BimmerFest BMW Forum banner

DIY Article - How to Replace the Thrust Arms on your E39 540i - 56k No!

214K views 64 replies 38 participants last post by  startun_ 
#1 ·
HOW TO REPLACE THE THRUST ARMS ON YOUR E39 540I BMW

(1997-2003 5-SERIES V-8 CARS)

Most drivers of higher-mileage E39 BMW's have probably experienced the infamous shimmy that occurs in the front suspension at speeds between 50 and 60 MPH. The shimmy is often very pronounced when braking through the same speed range as well, giving the false impression of an out-of-round brake rotor. Assuming that your tires are properly balanced and aligned, and your lug nuts are properly tightened, the likeliest cause of this problem is worn out thrust arm bushings. Removing the thrust arms and installing new ones, or simply replacing the bushings once the thrust arms have been removed from the vehicle is a job that is well within the capabilities of a reasonably experienced shade-tree mechanic.

Whether you want to replace the entire arms or just the bushings is up to you, and the decision pretty much comes down to cost. The amount of work is about the same. The entire thrust arm assembly costs about $100 per side for OEM quality Lemforder units, whereas the bushings alone can be replaced for about $40. If you replace the whole arm, you're also getting a new ball joint on the front end, which probably isn't a bad idea on a higher mileage car. My feeling is, if you can't afford to drop $200 for a pair of new thrust arms, you really can't afford to be driving this car, especially in an era of $3.50 per gallon gasoline.

This is an illustrated do-it-yourself (DIY) write-up showing how to change the thrust arms on an E39 540i (model years 1997-2003). The subject car is a 1998 540iA. The job is conceptually the same on the 6-cylinder cars, but the front suspension and steering are somewhat different, so the pictures may not be an exact match. The procedure I followed is the one outlined in the Bentley manual. The driver's side of the car is shown in my pictures, but the passenger's side is identical.

This write-up is provided as a courtesy to other E39 enthusiasts, but your use of the information herein is entirely at your own risk. I assume no responsibility in the event of injury or adverse outcome resulting from the use of this information. Above all, BE SAFE and don't get in over your head. The labor for this task is only a few hundred dollars at a good, independent BMW mechanic's shop. It isn't worth life, limb or damage to your vehicle if you don't have the experience necessary to competently perform this procedure.

Suggested Tools and Supplies

-Floor jack
-2 jack stands
-4 blocks or car ramps
-Breaker bar with 4-inch extension, or tire wrench
-17mm socket for removing lug bolts
-13mm deep socket for removing sway bar bracket nuts
-16mm and 18mm socket and combination wrenches for loosening pinch nut and bolt on strut collar
-22mm combination wrench for removing ball joint nut
-21mm socket and combination wrenches for removing thrust arm bolt and nut
-Torque wrench
-Large screwdriver, chisel, or other strong, flat-bladed tool for prying open pinch collar on strut
-Various lengths of extensions, universal joints, etc. for your socket wrench are helpful
-Ball joint removal tool (highly recommended)
-Permanent marker pen or paint to scribe reference line on strut tube
-Rags
-Denatured alcohol or lacquer thinner

Procedure

1) Make sure the car has a full tank of gas before you start (this is important later - you will need the weight of the fuel in the vehicle). Have the key in the ignition and unlock the steering wheel so you can turn the steering array as needed when you are working.

After loosening your lug bolts with the 17mm socket and breaker bar, get the car up on jacks. The front jack point for the E39 540i is shown in image #1 - you want the jack on those four big dented-out triangle sections which all point to that hole in the middle. I strongly suggest padding your floor jack and jack stands with a folded rag to avoid tearing up your car. You do not need to remove the splash shield from the bottom of the vehicle.



Images 2 and 3 show the car up on jacks from the front and side. I keep the floor jack under the front jack point as an added measure of safety. Chock the rear wheels for safety.





2) Lower the front sway bar - you need to do this to get room to reach the bolt that holds the bushing side of the thrust arm to the frame. The sway bar is held to the frame by two, large gold-colored brackets - one on each side of the car. You can see it in image #4 on the left side of the picture.



Remove the two nuts from the studs using a 13mm socket wrench, and pull off the brackets. The sway bar will only drop an inch or two, but that's all you need. You don't even need to remove the rubber bushings that are under the brackets - you can see one of these bushings in image #5.



