They are a terrible design. Always going to hold water & mud in the well and rust through.

 

IMO this is probably made substantially worse by the dirt which accumulates on top of the spring seat. This dirt gets wet and promotes rust, largely because it takes quite a while for the wetted dirt to dry out. This takes a long time because the dirt is not exposed to significant airflow, but is trapped in a space / void created by the pressed metal spring seat and by the rubber diaphragm which sits above the seat and beneath the spring coil.

The problem is that the lower 'spring seat rubber' isn't only a separating rubber membrane (located between the coil and seat), as it should be but for some reason isn't. It is also formed as a 'sheet' extending inward so that it is in effect a thin rubber diaphragm which creates a nearly enclosed void above the pressed metal spring seat. This void is not fully sealed so dirt and water can enter it via the drain hole (in the metal spring seat), and a small gap where the diaphragm sits around the outer damper tube.

The void is a space in which over time dirt collects, and when water also enters 'mud' is formed. Since the void is not well ventilated (only by the small drain hole - probably partially blocked - and the gap between the 'diaphragm' and damper body), the wetted accumulated entrapped dirt will remain wet for substantially long periods of time, particularly in rainier / cooler / more humid weather conditions. The trapped moisture will breed rust and so the spring seat will rot, and the longer the accumulated dirt remains wet the worse this will be. Salted roads wouldn't help...

The mud is more likely to dry out more readily and more often if the void is well ventilated. The best way to ventilate the void is simply to eliminate it, by cutting the 'diaphragm' away until only that part of the rubber sheet which sits directly between the coil and the seat remains.

Admittedly, dirt and general debris will now more readily collect in the 'well' at the base of the spring seat, but once wetted will tend to remain wet for a shorter time because there is now a great deal of airflow around the dirt sitting on top of the spring seat. Also, if the rubber diaphragm is cut away it becomes possible to hose out collected dirt / debris / salt(?) from the spring seat, which is impossible if the diaphragm is not so 'circumcised'.

The "diaphragm" is shown in this diagram:

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marked as part #1

Having written this, I have to admit that this is only speculation based on what I see in secondhand reports and photographs. I have never seen rotted spring seats, I assume because compared to much of Europe the Oz climate is not so wet, not so cold, not so humid(?), and the roads are never salted...

Regards,
John.

 

Definitely, although the new Monroe units have a bigger drain hole than the originals.

 

How old were they?

 

Well, I'm guessing they're the originals. So I can't exactly complain.

 

Not bad then for 11 years, changed mine a couple of months ago after the last MOT which advised that the rear coils were rusted so I thought so would the dampers. They were originals and most recommendations are to change them every 5 years.

This is one of mine.

 

Well they are cheap enough. Paid £56 each, delivered, shame the dust covers are always extra, as they never perish, ha ha .

 

Where did you get your shocks from? I had one go on my partner's last weekend.

 

Look nice when new, shame you don't see them....

 

They do indeed

 

After a preventative suggestion by Pud_238, I put spring compressors on and checked the condition of mine after lifting the rubbers. They were fine, with no rust, perhaps because - for one reason or another - my late '08 has had hardly any winter use since 2015, and no salt exposure. So I removed the (dried-out) silt and filled the wells to overflowing with Bilthamber S-50 wax, leaving the drain holes plugged until it'd dried. Any water than now gets in there can't puddle and will go straight out of the drain holes. Fingers crossed...

 

Just ended up doing the exact same exercise. Missus out, one collapsed. So lucky that neither one of us were driving at any kind of speed. Even managed to avoid having to replace the tyre!

 

And did you have any issues getting the old ones off?

 

Same problem - one of my rears collapsed recently (I was going at walking speed at the time). 21 years old !! Both rears replaced by the excellent Phil at Alfacraft.

 

In my experience, this seems to be more common on later cars and may be indicative of a change to inferior components. My 1997 156 was about sixteen years old when it died, but I never had this problem. Similarly, my 2003 147, sold last year, never had this. Conversely, my 2005 GT needed both replaced last year and those in my son's 2005 156 went when it was about 11 years old.