BillWilliams
BillWilliams

Suspension Rehab

This write-up was revised on 8 Aug 2013. The photos in the original post were lost due to me fiddling around on Photobucket and breaking the links. I tried to recover most of what was originally there but some photos have escaped me.

The suspension can be rehabbed in pieces or completely. Defining "completely" is scetchy. Completely can mean all of the bushings, brake components plus shock and strut components. Let's tackle the suspension bushings first.

This is not a technical writing but a guide or forewarning of what to expect.

There may be ways to rehab the suspension in the car but I will address the procedure as if the suspension is out of the car. Boy I feel inadequate to do this.

The front suspension rehab consists of replacing the bushing in the frame, front axle support and tension rod, at the very front of the car, sway bar bushes, control arm bushing or the control arm itself, ball joints and idler arm bushings

Copyofmotoronthefloor.jpg

Parts from a Paul Wegweiser list from years ago. Part numbers need verified, seems like BMW changes them often.

31 12 2 614 006 lower control arm (includes bushings)

31 13 1 108 439 ball joint (KIT)

32 21 1 113 178 safety bolt for steering arm to strut, each

31 13 1 108 373 front subframe bushing (std 2 per car)

31 13 1 108 374 front subframe bushing (turbo 2 per car)

32 21 1 115 116 idler arm bushings (2 per car)

Idler arm bushings.

I believe the control arm needs removing before you can rehab the idler arm. Remove the cotter pin and the castlenut, pop off the metal cap and persuade the idler arm to move down through the bushings. Remove the old bushing from the idler arm housing or off of the idler arm itself. It may require using punches, drifts or grabbing and twisting with vice grips.

To reinstall, place the new lower bush on the idler arm and the upper one in the housing. Insert the idler arm in the housing and through the upper bush. I need to verify if lubrication is needed. Place the metal cap on and the castle nut, torque to spec. 58-72 lb-ft

Idlerarm-before.jpg

Idlerarm-after.jpg

Bushing at front axle support and tension rod

You can use the stock, turbo or urethane bushing.

Frontframe1.jpg

The black one is the turbo.

Frameurethanesupportp_zpsa3000e8b.jpg

Red is the urethane.

Frame.jpg

This is a tired bushing and needs replaced.

Bushingtoolfrontframe.jpg

This is a home made bushing tool. It is a 1 1/2 inch PVC coupler cut in half, all thread and a series of washers. The concept is the washer that is bigger than the coupler has a washer up against it, the washers on the other end are the size of the bushing or a scooch smaller in diameter. As you tighten the nut against the large washer, the all thread and smaller washers pull the bushing through the PVC. The job of the piece of the PVC on the side being pulled through, keeps the bushing from "bunching up" before it pulls through the metal housing.

Bushingtool1.jpg

I had to place a wrench between the two pieces of PVC to keep them straight. I am sure there is a more sophisticated way to do this.

Use this tool to remove and install new rubber bushes. Urethane are split and install without a tool.Urethane bushes need lubed to reduce squeaking.

Sway bar bushes are pretty straight forward, just decide if you will use stock or urethane. Use hex cap bolts instead of hex head bolts. It is difficult to get a wrench or socket on the bolt head. Socket head bolts work the best. You can see the socket head bolts in the picture below.

Frontframe-after.jpg

Frontframe1.jpg

End Links

NewSpicerbushes4.jpg

NewSpicerbushes2.jpg

I used Spicer Teflon bushing for the end links.

Fronturethaneendlink9.jpg

Urethane is readily available too. I do not like the the way I did the bolts above. I like the threads up. Saves them from getting buggered up from the road.

Control Arms

There is a way to replace the inner and outer control arm bushes, they are different sizes and some suppliers have a hard time getting this straight so be careful if you order them. However, there is a lot to be said for just replacing the control arm. Inspect your old one and if it is bent from POs poor choice of a lifting point or if your not into removing the old bushes, just purchase the control arm and it comes with new bushes.

