Front Suspension Rebuild.

OK, this is not a "How to" post but rather a "How I" rebuild the front suspension of an E31, in this case, an 840Ci.

The owner had noticed that the handling and steering were not up to scratch so as the car had recently had a full KDS alignment at a BMW Main Dealer, it was decided to replace the OEM dampers with Bilstein Sports, the springs with an Eibach Pro-Kit and fit both front camberplates and rear strut reinforcing plates.

The first thing we did was replace the BROKEN REAR COIL SPRING, which had clearly been broken for an extended period shown by the corrosion build-up on the fractured section of the spring, and both the SPLIT REAR STRUT TOP MOUNTS with new ones as we replaced the rear shockabsorbers, fitted the strengthening rear top plates and installed the rear Eibach springs.



Next, we started on the front.

First job was to remove both front suspension legs, leaving sensors and drop-links installed but removing the discs to reduce the weight.




Next job was to compress the spring to strip down the suspension leg. The strut was carefully inserted in the compressor......



and the spring compressed to relieve any load on the top mount........



We then undid the top mount nut and removed the top washer to release the..................



SEIZED TOP MOUNT!! (Remember this has just had a KDS)



No amount of WD40 or oil would free the bearing up so the mount had to be replaced. The front spring and OEM bump stop were then removed and discarded.



Next, the strut assembly was securely held in a vice for shockabsorber removal.



Now, this is the collar that needs unscrewing, this one from one strut......



And this from the other LEAKING STRUT! (KDS?????). Good luck to anyone who thinks they will unscrew these.



SO, we dont try. We run a slot along the collar to split it with a die grinder....



Which loosens it sufficiently to unscrew it with some pipe grips...........



With the collar removed, the original insert can be slowly removed as it contains a fair amount of oil.



The damper insert can be drained and the strut housing also needs to be tipped upside down to empty the oil from it.



The rusty strut body thread can now be cleaned up.........



and the new Bilstein insert...........inserted.



The new Bilstein collar started and tightened by hand...........



Then fully tightened.



That essentially is the shockabsorber part of the strut done.

Next we start on the camberplates. Firstly, as the top mounts are not able to be dismantled, the 3 mounting studs need to be cut off as close to the surface as possible........





With the remainder of the stud being punched-out...............



To leave this................



So that the new camberplate can be loosely fitted..............



Permanent threadlock applied to the retaining nuts..................



and the fiddly job of fitting the nuts to the countersunk bolts.......



Tightening them immediately before the threadlock dries.



We can now continue assembling the strut assembly, starting with the new Bilstein gaiter and original washer, (NO BUMP STOP IS FITTED, IT IS INTERNAL ON A BILSTEIN INSERT)...........



followed by the Eibach spring..............



and the new top strut bearing assembly complete with camberplate attached, ensuring the spring seats correctly in the rubber seat of the top mount.........



(Note: the shorter Eibach springs do not require compressing to refit the top mount)

Fit the new (supplied with camberplates) smaller washer and top nut, torque to spec and all is done ready to re-install in the vehicle.



We then proceeded with the other side, freeing off the other SEIZED top mount. This car was therefore twisting the springs when steering rather than the struts rotating on the top mounts. Surprisingly not breaking the front coil springs.

We would normally do a KDS after this work but as it was recently done, and the technicians obviously used plasticene spanners so as not to mark the rust on the adjustment bolts.....


we just reset the front alignment.

8Tech.

Zitat von NickF;71183

Can you just replace the springs? They seem to be £225ish vs £800 for the shocks. What do the pricey shocks give you over stock? Or is it just a case that 20 year old dampers are probably knackered?

Yes, you can just replace the springs and this will lower the car slightly and improve handling through a combination of matched springs, higher spring rates and a lowered center of gravity.

The shockabsorbers control the motion of the suspension by reducing the "bounce" given by the springs. They will damp out unwanted motion and keep the wheels in contact with the road better. Dampers of even 10 years old will almost certainly be worn, but what is far worse is UNEVEN wear, where one side of the car is damped differently from the other and causes all sorts of instability issues. I have recently done one with 1 worn rear damper and one that had leaked all the oil out, (MOT!!!), having no damping effect at all, and was causing the car to try and steer from the rear. Rear mounts were split also. Additionally bear in mind that OEM front struts are £800+ EACH, so 4 for £800 is not too bad.

Another seen recently was shown in the original post with a broken spring, 2 split top rear mounts, and seized front strut bearings that had a current MOT and had been to a main dealer for a thorough suspension check and set-up. Must have been Stevie Wonder doing it!

Camberplates alter the tyre/road contact angle whilst cornering and increase grip over standard by increasing contact area during cornering, therefore vastly reducing understeer, (the tendancy for the car to plough straight on in a corner). They also increase steering feel and sensitivity to make the car feel nimbler in the corners and steering more precise. They even IMPROVE tyre wear!

Rear reinforcing plates are recommended for all E31's but especially cars with new rear dampers to stop the metal fatigue failure as seen here. Also shown is a result of a bodged repair, that then had to be repaired properly at a cost of £600 per side. Reinforcing plates are £30 a PAIR and take 10 mins to install.

Zitat von Lloyd;71186

Nick as mine is with Gerry at the moment I will hopefully be able to feedback tomorrow once the new springs (BMW CSI) and Bilstein on all four corners link arms and steering link arms.Together with a wheel alignment I then plan to get the tracking redone just to be sure. This should made the car spot on.

Leave it a good 100 miles or so before you re-track as we have already done it accurately Lloyd, and don't lift the wheels off the ground before you track it again or it will all need to settle again. Set tracking between parallel and 15' Toe-In.

8Tech.