E31 suspension rebuild illustrated

There's reason why E31 are priced around $6K on used car market. Restoring/rebuilding the thing is expensive. If you are looking for dealer/indy to do work for you prepare to pay about 3x more than price of the car.

But if you DIY, it is fun and even a bit pleasure. I will not cover whole process, just most interesting places and places that by today will need attention on almost every car.

I'll start with rear and cover ball joints, springs and struts.

Parts needed:
ball joints:




more ball joints:



wishbones



enlarged part number:



Also all new nuts for suspension. No pic.

Here are parts to be replaced:



Struts/Springs:



Tools needed:

BMW special toos/kits. Both are available from dealer ~$300 each. Takes about 2-3 months to deliver, my guess is they make them per request.
Doing this job without those tools will be much more painful.






Harbor freight kit:



Press (optional),
propane torch,



impact wrench (if you want to make process easier),

various tool grade bolts etc.






Now the process. I had exhaust already removed from the car. Jack up rear arm, remove strut:










Unbolt sway bar link. Unbolt cross member, lower jack remove spring:




Then remove wish bone and cross member. Rest is pretty much - unbolt all suspension components that use ball joints. Remove brake rotors and hand brake assembly, otherwise you will not have clearance to get to lower ball joint.





1st view on glory details:




Removing ball joint from cross member is piece of cake:




tool usage:


After:



Removing other ball joints requires right tools, and some fiddling torch heating and sweat:





Here's why you need to remove hand brake assembly brake cable do not lets to place tool in place to remove lower ball joint.



Later I used impact - much easier. Still need to heat up with torch:






Inserting new ball joints is pretty much straight forward. Make sure you heat up parts and chill ball joints:




Before putting things back, clean up your wheel arches:





Here's finished side:





Oleg.

Here are some observations about H&R springs and net rumors:

Original rear spring vs H&R:



Note H&H has one less coil.

Spring wire diameter:








According to basic physics H&R should be stiffer:

Spring calculator

Maybe I was "lucky" and got "right" H&R springs, but I'd call myth about H&R rear springs being weaker - BUSTED.


For reference. Here's pic comparing rear Bilstein & original strut.




Here's note about ball joints in wishbones. IMHO BMW is full of BS when they force you to buy new wishbones with ball joints. I pressed out ball joint out of wish bone - nothing special, same as in cross member, just different size. I'm sure by looking around one can find correct replacement part:













Oleg.

thanks man, need to tackle the rear here shortly so this will come in handy for sure!

Ho Oleg,

nice write up.
I fully agree with you on what you say about BMW and the rear wishbones. So far I haven't been lucky in finding a plug&play ball joint as a replacement. I tried turning down an existing new spherical bearing to the 39mm outside diameter but the cage isn't thick enough. It just fell apart.
So I'm actually taking an existing new joint, disassemble it in order to use the inner part of it and have the outer cage manufactured to my specs. Quite complicated and rather expensive but still only about 50% of the price of new OEM arms. And my arms are powder coated while BMW just paints them.

Dust covers are mounted after the bearings are pressed in.
http://www.wokke.de/WP2/Spherical_be...ar_axle/12.JPG

Thanks for that H&R spring comparison. I am not removing mines after all.

Nice write up and thanks for all the pictures. Job well done - much appreciated.

Hopefully for under $50 you replaced the upper shock mounts.

Gotta love write-ups with lots of pics. Thanks for the effort Oleg!

Tony

Maybe H&R has re-engineered their rear springs? A phone call would shed some light, if anyone is inclined. Here's the chart that MWrench put together a while ago:

http://www.mwrench.com/Whitepapers/M...ing%20Dyno.pdf

Bill, disregard my e-mail from earlier... shop was talking about lower ball joints. They lifted the car and showed me what they were talking about, made a lot more sense than the initial "you need new spindles", lol.

Thanks for the post Oleg! I too have to tackle the rear here soon.

Here's continuation - front suspension. I was lucky (or not?) dealer replaced front arms for previous owner, so I missed a bit of fun doing that. But I just redid front on my wifes E39 so I do not miss too much pressing out ball joints.

Anyway here we go ...

Front shocks come with new upper screw. Also bump stops sre build in,
no need to order new ones.


