Do you have ASTs?
10 March 2007, 11:53 PM
#1
Do you have ASTs?
Can anyone with ASTs help put my mind to rest?
My MY05 JDM STi has AST coilovers, plus whiteline lift/castor kit and 22mm rear ARB (fitted by PowerStation for the previous owner) and I'm concerned by the noise from the rear suspension.
Basically, the rear - particularly the rear left - is noisy over bumps. I'm not talking about the twang you get sometimes - this is more a basic crash/bump noise brought about by potholes, or a ramp taken at speed. It is almost like the suspension is bottoming out, but in circumstances where it really shouldn't.
PowerStation have had a look, and took it out for a drive but - sod's law, as always applies when you report a problem and it frustratingly disappears! - they couldn't get it to misbehave. They've checked there's nothing wrong with the shock, and discussed various theories about the coils binding when severely compressed, or the coil rotating relative to the top mount and it reseating - and assure me there's nothing broken or to worry about -but I'm not 100% convinced that everything is OK.
Basically, its simply noisy when driving over normal roads. The front rides bumps with no undue noise at all, but the rear sounds as if the suspension is cheap (which it isn't, of course). It handles beautifully, and I have no complaints on that front, but it just strikes me that it really shouldn't make that much noise.
Can anyone with ASTs comment on whether their rear suspension makes any crash/bump noises on normal roads?
If relevant, I normally drive with 7 clicks off soft at the front, and 5 at the rear, but I have tried softer settings. It might be my imagination, but it does seem quieter for a few days after any adjustment to the rear shock settings, and then seems to get noisier.
If there's anyone in the Andover/Salisbury area with ASTs, maybe we could meet and compare?
My MY05 JDM STi has AST coilovers, plus whiteline lift/castor kit and 22mm rear ARB (fitted by PowerStation for the previous owner) and I'm concerned by the noise from the rear suspension.
Basically, the rear - particularly the rear left - is noisy over bumps. I'm not talking about the twang you get sometimes - this is more a basic crash/bump noise brought about by potholes, or a ramp taken at speed. It is almost like the suspension is bottoming out, but in circumstances where it really shouldn't.
PowerStation have had a look, and took it out for a drive but - sod's law, as always applies when you report a problem and it frustratingly disappears! - they couldn't get it to misbehave. They've checked there's nothing wrong with the shock, and discussed various theories about the coils binding when severely compressed, or the coil rotating relative to the top mount and it reseating - and assure me there's nothing broken or to worry about -but I'm not 100% convinced that everything is OK.
Basically, its simply noisy when driving over normal roads. The front rides bumps with no undue noise at all, but the rear sounds as if the suspension is cheap (which it isn't, of course). It handles beautifully, and I have no complaints on that front, but it just strikes me that it really shouldn't make that much noise.
Can anyone with ASTs comment on whether their rear suspension makes any crash/bump noises on normal roads?
If relevant, I normally drive with 7 clicks off soft at the front, and 5 at the rear, but I have tried softer settings. It might be my imagination, but it does seem quieter for a few days after any adjustment to the rear shock settings, and then seems to get noisier.
If there's anyone in the Andover/Salisbury area with ASTs, maybe we could meet and compare?
11 March 2007, 08:46 AM
#3
I have had 2 sets of AST's over the last 3 years, the one way adjustables and the 3 ways.
Two very different designs.
With both I have had occationally the twang (which i belive is the NSR spring jumping about on it's spring seat after a sever low speed bump (speed bump for example))
I have heard from the same corner a bump or two in that time.
I race my car seriously and also 3000 gentle road miles too each year.
I take a lot of the suspension apart each winter to grease things and ALWAYS find the front and rear roll bar bushes neary seized solid and when they do move it is with a crack/knock.
I suggest you remove the rear bar and re-grease all the bushes of the bar to the mountings on the chassis legs. You don't even have to jack the car up for this work.
I have tried all kinds of grease but Coppa-Slip seems the best to me, but I will try a silicon based grease next time.
