Gents,
Please take a look at my posts on MLOC and SELOC reference my failed (terminally) Gaz suspension as fitted to my S1 Exige.
I hope the links work:
http://forums.seloc.org/viewthread.php?tid=403317
It might be worth breaking out a torch and mirror to check out your suspension…
Cheers,
Kurt
gnarly
Close proximity of aluminium & steel, especially in an area like this that can get wet (rain, road salt, etc.), will give rise to corrosion.
Although the oxide layer on aluminium is reasonably protective, both crevice and galvanic corrosion can (will…) occur as in this case. The overall mechanism of the corrosion is complex, but basically:
Rusting - steel parts
Crevice corrosion - aluminium - occurs in narrow gaps, where water can creep in
Galvanic corrosion - steel & aluminium - dissimilar metals & an electrolyte (rainwater with road salt is excellent for this…)
Here both the steel and aluminium have corroded indivudually - the white deposits are aluminium oxide, the rust is obvious - as well as galvanic corrosion occurring between the two. Not only have both metals corroded but the increasing amount of corrosion products has expanded and cause stress cracks in the outer material (aluminium in this case), which itself has already been weakened by the corrosion processes.
At the very least I would have expected to see the steel inserts painted with something like Duralac before fitting; better, still, to have avoided having the two metals together in the first place.
Does Stainless Steel react with Ally in the same way???
mmmm quality!
Yes Sean.
This is exactly why any aluminium part used should be hard anodised and not just made to look pretty with a colour … of course the base material needs to be suitable -
Look at any safety critical part, like for example a brake bell, and think what would happen if similar corrosion happened.
The greeny, bronzy finish may not look bling but its sure will resist corrosion for longer.
are the inserts steel?
Chemically there isn’t any difference between anodising & hard anodising. Both use the same process, just that the conditions for hard anodising are different (colder temperature and higher acid strength) which give a harder coating, usually for better wear characteristics than anything else.
As Elise111S says, the combination of stainless steel and aluminium will also give rise to corrosion. The only real difference in this case is that the stainless itself probably wouldn’t have rusted (although it is prone to crevice corrosion with chloride ions present, eg. from road salt).
Muu - the MLOC photos show the insert to have a steel outer that is in direct contact with the aluminium eye.
Love this Chemistry stuff
Kind of wish it wasn’t at the expense of your dampers though
This is why I have a loathing of road salt!
As well as its ability to cause all sorts of corrosion, I’ve never been convinced that it does much to improve road safety either (a bit like scameras, then…). It’s always seemed to me that the gritty stuff liberally scattered all over the roads just makes a greasy slurry (salt + water + grit + oil + rubber + etc.) that has very poor grip.
Now, as it melts the snow/ice, the concentration of the salt goes down, so it has a decreasing ability to prevent freezing; this means the will be a critical point - eg. early evening in winter - where the temperature drops below the freezing point of the salt solution, rendering it useless.
Also salt is hydroscopic (ie. it absorbs water) so throwing it all over a dry road will actually attract moisture and make the surface damp. Taken in conjunction with the details above, why do we put up with it?
I agree. It’s good on chips and stuff though!
Yea and in butter
Me too! I’m utterly damperless! That’ll make undoing the rear hub nuts challenging as I progress my refresh…
I’m considering options for replacements, but I’m on a budget, that said, it won’t be GAZ.
Kurt