1st steps do with shock in the car - this will save a lot of wrestling on the floor.

Lift rubber dust cover and pop up top cover. Noe you can loosen top mount (good luck with that). Do not unscrew it completely now - it will get really messy.


Disconnect ABS sensor.


Remove sway bar


Loosen, but do not remove 3 mounting 19mm bolts on bottom of the strut. Jack up whole suspensoin few inches up.


remove rotors and calipers


I use impact to remove top bolt. Make sure your jack is secure. After bolt is removed lower jack slowly, hold strut and spring whole thing will pretty much lower down.


Remove lower 3 bolts, holding the rest of the thing. Strut/spring will fall out


Here's shock and spring.


comparison of H&R and stock spring


Wire diameter


Carefully unscrew top nut, some oil will spray out, remove nut, remove factory strut,
Drain the oil


Clean wheel arches - mandatory:)


Insert Bilstein, hand tighten new nut. You will tighten it up when strut is in the car


Put jacj under suspension


Put strut/spring dust cover, upper washer back, fit lower part, loosely screw old bolts,
Guide top of the strut in hole. Jack whole thing up.


Use o2 sesor wrench and hex bit to put right torque.


I used new lower strut bolts and thread locking compound




Suspension is in place.


Oleg.

Thanks for showing those rear bushings! It's nice to see how those go in.

However I must be the one to... :deadhorse:

Quote:

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Originally Posted by perelet

Here are some observations about H&R springs and net rumors:

According to basic physics H&R should be stiffer:

Spring calculator

Maybe I was "lucky" and got "right" H&R springs, but I'd call myth about H&R rear springs being weaker - BUSTED.

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They are not "net rumors." Numerous people have proven through either scientific testing or driving experience that the rear H&Rs are incorrectly sprung. People who end up removing them can't believe the difference it makes.

Your smug and simplistic approach is the same mistake that H&R made when they designed them. The E31's suspension geometry is fairly complex. Forgetting to square a number or making the coils skinnier, even by less than a full millimeter can be a big deal. That small reduction in coil diameter is how they get the height drop out of them. Your "spring calculator" would work on most applications, but not this one.

http://mwrench.com/Whitepapers/Mwren...ing%20Dyno.pdf

http://mwrench.com/Whitepapers/Sprin...ear%202009.xls

Auraraptor's E31 Suspension Sticky

H&R Rears + Passenger = Dangerous

I agree that too many times people base their opinions on forum-majority opinion and nothing else, but this is one of those things that has been objectively measured and recorded as well as road tested. Don't ignore the amount of effort and time that was spent researching and testing this phenomenon and just say "according to basic physics H&R should be stiffer" because they aren't...even though you are are correct in thinking that they should be.

Awesome post....thx for taking all those pics

Brilliant, informative post. Thanks for your efforts in sharing the process, makes the E31 slightly less enigmatic to non mechanically trained people like me. Makes me want to do my own

Thanks for the post. I have been struggling with how I was going to remove the old inserts. Your approach was extremely helpful. I was going to add bumpsteer spacers with the lowered front end. How does it drive with the new suspension?

How much are we talking for a full suspension overhaul? $2000? (in parts)

Informative and helpful post for the forum... Thanks

excellent illustration....I'm curious, why didn't you use the spacer plates from Phoenix motorsports?

+1 :

Quote:

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Originally Posted by CaifanSC

excellent illustration....I'm curious, why didn't you use the spacer plates from Phoenix motorsports?

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(I need to get those things)

And about the spring diameter, the H&Rs are narrower... wouldn't that make them softer, not stiffer?

Thanks for all the detailed photos perelet.

I need to replace #2 bearings at both ends of the cross member (#1) and #23 bearings at the top of the wheel carrier (#22).







No play yet, but just a matter of time with the seal compromised. Has anyone had experience replacing these bearings using something other than the factory tools? Don't mind buying tools, just not spending $300 for a tool that I will likely use once.

It appears that these two bearings are unique to the E31.

I was the individual that originally announced in 2005, on Roadfly that the H&R rear springs was -17% weaker than the stock E-31 rear spring. The H&R rear spring dimensions I had were .0551 wire dia. x 3.8” coil dia. x 8.65 coils = 341 lbs/in”.
That fact didn't go over very well at the time but this is a fact that has been independently confirmed numerous times.