Make sure the area where the bushes go around the bar are smooth. These are bearing points so treat them as such.
Power Station are no shysters, I would not go there if they were, so if it persists go back. Curtis is a perfectionist and knows the system well.
My car drives like a dream, and when you do literally enter a car-park sized '90 left' at 80 mph you rely on Curtis to know his stuff!
Keep at it.
Hope this has helped you.
Two very different designs.
With both I have had occationally the twang (which i belive is the NSR spring jumping about on it's spring seat after a sever low speed bump (speed bump for example))
I have heard from the same corner a bump or two in that time.
I race my car seriously and also 3000 gentle road miles too each year.
I take a lot of the suspension apart each winter to grease things and ALWAYS find the front and rear roll bar bushes neary seized solid and when they do move it is with a crack/knock.
I suggest you remove the rear bar and re-grease all the bushes of the bar to the mountings on the chassis legs. You don't even have to jack the car up for this work.
I have tried all kinds of grease but Coppa-Slip seems the best to me, but I will try a silicon based grease next time.
Make sure the area where the bushes go around the bar are smooth. These are bearing points so treat them as such.
Power Station are no shysters, I would not go there if they were, so if it persists go back. Curtis is a perfectionist and knows the system well.
My car drives like a dream, and when you do literally enter a car-park sized '90 left' at 80 mph you rely on Curtis to know his stuff!
Keep at it.
Hope this has helped you.
Last edited by 911; 11 March 2007 at 08:49 AM.
11 March 2007, 07:09 PM
#6
I have had 2 sets of AST's over the last 3 years, the one way adjustables and the 3 ways.
Two very different designs.
With both I have had occationally the twang (which i belive is the NSR spring jumping about on it's spring seat after a sever low speed bump (speed bump for example))
I have heard from the same corner a bump or two in that time.
I race my car seriously and also 3000 gentle road miles too each year.
I take a lot of the suspension apart each winter to grease things and ALWAYS find the front and rear roll bar bushes neary seized solid and when they do move it is with a crack/knock.
I suggest you remove the rear bar and re-grease all the bushes of the bar to the mountings on the chassis legs. You don't even have to jack the car up for this work.
I have tried all kinds of grease but Coppa-Slip seems the best to me, but I will try a silicon based grease next time.
Make sure the area where the bushes go around the bar are smooth. These are bearing points so treat them as such.
Two very different designs.
With both I have had occationally the twang (which i belive is the NSR spring jumping about on it's spring seat after a sever low speed bump (speed bump for example))
I have heard from the same corner a bump or two in that time.
I race my car seriously and also 3000 gentle road miles too each year.
I take a lot of the suspension apart each winter to grease things and ALWAYS find the front and rear roll bar bushes neary seized solid and when they do move it is with a crack/knock.
I suggest you remove the rear bar and re-grease all the bushes of the bar to the mountings on the chassis legs. You don't even have to jack the car up for this work.
I have tried all kinds of grease but Coppa-Slip seems the best to me, but I will try a silicon based grease next time.
Make sure the area where the bushes go around the bar are smooth. These are bearing points so treat them as such.
My post was to try and ascertain if, simply, I should not be so fussy - if all ASTs make crash/bump noises and it was a well accepted compromise then I would happily have ignored the noise, since it appears to make no difference to the handling - or enjoyment - of the car.
But now I know differently, so I'll keep on trying to get to the bottom of it. Powerstation are a 2 hour drive away, so it is not that easy to simply pop in and show them the fault.
It has, Graham, very much indeed: thanks!
11 March 2007, 07:12 PM
#7
I don't think so - but if there's an easy way to tell, let me know!
Last time I had a wheel off and had a look, from memory I'm sure there's just a simple small diameter coil spring over the shock, with a top and adjustable bottom seat, and that's all.
They are the 12 click types, fitted about 2 years ago, if that helps.
Last time I had a wheel off and had a look, from memory I'm sure there's just a simple small diameter coil spring over the shock, with a top and adjustable bottom seat, and that's all.
