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Author Topic: My recent BMW suspension project  (Read 989 times)
Grand Master
Posts: 3386

Resident asshole of TAL

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« on: December 29, 2008, 04:29:39 PM »

This the project I began this past March.

For another view of the project, providing larger pics, you see the original post at:,1980.0.html

The six had no real issues with the suspension, just some creaks and moans when turning sharply, which, if you did not drive it often, you may not even have noticed. However, late last year I pulled it out of the garage to make room for a quick shuffle of some other things in my bottomless black hole of a garage and noticed the left rear appeared to be leaning a bit more than the right side. Upon backing it into the garage again after said move of crap was done, I took some measurements and sure enough the left side was about 1 and a half inches lower than the right rear. I sucked it up and began to plan a suspension overhaul.

My logic was that if Im going to replace one thing as in the spring/shock, I may as well replace many parts as long as Im under there. After all, the car just turned 21 years old and many of the parts are original. The car now has a notch over 120k on the clock so with that in mind, there needs to be some proactive maintenance done on it.

The plan was to replace the following items:

-All four springs
-all four shocks/struts
-rear dog bones (these eventually were not replaced, after evaluation, they are not original and were fine)
-front thrust arms
-front control arms
-ties rods
-sway bar linkage

These parts were ordered and came in over the next few weeks. Note that most of the parts to be replaced have bushings, and seals which upon examination were WAY over due to be changed simply due to age. The mileage on the car was not reflective of wear and tear, these things were just O-L-D.

My plan was to begin on the rear first given that, there are two routes in which to remove the rear springs from an e24.

Through the trunk, or by removing the rear seats. My first task was to evaluate which was easier. Here I began by looking into the trunk area to see if this was possible just because I was hpoing to avoid removing the seats.
In the pic below, there are the two panels that need to be disconnected in order to view/feel around the rear shock towers.

After removing the snaps that hold the side sound insulation, I could then remove the top sound insulation as seen here.

The L6 model differs a bit from the regular 635CSi in that there are additional sound proofing components. I figured this out through many discussions with my fellow sixers on BF.c and other forums. A HUGE amount of debt gos out to al those guys for their input.

After removing the top insulation panel and feeling around, I determined that removal of the shock tower components through the trunk was not going to work. There was simply not enough room to navigate and work.

Plan B, remove the rear seats.  Tongue

Action time:

The plan is to now, get the rear end up for some evaluation, closer inspection to see if anything else needs to be replaced as in the sub frame bushings. These pics illustrate the process.
I secured an extra set of jack stands to insure a safe resting place for an EXTREMELY heavy car despite its small size.

The rear lugs loosened and jacked up.

Armed with WD40, JDs best and PB blaster I began to look at the parts to replace.

Here I examined the dog bones and determined that despite being dirty, they are good for a little longer. If a significant car show was not on the horizen, I may have added these to the replacement list as well, but in the interest of time, I left them alone.

The next inspection began of the subframe bushings shown here.

A little closer.

In the pics, I have my block of wood covering the bottom where you actually need to view the bushings themselves. After snapping these pics, I lowered and raised the car again so I could see the bushings directly.

Despite their age, and they should have been replaced, I decided against it due to the extensive time needed and a good level of difficulty associated with the process. Not some much difficult, just a real ball-breaker.

So I opted to leave the subframe bushings for the upcoming winter project when the six will be stored away during the foul weather.

I did some basic snooping around to see if there are any obivous issues that need to be addressed as long as I was on the job.

The rear shocks.


Here is the view up into the tower assembly where it meets the car frame. There is some corrosion that can be seen on the spring, nothing too significant.

Inspection of the rest of the rear suspension components shows nothing else in dire need of replacement, just some accumulated road grime.

Arrival of the parts.

Here my assistant has caught me doing the actual inspection of the rear components.  Grin

Ok, now that I have an idea of what needs to be changed, and how I am going to tackle it, I begin. With the car lowered again on the wheels, I begin disassembling the rear seats.

They are remarkably easy to remove, two screws under the front of the seat and out they come.

They basically slide up and out at a 45 degree angle.

With the seats out, I need to look around to see how to remove the deck in the back near the rear window. First the speaker pods need to come out to allow access to the other clips holding the deck in place. Note the long screws holding the speaker pods in.

another shot.

The rear center brake light assembly had to be removed also.

Once the seats were removed, I wanted to check the condition of the rear refrigeration unit.

This appeared fine, all the connections were intact so no fix required here.

After both seats were removed, I needed to remove the center console that rests between the seats. This was easy to remove, just a pair of screws on each side.

Once the seats and console were out, and the speaker pods removed, I could begin removing the rear deck to allow access to the shock tower connections.

A shot of the rear with all the parts removed from the seating area.

Showing where the tabs are, a close up.

These were held down be approx 8 plastic tabs as shown.

