Fractured lower rear shock mount

flaviaman

Daily Driver
A beautiful afternoon and I decided to take the 100GBC for a drive in the Oregon coast range. About 45 miles into the drive the LH rear shock mount on the control arm gave way, has anyone seen this before? First time in the 8 years this car has given me grief while driving.

Short term plan is to weld a thick fender washer in place and replace the damaged shock. I will keep my eyes open for a control arm for the long term....I wish Koni would do a run of 850 shockers.....I have read that besides being expensive Spax units are far too stiff. The car has KYB’s and I wonder if that is what caused the issue (not enough travel).

76 miles round trip in 1’46”. Needless after the shock issue I motored home with discretion.
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obligatory pictures.....
 

Jeff Stich

True Classic
I've never had that happen on any of my 850's, but I have seen it a few times on parts cars I've bought or on junkyard 850's. Always wondered what had occurred to have that happen...

Btw, the 850 Spax shocks are adjustable (via a valve that you can adjust using a screwdriver, not like the Koni where you have to remove the shock from the car, adjust it, then reinstall). I had an 850 Sedan long ago with Spax set to medium, firm but didn't seem too harsh.
 

Dr.Jeff

True Classic
I'm not familiar with 850 suspensions, but I have seen the same failure on other vehicles with really stiff shocks on them. However that looks like the "non-gas" style KYB - i.e. the double wall low pressure vs mono tube high pressure. Those are not stiff or harsh and I would not expect them to cause a mount failure on any car. Perhaps some other "stiff" shocks were installed in the past (prior to your ownership) that started a stress fracture? Or a frozen/seized shock might do that. Was the KYB still working?

Koni makes adjustable shocks with various types of adjustment mechanisms, including some with the little "screw" that do not require them to be removed. So I assume they don't offer that style in a size that fits the 850?

I've had Spax shocks on a few vehicles; some were adjustable and others were not. For the most part I liked them. However sometimes they were prone to premature seal failures. But otherwise they gave a good balance between ride quality and handling, with or without the adjustment feature. They used to be a lot less expensive then Koni or Bilstein, but I haven't priced any in ages.
 

kmead

Glutton for punishment
Bummer, odd fracture. Stupid question, does the shock travel through its full stroke?

The wear pattern (the shiny area underneath) doesn’t extend around into the fracture area. Definitely an odd failure, there must have been an existing crack on the vertical section as it doesn’t show it bending around the vertical section.

Something to look for on mine.

Nice car and thank you for the obligatory pictures.

What are the three screws inline showing on the rear quarter behind the wheel but above the bumper?
 

Loren Field

Daily Driver
That looks like a drag. What KBYs do you have installed that make you suspect that there could be a problem with travel?

There is a place in Switzerland that stocks new ones (price listed is per set):

Also Matt at Midwest Bayless stocks used ones:

Let us know how it goes. Best, Loren
 
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