The large bolt you will eventually remove to drop the bushing side of the thrust arm from the frame can be seen above and to the left of the rubber bushing on the sway bar in image #5.

3) Image #6 shows the bottom of the strut tube and the steering knuckle. At the bottom of the strut tube you can see two large nuts. The rear nut is the one that fastens the ball joint side of the thrust arm to the steering knuckle. The bottom of the strut tube is so close to those nuts that you can't get a wrench or ball joint puller on them. This necessitates lowering the steering knuckle.



In order to lower the steering knuckle (slide it down the strut tube), it will be necessary to loosen the pinch bolt in image #7 (also seen from the bolt end near the top of image #6). I used a 16mm wrench on the bolt and an 18mm wrench on the nut to do this. PRIOR TO LOOSENING IT, clean the area where the strut tube comes out the bottom of the pinch collar, and using paint or permanent marker, draw a line exactly where the strut comes out of the collar so you can properly reposition it later.



After you have loosened the pinch bolt (there is no need to remove it entirely), stick a large, heavyweight screwdriver, a large chisel or some other prying tool right in that slot where you see the middle of the pinch bolt in image #7, and pry the collar open a small amount. You can also stick a small chisel in the slot and then use a wrench to turn the chisel and pry the collar apart - this very closely simulates the special tool BMW dealer mechanics uses for this task. Either way, it will take a bit of force.

When the collar is open sufficiently far, grab the brake caliper or rotor and slide the steering knuckle down on the strut tube by pulling downward - it only needs to come down an inch to an inch and a half. Look at image #8 - you can see the clean, shiny part of the strut tube that was exposed after I slid the steering knuckle down. You may need to jiggle the steering knuckle assembly a bit, but it is heavy and should slide down without too much trouble.



4) As you can see in image #8, there is now enough room to get a wrench on the ball joint nut. Remove the nut using a 22mm combination wrench.

Now, the hard part - pressing the ball joint stud out of the steering knuckle. It is in there TIGHT. I would not do this job without a ball joint press of the type you see in image #9 and #10. I bought mine at ZDMAK Tools (www.zdmak.com) for $40, and it's a pretty decent unit. There are many sources, and you can pay less, or a whole lot more - up to $263 for the gods-honest BMW tool.

I have read posts from guys who say they've been able to remove the ball joint using a pickle fork, or by banging on the top of the stud. You're on your own if you decide to go that route. I rejected that option from the start. Space is just too limited, and you're talking about banging around on aluminum suspension components here.





HOWEVER YOU DO IT, DON'T DON'T DON'T DAMAGE THE BALL JOINT AND BALL JOINT STUD IF YOU'RE JUST GOING TO CHANGE OUT THE BUSHINGS AND WILL BE RE-USING THE OLD THRUST ARM AND BALL JOINT. If you're replacing the whole thrust arm, then this isn't an issue. The steering knuckle will look like image #11 when you finally get the ball joint stud out.



5) Now we're ready to remove the bushing side of the thrust arm from the frame. This is easy by comparison to the last step. Image #12 shows you what it looks like in place.



Image #13 shows the 21mm socket wrench on the bolt that goes through the center of the bushing and holds the thrust arm to the frame. You can also see the end of the bolt in Image #5. You may need to jiggle the steering back and forth a little bit to get the socket wrench on the bolt - I did this just by grabbing the brake rotor and turning the steering a tad. There's not a lot of extra room to maneuver. You'll also need to have a 21mm combination wrench on the nut to keep it from slipping.



Once you have the nut off, pull the bolt out and you can drop the thrust arm. Again, you may need to jiggle the steering a bit this way or that to give yourself room to pull the bolt. Image #14 shows how the frame side looks with the thrust arm removed. Image #15 shows the old thrust arm with bushing, ball joint and retaining bolt and nut. At this point, you're halfway there on the driver's side, and the hardest part of the job is behind you.





If you're only replacing the thrust arm bushing and are re-using the old thrust arm and ball joint, this is where you will press the bad bushing out of the thrust arm and re-install the new one. I went with all new thrust arms, so I regret that I can't provide you with any counsel on this step. I understand it is possible to do this yourself, though it's a lot less trouble to simply take your old thrust arms to a mechanic's shop that has a hydraulic press and remove/replace your bushings that way.