They are the 12 click types, fitted about 2 years ago, if that helps.
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12 March 2007, 08:20 AM
#8
I would be surprised if the system did not have helper springs.
The purpose of the helper is to keep the main road spring compressed slightly with the wheel in the air, ie at full droop.
This ensures the spring does not come out of it's seat(s).
The spring is a coiled flat section spring, designed to fully compress 'coil-bound' when the car sits on the ground.
There is theory that it is the jump between the two springs that can produce twang/creek noises.
Silicon spray can work well applied to the spring interfaces.
Should also be noted that a coil spring twists/rotates during compression to some degree so ensure the spring top mounts are free to rotate.
Graham.
The purpose of the helper is to keep the main road spring compressed slightly with the wheel in the air, ie at full droop.
This ensures the spring does not come out of it's seat(s).
The spring is a coiled flat section spring, designed to fully compress 'coil-bound' when the car sits on the ground.
There is theory that it is the jump between the two springs that can produce twang/creek noises.
Silicon spray can work well applied to the spring interfaces.
Should also be noted that a coil spring twists/rotates during compression to some degree so ensure the spring top mounts are free to rotate.
Graham.
12 March 2007, 06:22 PM
#9
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I have AST suspension on a MY04 STi with the ARB and antilift kit supplied and fitted by Powerstation.
Fantastic piece of kit no doubt, but yes, it doesn't like the sudden impact on potholes, the sound is like breaking a bone.
Kind of 'gut wrenching', but i've learnt to avoid potholes and i crawl over bumps.
Hope that puts your mind @ rest. Unfortunately I'm not a techie, so i cannot apply my explanation in a more technical manner.
Fantastic piece of kit no doubt, but yes, it doesn't like the sudden impact on potholes, the sound is like breaking a bone.
Kind of 'gut wrenching', but i've learnt to avoid potholes and i crawl over bumps.
Hope that puts your mind @ rest. Unfortunately I'm not a techie, so i cannot apply my explanation in a more technical manner.
Last edited by AllenJ; 12 March 2007 at 08:33 PM.
12 March 2007, 07:04 PM
#10
So, I'm not alone ;-)
Yes - it is gut wrenching!
On the approach to my office, there is a private road (really, it is!), with a straight flat section a few hundred yards long, that then starts to rise for a short while before a nice tight left hand bend. The rise is a bit like a ramp, and not anything you give any thought to at normal speeds.
You can easily hit this ramp at 70, and I have done so at quiet times in all the cars I've ever owned with no ill effect...except in the STi with AST. If you do the same, you get an almighty great bang that, first time, made me go "oh f*ck, what have I broken...". But actually there was no damage. Obviously I trat it with more caution now.
Same goes for potholes - a bang from the rear left if you hit it at a "normal" speed, albeit faster than the speed you might have hit it if you'd spotted ir - if you see what I mean.
Even on normal roads, the rear (usually left) is quite noisy.
I am beginning to conclude that a number of factors are at play here:
- the spring coils hitting each other when severerly compressed, such as the ramp or pothole situation. PowerStation offered this theory, and it holds water. They say that they now use conical springs, that will avoid this issue.
- binding ARB as per 911/Graham's theory. Unproven, but I bought a tube of copper grease at lunchtime and will try this when I get a chance.
- the "twang" caused if/when the spring unseats itself.
- a change in shock absorber behaviour when you adjust it. Can't explain this one, but a tweak from 7 to 5 off soft, for example, quietens the whole lot down for a few days. Bizarre.
Anyway, thanks for the replies - I'll let you know if I find anything more out.
Yes - it is gut wrenching!
On the approach to my office, there is a private road (really, it is!), with a straight flat section a few hundred yards long, that then starts to rise for a short while before a nice tight left hand bend. The rise is a bit like a ramp, and not anything you give any thought to at normal speeds.
You can easily hit this ramp at 70, and I have done so at quiet times in all the cars I've ever owned with no ill effect...except in the STi with AST. If you do the same, you get an almighty great bang that, first time, made me go "oh f*ck, what have I broken...". But actually there was no damage. Obviously I trat it with more caution now.