The difficulty here was not to break any of the parts as in the rear deck itself. Many of these interior part are very hard to come by when/if they are available.

Once the deck was free of the connections, I could pull it up and out part way. The deck would not come all the way out due to the seat belt straps threading through a slot on each side. I disconnected the seat belt from the bolt holding it on each side of the car, but, could not get the belt unfastened from down inside the deck area. Unfortunately, I dont have a lot of pics, I think I may have deleted several of the set. Although it is not incredibly difficult to intuitively follow through and see where you disconnect the seat belt from the side of the car (where its hidden under the side of the seats), and this was enough to allow me to slide the deck up and away from the rear to access the shock towers.

Here is a repeat of the rear deck and you can see where the arrow (ignore the circle) points to the place where the shock tower nuts are attached.

I was now able to access the three shock tower nuts to release the shock tower from the frame and allow me to pull it down and out of the wheel well area.

I had several pics showing the awkward access to the shock tower bolts, here again, I believe I deleted them by accident. Despite the better access from inside, they where still extremely difficult to access with a ratchet. The bolts were in just under the structural frame of the car, requiring the use of a regular wrench which made the process very tedious. There was limited room to turn the wrench requiring far more short turns again adding time and frustration to the process. Once you pull the rear deck off, you will immediately understand what I am referring to.

This is not impossible, just tedious.  Angry

Here is another view from the inside and the arrow indicates where the access to the shock tower bolts are.

Once both shock towers were free, I left the inside torn up and returned to the floor to raise up the car and remove the shock towers.

The rear towers/shocks were relatively easy to remove. Despite being on there many years, I was able toe breal the nut loose using a 1/2 drive ratchet and a small cheater. The single nut is shown here by the arrow.

Once the nut is loosened, the tower slides right down and out.

Some side notes. I have a set of spring compressors, I was not sure if they would be needed to remove the tower from the car, they were not needed.

Once the shock towers were removed, I wanted to remove the springs from the tower assembly as soon as possible, so, I immediately began to compress the springs (after they were out of the car) and then removed the self locking bolt on the top of the tower assembly.

Obviously care has to be taken with compressed springs, I however, had no problems just using common sense in the placement of the compression rods and equally tightened each side down.

I reused the rubber spring seats as I forgot to order new ones. I made the decision in part because they were actually in very good shape almost looked new. Once I removed those, I cleaned them well and applied a silicone preservative to them (several times to soak them well) and then let them sit for a while.

The shocks need to be released from the tie down strap at least 24 hours before installation, so, following that prep period, I was able to begin re-assembling the shock towers.

They went back together again very easily, I placed a small amount of motor oil in the bottom of the tower, this helps reduce friction when the shock rubs inside the shock tower. Replacing the spring in the seat, and attaching the self locking nut on the retainer prior to releasing the compressors all wen smoothly. Since this was done solo and needed two hands I do not have a set of pics to illustrate.

The tower went back into the wheel well and attached easily as well, the only complaint was as was stated when removing the nuts, they were a pain to retighten after the shock tower was in place.

I lowered the car and replaced the interior before taking it for a road test. Success! The rear part was done. Some of you may remember, I drove the car to a meet that night.  t-up

The Front suspension.

Ironically, the front looked a lot easier, at least on paper. Boy was I wrong.

For the front I purchased another set of jack stands, I would spend a greater amount of time underneath and am a believer in safety.

My plan was to remove the shock towers first, and then begin removing the other components when that was out of the way.

Before removing the shock towers, I need to off course remove the brakes, calipers/rotors, these came off quickly, I have had them off several times and properly torqued them for future ease of removal.

Before removing the shock towers, I did a little inspection of the parts. Here it is clear that the bump stop is toast.

Because the control arm knuckle was still tightened to the control arms, in order to remove the shock towers, I had to loosen the nuts that held the arms to the knuckle. That would allow me to lower the knuckle and slide the shock tower out/off. These nuts, the ones on the knuckle were not very hard to break loose, I was expecting a real struggle.

I also removed the sway arm linkage, the condition of the joint can be seen here.

Another view from below.

At this point, upon inspecting the tie rods, I decided it would be good to replace them. I was considering this initially, but, once I have a clear view of them, they needed to go. The joint connection to the knuckle is circled here.

And here is another view of the tie rod connection in the lower right.

Once the tie rod is off, it is clear that the seal has seen better days.  :Smiley

At this point I could either continue removing the control/thrust arms from the knuckle, or from the frame, or I could start working on removing the old struts from the tower. I choose to begin with removing the struts from the tower.

This was another of the glitches I ran across. Once the knuckle was loosened, I slid the tower free. There is a cable that is the abs sensor unit attatched to the tower assembly that (I dont have a direct pic of) links up behind the rotor and of course "senses" when the wheels are locking up. This is attached to the tower with a 5mm allen type screw. As I tried to remove it, of course it stripped.  Angry

In the interim, I turned the tower over and placed it on the ground as seen here.