6) Image #16 is a picture of the new Lemforder thrust arm. Leave the protective cap in place over the ball joint stud until the last minute when you are ready to push it into its hole on the steering knuckle. Wiggle the bushing side of the thrust arm into its place in the bracket on the frame of the car. Push the 21mm bolt back in and thread the nut back on. DO NOT TORQUE THE BOLT DOWN AT THIS TIME! Just put the nut on the bolt and hand-tighten it. Image #17 shows the new thrust arm in place on the bushing/frame side.





7) Remove the protective safety cap and insert the ball joint stud in its hole on the steering knuckle. Thread the 22mm nut onto the stud and tighten it. As you tighten the nut, it pulls the ball joint into its proper position - there's nothing special you have to do here. See Image #18. Using your torque wrench, tighten the 22mm nut to 80Nm (59 ft-lb).



8) Reposition (raise) the steering knuckle on the strut and tighten the pinch bolt. Using your torque wrench, tighten the pinch bolt to 81Nm (60 ft-lb). Again, this took a 16mm wrench on the bolt and an 18mm wrench on the nut on my car.

9) REPEAT STEPS 3 THROUGH 8 ON THE PASSENGER'S SIDE OF YOUR CAR.

10) Use denatured alcohol or lacquer thinner to clean your brake rotors if you grabbed them with your hands at some point during the procedure. Put the wheels back on the car and torque down the lug bolts. The lug bolts are 17mm, and should be torqued to 120NM (89 ft-lb) plus or minus 10Nm (7 ft-lb).

10) NOW we're going to tighten the bushing bolts on the thrust arms. The car needs to be LEVEL and SITTING ON ITS TIRES up on blocks or ramps, about 8 inches off the ground in front AND back. The car needs to be at spec ride height before you torque down the bolts. In addition to a full tank of gas (remember this?), you need about 150 pounds in each front seat, 150 pounds in the middle of the back seat, and 45 pounds in the trunk. If you're really anal you can measure and adjust the ride height further following the procedure in the Bentley manual, but this gets you plenty close enough. NOW you can get under the car and torque down the bolts that hold the bushing side of the thrust arm to the frame. Torque these 21mm bolts to 110Nm (81 ft-lb).

11) Re-install the sway bar brackets, making sure that the little nub on the rubber bushing fits in the corresponding hole in each bracket (See Image #5). Torque the 13mm nuts to 24Nm (18 ft-lb).

12) Lower the car to the ground and enjoy your shimmy-free ride! Incidentally, it is not necessary to have an alignment done following this procedure.
 
See less See more
18
#2 ·
Hey guys, a couple of edits to this write-up. Thanks to CHIVAS for the suggestions.

Regarding the ball joint removal tool: There are a number of different styles of tools, and depending on the one you get, you'll be doing a little bit of trial and error to figure out how best to position it for maximum effect. With some of them, the fit is better if you pry the ball joint boot up and out of the way. I simply used a hammer to lightly tap the bottom of the tool into position over the boot.

It takes a lot of force from the tool to break the ball joint loose. Towards the end, I had a rag wrapped around the wrench to pad it, I was torquing so hard on the tool. Just about the time you're thinking "this is not going to work", it breaks loose. Now here's a "heads-up" - when it finally does, it's with an explosive report like a pistol shot, so be ready for it. I thought I'd broken something when I heard it the first time.

--------------------------------

Regarding removal of the large bolts that hold the bushing side of the thrust arm to the frame: The ones on my car slid out very easily, but I've had other guys tell me that theirs took a little more work to remove, and that they had to use pliers. This may be due to water or some other fluid having seeped in and seizing the bolt.
 
#59 ·
I've used/broken SEVERAL HF type tools as mentioned here--junk. I ordered both of these, and they are IDENTICAL. I used the gear wrench and it worked much better than what I remember of the HF tool. I think the HF tool flexed a lot. The GW one only needed about a dozen or so turns of the screw, and BAM/POP! Worked great. It's much thicker/stronger where it counts and fits perfectly.

http://www.amazon.com/gp/product/B003YVWHOE/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

http://www.amazon.com/gp/product/B0015PN010/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
 
#5 ·
I used the same ball joint tool from ZDMAK. Hit the stud with a good shot of PB before clamping down the tool. I tightened it until it got difficult to go much further with the wrench. Left to go out to eat, and when I got back the ball joint had popped loose! So I did the same thing to the other arm.. clamped the tool down and went to bed. Woke up and the same result.. So have a little patience and no need to kill yourself turning that wrench until the arm pops loose.
 