Same goes for potholes - a bang from the rear left if you hit it at a "normal" speed, albeit faster than the speed you might have hit it if you'd spotted ir - if you see what I mean.
Even on normal roads, the rear (usually left) is quite noisy.
I am beginning to conclude that a number of factors are at play here:
- the spring coils hitting each other when severerly compressed, such as the ramp or pothole situation. PowerStation offered this theory, and it holds water. They say that they now use conical springs, that will avoid this issue.
- binding ARB as per 911/Graham's theory. Unproven, but I bought a tube of copper grease at lunchtime and will try this when I get a chance.
- the "twang" caused if/when the spring unseats itself.
- a change in shock absorber behaviour when you adjust it. Can't explain this one, but a tweak from 7 to 5 off soft, for example, quietens the whole lot down for a few days. Bizarre.
Anyway, thanks for the replies - I'll let you know if I find anything more out.
12 March 2007, 07:21 PM
#11
believe it or not I got thumping when hot on a normal struts and springs... it turned out to be a wheel bearing gone... funny thing is it didn't whine it just clunked when hot on extreme bumps... it eventually took the ABS sensor top off as it was that bad 
so it MAY not be the coilovers... other things to consider are ARB bushes or drop links....
so it MAY not be the coilovers... other things to consider are ARB bushes or drop links....
12 March 2007, 08:35 PM
#12
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believe it or not I got thumping when hot on a normal struts and springs... it turned out to be a wheel bearing gone... funny thing is it didn't whine it just clunked when hot on extreme bumps... it eventually took the ABS sensor top off as it was that bad so it MAY not be the coilovers... other things to consider are ARB bushes or drop links....
so it MAY not be the coilovers... other things to consider are ARB bushes or drop links....In my case it's definately the coilovers.
Out of interest, will upgrading the droplinks make a difference ?
12 March 2007, 09:04 PM
#13
I have the 3 ways.
As these are coilovers with relatively stiff springs (60/50's) I never expected them to be quiet. My car is stripped out, but to be honest I dont have other noises than I did prior to the struts being fitted.... apart from an occasional knocking noise. This was apparantly down to wet weather and a spray of silicon soon sorted it out.
As these are coilovers with relatively stiff springs (60/50's) I never expected them to be quiet. My car is stripped out, but to be honest I dont have other noises than I did prior to the struts being fitted.... apart from an occasional knocking noise. This was apparantly down to wet weather and a spray of silicon soon sorted it out.
12 March 2007, 09:21 PM
#14
I have the 3 ways.
As these are coilovers with relatively stiff springs (60/50's) I never expected them to be quiet. My car is stripped out, but to be honest I dont have other noises than I did prior to the struts being fitted.... apart from an occasional knocking noise.
As these are coilovers with relatively stiff springs (60/50's) I never expected them to be quiet. My car is stripped out, but to be honest I dont have other noises than I did prior to the struts being fitted.... apart from an occasional knocking noise.
Silicone, I presume (sorry to be pedantic)? Graham mentioned this too - can you give me an example of a suitable spray that I could buy and try? I'm open to any suggestions to pin down or fix the cause!
Last edited by TimH; 12 March 2007 at 11:45 PM.
12 March 2007, 10:46 PM
#15
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I have had the AST for nearly one year after my original dampers started knocking/leaking. As the car was a Jap import Subaru UK avoided the warranty issue and I figured at the time for a few hundred more I could get my whole suspension renewed/upgraded. I was also not convinced new standard dampers would not also eventually cause problems.
I must admit the car rides smoother on the AST(7front 5rear), still a bit harsh at times, however better than standard and also feels very good on fast cornering.
I must admit the car rides smoother on the AST(7front 5rear), still a bit harsh at times, however better than standard and also feels very good on fast cornering.
Last edited by JK JDMSTi; 09 August 2007 at 11:30 PM.
