Rear Suspension Troubles

[1823alex]

I've recently acquired a 2003 4.6is imola rot with relatively low miles (well the lowest mileage old bmw I've owned yet lol). At 110k miles when I purchased it I've been slowly combing through the truck to get it back to proper road tripper status. Anyways the truck is on OEM sized tires on style 87s. 9.5" wide front rims and 10.5 wide rear rims with 275 somethings up front and 315/35/20 in the rear. Now the previous owner did a air to coil spring conversion which I'm not a fan of since they went with cheap Chinese parts. Ever since I owned it it's had an annoying rubbing noise in the rear passenger wheel area. I found the aftermarket spring is rubbing up against the chassis on the outer wall of the area the spring goes up into. I plan to convert the car back to OEM air suspension as I already have most of the parts on hand and have new arnott airbags. I also removed the previous owners rear wheel spacers as I was getting some awful rear camber wear too. After removing the spacers i now have just the passenger rear tire occasionally rubbing on the inside part of the chassis. Now I know the rear suspension needs a refresh of sorts so I decided to purchase adjustable rear camber and toe arms from silver project eu. I'm hoping this will solve my uneven tire wear issues. However I'm concerned that when I install the new air bags in the rear that the air bag might still rub on the chassis. Has anybody else ever had any issues like this before with rubbing on stock wheels and tires? I don't want to put the new bags in and then have the passenger rear blow out because it's rubbing against the chassis too much.
There were no Carfax reported accidents, the truck was taken care of relatively well until it seems about 80-90k miles as it had some sort of CPO contract and got some things replaced under that but unrelated to the suspension. To be clear it's quite a multi part problem the inside of the rear passenger tire only runs on the inner chassis wheel liner, and the spring itself that was added for the coilvoer conversion rubs on the outer part of the chassis right where it begins to go up by the mount

Is it possible I need new subframe bushings and that the frame could have shifted over, is that common? Or can really badly worn rear control arms cause stock tire rubbing on the inside of the wheel well? Would this also cause the spring to rub on the chassis or could that just be a case of installation error? I can't imagine it to be that hard to position the spring on the perch correctly and what not though, although the most recent owner has surprised me many times with their hackjobs on the rest of the truck.

In addition to converting back to OEM rear air suspension I'm planning to replace the rear shocks, shock mounts, and add adjustable upper and lower control arms for rear toe and camber adjustments. Will this be enough to solve my awful rear tire wear and rear end rubbing noises?

[andrewwynn]

There rear tire wear is almost always from the ball joint on the wishbone link being worn. You can have 3° of neg camber without wearing the tire it's the negative toe while braking that causes the wear.

There was a recent thread where somebody that added adjustable links had rubbing like you described and figured out a fix. Factory links will not rub with any of the factory size tire options.

Also: unless there is some damage you will be able to get the car adjusted to spec without special arms unless you lowered your car it's the only time I'm aware of where the special arms are needed.

I've never seen an example of "can't get to spec" and "too much neg camber" that was inaccurately blamed on inside tire wear that wasn't either the wishbone link or the rear ball joint or both.

If the wishbone link is shot, it can be possible to still align the suspension when not moving but when you hit the brakes the loading of the suspension will steer the wheels outward add much as 2° and eat through tires very quickly.

When I replaced mine, I could move both the bad joints over 1.5mm that equates to well over 1° of steering motion!

I can't remember the exact trick the guy used to fix the rub but I would cross that bridge if it comes up. It should cure itself as you swap back to factory parts.

[nick325xit 5spd]

Virtually everything in the rear suspension is going to be trash after 80k.

[andrewwynn]

Mine lasted well over doubl that. Highway miles cause very little wear on suspension parts so there is no direct correlation between end of life and odometer.

Every year or so it's good to take the pressure off the springs and push all the ball joints around to see what is worn. You can't tell when the spring is pre loading the joints.

[StephenVA]

+1^

On 4.6 and 4.8is applications the torque of wide open throttle will wear out rear suspension parts at a higher rate than any 3.0 application. Uppers are long gone at 80-K. Ball joints might as well get replaced as they are simple and removes any worries. Look for any premature wear on the lower suspension arm inner bushings coming from owner/road abuse. Making a big fat BMW handle comes at a cost of replacement parts.

Take a ruler and confirm that your rear subframe is centered.

Replace everything suspect and you will have lots of driving enjoyment.

[andrewwynn]

Very valid point on the bigger motor and like I said largely based on how many highway miles. WOT wear is 1000s of times harsher than expansion joints and curves.

[nick325xit 5spd]

Originally Posted by andrewwynn

Very valid point on the bigger motor and like I said largely based on how many highway miles. WOT wear is 1000s of times harsher than expansion joints and curves.

I've never encountered an E53 with over 100k on it that didn't need close to a 100% suspension rebuild. IMO, the bushings and balljoints were very much underspecced for the job.

[andrewwynn]

Both of ours were very gently driven before we bought them.

Fronts lasted about 140-150 rears lasted about 160-180.

[nick325xit 5spd]

Originally Posted by andrewwynn

Both of ours were very gently driven before we bought them.

Fronts lasted about 140-150 rears lasted about 160-180.

My experience is that in typical use, the tension strut bushings in the front end are good for more like 30-50k.

[andrewwynn]

That was the first to fail on both or cars. Both made It over 130,000.


Sent from my iPhone using Tapatalk Pro