#12 · (Edited)
There's another recent thread floating around re: thrust arms. That along with this thread have given me the courage to tackle this next job on my 525I.

I'll be ordering my arms from Mark at EACTuning, and ball joint removal tool from Harbor Freight.

My question is it looks like the final two steps in this process are a - tighten bushing side of arms down, then b - tighten sway bar bolts down.

However, it looks like this job gets done under load with the car resting on it's wheels and about 400lbs of weight inside. I'm not sure if this was addressed but those that have done this work, is there an alternative to buggin your wife, neighbor, kids, dogs to sit in your car while you tighten bolts down?

Though not very exact, my thinking to ensure proper alignment/height after this install is to mark each bolt and stud with paint that indicates where the original position was before I loosened the part.

Could that work?
 
#7 ·
Thrust rod

I just got an estmate for my 850i , they want to change the thrust rods and bushings and the ball joint

thrust rod and bushings at a cost of 1000, CAN dollars
and lower ball joint s at a cost of1400. CAN dollars.

are you saying that if i replaced the entire thrustrod assembly that the lower balljoints are included.
 
#9 ·
I just got an estmate for my 850i , they want to change the thrust rods and bushings and the ball joint

thrust rod and bushings at a cost of 1000, CAN dollars
and lower ball joint s at a cost of1400. CAN dollars.

are you saying that if i replaced the entire thrustrod assembly that the lower balljoints are included.
BMW control/thrust arms ( I'm more familiar with E28 and E34 than others) ALWAYS come with the ball joint installed. The ball joint is not a replaceable item. If your shop is quoting the ball joint replacement as a separate job, then they have some 'splaining to do!

bmwfans.info has great diagrams and parts cross refereces.

nice car.
 
#11 ·
The postings on this thread have been most helpful and I have been fortunate enough to take advantage of the notes and postings in my latest Endeavour with my 2001 540I – v8 - and the front-end shimmy. I, too, had the infamous front –end shimmy between 45-50 and 70 mph. After reading this thread – and may I take this opportunity to thank my esteemed colleagues for their summations of their adventures; because without them, you wouldn’t be reading this drivel - and listening to my mechanic tell me $1200.00 was the price for the rear control ball-joints, I decided to have some fun and do it myself.
My comments are intended as additional detail to the above thread and is in no way intended to be construed as a criticism of the text of this thread; quite the opposite. You will encounter considerable tongue-in-cheek dialogue; sorry, that is how I write. Without humor, why do we work on our own cars??? I already know ALL of the deleted expletives associated with this sport; my grandfather was a mechanic from 1918 until he retired in 1965. He would only supervise, I had to do all of the work, but his language… we are all rank amateurs.