13 March 2007, 08:18 AM
#16
Just a theory but it is always the rear NS cornier that causes issues.
The working parts of AST's are the 'same' just the spacing of the damping washer stack and a few valves etc and I wonder is the crack is to do with that, but why just that corner.
Some of us (Shaun and I at least) have the AST top mounts on the suspension which eases a lot of binding on the strut, so the NSR corner issue is a mystery!
Mine behave exactly as Shauns, have done for years, road and race conditions and all is well.
Performance is always a compromise.
Graham
The working parts of AST's are the 'same' just the spacing of the damping washer stack and a few valves etc and I wonder is the crack is to do with that, but why just that corner.
Some of us (Shaun and I at least) have the AST top mounts on the suspension which eases a lot of binding on the strut, so the NSR corner issue is a mystery!
Mine behave exactly as Shauns, have done for years, road and race conditions and all is well.
Performance is always a compromise.
Graham
13 March 2007, 11:23 AM
#18
Absolutely and as Graham says above. Apart from the odd "dry" knock which was cured by using silicone spray, these competition 3 way struts have been brilliant, but as Graham says we are both using the AST top mounts as well.
Tim,
To be fair, you really need to get back to PowerStation and take them for a good drive again. If it doesnt happen when they are in the car, it's very hard for them to diagnose as I presume you appreciate.
Tim,
To be fair, you really need to get back to PowerStation and take them for a good drive again. If it doesnt happen when they are in the car, it's very hard for them to diagnose as I presume you appreciate.
13 March 2007, 01:15 PM
#19
Since it is a 2 hour drive up there, I wanted to make sure that I wasn't being unrealistic in my expectations of the ASTs before making the trek.The consensus seems to be that they *probably* shouldn't be noisy in the way I have described, so I will try and get back up there soon. In the mean time, I'll try the copper grease and silicone spray too - I might as well, since its easy to do.
Any suggestions of a suitable silicone spray?
13 March 2007, 01:50 PM
#20
I think you will find some in Halfords, BUT, now you have the Coppa slip take the rear off the chassis, clean everything and put back using stacks of the grease. It should exude out of the bush copiously when done tight.
While it is off the chassis make sure the drop links are free too.
When you go to Power Station get them to drive the car to Prescott Hillclimb as those roads will make it clonk driven slowly (a route very well known to me and my Sti)
While it is off the chassis make sure the drop links are free too.
When you go to Power Station get them to drive the car to Prescott Hillclimb as those roads will make it clonk driven slowly (a route very well known to me and my Sti)
13 March 2007, 04:04 PM
#21
I think you will find some in Halfords, BUT, now you have the Coppa slip take the rear off the chassis, clean everything and put back using stacks of the grease. It should exude out of the bush copiously when done tight.
While it is off the chassis make sure the drop links are free too.
When you go to Power Station get them to drive the car to Prescott Hillclimb as those roads will make it clonk driven slowly (a route very well known to me and my Sti)
While it is off the chassis make sure the drop links are free too.
When you go to Power Station get them to drive the car to Prescott Hillclimb as those roads will make it clonk driven slowly (a route very well known to me and my Sti)
13 March 2007, 04:36 PM
#23
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I've got the 10 way adjustable sportline AST's on my MY02 STI.
Rear left twangs from time to time, and if I over over a massive pothole I get the bang noise from the rear left too.
Be good to catch up with you again Tim
Rear left twangs from time to time, and if I over over a massive pothole I get the bang noise from the rear left too.
Be good to catch up with you again Tim
13 March 2007, 04:46 PM
#24
Hi Mark!