Idlerarm-after.jpg

I found this link (thanks to Jerry, Pinepig and Zenon) with great instructions on replacing the control arm bushing.

http://www.bmw2002faq.com/component/option,com_forum/Itemid,50/page,viewtopic/t,283064/highlight,/

The pictures below may help you get the spacers and washers in the proper order in case you did not document this well when it was disassembled.

Drawingofstrut-1_zpsd0cd324b.jpg

Drawingoffrontsuspension_zpsa983b6b2.jpg

strutbearing.jpg

Ball Joints

balljointparts-1.jpg

I failed to get good photos of the ball joint replacement. One of the big challenges is getting the bolt that holds the ball joint to the pitman arm off. Use your best and biggest tools to get it loose.

Redgreaseinballjoint.jpg

On reassembly, fill the cavity with grease to make it easier on your son when he has to replace it again in thirty years. Uncle CD says all mating surfaces should be clean metal, no paint or powder coating

Be diligent in using the right grade of bolts. New ball joint kits come with the correct hardware. Grade 8.8.

When you attach the struts to the pitman arms, most will recommend to use the bolts with the nut with the hole in so all three bolts can be safety wired together part number 32 21 1 113 178. Some will make an argument that high grade bolts with locktite is safe. BMW recommends the safety type bolts and safety wire. I have done it both ways.

Completed front suspension.

5Feb.jpg

Struts

One of the harder parts in replacing the strut inserts is deciding which ones to use, Bilstein HDs or Sports, Boge, Koni, etc. Once you decide, disassemble the strut assembly using safe spring compressors. Most strut inserts have a socket head on the end of the strut so you can hold it while you spin the Nyloc nut loose.

Strutpoo.jpg

You may find some poo inside the strut tube. Many stories on what it is and why it is there. No need to replace whatever it was.

Replacingstruts.jpg

ReplacingStruts2.jpg

Be careful trying to coat the inside of the tube with paint or POR-15. It can make things too tight for the insert to go back in.

Reassemble and use new strut bushing if you need them. I believe the ones for the e-21 (GUIDE SUPPORT M8X18 31 33 1 110 195) have shorter studs and make the top of your inner fenders look tidier. Lube the strut bushing bearing. I like that good red grease for this.

Drawingofstrut-1_zpsd0cd324b.jpg

This is a shot of the washers and cups for the strut bearing and shock assembly, thanks to someone who posted this on the FAQ,

Frontstrut5Feb5.jpg

The photos below is my youngest son, Revvin Evan, doing the safety wire for me. He does all the connectors on his bike so he is pretty good at this.

Evansafetywire2p_zps2a07bc69.jpg

Evansafetywire3p_zpsc4a6089a.jpg

Evansafetywire6p_zpse5bc1558.jpg

Safety wire is available at speed shops, bike shops, JEGS, Summit etc. The safety wire tool makes spinning the wire easy.

When you install the struts on the pitman arms, use new safety bolts and safety wire. Wrap the safety wire so it traps the bolts and does not let it turn.

Shortened Springs

wireonfrontsprings9-1.jpg

Shortened or shorter springs want to move from the rubber pads when the car is jacked up. To seat them properly involves putting your hands around the springs when the car is lowered. To eliminate this, the springs can be wired to the upper metal cap. Drill a hole in the cap and use a stainless steel wire to catch the upper coil on the spring and the spring will stay in place when the car is jacked up.

The words below are from Creighton Demeresk. His post and illustrative diagrams can be see at:

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/topic_view,threads/p,365939/t,282258/

go with the .028" wire and/or 0.032"

buy from any Racers Supply on line

Safety Wiring Techniques

Safety wiring is not mysterious or difficult. It really only takes some time and practice, and will soon become second-nature for you at the track. Safety wiring should always be done to keep bolts or nuts from backing out. That means always wire in the direction that will tighten the bolt. Safety wiring is also done to prevent any part that does come loose from falling onto the track and causing damage to another bike or rider. It never hurts to safety wire any critical part of your bike, such as controls, beyond the requirements in the rulebook.

