definitely use some body weight and push down on each corner of the car several times to get everything relaxed and settled. After driving up the ramps and I am going to add the weights to the vehicle and torque the bolts. I was wracking my brain trying to figure out how to come up with 150 and 250 pound weights. Something I thought of that may be helpful to others is using large heavy duty plastic totes and water; 150 lbs = 18 gallons / 250 lbs = 30 gallons. Just need to be careful not to slosh things around. After the bolts are torqued I am just going to use a pail to "bail" the water out of the totes.

Just one question though because I am curious; is it true that BMW engineers designed the ride height on the driver side to sit slightly higher with no load in the car so that when the driver sits in the car it has a level stance? Not sure if this was fact or fiction...

Like you I have a soft spot in my heart for my E39. I am in Wisconsin near Green Bay and I have made several trips down to Chattanooga TN. I have the 5 speed transmission in my 530i which I love. I just don't groove on a sports sedan with an automatic! The E39 was the last 5 series to have body lines that could be traced back to the hand drawings of the early 70's. No offense to the E60 guys, but I just don't like the headlights or taillights! VCG and plugs next week and then on the road again down south! 220k miles and running strong!!!

Thanks again to everyone on this forum for their help over the years!!!
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[ross1]

A pre-loaded bush CAN effect ride height, until it fails.
No harm in loosening and re-tightening the bushings while the car is supporting its own weight. I've never bothered to load the car or fill the tank and I don't think most shops do either.
Could be a sagging or broken spring too, don't forget to check the rears.