1. Lowering the strut to reach the nut for loosening the front and/or rear control arms: Instead of a half to one inch for space to loosen the nut, I suggest at least two to three inches to leave room for a three to four pound sledge – to drive the bolt from the aluminum frame – if necessary, once the nut is removed. MY experience is the bolt really does not want to come out; it appears to be very comfortable there. A lot of BP and/or WD-40 –C4 if you have it- on the bolt is an absolute necessity.
2. The Ball Joint Separator tool pictured here actually required at least a four pound baby sledge to drive the tool between the members. Once in position, while attempting to force the ball joint out of the frame, the tool broke; btw, the ball joint did not come out. $40.00 down the drain. The aluminum tool, in my opinion, is too light for this duty. I purchased the similar tool from FreightHouse – Heavy gauge STEEL – for about $15.00. In ten minutes, I had both rear ball joints removed.
BTW, on the driver’s side, while the ball-joint did pop-out, please be advised that there is a “steel” insert within the “Aluminum” frame that came out with my ball-joint. I had no warning about this. I subsequently: had to “press the steel insert off” of the old ball joint fixture – press the “steel” insert back into the same aluminum frame opening using the same ball joint separator tool used to extract the ball joint initially. I can explain, in excruciating detail, if it happens to you and you need assistance.
3. Because I was removing the rear control arms and because I am a masochist – and the cost each front control arm was under $50.00 each and because the front control arm was in the way of replacing the rears, not to mention 1280 more dollars– I decided to replace both the front and the rear at once. After all, you are there and so are the front control arms, and… they are in the way.
4. Removing the front control arms cannot be accomplished using either ball joint tool mentioned herein – the tools are too small, the jaws do not open fully enough to accommodate the front control arm bolt. The good news is, the front control arms are easier than the rear to replace; just more fun/challenging to remove. As I mentioned earlier, these ball joints really do not want to come out; the fronts are no different than the rears.
5.
6. In order to remove the front control arms – conveniently, without any manual labor – use a pneumatic hammer!!! I used a hammer with 90PSI, 4.5cfm and 3200 blows per minute- BPM. Three healthy bursts ----with mucho BP and WD40 on the bolt- and the stud will submit. The new front control arm will slide right into position – bushing first and ball joint last – at least it did for me. And, let me tell you a short story, I beat the bejesus out of those studs with my 4-lb sledge and they wouldn’t budge. But, the pneumatic hammer took maybe 5 minutes – three bursts with the hammer and liberal dose of BP and WD40.
7. Now that we have the old OUT, Let us turn our attention to installing the new parts:
a. Always install the BUSHING end first, both front and rear. The front will slide in without any considerable labor The ball joint slides right in – at least it did for me.
B. Regarding the rear control ball joint installation: I used a hydraulic jack to support the ball-joint – while the stud of the ball-joint is inserted into the hole – and then slowly rotate the steering wheel from left to right until the stud “finds” it way into the hole. So do not “force” the stud into the hole in the aluminum frame. Instead, use the jack to “support” the ball joint from the bottom – while not forcing - but guiding - the stud into the opening. While rotating the steering wheel from left to right, SLOWLY, one-quarter turn at a time, the “guided” stud will find its way in. Tighten up and away we go.
Another note: For what it is worth: each “new” appliance – new part – will come with it’s own bolt. I did NOT have good luck with these… they refuse to “snug up” to tighten to the new ball joint. Therefore, I used the “OLD” nuts, and they worked fine. Just an FYI… Your mileage may vary…
6. So, I replaced the rear and the fronts, in the same excercise. Not for everyone but it worked for me.
7. If you have more specific questions - believe me I had plenty - I will be happy to relate my experience as reply to your questions. I apologize for the lack of pictures, I really was busy…Thinking, cursing, wondering why my god had forsaken me, etc. etc. ……..
 
#13 · (Edited)
Very doable job. Total time for this DIY was just 3.5 hours. Specific to 525I owners out there, I do have additional advice to help you along in this DIY.

1 - Universals for the socket wrench - NOT NEEDED. You'll be able to reach every single bolt either with a socket or spanner and turning the steering wheel to accommodate the wrench. Also, there's a step where you have to loosen and then lower the sway bar to get at the thrust arm. Again, I think that's specific to the design of the 540's, but for the 525I, there is no need to touch the sway bar or it's end links.

2 - You'll definitely be removing body panels under the car. The panels that will have to be removed are: lower 1/2 fender well, lower engine cover, and there's even a cover for the bushing side of the tension strut as well. So you'll be making good use of that 10mm socket, 8mm socket, and philips screwdriver.

3 - Keep an allen wrench handy. I may have overlooked it or not read the directions from various DIY's, but you will definitely need an allen wrench to hold down the ball joint bolt as you are tightening it down and setting it into the steering knuckle with your 21 or 22mm spanner wrench. However, once your ball joint seats itself in the knuckle you should be good.

4 - As for pre-tensioning the bushing side when you tighten it down per BMW specs, (150lbs in the rear seat, 50 lbs. weight in the trunk, yada yada). I didn't do that. I basically took a measurement from the ground to the bottom center of the fender before I did the work. When I was done, I had my 200lb. dad sit right on the radiator area (ahhh! oooh! - no worries that area seems to be able to hold a lot more than 200lbs.). I got under the car and torqued down the bushing bolts to spec. Took another measurement and got a spot on match.

Lastly, the ball joint removal tool is a must have for this job. Be sure you've really jammed the fork side into the ball joint crevice and that the hammer part that fits over the threaded bolt covers it well. Tighten like crazy and POP! (I wore earplugs, but it is very loud)

Seat of the pants result? Simply awesome. No more shimmies at 40-50mph and no more shimmies when braking at any speed. Definitely tighter steering around corners. As for comments from other threads about car driving like it's new again, I can't say that. But who knows, maybe when it comes time to change the upper control arm, links and other ball joints, I may get that feeling.

