Broken Shock Mount

nealf

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Hi: I have noticed a banging which sounds like it is coming from the C-Pillar area in the passenger compartment. Is this something I can diagnose without taking all the elephant skin material iff the rear shock tower? What is the fix for this?
 
Large tin worms maybe? Better to strip the skin out of the way before the shock mount pops through it altogether. Scary thoughts indeed but need to know much more before taking a guess at this one. Is this going over bumps at a certain speed? Noise at top of bump or bottom? Is noise consistent or sporadic? Notice any wheel scuff marks in wheel well? Muffler brackets intact? Can someone follow you and watch wheel movement? Condition of shocks? etc........
 
First of all it could be various components which are moving about

1... Rear subframe bushes just infront of the rear wheels
2... Swinging arm bushes
3... Diff "hanger bush"
4... Shock absorber top and bottom bushes

General....
If possible look under the car with is sat on it's wheels and see if there is evidence of the above noted by fresh scratch marks, rubbed areas, and obviously stuffed bushes! Leaking shocks are pretty obvious.
Please be careful when doing the following, never get under a well supported car!

To check the above.....
1.. Subframe
Place a trolley jack under the subframe and slowly jack the car up. observe the the bush as the load is taken up. lots of movement? Metal hitting metal? Do both sides
2.. Swing arms
Jack up car, pull and push on wheel, any movement in or out? Could be bushes or bearings.
3..Diff "hanger"
Place jack under diff and slowly raise, does the diff go up and the body stay still?
4..Shock absorbers
Look for damaged lower bushes on the swing arms. Support body on suitable stands, take off road wheel and jack up arm, any movement between arm and lower shock bush?
Use a light up the shock towers from below, see if the bushes look ok?
Repeat raising and lowering of arm while observing the top of the shock in the boot (trunk) Remove rubber "teets" if present, Any movement?

What else,
Check the exhaust system is hanging corectly
nothing rolling around in the boot? Once found a golf ball under the spare tyre in a car which caused all sorts of thuds when going round corners!
HTH
Malc
 
This is one of the classic failures on our beloved coupes. Cracks usually develope on the shock tower's top metal surface. This can range from some small cracks on the metal to a protruding shock that has completely broken through the cracked shock tower. Last year, I had a failure of the latter type on one of shock tower. It was repaired by cutting out the cracked metal and welding a new upper perch steel plate. Playing it safe, this procedure was also done to the other tower also. Repair cost was about $400 per side. The repair was done in San Francisco, CA.

It is impossible to get a visual check on the shock towers without taking off the elephant skin vinyls. To avoid possible damage to the vinyls, remove them very carefully. Now you can easily check for any visible damage to the shock tower, you may already see the cracks. If cracks are not clearly visible then push down on the car, if you see any flexing on the shock and if any creaking and groaning noises are evident then most likely your tower is damaged and it will need to be repaired ASAP.

Bert
72 3.5 CSi
88 M6
a0d61c858e154dd6d5eb645e4f9bd8cf.jpg

This was the damaged left shock tower. note the repair is barely noticeable. See the raised welded plate sitting below rubber mount.
cb5e13889f76224ef6d5cae37415d353.jpg

This was the 'insurance policy' repair done to the right shock tower.
 
Bert,

In your picture I see you have two white wires unattached as I do near your rear left shock tower - any idea of their purpose?

I've thought maybe they were for a prior owner's rear shelf speakers but now that I see yours I figure they are not custom but actually factory wires.

I checked my wiring diagram but couldn't find them. Any info from the board is appreciated here....

Thanks
 
rear shock tower fatigue

I do not know how common this is but I have seen it in at least 3 coupes. In one that I knew personally, rust did not seem to play a part. One top broke off in large bent shards. The metal looked clean and not rusty - unlike many other areas of the car.

Car went to welder, who tack welded and massaged the pieces to their original position and then fabricated a cap to secure the whole assembly. Remaining tower had noticeable stress cracks, so they (the cracks) were welded over too.

In two of the above cases, there are strong suspicions that the breakage may have been accelerated by the use of very stiff gas shocks. But then again, it seems the right railroad crossings can bung up a driver's teeth despite the best shocks.

Unofficial census:

Number 2 popular weld: area where rear differential mount attaches to body':?

Number 3 popular weld: emergency/hand/parking brake where it mounts to transmission tunnel. :roll:
 
Tom,

How's it going neighbor? I've never given these two wires much thought, but now you've gotten me curious. As I recalled, the other CS I owned previously also had these two wires, it too terminated at the same proximity near the left shock tower. Does anyone else know what these two wires(one white, and one white-green) are for? Thanks.