Now that you know what you need to safety wire, you're probably wondering how to do it. First, go out and get the following items:

Safety wire pliers. Just buy a pair just like the ones in the picture. These are available at larger bike shops, racing supply companies, and even JC Whitney. Some people might suggest that you can use a "twirl tool" or a pair of needle-nose pliers, but you will be much happier with a pair of real safety wire pliers. Borrow a pair if you must.

A can of stainless steel safety wire. Some racers use ½ to a full pound can per season. The best overall size to buy is .032" diameter, although having a can of .028" and some .050" can be handy for tight spaces or damage repair. Safety wire is available at most motorcycle shops.

A variable speed drill and a dozen 1/16" drill bits. If you have access to a drill press, that can make the job faster. The tiny drill bits will only last 4 to 6 bolts. They will break often, even if you're careful, and dull quickly. Pick up a few 3/32" bits also. Be sure to keep the bit lubricated while drilling.

How to drill

Except for a few places on your bike where bolts are already drilled for a cotter pin, the nuts and bolts on your bike will have to be drilled before they can be wired. There are various ways to do this. It is best to use a drill press and a small vice to hold the fastener or part. Whether you have a press or a hand drill, here are some tips. First, go easy with those little drill bits. It takes very little force to break one. Lubricate the drill bit periodically with light oil. This helps it cut faster and also cools the bit. When the bit is about to clear the far side of the item you need to be careful that you don't snap the bit. Many nuts and bolts are surface hardened and that last section takes the longest. Throw out a drill bit when it gets dull.

Most bolts can be drilled straight through the hexagonal head, as in the first figure. Drill from flat to flat, and keep the hole centered. For the studs of some mounting bolts where a portion of the threads protrude, you might opt to drill through the shaft and wire in the fashion of the cotter pin found in most rear axles. If you do this, put a nut on the bolt first so that you can clean up the threads by taking the nut off. Banjo bolts (used on brake and oil lines) are hollow and cannot be drilled straight through. These must be corner drilled, as shown in the next figure.

Hexagonal nuts are drilled across one of the corners. This is a three step process. The drawing shows the drill bit pointed at the flat of the nut. Drill straight in until the bit is in about 1/16 inch. Then turn the nut in the vice about 15 degrees. Continue drilling until the bit is in about 1/8 inch. Finally, turn the piece again so that you can drill all the way through the corner.

Allen head bolts may be drilled through either one or both sides. Be sure to drill though the flats of the allen or you will weaken the grip offered the allen wrench. Drilling through both sides will make wiring the bolt easier.

How to wire

Once you have the nuts and bolts drilled and reinstalled, you need to wire them in place. You should first ensure that everything is torqued properly. Over-torquing a fastener will weaken the threads, and repeated over-torquing can lead to failure. Your bike's manual will have the torque and thread treatment specifications for each fastener. If appropriate, loctite or lubricate the threads first. You then need to wire the item as an insurance procedure.

When wiring nuts or bolts, there are several techniques used. The first is to wire the nut or bolt to a convenient fixed object, such as the frame or a fork tube. Another common technique is to wire two or more fasteners together so that none of the fasteners can back off. A third approach is to wire the head of a bolt to the nut on the other end. The figures show the first two of these techniques. Most drain or fill plugs will be wired to a frame member or engine part. Brake caliper nuts and bolts are usually wired together. Fork pinch bolts can be wired together or to a fixed item. A muffler mounting bolt is usually wired to its own nut.

The figure on the left shows a nut wired to a fixed member. It is best to start by looping the wire around the member and twisting the wire together. Continue twisting until the twisted part reaches just short of the nut or bolt. Thread one piece of the wire through the hole on the nut or bolt. Pull the wire tight and then continue twisting the wires together. Leave about 1/2 inch of twisted wire and cut off the rest. Throw the ends in the garbage can immediately. Tuck the end around so that you can't cut yourself on it. Tension should be kept on the nut or bolt in the tightening direction. The diagrams here show the wire in a loose fashion so that you can see the idea. Your completed wiring should be neat and tight.