Props to Hotswimmer for this awesome DIY.
 
#15 ·
Depends, have you had other suspension components replaced before? If you know the history of the car and are running on original suspension, you're definitely on borrowed time.

My 2003 car had 113K when I did this job, the thrust arm's ball joints which I replaced with new were literally wobbling. I know the rest of my suspension is probably in the same condition or worse. If I were you, I would start with the thrust arms (even if they were replaced, they typically have to be renewed again every 75K), but plan to replace most of the front and possible rear suspension.

Just typing those words, gives me pause thinking about the mountain of work that lay ahead for me in the not too distant future!
 
#16 ·
Great wright up! I recently received my powflex bushings in the mail and after looking at your pictures it sees like i could make a tool to press the old bushing out while the ball joint is still attached. I was thinking a large c-clamp, a welding machine and two perfect sized pieces of pipe. Im going to give it a try and i will post pictures if im successful. It seems like someone has always already made a specialty tool when it comes to things like this so im going to do some more searching on the internet.
Thanks again,
Joe
 
#17 ·
I just did this to solve my "50 mph shimmy" so I thought I'd throw in a couple observations.

First a great write-up. This is the reason I decided to replace my thrust arms myself. Kudos to Hotswimmer and others comments. I used EACtuning thrust arms with the HD inserts. Mark shipped them the same day. Great service.

I did use the ZDMAK press but I had problems with it. First make sure that the bottom lever of the press tool is oriented like the picture, flip it if it isn't. That was a no brainer ;)

I tried for more than a few hours to press the first ball joint out but each time I tightened the press it would eventually force itself backwards and off the ball joint stud. After a bunch of resets, wiggling, repositioning the knuckle, and hammering it back in I decided to drop the bushing side of the thrust arm. That solved my problem. Lowering the arm let me drive the press into the knuckle until the threads hit. It must be that close or it will wedge itself off when tightening.

Check the ball joint bushing for movement as you press the ball joint out (see image #11 center piece). It is pressed into the knuckle and you don't want it to come out seized to the ball joint stud. My driver side bushing pressed half out of the knuckle when the ball joint (luckily) released. I was watching for this on the passenger side. It was 3/4 of the way pressed out when I stopped to regroup. Luckily I did because a minute later the ball joint let go and solved my problem.

I recommend if this happens you just take a breather and see if the ball joint will let go by itself. My guess is that it will pop out if you give it some time. I pressed both the bushings back into the knuckle with a large bolt, a few washers, and also by placing the ball joint "washer/spacer" on the top side of the knuckle.

Hope this helps. My shimmy is gone and the car feels tighter.
 
#22 ·
Hi.

Great DIY write up. Very useful. I will be doing this procedure myself at some point in the next couple of weeks on my M5, presumably it is the same??

With regards to adding ballast to the car before torquing up the bush bolts, is there another way round it? Unfortunately, I don't have 225kg of ballast kicking around in my garage, or a a family of four??
 
#23 ·
I am in the same boat as Bazzer......... any other ways of getting proper ride height without the weight??? and just to be clear I have a 525 the thrust arm is the straight arm towards the rear which has the ball joint entering up from the bottom into the knuckle correct?????? I know the differ from the 540....
 
#24 ·
Just want to thank everyone who's contributed to this thread. I swapped my control arms out for the Meyle HD at 108k miles and it went pretty smoothly thanks to the detailed write-ups. I used the Harbor Freight Ball joint separator as others have mentioned and the balljoints separated easily.

When tightening down the balljoint, I found it tricky to tighten the 22mm nut while holding counter torque with the 5.5mm-6mm L shaped allen key. Tightening the 22mm nut by itself just causes the balljoint thread to rotate with the nut without counter torque. Despite lowering the hub assembly from the shock , there's still very little clearance to fit the allen key on the end of the balljoint thread. Wiggling the steering back and forth was necessary to get proper clearance. When tightening the bushing side of the arm, I used my jack to raise the hub to "preload" the suspension to simulate the static ride height. Probably not the most accurate way of doing it, but time will tell if they fail prematurely.

Interestingly, the old control arms/bushing that came out was labeled Contitech instead of lemforder, so not sure if these were the original stock or the prior owner had swapped them out once. Despite significant cracks and tears in the old bushings, I never had the classic low speed "shimmy" just some steering vagueness. The new bushings actually don't feel all that different.
 