At this point it was late and I didnt have a screw extractor and everything was closed so I switched gears and began the attempt to remove the ball joints using the pickle fork. This can be seen above, and some additional below.
Here trying to remove the lower arm.

The attempt to use the pickle fork to remove both arms failed. I ended up going to rent/buy a ball joint separator the next day as well as my screw extractors.

When I went to advance auto parts, their ball joint removal set was like $150 (deposit if returned), so I opted to buy a single pitman arm puller. I know not the correct tool exactly but it was worth a try and a lot cheaper. I also picked up some cheapo screw extrators there (against my better judgement).

I do not have a lot of pics of this process, it was usually done late in the evening and I was just trying to get it done.

This is not finished. See following posts for the rest of the story.
« Last Edit: December 29, 2008, 04:39:40 PM by LSixer » Logged

Grand Master
Posts: 3386

Resident asshole of TAL

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« Reply #1 on: December 29, 2008, 04:34:45 PM »

Due to the length of this project, I need to put the rest in a "reply".

Before I tried the pitman arm puller, I attempted to free the stripped screw from the tower. The first side extracted nicely, no issues, I was able to release the ABS sensor and pull the screw free easily.

The other side was my nightmare on elm street.

The cheapo extractors broke, one after another, again, leaving me at 11pm with no working extractors.  Angry

The next day I made the right move and went to sears to get a proper set. As soon as I tried the better extractors, it went right in, but, somewhere in the failed attempts, the metal must have weakened and the head broke off leaving the busted screw in the tower with out any room to vise-grip it out. ARRRRGH!!

I had to take the tower the next day to local welder where we welded a head on the screw and popped it out.

Once both tower were free, I did a quick inspection of the condition prior to removing the spring.
Here there is a small amount of corrosion, not enough to worry me though. I thoroughly soaked it in WD40 while I was working on compressing the spring.

Here is the top end of the tower assembly, the self locking nut can be seen in the middle. It is my understanding that the best way to remove the spring is to loosed this nut slightly, just enough to break the locking plastic before compressing the spring.

Captain Obvious says: DO NOT LOOSEN TOO MUCH! Otherwise you have a un-guided missle unleashed.

I loosened it a little and the attached the compressors.
Heres a shot of the business end of the MX missile just before I loosened the nut the rest of the way.

Once the nut is off, the cap and rubber seat come right out.

Again it needs to be said, as with the slow deliberate process of compressing the spring, the same slow process needs to be followed to release the compressed spring.

Once the spring is out, we can do some more inspection.
Here is the strut retainer threaded cap. This guy was not looking like he was gonna come off without a fight.

Surprisingly, I placed the tower assembly in the vise, and with a large pair of pliers, they broke free.

Once the old strut was out, I placed the towers on a paper towel upside down to let the old oil drain out. I then broke out the new struts and released the compression strap to allow them to fully extend out. This is recommended per the instructions, they should be allowed a 24 hour period in  which to decompress prior to installation.

With this done, it was time to begin working on pulling the upper arms out, again.

As was stated earlier, the pitman arm puller worked on the lower arms, but, would not budge the uppers. As luck would have it, the spot where they connect to the frame leaves little room to work, and you need to have a wrench/ratchet on both ends as they spin nicely within the bushing. The problem started when I tried to use my 12 point wrench (22mm) because I could not find a 6 point anywhere! I tried Mac tools, snap on etc .... there were up to 19mm 6 pointers, after that only 12 pointers. SHIT! After several attempts using a 23mm (6 point ratchet) on one side and a 22mm 12 point (open/box wrench) on the other, including banging away with a small sledge, I got no where. I worked on this several days, a couple hours at a time.

Finally a break came and Im not sure what happened, but they did break loose. VERY lucky because I was starting to strip the one side. In fact, I had just bought a new cutting wheel to use and cut the (getting) striped nut away.

Once the control/thrust arms were free from the frame, the next step was get the thrust arm free from the knuckle. The pitman arm puller is supposed to have broken this free, but did not. As well as repeated attempts with the pickle fork and as stated, no luck. I do believe though that these attempts did have an impact in loosening the ball joint.

I understand that the ball joint can be freed be placing the knuckle in a vise an with a couple well placed blows, it will pop out. This was plan B and plan B was the WINNAR! It actually took about 5 blows with my hand sledge and the joint popped out. This worked for both sides and the front disassembly was finally complete.

Now begins the re-assembly.

The re-assembly should begin with attaching the new control/thrust arms along with the tie rod and sway bar linkage to the frame, and then subsequently to the knuckle. Actually the sway bar linkage will be attached once the shock tower is in place, because that actually attaches to the shock tower.

