Suspension Fault

[James5]

Afternoon peeps,

Just after a little advice really, last week I had a slightl problem with my 5 in that the rear shock absorber on the drivers side decided to snap Now at the time of driving I was doing the speed limits. Anyway I eventually pulled over as the banging from the rear of my 5 was worring.

So I had a look under the car with my torch and couldn't really see much but then this was about 12am in the morning so light was not good. I got the car home and decided to have a look the next day after work and first look I thought I had bent the shock absorber piston rod. Car then chucked on axle stands and wheels off and started to remove the shock absorber for a better look only to find that the piston rod had snapped flush with the top hat eye connection.

I don't see this as general wear and tear, the shocks are in very good condition both in appearance and working condition and haven't really been abused. I see this as a manufacturing fault but I am after peoples opinons on this.

Now I have contacted spax and sent them pictures of the damages. Now the suspension falls outside of its 2 year warrenty but I know that under the sales of goods act 1979 that I really have up to 6 years.

Any advice or suggestions as to the cause? and what to do?
(Let me add that I am going to be raising the rear of the car by about 1" but surely being shorter dampers and being lowered this should have not caused the damage it has the other damper is fine)

[Alex]

That's really quite worrying I take it the car is really really low?


Edit: I think I'll check my rear dampers now! (not that I have Spax)

[James5]

That's really quite worrying I take it the car is really really low?


Edit: I think I'll check my rear dampers now! (not that I have Spax)

The car was bordering Spooky low but still it's not used every day and never really abused.

I have now raised the car 1" @ the rear so it sits a bit higher. about 10mm above the top of the actual alloy (15"). I was going to replace both rear shocks with a pair of standards for now just to keep the car on the road but one of my spare rear shocks was leaking so have only used one and the other side still has the other Spax on All seems good at the mo.

Spax have offered me a discount on new shocks but to be honest I am not sure i want to go back with Spax again. So will be looking into other brands.

[robbie506]

The car was bordering Spooky low but still it's not used every day and never really abused.

I have now raised the car 1" @ the rear so it sits a bit higher. about 10mm above the top of the actual alloy (15"). I was going to replace both rear shocks with a pair of standards for now just to keep the car on the road but one of my spare rear shocks was leaking so have only used one and the other side still has the other Spax on All seems good at the mo.

Spax have offered me a discount on new shocks but to be honest I am not sure i want to go back with Spax again. So will be looking into other brands.

ill have your discount

[Russ B]

Could it be that its so low that the damper is actually bottoming out, so no travel left? When the rear arm moves it applies a longitudinal force to the damper & it compresses & damps. If its bottomed out, then the force would become more lateral as it can't move in any further. Perhaps over time this has stressed the weld & finally failed. Just an idea.

[tiff_lee]

Could it be that its so low that the damper is actually bottoming out, so no travel left? When the rear arm moves it applies a longitudinal force to the damper & it compresses & damps. If its bottomed out, then the force would become more lateral as it can't move in any further. Perhaps over time this has stressed the weld & finally failed. Just an idea.

I mentioned something similar to that in the coilover thread. Having the damper partially compressed all the time due to lowering surely would cause a reduction in the actual damping force?

[Matt Cole]

Could it be that its so low that the damper is actually bottoming out, so no travel left? When the rear arm moves it applies a longitudinal force to the damper & it compresses & damps. If its bottomed out, then the force would become more lateral as it can't move in any further. Perhaps over time this has stressed the weld & finally failed. Just an idea.

Sensible explanation that Russ. Also it depends on the allowable travel within the shockers specification, ie was it used within its designed working tolerance?

Lowered Spooky style i would say not!!

[tiff_lee]

Also it depends on the allowable travel within the shockers specification, ie was it used within its designed working tolerance?

That's it, if the car is lowered say 50 or 60mm how does that reflect on the piston stoke? reduced by a third? a half?

I've been looking at the Gaz GT range of dampers which you can buy in various stroke lengths and was thinking of getting some shorter ones that won't be compressed at all when the car is lowered and no additional weight in the back.

However that said is the fundamental problem more to do with the way the torsion bar moves in relation to where the damper is mounted to the car. I struggle to articulate my point on forums so please see my crude paint special.



What i'm trying to get at is that as the car is lowered the angle of the damper changes (becomes more horizontal) and so less of the damping action is actually pushed directly into the damper? or that could of be tosh just the way I see it.

[RussellT]

My first impression was that this is a very strange failure. its in the drivers side and with driving on the left and going around roundabouts clockwise the nearside rear takes far more loading in general day to day driving.

I would check or have checked your rear beam and mounting trailing arm rear wheel bearing to make sure something wasnt sending a vibration up your trailing arm.

[SCHWARTZ]

i would of thought if it was bottoming out it would bend the mounting bolts before snapping the shaft surley

[Matt@CodeRedMotorsports]

Check the diameter of the damper shaft to the damper bolt diameter.......

[SCHWARTZ]

damper shaft has to be made of something a bit stronger than a standard bolt tho surley. I mean more the direction of impact would be along the shaft but side on to the bolt if that makes sense

[Matt@CodeRedMotorsports]

Now look at which one of those two items has been welded......and where the weld is.

[SCHWARTZ]

is the shaft not one solid piece screwed into the top bit then?

[Matt@CodeRedMotorsports]

Not normally......stick a nut in a big vise...wind a bolt into it....hit the head of the bolt alot....see what happens to the thread of the nut and the bolt......

Now weld the bolt into the nut....hit the head of the bolt.....

Weld a bolt into a hole....and bend it...see what happens then.

[SCHWARTZ]

oh ok then i could see why it snapped there then

[tiff_lee]

Would it be possible to cut a thread on the damper shaft and modify the top part, drill and tap or fabricate something new entirely to mount it?

[Matt@CodeRedMotorsports]

Try it.....

[Scoff]

apologies if it's been mentioned already, but since they're shortened dampers I think it's more likely that you've topped that one out and it's pulled the shaft away from the hat.

[tiff_lee]

Try it.....

I dare say you know something I don't but considering it was effectively now scrap thought might be worth a shot

[Matt@CodeRedMotorsports]

No probs, I'm not being arsey....

[Tony Walker]

Bolts are usually more likely to bend than the hardened steel of the shock absorber. hardened steel snaps and is brittle. Especially as mentioned if there is some sort of vibration.

[RussellT]

Having just bought a pair of these dampers, I might have discovered the reason for this failure.

The top mounting bush is too thin and the damper body fouls the shell. It needs spacing out.

By the way the ends are screwed on not welded.

You had better look at the nearside and have it fettled

[James5]

Having just bought a pair of these dampers, I might have discovered the reason for this failure.

The top mounting bush is too thin and the damper body fouls the shell. It needs spacing out.

By the way the ends are screwed on not welded.

You had better look at the nearside and have it fettled

Cheers Russell, will take a look at the other side yeah I noticed the other day that they are screwed on was considering getting the old bit of shaft removed from the top hat and getting some of the remaining shaft threaded (Defo will have a shorter damper then)

[tiff_lee]

Cheers Russell, will take a look at the other side yeah I noticed the other day that they are screwed on was considering getting the old bit of shaft removed from the top hat and getting some of the remaining shaft threaded (Defo will have a shorter damper then)

I got the impression it wasn't possible to cut a thread on the remaining shaft when I mentioned it above

[James5]

I got the impression it wasn't possible to cut a thread on the remaining shaft when I mentioned it above

Just read the above bits, looks like it's scrap now might keep as a souvenior of what can happen