Unfortunately it is not a myth nor is an H&R springs with a 14.47mm (.562”) wire diameter stiffer than the stock rear springs.

I’ve calculated tons of springs and adding +.010 to a spring wire diameter does very little to the spring rate!! It is also possible the +.010 could be contributed to a thicker paint. If it is actually a larger wire diameter the spring rate would still be only 370 lb/in and -10% weaker than the stock E-31 rear spring at 410 lbs/in.

After disputing with every one I could reach at H&R, that their rear springs were 17% weaker than the stock E-31 and their less than willing to listen attitude, I personally had the H&R rear springs measures along side the stock 850, CSi and Dinan Stage-1 rear springs. All H&R did after I sent them the written results was to give me my money back!!

Quote:

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Originally Posted by Mike in CT

Thanks for all the detailed photos perelet.

I need to replace #2 bearings at both ends of the cross member (#1) and #23 bearings at the top of the wheel carrier (#22).

No play yet, but just a matter of time with the seal compromised. Has anyone had experience replacing these bearings using something other than the factory tools? Don't mind buying tools, just not spending $300 for a tool that I will likely use once.

It appears that these two bearings are unique to the E31.

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This will sound pretty low rent, but those spherical bearings will go on damn near forever if you inject some thick grease into what's left of the boots. You could even simply clean them up, squirt a shot of oil down into the interior, and then judiciously apply some bloogoo to seal them up again. Not primo practice, of course, but the point is that these things are ridiculously overbuilt and strong. After 200k miles they only loosen to the point that you can wobble the ball in the socket by hand a little easier, instead of real tight when new.

You can grind down a cheap socket to press them with, on a press or with an acme thread. The threaded rod is easier; they're awkward to position on a press.

I actually did that with the grease Bill. Used a marine grease used for outboard motors that resists getting washed away.

http://www.easternmarine.com/johnson...-grease-508298

I had the cross member disconnected for removing springs, so I was able to work quite a bit into the bearing.

Quote:

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Originally Posted by Mike in CT

Thanks for all the detailed photos perelet.

....
No play yet, but just a matter of time with the seal compromised. ...

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Mike, mine were not worn badly - just a bit play, felt only after I removed them. But my car had that CSI with rear steering feel - fancy but felt weird:). Rear had life on it's own and went where it wanted. I guess a bit of play makes for good change in rear toe in/out.

Now after I put car together and aligned (with a correct toe in in front) I can feel what this car was meant to be - quiet and straight going at speed. No more that boat feeling. Honestly I have hard time understanding why people put laud exhaust on e31's. Get yourself 911 for that :lol

Quote:

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Originally Posted by sctttoth

... I was going to add bumpsteer spacers with the lowered front end. How does it drive with the new suspension?

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Scttoth, after putting car together and aligning I measured front camber - 0.7 deg that's even desirable amount of camber. With this amount no need to worry about bumpsteer. Bumpsteer is usually get's in play with hard A arm aka 911, 2 ball joint bmw front geometry does not need it at such small lowering.

Rear suspension has about +- 1deg of camber adjustment, I set it 0.3deg.

Oleg.

i was wondering if you have the pics available for this post? im rite in the middle of doing this exact same DIY'er and i'm looking for all the help i can get.....
thanks!

SO factory rear springs for e31 (no CSi) are stiffer than H&R huh. Nuts.
Maybe I should put my factory ones back in and that may help for the "difference in drop" compared to the H&R springs in the front too.
has anyone here kept factory rear springs and installed aftermarket springs only in front?

I have never seen a front McPherson strut taken apart without a spring compressor. So...you are saying you did it with no spring compressor? Neat! Damn...now just more stuff to take apart and clean......

Quote:

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Originally Posted by rogbmw

I have never seen a front McPherson strut taken apart without a spring compressor. So...you are saying you did it with no spring compressor?

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It is actually the easiest and safest way to get them apart since your face and body are never in range of the tensioned spring. You just slowly lower the strut and the spring decompresses. Once you swing the strut out sideways, you can swap the strut insert/spring and just jack it back up into position. The top mount stays in place.

+1 on the spring removal tip - that is how we do it at SPM.