I took the new parts out to visualize the fitment and made sure that all would be correct.

The tie rods are adjustable, so I used the old one as a guage to lengthen the new one as shown below.

Once the tie rods were set, I went to work attaching the control/thrust arms to the frame.

Here the thrust arm is attached, although it should only be torqued enough to hold it horizontal. Final torquing comes after the car has the full weight on the wheels.

A close up to show the limited working space.

Above the self locking nut is the one lower in the pic. This is the 22mm and I could not get a socket onto that guy. Again its hard to see all the detail. THe upper one is the actual bolt and that is 23mm and I was able to get the socket head onto that guy.

Here is another view, the thrust arm connection to the frame is in the lower part of the pic. Its not the best but upside down pics are not so easy.

Another view of the same connection.

Here the thrust arm is in place, again, not too tightly connected, just enough to keep it horizontal.

Here I have the lower control arm connected, I have not tightened it enough yet to maintain the horizontal angle.

Here I have both upper/lower tightened enough and in position to attach the knuckle.

The knuckle has to be fitted here to match up the holes. The blue covers can come off now and screw on the new arms.

Dont forget the locktite!

Here the two control arms are in place and I also attached the tie rod to both the frame and the knuckle. The tie rod can be torqued down to its proper level now, no need to wait until lowering the car.

Another view.

Just finishing tightening down the tie rod.

The tie rods connection to the frame.

All done! Just forgot to remove the ratchet.

Now with the parts connected to the knuckle, with the exception of the sway bar links, we can place the shock towers into position.

Its worth noting, because when you attach the bering cap to the shock tower, or when you take it off, it is not very distinguishable. In this pic, you have to look hard to notice that the screws that go up into the fame are not completely symetrical. That is to say the two screws closet to the bottom are closer together than they are to the screw at the top.

What difference does this make? None really, but, if you were not aware of that and had to try and hold the shock tower which is not lightweight upright and try to line up screws that are not meeting up with the holes, you can frustrated in a hurry.
Case i point. My son was helping me on top, lining the screws up and I was propping the tower up on the knuckle, but, still holding much of the weight in my hands. The support of the knuckle was just to keep th eproper angle up into the shock tower housing.

After several minutes of trying to line it up, my son said I think you got the wrong size, it doesnt line up. Im my infinite wisdom, I forgot to tell him about that anomoly. Once we were on the same page, the tower slid up and in and he attached the nuts on top as I attached the nuts to secure it to the knuckle below. IN!

The shock tower in place.

The upper view of the reinstalled shock tower.

Again, the nuts that are on the knuckle end of the

tie rods
Thrust arms
control arms

These can be (should be) torqued down to their proper levels. Where the control/thrust arm connect to the frame, these are to be left fairly loose, only to be torqued down once the car has the full weight upon the wheels.

Once the towers are in place, we can attach the sway arm linkage.

A before (old) and after (new) pic.

Here is a crude indicator of where the sway arm links go.

I retightened the sway arm itself, I had loosened it during the process to give me extra room. Here I am making sure that the spacing is correct before connecting the links.

Now that I have the tower connected and all parts connected, I need to account for my ABS sensor (on the left) and the brake fluid line (right side).

The brake fluid line needs to attach to the caliper which at this point is not on yet - thank you captain obvious. But we can attach the ABS sensor. This attaches to the inside of the shock tower and just slips in and gets secured by a 5mm hex screw. No pics of this process because it almost impossible to get my camera behind the dust shield.

The screw is secured and now we can replace the drums and calipers.

The drum/caliper replacement was nothing extraordinary, everything went on fine. No pics of this again, two handed and a novice level job.

The last thing is to replace the wheels and lower the car!

But wait! We still need to torque down the thrust/control arms. What to do with that? Once the wheels are on and the car is lowered, Its a tight fit under the car to reach the arms.

Idea. Rather than lowering the car on the wheels, place a jack stand under the knucle and lower the car onto the jackstand to simulate the cars full weight! Brilliant!

I carefully placed a jackstand under each knuckle one at a time of course and when the full weight was lowered on the jackstand, I was able to torque the thrust/control arm nuts. The ones that connect the arms to the frame of course, the ones on the knuckle shoud already be tight. I regret not getting pics of this, but, given the obviousness of this task, it should not be too hard to visualize.

Thats about the finish of it. I attached the wheels and lowered the car and pulled it out for the first time in several months.

IT lives!!

The summary.

The car needed to have an alignment as any car should following the replacement of the suspension parts. Although I have to say, the drive to the shop was very smooth. The alignment was not all that bad!

Bleeding the brakes was a bit tedious, I had to redo it several times and they still did not feel 100%. So, while the alighment was done, I asked the indy to go ahead and pressure bleed the brakes.

Project over!
« Last Edit: December 29, 2008, 04:38:09 PM by LSixer » Logged

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