Bert
 
Wires - rear fog light?
I have "played" with cars with mystery wires before and they are often for "Extras" that were never fitted. It's cheaper to build thousands of standard harnesses rather than bespoke ones for each market, even if all the circuits are not used.

Funny never seen a problem with the shock towers failing before. My 2002Tii is basically the same and they are fine. The buckets ones are ok to though there is a reinforcing plate factory spot welded on the top. Maybe this was a fix at some point.
However I will look carefully.
Any UK/European folk suffered this problem?

A final thought is that if the shock absorbers are too stiff the "shock" loading on the towers maybe very high leading to failure

Food for thought
Malc
 
broken rear shock towers

For Malc's benefit, my experience with the mounts occurred on a 72-73 csi. That car originally made its home in rust-frei Frankfurt.

I really can't remember that far back, but when first testing the rear shocks it was virtually impossible to get the rear end to deflect. In fact, I think someone dented the boot lid by testing the shocks! Hence the shocks were frozen or very stiff. After we started driving the car, everything loosened up to the point where I first thought we were piloting the Kon Tiki in the North Sea. Despite the well intentioned suggestion that a muffler hanger gave way, it was obvious when the left rear suspension sagged with a full trunk load of miscellaneous parts.

As far as your 02, there is far less weight back there and thus the forces are not likely as great. I have heard a lot about rusty strut towers on 02's but admit I have no idea if some were merely fatigued but unrusted towers. Jaymic may have an answer. but I am sure you know that.

I noticed you were looking for a lsd but not a 6 cyl side loader. Two things come to mind. First, I would focus my attention toward e-21 (320) models. In the states, the 320 sport models featured the same differential, although depending upon year, you might need spacers between the half shafts and the diff. There may have been a Continental version using a different badge. Second, there are a few folks that seem to always have lsd's available, at least in the states. You might look at the 320/e-21/02 boards in your neighborhood or more likely across the channel.

Good hunting.
 
No, I don't think those wires serve that function.

The switch that controls the trunk light is I think brown and its just one wire with a ground to the body.

I guess the mystery is still alive!
 
Oh No !!!

If it is not one thing it's another. Looks like I am going to have to revive this out post since my Coupe now has this same issue. Note: I actually had this repaired at Midas over 9 years ago and now it has finally given way.

http://www.flickr.com/photos/997309...t the end of the link so that it will show...[/url][/img]
 
Green & White Wires

The wires are for the rear deck speaker. The cars came pre-wired for a mono speaker in the rear deck. The wires terminate to a harness at the center console along with a purple for power and brown for ground.

Hope this helps
Terry
 
ummm

failures for 2002 model inner fenders are not uncommon in cars from the USA northeast regions. It's one way I have used to spot "off-island" cars, that show up here in Hawaii.
 
bert35csi said:
-snip- It is impossible to get a visual check on the shock towers without taking off the elephant skin vinyls. To avoid possible damage to the vinyls, remove them very carefully.

and an excellent preventive strategy to avoid the cracking is to place a SMALL space-heater (or hair dryer set on "low") on a fireproof mat in the trunk, close the trunk lid, and allow the plastic to warm thoroughly, this will mitigate (to a small extent) the brittle propensity to cracking. Do not fret too badly about doing this, everything in the trunk can take a fair amount of heat. BUT DO NOT DO THIS IF YOUR GAS TANK LEAKS OR EVEN 'SMELLS' LIKE GAS THE HEATERS WILL BE IGNITION SOURCES AND YOU COULD HAVE A BAD FIRE if that warning concerns you, just use the hairdryer to blow hot air at the elephant skin covers but DO NOT DO THIS IF YOUR GAS TANK LEAKS OR EVEN 'SMELLS' LIKE GAS THE HAIRDRYER WILL BE AN IGNITION SOURCE AND YOU COULD HAVE A BAD FIRE OR EXPLOSION
 
shock noise

I had the same problem with a new set of heavy duty Bilsteins. Turns out that a shock failed. Mechanic (BMW specialist and E9owner) said it was the first time he's seen it. Worth a check since its warranteed.
-Keith
 
Removing Vinyl from rear shock towers question

HI Do I have to take the bolts out for the trunk lid to effectively remove the skin in order to assess the rear tower banging that I have put off to date?

Can anyone tell me how to go about this procedure in steps? It is the pass side tower in question. Thanks.
 
Wheel well covers

If you want to remove the thin plastic covers for the wheel wells from inside the trunk you don't need to remove the trunk lid, if that is your question. I removed the floor boards and the white flexible comb that joins it to the small covers and gently lifted it out. It should lift over the shock mounts easily. I put duct tape on the backside of any cracks that had started.
 
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