Always discard your excess wire in a trash can. Those little pieces of wire can flatten a tire in no time. Always use caution when working with safety wire. The ends are very sharp and can easily cut your fingers. When you have finished wiring a nut or bolt, bend the end of the wire so that it doesn't protrude and create a hazard.

This figure shows two nuts wired together. The procedure is similar to wiring to a fixed object. Loop the wire through the hole of one of the nuts (or bolts). Twist the wire and maintain tension on the wire in the tightening direction of the nut. Continue twisting until the twisted wire reaches just short of the hole for the second nut and wire that nut. The wire should pass between the nuts to maintain tension on both nuts when the job is done. This process may be continued to wire additional nuts in succession, such as an oil filter cover, sprocket nuts, or water pump.

If your bike has a spin-on type oil filter, it can be wired in place by placing a hose clamp around the filter, then running a piece of safety wire from the clamp to the frame or another fixed object.

Another area which requires special techniques is fuel and water lines. You can use the spring loaded clips that come stock on most bikes, or use small hose clamps. If you use safety wire, be careful because you can cut through the hose by using too much tension. Small zip ties will also work.

Water lines are usually clamped with standard hose clamps. One precaution you can take is to thread same safety wire through the slot on the screw of the clamp, then attach the wire to the clamp. This will keep the hose clamp from loosening.

Rear Suspension

The car needs supported some place other than the usual place on the subframe. I run a 4x4 across the car in front of what BMW calls the Push Rod (these are the bars that connect the sub-frame to the body) and set that 4x4s on jack stands.

Disconnect the flexible brake lines and curse the nastiness of brake fluid that goes everywhere but in the pan. Disconnect the emergency brake cables, shocks, differential support bracket, two large nuts that connect the suspension to the body, support bars and the driveshaft. You may find disconnecting the shocks easier from the trunk. On most shocks there is a allen socket in the top of the shock, you can place a box end wrench around the nut on the top of the shock, hold the shock securely with the allen wrench and loosen the 17mm (guessing) nut on top of the shock, that is usually a nyloc nut.

Disconnect the drive shaft with a friend. Engage the parking brake, break loose one of the nuts on the drive shaft at the differential. Have your friend release the brake, rotate the shaft, engage the brake, break loose the next nut, so on and so on. By the way, after you have done this once, you will find a way to put a set of flex head gear wrenches in your tool box. Working these nuts is worth the price of these wrenches.

Lowering the suspension justs involves placing a floor jack under the differential and lowering it slowly while balancing everything.

The spring will just fall out as you lower the suspension.

Going at it this way allows you to refresh the brake fluid and the flexible brake lines.

Tired rear suspensions look like this.

originalrearsubframe.jpg

Again, this parts list is old, one I got from Paul Wegweiser years ago. Part numbers need verified, seems like BMW changes them often.

33 33 1 103 926 rear sub-frame mounts (up to 1974)

33 33 1 113 342 left rear sub-frame mount (1974 on)

33 33 1 113 343 right rear sub-frame mount (1974 on)

33 17 1 104 266 diff bushing inserts only

33 32 9 061 945 trailing arm bushing set (4 bushings total)

As a note, install the end of the flex line that attaches to the bottom of the car first, even before the sub-frame is placed.

Aug2602-1.jpg

For some reason BMW placed that connection just above the rear sub-frame and it is difficult to get to once the sub-frame is in place.

Rearflexline10p_zps9b08ed9a.jpg

Inside the sub-frame is a captive nut like thing that holds the hex head thing on the flexible brake line.

Sway Bar Link Bushes

As with the front sway bar link bushings, these are pretty straight forward. Just decide on what you want, stock, urethane or teflon.

NewSpicerbushescopy.jpg

Teflon

Urethaneendlinksrear3.jpg

Urethane

Bearings and Races

Even though replacing the bearing races and seals are not covered in this post, one method of pulling the hubs is shown along with the spacers inside the rear hubs.

pullingrearhubJPG.jpg

reartrailingarmsbearings.jpg

reartrailingarmsbearings1copy.jpg

Trailing Arm Bushings

Removing the trailing arm bushing is accomplished in several ways. One way is to stink up the place and burn the rubber out and then remove the steel sleeve.