#25 · (Edited)
I'm aware of how old this thread is but it was a great asset when replacing my thrust arms. I wanted to recommend a tool that can be purchased locally and for cheap for popping the ball joints loose.

If you have a Harbor Freight store near you, simply purchase their ball joint separator, Part # 99849.

http://www.harborfreight.com/3-4-quarter-inch-forged-ball-point-joint-separator-99849.html

"3/4" Forged Ball Point Joint Separator

Item # 99849 Manufacturer: U.S. General"

When I went to the local store in Raleigh, they had 9 of these in stock and they only cost $18 out the door. Using this tool made popping the ball joints out the easiest part of the job. I turned the hub to where the wheels were mostly straight, positioned the tool and held it in place while I began tightening the drive bolt. This was done after liberally applying PB Blaster(or your choice of penetrating spray). After a moderate amount of rotations on the bolt, I gave each ball joint around 2 minutes to sit. Even with only moderate pressure(nothing near excessive) with turning the bolt on the tool, both ball joints popped quickly.

It was a great relief to have this part of the job out of the way. The part where I got hung up is adjusting the spindle up and down on the shock/strut tube. Make sure you utilize a decent sized chisel and apply torque to it with the closed end of a wrench. Be careful to mark the original location of the shock/struts.

After finishing, Ive come to realize that my front ride height has inadvertently been raised by about half an inch. This, in turn, has messed with my headlights with the auto-leveling headlight feature.

Just thought id throw out some advice as this seems to be a very ubiquitous repair.
-Cameron
 
#26 ·
I just had lower control arms (and tie rods) replaced but still have a little shimmy. I am not at all sure whether lower control arms are the same as thrust arms. I did a complete front brake job (OEM rotors and Pagid pads) and was blaming un-even lug nut torque (or possible out-pf-round rotors) for the shimmy, which was less after an alignment.

I will also take this opportunity (I can hardly believe I'm doing this!) to give a thumbs-up to local dealer Critz. Reading the codes (to sort out a ABS thing that turned out to be a bad LR speed sensor) was only $65 and complete alignment was $129. After years of Critz=-bashing they seem to be coming around.

Rich
 
#27 ·
I just had lower control arms (and tie rods) replaced but still have a little shimmy. I am not at all sure whether lower control arms are the same as thrust arms. I did a complete front brake job (OEM rotors and Pagid pads) and was blaming un-even lug nut torque (or possible out-pf-round rotors) for the shimmy, which was less after an alignment.

Rich
I did mine recently and my control arm ball joint had some play in it as well. The thrust arm is the rear arm with a large bushing for the frame, and the other control arm is the front one that is tubular and straight.

Tips I can share from having done the thrust arms:

When tightening the ball joint nut, I suggest torqueing it down, back it off, then torque to spec again. The taper may otherwise throw off your torque value.
New BJ nuts are highly recommended, but thread lock can be used if you lose the new ones.
Use an allen key (8mm?) in the ball joint to keep it from spinning as you tighten it. If the spindle is under load (jacked up), this is not necessary.
To tighten down the bushing side of the arm, professionals will usually jack up that spindle to ride height and then torque it down.
Inspect the tie rods and front control arm for play after doing the thrust arm. Worn thrust arm bushings or ball joint can cause premature wear on those components. Have someone wiggle the wheel for you.
I suggest throwing in all new sway bar end links - they can get pretty loud for their size when they go bad.
You can grease the inside of the sway bar bushings with brake compound or other grease to mitigate squeaks down the road. Do not grease the bracket side of the bushings.

Harbor Freight is a good source for the 21-22mm wrenches ($15 for a full set up to 24mm), 21mm 1/2" socket ($3, 12-point is OK), and ball joint separator ($20). Ear plugs aren't a bad idea either :)
 
#28 ·
Not trying to derail the thread, but how can you tell exactly what the culprit is? As I mentioned-- I had the tie-rods and control arms replaced and also replaced the front rotors and pads with stock rotors and Pagid. After this I noticed slight shimmy when braking lightly form 70mph to 35mph. I suspect the rotors, but also suspect front shocks (there are 200k miles on these). The shimmy is getting more noticeable--

Rich
 
#29 ·
Rich, I wasn't trying to tell you what was causing your shimmy, just sharing my experience that may be causing it issues as well. Your symptoms can be caused by anything from poor wheel balance, tire cupping, rust on the hub causing the wheel to be mounted off-center (always sand it down and apply anti-seize), or any worn suspension component. I wouldn't put the shocks on the top of my list, but after 200k, you may be better of counting parts you can keep rather than parts to replace.

