TimH

iTrader: (11)

I've got AST whiteline suspension, arbs and alk (type 20 spec) on my recently purchased MY05 JDM STi (it came with the suspension already fitted, by Litchfield/Powerstation nearly two years ago).

There's a quite loud knocking noise from the nearside rear suspension when you drive over lumps and bumps at low-ish speeds (20-30 mph).

Any ideas what it might be/what I could or should check?

MrRA

This issue has been covered already. Do a search, I'm sure you'll pull something up regarding the issue.

Several people have encountered this problem, each time it is the n/s rear that is playing up. Is this some kind of design fault maybe?

TimH

iTrader: (11)

I did a search *after* I posted - bad form I know, sorry!

Does sound like a design fault, yes. It's interesting that it's the opposite diagonal corner to the driver, and often sorted by having a rear seat passenger or a loaded boot - I wonder if the slight diagonal imbalance of a driver-only car has anything to do with it?

In any evern, folk seem to either to be putting up with it, or finding that a spring swap sorts it - and I'm glad it isn't anything serious.

I'll speak to Litchfield/Powerstation and see what they say out of interest.

911

My one-way AST's with 50/40 and 60/50 springs did not 'clunk' as you describe.
My 3 way AST's with 60/50 springs do it on N/S rear
Some say it is the spring seating
Some say the top mount (one way had stock Sti, and 3 way AST adjustable mount)

My money is the spring seating on the adjustable threaded collar/ring.(or the top collar) The clunck is followed by a real spring 'boiyng' sound (technical term that ) which I think is the spring end re-positioning to the collar on compression.

The suspension works faultlessly.
I am sure PS and Litchfield will sort it.

Graham

Red Man

Hi Tim

I have exactly the same problem. If you take off the rear wheel I found you can move the helper spring from side to side in the top mount and it makes the noise we are hearing (I have 65front/50rear springs).

I have contacted Curtis and he suggests he will probably need to fit a single spring arrangement instead. The noise is anoying but does not seem to affect the handling of the car. Planning to get it looked at in early December when I am down in the Bristol area.

If you get it looked at before then let me know.

Dave

p1doc

bizarrely mine has gone quiet-almost like the spring has settled
martin

Mother Theresa

My drivers side front does the same with the Ohlins, I wonder if cable ties used between the two springs might be enough to stop it. A project for the week-end....

Red Man

MT of SIDC GRIP fame I presume - let me know if it helps. Will be pounding around Cadwell on Saturday - because the best way to ignore the knocking is to stick a hemet on

Dave

p1doc

no noise for me at nurburgring either
martin

Jza

I had the knock noise first time i went over speed bumps - a real "crack" noise even at 5mph.

I was going to go back to Powerstation to get them to look... but bugger me if is hasnt stopped doing it?

Maybe ride it a bit more and see again incase it just needs settling in?

Jza

TimH

iTrader: (11)

I thought it had gone away as it was quiet for a good few days, but it's starting doing it again today

I'm wondering if it is to do with the spring seat, and it depends on how it's sitting as to whether it makes the noise or not, and the way it sits depends on chance. But it's still inexplicable as to why it's only the rear nearside that does it.

All in all it the sound is like a car with poor suspension (which it obviously hasn't) that's hitting the bump stops badly (which I don't think it is!)

pippyrips

touch wood ASTs are pretty much silent

TimH

iTrader: (11)

Do you mean generally, or yours!?

911

It is almost spooky that the coil-overs (some AST/my old AVO's/and some LEDA's) can rattle/bump on the near side rear, not the other corners!

Most make the noise ove a sleeping policeman at 5 to 10 mph.

Many theories, but coil springs do 'twist' on compression/extension which is why the top of the mounts are rotatable to allow this twisting movement.
Does the spring/seat move under these slow speed/high deflection circumstances, and then 'jump' back to a settled (noise free) position?

