Strut Tops

[Dommo]

Hi all

I was wondering whether to worry about these strut tops?

I've always been under the impression that the part the strut gaiter mounts on should protrude down from the rest of the strut top by around 10mm, as seen on this picture of my VSX:





However not all strut tops are like this, as can be seen in this photo:



Should I be worried about this strut top? The underbody mounting area looks absolutely perfect, however the strut gaiter mount looks to have gone upward.

In the first picture I had to pull the strut gaiter off, however in the second photo the strut gaiter was hanging off already - does this point at the gaiter mounting being too high?

Thanks!

[Old-Guy]

Short answer, "YES!"

It does look a bit too high, but your not comparing like for like. The significant and worrying thing is that the rim that the boot should grip onto is obviously distorted. Boot refusing to stay in place because the inner cone is distorted is the classic warning sign of imminent strut mount failure. Usually in the UK it's the visible mounting flange under the wheel arch that rots away (what happened to the Green Lady's O/S mount). In your picture it looks as though something else sinister has happened out of shot - perhaps the upper rim of the inner cone has rotted away or the rubber bush is separating from the steel. Don't forget that it's a daft bit of design: the rubber bush is in tension between a pair of steel 'cones' and if either cone rusts seriously or the rubber/steel bond fails then the strut mount comes apart 'spearing' the bonnet and possibly snapping the hydraulic pipe (LHM everywhere).

Have a good look under the bonnet and post a picture or two of what you find. Non-Hydractive S1 strut mounts are NFP, but S2 ones are direct replacements provided you also fit the corresponding S2 boot (the flanges are a different size. Not a difficult or long job, but new mounts aren't cheap (about £170 each ).

[Mandrake]

The centre rubber where the boot attaches being distorted out of round so that the boot falls off easily is indeed an early warning sign of impending failure - but of the rubber block, not necessarily the metal plate.

In NZ and AUS strut tops fail not due to the plate rusting but due to the rubber block perishing from heat and humidity which leads to cracking, distortion and eventual shearing of the rubber block. My otherwise immaculate 8 year old 1997 Xantia (in NZ) had strut tops with significantly worse distortion than that pictured when I first looked at buying it.

On a S1 strut top there is no overlap between the top and bottom cones so a sheared rubber block equals a speared bonnet.

Its unusual to see this failure mode in a UK car where the plate rusting is usually the cause of failure but if the car is kept rust free then its conceivable that it would eventually fail through the rubber block perishing as it does in warmer road salt free countries...

S2 strut tops are considerably more robust in construction and I believe are designed with overlap in the metal cones such that even shearing of the rubber block won't result in the complete collapse of the strut top and thus a speared bonnet. My S1 had a pair of new strut tops fitted which judging by the more robust design and the different concertina boots must have been of S2 design.

[Dommo]

I thought it looked like a different type of failure to the usual rust initiated failure of the mounting surface. I'm glad you said it seems like a typical failure of a rust free car as that's what the second picture is from.

Guy - what makes you say I'm not comparing like with like? Both are s1 vsx's, one with new strut tops one with originals. The reason I ask is because I've seen a few strut tops in scrap yards that look similar with perfect condition mounting surface but the gaiter mount too high for my liking. Which made me wonder whether there were two designs, but it seems not. There's two designs for the metal cones, but the gaiter mount should be the same on both? (Should protrude down from the rest of the strut top underbody?)

Thanks - and apologies that I can't write a larger reply, I'm on my phone at the moment!

[Old-Guy]

Apologies, for some reason I thought the car pictured was a non-hydractive S1, hence my comment. Having caught the the classic failure mode just in time, I am puzzled by your dubious mount.

I've dug out my failed strut mount for another look: the worst rust is actually on the top of the flange, where it's exposed inside the bonnet. The exposed under-surface of the mounting flange under the wing is quite well protected by rubber (as the pictures above show), the protection of the edge tends to be rather variable, but the upper surface that actually sits against the underside of the inner wheel-arch only has a thin coat of paint. I remember being surprised and pleased that the underside of the wheel arch was in perfect condition.

It looks as though (on this one at least) salty water has crept through the joint face and attacked the exposed part of the flange inside the engine bay, on the 'outside' (nearest the bonnet shut line). The worst of the corrosion would have been visible from above if I'd looked for it carefully. I suggest that any visible signs of corrosion should be investigated:

• de-pressurise the hydraulic system fully
  while the front struts are still fully compressed, undo the supply pipe and remove the sphere (otherwise the strut will suck itself full of LHM as it extends)
  support the car and remove road wheel
  DON'T undo the strut retaining nut,
  Wrap the head of the strut mount in lots of paper towel and then in cling film (to keep dirt out of the hydraulics and limit how far LHM spreads)
  undo and remove the 4 securing bolts
  carefully lower the strut top so the the flange can by inspected and photographed through the mounting hole.

I've not tried this, but it's based on my recent experience (and mistakes) when replacing a strut mount.

I don't know about there being two designs for the inner cone - I wouldn't have thought so but with Citroen, who knows? Original S1 boots/gaiters do not fit the later S2-type mounts which are otherwise fully compatible. You can tell the two apart because S1 gaiters have square-shaped 'dimples' around the top (as in the photos above) while on S2-type gaiters these are rounded.