Have you tried wiggling a wheel and tire up/down and side to side? If there is freeplay, you should be able to pin point the (or a) culprit. Mine was the front ball joint on the driver's side, which requires a new control arm basically (pair). If you don't have any noticeable freeplay, it may be time to do a deeper inspection of the front bushings and joints using a pry bar.

Oh, and if you are able to detect the shimmy in the steering wheel, I recommend concentrating on the front;conversely, shimmy felt through the car seats and floor are more likely indicative of rear end vibration. Good luck and post back if you are able to narrow it down!
 
#30 · (Edited)
Ok someone help me out here just created an account to get a little assistance.. Ive just recently bought a 97 540i and just did a shtload of work already cause previous owner was brain dead i suppose. So I just replaced the rotors and pads in the front which ended the vibration at low speeds while braking.. Now after driving today I noticed the strong vibration at 50-60 while often having to over steering to the right while headed str8 (too loose?).. So I jacked the car up and the driver side wheel has a lot of play, not from top and bottom pressure but has lots of play from side to side (a lot of play actually)..

So ive read through this forum and with all the terms upper control, Lower arm, right upper, rear lower, thrust arm, traction strut, wishbone.. and theres actually more ive heard etc.. So when i look under at whats moving I see three main bars all of which are moving a bit under there, so which do I change first.. Is there 1 main arm that will prevent the whole assembly from moving around?? The one thing im clueless on with cars is this crap... thanks in advance for any help!
 
#31 ·
You need to step back and figure out which is the issue before you proceed. The movement you're describing can be due to any link down there.

Before we proceed, I should clarify the common names for those components..

Two aluminum bars, silver in color:
1. boomerang shaped one, closer to the back, mounted at 45 degrees to the car is the thrust arm. This one should also have a warning stickers about not hooking to it.
2. straight one in thefront, mounted perpendicularly to the car is the control arm, as they call it.

The last link you're seeing is part of the steering system, black in color (not aluminum), and should have some threads exposed. This is the outer tie rod.

The bad news is, they all wear and go bad. The good news is that you can figure out which by wiggling the wheel and looking for freeplay in a few key spots, essentially where the bushings and balljoints sit. This is easier with an assistant, obviously. The thrust arms also last about 60k miles so you may as well replace them anyway.

So take a look at where the freeplay is, then search around how to replace the part (always in pairs) because it isn't exactly straightforward. Popping the balljoints is a bit tricky, as is properly reinstalling the tie rods (count threads), bushings (torque under load), etc. There are a few very good DIYs here for all if those.
 
#32 ·
Thanks for the quick reply..

I pretty much see the thrust and control arms moving a bit.. So i guess i assume what ever has play all must be replaced? That last tie rod arm in the back is also moving.. So does this mean im suppose to buy 2 control arms, 2 thrusts, and 2 tie rods? I may just fix one side at a time this sounds expensive..

I read through the diy i have a pretty good idea what I've gotta do, just wasnt sure if either the thrust or control arm going loose would cause the other to move or not, like I said im clueless in this area... thanks again
 
#33 ·
Thanks for the quick reply..

I pretty much see the thrust and control arms moving a bit.. So i guess i assume what ever has play all must be replaced? That last tie rod arm in the back is also moving.. So does this mean im suppose to buy 2 control arms, 2 thrusts, and 2 tie rods? I may just fix one side at a time this sounds expensive..

I read through the diy i have a pretty good idea what I've gotta do, just wasnt sure if either the thrust or control arm going loose would cause the other to move or not, like I said im clueless in this area... thanks again
Check Amazon for decent prices on Lemforder parts, you can pretty much count on $110/arm and much less for the tie rods. There is no reason not to replace them in pairs, because if one side is bad then the other will soon go.. while chewing through your tires.

All play needs to be eliminated. With everything working as it should, you should have virtually 0 freeplay in your wheel tire assembly (aside from tire flex). This is well documented and you'll quickly see that it's best to replace it all, and always with GOOD parts. Going the cheap route, with fcp or similar, has shown to be a mistake on more than one occasion. I myself went with all Lem parts, threw in sway bar links, and left the tie rods alone because they were tight.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top