complete suspension/steering arm replacement - The Unofficial BMW M5 Messageboard (m5board.com)

roortube · 5th February 2009, 00:24

Alright guys, in the spring I'll be doing a major chassis overhaul to include all control, track, trailing, steering arms and rods, all bushings, engine/gearbox/rear diff mounts, and the clutch/rear main/guibo/trans seals.

I have done complete jobs like this on other cars, and understand that if I take it all off and put it all back on afterwards I wait to torque the various nuts and bolts to spec until the weight of the car is on its wheels so as to allow things to settle into place. I have also replaced single control arms and such and not had to do this. Question is, if I R&R one arm or rod at a time, can I torque everything to spec without setting the car down or will I still have to let it all settle. I only want to do this one time (that is until the bushings wear out again) and would hate to do it and find that something stupid like this upset the handling of the car.

p.s..don't drive these cars for any length of time with bent wheels

///Manuel · 5th February 2009, 16:36

Torquing the bushings under load really just means that they need to be tightened in their neutral position. I believe it's best to have the car level since it will insure the bushings aren't twisted in any way but what's most important is to have the wheels at their normal resting height.

I simply raise the wheels until they are at their correct height (without access to a lift) and then tighten everything (measure before jacking up the car, suspensions take some time to settle after being jacked up, I also believe that driving on ramps without raising the rear might not put enough load on the front suspensions but that's just me).

You can certainly have the front or the rear up while tightening as they are independent besides very minor body flex. Let me know if that doesn't make sense.

erikm54life · 9th February 2009, 11:00

With the way I drive i've had bushings go on me ( with the 535i ) 2 days after an incorrect installation.

I don't know if this is right but.......after lowering the car we usually roll it a few feet forward and then backward for the front tires to settle to their normal posiiton before final torquing.

You'll notice that after jacking a car up and then lowering it the front tires are still not at their normal position hence the perceived ( at least by me ! ) need to roll the car a few feet in either direction to return things to normal.

I may be wrong with this procedure but it seems to have worked for me.

Other more knowledgeable members may correct me as necessary.

Cheers

Erik

///Manuel · 10th February 2009, 01:22

You are absolutely correct, the height difference can be as much as 1" depending on how long the car was off its suspensions. Bolts also need to be loose enough so they can rotate inside the bushings as the car gets lowered. Simply rolling the car back and forth might not be enough to restore stock height but applying up and down pressure might (one simply cannot go wrong by measuring stock height between the center of the wheel and the fender arch).

I changed my upper control arms (lemförder's) last weekend and it was one of the easiest jobs I've ever had to do on a car. Next it will be the lower ones' turn.

roortube · 10th February 2009, 02:11

When I do jobs like this I usually do the replacement of parts on one of my dual post lifts, then lower the car and drive it over to my alignment rack. Involves 30 meters or so of rolling. Then I'll put it up on the rack, bounce the car a few times, and commence with torquing and aligning. Like I said, I've done this a few times before, but really hate trying to access all of the fittings when space is so severly limited as it is on my aligner. I guess it's not really worth trying to take a short cut if I want the best result. On a side note, I was reviewing the PO's maintenance records this weekend, and he did a complete front and rear suspension/steering arm and bush replacement about 18k miles ago. I was only considering the suspension overhaul cuz I'll be under the car for a day or so on the clutch and driveshaft overhaul, and I had been getting the telltale brake shimmy around 45-50mph. This shimmy disappeared today when I removed the bent wheels that had been on the car and replaced with freshly refurbished M systems. Much better. I may end up skipping the suspension work this spring and just do the clutch, engine, trans, and diff seals, and the brakes. I already have all the parts for this and I would still need to purchace the suspension peices.