I just rebuilt my front end too. Control arms, draglink, tie rod ends, steering ends, lower wishbone and new Bilsteins B6 Sports shocks. I had the springs sent in to a local spring works who dropped them by 30mm and stiffend them up. Must say the front end handles so much better after spending time and money on it.

Im now looking at doing the rear, I already put in Bilsteins B6 at the rear as the shocks were collapsed about 2 months back and inserted the strengthening plates on the shock towers that were torn on mine. Didnt have the time to do the full strip down but I am very keen to get started.

Quote:

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Originally Posted by clockwork

SO factory rear springs for e31 (no CSi) are stiffer than H&R huh. Nuts.
Maybe I should put my factory ones back in and that may help for the "difference in drop" compared to the H&R springs in the front too.
has anyone here kept factory rear springs and installed aftermarket springs only in front?

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I suggest you install the BMW Euro M-Sport rear springs BMW p/n: 33 53 1 138 738 with the H&R fronts. The M-Sport rear spring rates are a good match with H&R front spring rate. The stock rear springs are better than the H&R rears but are still too soft to work with the H&R fronts. The issue with H&R in total is they leave very little suspension travel and the suspension is close to riding on the bump stops. Hey who knows what the H&R suspension engineers were smoking when they designed their E-31 spring set? Low slung isn't everything since you still need a suspension!!! So guess what? Eibachs are stiffer but for cornering performance they are hardly any better. The best is BMW Euro M-Sport Springs all around (BMW M Division design) and if you want a great performing suspension you'll also get the M-Sport Dampener that 100% match the springs. Front M-Sport Spring 31 33 1 138 735. BMW M-Sport front strut 31 31 1 139 653/654 and rear dampener 33 52 1 137 474. After that the CSi is an even stiffer spring set however I would only use the BMW CSi dampeners and forget the Bilstein universal dampeners.

I have M-Sport springs all around on my car with Bilstein shocks. Excellent balance of handling, comfort and stance. Check sig bellow.

thanks M6bigdog. I'll have to look into those, for sure!!!
I just happen to have my factory 850i springs sitting around and was thinking of installing them agian, OR even cutting off a coil to make it stiffer/sit more equal with the H&R front springs, but not if it's going to upset the balance of the ride over bumps.
again, thanks for the part numbers.

Great info. I will be doing mine soon.

I have a set of rear springs "allegedly" from a EURO 850, the part number stamped on them is bmw 1138 112 LP 051... They have 10 coils and are a bit shorter than the H&Rs,, does anyone know this part number ??

DMPrentice: 33 53 1 138 112 - Appears to be the rear springs for pre-April 1992 ECE-spec 850i with electronic damper control (EDC).

Hi Folks, I have googled and searched this forum for information on front suspension overhaul or rebuild. Being a relative newbie, if someone could point out the bushings/bearings that most likely need to be checked or replaced from the diagram in post #20 (i.e. #s 2, 23, 15/16 and 7 ??) of this thread that would help. I don't want to spend a bucket load of money for specialized tools either. I do plan on doing the wrenching myself though. Any other links would be helpfull also. Thanks I appreciate everyone's advice here.

Typically, upper and lower control arms, sway bar links, and sway bar bushings. Tie rod ends if they look bad. I would change the control arms vs just the bushings. If you afford it, get Wokke's spherical bearing uppers, if not, Leomforder is the preferred mfg for all of the above

Jeremy, Thanks, man i must be tired, i just realized i was looking at the diagram for the rear suspension... similar advice, i presume applies to the front suspension. Leomforder and Wokke it is then! Thanks! Good stuff here!

thanks for the info... will come in handy

Quote:

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Originally Posted by olinjohnston1

It is actually the easiest and safest way to get them apart since your face and body are never in range of the tensioned spring. You just slowly lower the strut and the spring decompresses. Once you swing the strut out sideways, you can swap the strut insert/spring and just jack it back up into position. The top mount stays in place.

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Very true....I was once removing a spring off a strut on a bench .....the strut was held in a vice at the time. The cheap spring compressors jumped off and the force was unbelievable. It flew across the workshop and hit a big dent in the steel fire door. If that had hit me I doubt I'd be here now. My other lesson was getting under a car using only a scissor jack, I was trying to look at the steering rack on a Delorean of all cars. I couldn't quite get my head in the right place so I got out from under the car .....I only got about half a turn on the jack before it snapped!!! very lucky escape.