Graham

mickaldo

I put it down to ast,s being crap!!!

pippyrips

whoops, i meant mine

911

Based on what facts micaldo?

mickaldo

Based on the fact that I had these fitted to my 06 STi and had numerous problems ie. both wing liners were worn out, back down to Power Station from Manchester, harder springs fitted to the front - still bottoming out - then the rear one started to knock! Also, the top adjusters did not click when adjusting.

All this within the space of two weeks, and on the third trip down to Power Station they removed them and put my standard suspension back on.

I have now had Intrax fitted by Simpson Motorsport and the difference is night and day. Also, before they fitted the suspension they checked the geometry and found one side had positive camber, and one had negative camber.

So, my experience of Power Station and AST's is pretty poor.

Have spoken to several New Age owners at track days and they have experienced similar problems with the suspension bottoming out.

Hope this explains my reasons for negativity towards AST's and Power Station.

911

Thanks, always good to get comments!
What spring rates did you have?
One of my AST one-way's had ill-defined clicks, but the 3 ways are good on all 3 adjusters.
Can't imagine it is a New Age only thing?

Graham

XR-Wayne

I was thinking about getting this kit, This Thread has put me right off.
Glad i did a search before hand.

Might keep to Std Impreza Shocks and Springs i think.

Jza

Anyone care to comment on if they got a result on this one? Mine knock like mad over small bumps

911

I have had 2 sets on my Sti V3.

I do get the odd knock on the inside rear over sleeping police men and suchlike.

If they rattle then get the car back to Power Station or whoever fitted them, as something sounds loose?

stockcar

for similiar money but a far more refined set-up then the Exe-TC set-up is second to none......................

alyn

andy97

iTrader: (1)

It wouldnt be such a bad thing if powerstation were to post a comment re knocking on suspension/possible cause/cure. Mine have done this, but I cant afford to change £800+ worth of suspension to another make.

Andy

TimH

iTrader: (11)

There's another thread related to this - here's what Powerstation said to me.

https://www.scoobynet.com/suspension...ml#post6786063

Floyd

iTrader: (9)

Snap, my wing liners wore out and I had bottoming on compressions on the Ring and UK roads. I paid PS for harder springs to try and cure the fault (and re-realignment!) and although better they still rub. This was with OE 16's and tyres. Now I have the NSR knocking.

F

911

It is good that people speak as they find in a factual manner.

As many know, my experiences are not the same, but if a wing liner wears using stock wheels/tyres then that is about Subaru design/clearances?
The geometry is fixed by the dimensions of the suspension, and if the spring was removed altogether as a test, a jack used to move the assembled suspension up/down to maximum and max left/right lock applied, then you would expect the wheel/tyre to miss everything? (with factory geometry)

Change that geometry to where we tend to set it (2 or 3 deg neg camber/5 or 7 castor) and those clearances tend to change, obviously to interference to the wheel well covers.(possibly only on one side too due to manufacturing tolerances)

Now, is this the fault of AST or is it a penalty of changing from stock components/settings?

I bet Subaru would argue the latter if you complained to them.

What alows the suspension to reach the bumpstops?
Weak spring/light damping when a compression change is fast/slow (sleeping policeman hump v dive down Cranner Curves at Donington) or the compression length is too short/the bump stop is in the wrong place/the spring length is too short etc.

If all the above are not engineered correctly (and some of the above are nothing to do with AST) then you could have probs.

As to the NSR knocking? Bit easy to say 'they all do that' but I think I'm close to say that is correct, even Subaru's parts do that.

Before Floyd hits me, I declaire that both my AST suspensions (one way, now 3 way) were supplied FREE to me, aligned for free and have not shown driving fault in 3 years. The car is a road driver with serious hillclimb use.

A hillclimb is nothing more than driving quickly down a B road knowing nothing is coming the other way.
I have learnt that spending real quality time setting up is critical to getting the most out of the chassis mods, and I'm sure that goes for systems other than AST too.

Graham.