Removaloftrailingarmbushes1copy.jpg

The way shown here is using a BMW bushing removal tool. A homemade tool with PVC, washers and all thread works too.

Once you know how to use the tool to remove and insert the bushes, it is an easy process.

PC050006.jpg

pc050004.jpg

PC050002.jpg

Oldest son using a bearing and race set to set the races/bearings

Upper Shock Bushings

Not a big deal to replace these. Just find a way to remove the old ones, prising with a screw driver works, them just lubricate with your favorite soap or glycerin and push them in from the top.

Rear Carrier Bushings

The rear carrier bushings come in a "bolt-on" unit. To replace, just unbolt the old unit and re-bolt the new unit on. Just be aware, the units for round and square light cars are different. Note: Insert the bolts in the bushing unit then insert the bolts through the sub-frame. The bolts can not be inserted if you place the bushing unit flush against the sub-frame. Nobbs go up!

The rear carrier is different for earlier and later cars, be careful ordering parts. The rear carrier bushes can not be flipped on early cars.

Rearcarriesbushes4p_zps6edbbe10.jpg

Differential Carrier Bushings

Rearcarrier.jpg

BMW used to offer the carrier and the bushings as one unit, now they only offer the bushings. To replace these, I had them pressed out and the new ones pressed in with a press.

Rear - After

Finished.jpg



User Feedback


Awesome!

 

Could you also resurrect the heater rebuild "How To" - this is one of the biggest jobs for a 2002.

 

Unfortunately it looks like the pictures and links were lost like this one. 

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Very informative. I did my sub-frame front bushings using some of Bill's techniques, especially the Pvc pipe. Difficult but it eventually worked with some strength and patience.

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Awesome write up, thank you! I'm about to dive into a front suspension overhaul and this is a big help.

 

I do have a question regarding your picture of the pitman arm (filled with grease) you say: "Uncle CD says all mating surfaces should be clean metal, no paint or powder coating." but your picture appears to show a painted/powdercoated surface. I've seen others on the board that are painted as well.

 

Am I missing something?

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Bill - Great write-up.  I have referred to it frequently during my subframe refresh and have found it very, very helpful.

 

Were you ever able to verify whether there should be lubrication applied to the idler arm when reinserted into the new idler arm bushings?

 

Greatly appreciated,

 

Scott

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I actually found the PVC a big fail in making a bushing compressor as it buckled under pressure, but discovered that a couple of old tii strut tube caps worked perfectly and didn't need the extra wrench to keep it aligned. A later iteration included about 3/4in. of the PVC on the outer side between the cap and frame.

 

bushing_compressor.jpg

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The big torsion bar bushing at the front of the subframe is easy as pie... You absolutely don't need the home-made PVC/all-thread compressor tool.

 

Remove the old bushing by cutting the lip of the old bushing with a sharp knife and pry it out with pliers, screwdriver, etc... easy.

 

I'm assuming the car is on jackstands for this...

 

To install the new bushing, liberally lube the bushing and subframe hole with brake caliper grease (Syl Glide at NAPA) (not harmful to rubber). Put the torsion bar thru the subframe hole and install the bushing onto the torsion bar with the front washer and nut. You only need to spin the nut on a few turns.

 

I laid on my back, with my foot in the fender well.  Grab the rear portion of the torsion rod, and pull back, using your legs for maximum effort.  You may need to twist the torsion rod to get it started, but I found both of mine went in with very minimal effort.

 

This was the simplest part of the front suspension rebuild, IMO.

 

Hope this helps,  PM me if you have questions,

 

Ed Z

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Starting the rebuilding of my suspension as well. I'm using H&R Springs and Bilstein Sports. I purchased the fixed front camber plates from Ireland Engineering but i'm concerned that they might raise the front ride height. Any thoughts?

 

This article is greatly appreciated. 

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Awesome article. Did you repaint your subframe or have it done? What does this cost roughly and what is the paint type required? Is it powder coated? Cheers, C.

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