Wow Omega. Scary stories

Quote:

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Originally Posted by Omega man 1969

My other lesson was getting under a car using only a scissor jack

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:nono

so I just did the rears. noticed the rear of the car was sagging (2" gap in front suspension, 0.5" gap from tire to wheel's fender) so I cut half of a coil on my factories ad went to install. THEN I realized I have Eibach's and not H&R's after all.
Anyhow, does the car need to be on the ground (suspension loaded up) before I tighten the offset bolt and nut in the rear subframe? I'm guessing so with factory bushings (no Wokke specials installed yet)...

As a general rule:
if a rubber bushing is installed you have to preload = car on the ground (or 4-post lift).
If a spherical bearing is installed like in upper & lower wishbones on the rear axle no preloading is required.
I don't know what offset bolts are but if you mean the eccentric bolts for the rear axle adjustment you can tighten them without preloading.
For a correct job though a four wheel alignement is required once those bolts have been openend.

Quote:

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Originally Posted by wokke

As a general rule:
if a rubber bushing is installed you have to preload = car on the ground (or 4-post lift).
If a spherical bearing is installed like in upper & lower wishbones on the rear axle no preloading is required.
I don't know what offset bolts are but if you mean the eccentric bolts for the rear axle adjustment you can tighten them without preloading.
For a correct job though a four wheel alignement is required once those bolts have been openend.

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thats what I thought Wokke, Rubber needs to be pre-loaded/spherical does not.
and yes I meant the eccentric bolt/washer as shows as part $2 in the diagramAttachment 495036

I will be getting a 4 wheel allignment in a few weeks, as soon as I put new front shock mounts in. I sheared one off when I hit a pothole.
Attachment 495049Attachment 495050

can the rear shocks/struts be removed from the car without having the drop the exhaust (mine is all one welded piece from headers back to mufflers) OR not removing the wishbone?
I don't mind loosening the exaust from the hangers from mid point back, just trying to avoid removing the entire exhaust again... its a huge PITA.
I just got a wheel alignment yesterday and I want to now buy/install the Phoenix motorsport rear shock/strut bump stops but was hoping I could just undo the 2 nuts (in the wishbone) by the rear wheel hub and not undo/loosen the top of the wishbone (in the cross member) and perhaps the wishbone would sag enough (probably would strike the muffler pipes) to allow me to remove the strut/shock to allow for install of the dust cover and bump stops.
Thoughts?

Quote:

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Originally Posted by clockwork

I will be getting a 4 wheel allignment in a few weeks, as soon as I put new front shock mounts in. I sheared one off when I hit a pothole.
<img src="http://forums.bimmerforums.com/forum/attachment.php?attachmentid=495049"/><img src="http://forums.bimmerforums.com/forum/attachment.php?attachmentid=495050"/>

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That must have been one nasty pothole

Larkin, you have NO idea, and I pray no one ever has to. thank god it was a CHEAP/SUPER easy fix.
an excuse to install my front K-Mac sway bar. rear to be installed some other time :)

so I completed my rear end rebuild,

thread link
http://forums.bimmerforums.com/forum...ar-End-rebuild

Great stuff.

Hi There Perelet,

thanks so much for your very good illustration and hard work on this 850 suspension...
I have done ( a friend mechanic ;-) ) the replacement of the shocks Bilsteins, lower springs and strut mounts.
as he is putting everything together, he told me he could not install the bumper stops, because it was not fitting on the new struts...
He completed the installation and I have driven the car for 5k miles or so...
but I have 1 deal of noise on the right side front tire (which looks like is something plastic flapping/hitting the tire when I turn the car to the left)...
I can not see and touch anything that is loose...
and sometime at 40 miles a hour, the car (the steering wheel) starts to shakes like crazy.... but it goes away at 45 and the car is as straight as an arrow....

what you think could be?
bumper stops or wheel bearings
is just nuts...

I see you had the bumper stoppers, but I could not see if you used it.... have you?

Thanks for your advice

The bump stops are internal on the Bilsteins. No need to use the OEM on the top (they shouldn't fit).

