UKKid35

Can anyone tell me why the bushing has become deformed, so that the shock body is actually touching the front wing of the "butterfly". It's happened on both sides of the car.

I've taken the Koni off the car and replaced it with a Bilstein, I'm concerned that the same will happen again. The other Koni gets replaced tomorrow after work (if I'm not too lazy).

Thanks in advance.

Ketchmi

It looks to me like the shock body has moved on the bushing, the gap at the rear has increased. Worn out bushings that have become detached from the shock body and/or sleeve can cause this.

UKKid35

Yes they have moved on the bushings, but why? The shocks are nealy new, only been on the car for 20k miles and about 18 months.

jpitman2

Its failed in two planes - the shock eye has moved laterally on the bush to contact the support, but also it has failed radially, and will (to me eye) allow the eye of the shock to move vertcially and pound on the support. I would watch what happens when you jack the bottom ball joint upwards and take the load off the shock.
Sounds like it has suffered some heavy pounding on corrugations, or the bushes are not up to the task at all.
jp 83 Euro S AT 49k

UKKid35

I think you're right JP, I'll take another pic of the bushing now the shock is off the car.

AO

I find it hard to believe that this would deform to this extent as the bushing would have had to disintegrate - because they can't flow, but anything is possible. I would suspect that the wrong shock was installed with a too-large a bushing - but manufacturing defects do happen. So if you are sure it was the correct size when you (I assume you did it yourself) installed them, then it must be a defect from the factory - otherwise I would say you got the wrong one or a mis labeled shock.

UKKid35

Thanks Andrew, it is the correct model shock, I checked the part number with Koni before I fitted them. Everything fitted snuggly, there was no sense that they weren't quite right, and the bushing is the same size as that on the Boge I removed and the Bilstein I've just put on.

drnick

maybe boge are just inferior? did it affect your driveability?

UKKid35

Hi Nick

The bushes on the ancient Boges I took off last year are just fine, it's the bushes on the 18 month old Konis that are a mess. My concern is that I may have changed the suspension geometry somehow so that the bolt securing the bottom of the shock is no longer perpendicular to the shock body. I can't see how this could have happened, but why else would the bush deform in this way?

drnick

hmmm dunno.... suppose its a good thing youve got new bilsteins !!

jpitman2

I think if you look at the mounting bracket, its asymmetric - one side (front in this pic above) has a stiffening wrinkle in it, that is not present on the rear side, and the vertical plates are offset wrt the bolt heads. Something in the back of my brain is saying something about this.....My 83 had alloy ball joints when I got it, and I replaced them with steels and new brackets (different bolt lengths), and the brackets had to go on a particular way - they are handed. Is it possible the brackets were pulled when the Konis went on (to replace bottom ball joints?), and went back on the wrong sides? If you swung the plate around 180, the vertical plates would move forward, I believe. I will check mine when I get home for where the wrinkles are, front or rear side. Being an 87 it should never have needed a ball joint upgrade as such.
jp 83 Euro S AT 49k

ErnestSw

Are you certain you put the correct shocks on front and back? The front shocks have the mounting "eye" square with the shock, the rears have the "eye" offset at an angle to the shock body.

jpitman2

I doubt the bolt would align with the bracket if you tried to fit a rear in the front, and it would be pretty obvious when you tried to align the top if you did get the bottom fitted.....having done both ends of mine.
jp 83 Euro S AT 49k

Garth S

Porsche assure that it is difficult to make a mistake ... but not impossible.
The lower front shock mount ears are one p/n for both left and right lower control arms, so no mistakes here, even though they are asymmetric: also, if they are installed backwards, the shock will never enter the upper A-arm, nor allow the spindle to fit.
The front shock spring perch sits ~8.5" up from the lower eye center vs ~4" for the rear measured from its 'off angle' eye .... leaving an impossibility in setting suspension heights if a switch were made. Also, the front lower eye/mounting bolt is a mere 12mm vs the 22mm hole required for that monster rear pin that ties the rear suspension together.
Having noted that, I don't have an answer either ....

EDIT: ... speaking of mistakes, namely mine ... JP is correct .. the brackets are specific to left/right! ( I have 3 of them in a bag for an upgrade proj on the '80 .... guess which 2 were pulled out for a 'look see' ... I'll check my shoes before leaving the house, just in case I'm wearing two rights ....). Something didn't seem quite right, so checked the brackets again
Having said that, Paul's pic looks like the right front control arm ... with the correct bracket in the correct position..... so the problem remains ...

ErnestSw

Details, details, details. A truly talented screw-up could do it!