Just finished up the front suspension using tips from this thread. I have never "decompressed" the spring on a front strut the way described in this thread. It worked great. While I had everything out, I repainted the struts and detailed everything. The Bilsteins were inserted. For those that want to file away the information, the top strut nut - that big Bilstein nut that screws down onto the strut housing - is torqued to 95lbs using the Bilstein tool. Bilstein also recommends antiseize grease on the threads.

Quote:

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Originally Posted by rogbmw

Just finished up the front suspension using tips from this thread. I have never "decompressed" the spring on a front strut the way described in this thread. It worked great. While I had everything out, I repainted the struts and detailed everything. The Bilsteins were inserted. For those that want to file away the information, the top strut nut - that big Bilstein nut that screws down onto the strut housing - is torqued to 95lbs using the Bilstein tool. Bilstein also recommends antiseize grease on the threads.

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Roger , I think that should be 'thread-lock' blue (not anti-seize). That's what I used as you don't want that puppy coming loose down the road.

Quote:

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Originally Posted by Dr. T

Roger , I think that should be 'thread-lock' blue (not anti-seize). That's what I used as you don't want that puppy coming loose down the road.

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Actually - the recommendations came straight out of the Bilstein instructions (Yes - I know - I am one of those guys who actually reads all that fine print!). In torqueing down that large nut, when torqued to 95ft-lbs it is pretty tight. Tonight when I get home I will see if I kept the instructions and include a copy here. I did use the high strength (red) thread lock on the 3 new bolts on the bottom of the strut housing.

I just finished a front-end rebuild and noticed the bump stops on my shocks were turning to powder. I ordered a new set (31331140140) which are #9 in the attached link.

https://www.realoem.com/bmw/enUS/sho...diagId=31_0455

I'm no expert mechanic, but the new bump stops seem way too long. I see exactly where they seat in the shock shaft, but they are too long at the top and don't leave enough thread on the shaft to accommodate all the components (#3, #8, #1, #5) plus tighten the #6 nut. Are these new bump stops meant to be cut to size? I think I would have to cut 1.5" of the top. Much appreciated.

Sean

Where are all the pix from this post :(. I could use them, doing this in the next couple weeks.

Quote:

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Originally Posted by Sniff38

I just finished a front-end rebuild and noticed the bump stops on my shocks were turning to powder. I ordered a new set (31331140140) which are #9 in the attached link.

https://www.realoem.com/bmw/enUS/sho...diagId=31_0455

I'm no expert mechanic, but the new bump stops seem way too long. I see exactly where they seat in the shock shaft, but they are too long at the top and don't leave enough thread on the shaft to accommodate all the components (#3, #8, #1, #5) plus tighten the #6 nut. Are these new bump stops meant to be cut to size? I think I would have to cut 1.5" of the top. Much appreciated.

Sean

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OK, I figured it out. You do not cut the bump stops down. They are really tight and need a bit of coaxing to slide onto the thicker part of the shock shaft.

This is a question for anyone who did a front end refresh. After you replaced all your components (upper and lower control arms, sway bar links and bushings, tie rod ends, etc.), did you notice your steering was noticeably stiffer afterwards? I haven't been driving my car much lately, so I may have forgotten what it feels like behind the wheel of an E31. However it seems to take a bit more effort to turn the wheel. I definitely have power steering, it just doesn't seem to be as easy as I remember.

Sean

I noticed more response, not stiffer (more power needed to turn steering wheel)

I've been asking around and have been told this is normal since all the ball joints and bushings are new. Makes sense. The ball joints on my old control arms, tie rods, and sway bar links took very little effort to move. The new ones are very tight. Much more resistance for the power steering system to overcome.

Sean

Same here. Anyone know how we get them back?

Quote:

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Originally Posted by rv1890

Same here. Anyone know how we get them back?

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I was told over time the new components would loosen up and the steering would become lighter. I actually like the way my steering feels right now . . . sort of feels like the 997 I once owned. I guess the reason I posted the question is it was such a noticeable change from before. I wasn't at all expecting it so it caught me by surprise.

Sean

Quote:

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Originally Posted by CaifanSC

Where are all the pix from this post :(. I could use them, doing this in the next couple weeks.

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I should clarify my last post. I meant so say I was wondering the same thing. Anyone know if the photos can be retrieved?