Twanging I can cope with but having a bang worries me
It would be good to meet up again, Mark - I'll try and come to a Hants meet soon - perhaps we could see who's best at knocking
Are you going to the Castle Coombe track day in April? I'm hoping to make it, so I can practice all that training from Ben Elliott - *I* think I'm worth it
Twanging I can cope with but having a bang worries me
It would be good to meet up again, Mark - I'll try and come to a Hants meet soon - perhaps we could see who's best at knocking
Are you going to the Castle Coombe track day in April? I'm hoping to make it, so I can practice all that training from Ben Elliott - *I* think I'm worth it
13 March 2007, 06:03 PM
#25
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i get twang and bang from rear left as well,had local dealer look at it , they reckoned the spring was bouncing slightly going over bumps funny how it is rear left all the time.
was at ring last year and fellow ast driver said powerstation were going to fit differently rated springs to fix fault?!
martin
was at ring last year and fellow ast driver said powerstation were going to fit differently rated springs to fix fault?!
martin
13 March 2007, 06:59 PM
#26
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On mine the AST Sportline II's were noisy and clunked much of the time. Twangs and boings from the springs too and an odd 'two-stage' feeling on larger compressions. Big bangs from the bumpstops now and then, just not enough strut travel.
AST Sportline I's and the new spring design fixed that - no bumps and clunks and even over a big pothole the 'bang' is relatively subdued, more of a 'thud'. The springs are now 7 Kg/mm front and 5 rear on a Forester STi.
The ride now is a kind of 'smooth stiffness' (ooh-er !), while the older combo (with softer springs) excelled at jiggling. Paradoxically the stiffer springs have made it a better ride.
From the description of the noise with a ramp I'm wondering if this is due to hitting the bumpstops due to either too low a height or too soft a spring, there would certainly be compression at the start of the ramp. The spring details are normally visible on the side of the coils.
What is the effect from speedbumps taken very slowly/slowly/reasonable speed ?
AST Sportline I's and the new spring design fixed that - no bumps and clunks and even over a big pothole the 'bang' is relatively subdued, more of a 'thud'. The springs are now 7 Kg/mm front and 5 rear on a Forester STi.
The ride now is a kind of 'smooth stiffness' (ooh-er !), while the older combo (with softer springs) excelled at jiggling. Paradoxically the stiffer springs have made it a better ride.
From the description of the noise with a ramp I'm wondering if this is due to hitting the bumpstops due to either too low a height or too soft a spring, there would certainly be compression at the start of the ramp. The spring details are normally visible on the side of the coils.
What is the effect from speedbumps taken very slowly/slowly/reasonable speed ?
14 March 2007, 10:10 AM
#28
On mine the AST Sportline II's were noisy and clunked much of the time. Twangs and boings from the springs too and an odd 'two-stage' feeling on larger compressions. Big bangs from the bumpstops now and then, just not enough strut travel.
AST Sportline I's and the new spring design fixed that - no bumps and clunks and even over a big pothole the 'bang' is relatively subdued, more of a 'thud'. The springs are now 7 Kg/mm front and 5 rear on a Forester STi.
The ride now is a kind of 'smooth stiffness' (ooh-er !), while the older combo (with softer springs) excelled at jiggling. Paradoxically the stiffer springs have made it a better ride.
AST Sportline I's and the new spring design fixed that - no bumps and clunks and even over a big pothole the 'bang' is relatively subdued, more of a 'thud'. The springs are now 7 Kg/mm front and 5 rear on a Forester STi.
The ride now is a kind of 'smooth stiffness' (ooh-er !), while the older combo (with softer springs) excelled at jiggling. Paradoxically the stiffer springs have made it a better ride.
From the description of the noise with a ramp I'm wondering if this is due to hitting the bumpstops due to either too low a height or too soft a spring, there would certainly be compression at the start of the ramp. The spring details are normally visible on the side of the coils.
I will take a look at the spring rates and report back - but I probably won't get a chance for 10 days or so due to very hectic weekend coming up, and no garage to look at things in the evening.
Slowly - still OK, but you sometimes get some noise from the rear. Often it sounds like the wheel jack is loose in the rear arch cavity and it is jumping around (no, there's nothing loose in there, I've checked).
Reasonable speed (e.g. taking a bump in a 30mph limit at 25-30mph, which is what they're designed for) - I now don't do it as it is noisy - not a bang, but certainly crashy and unpleasant...some of the time, and that's the annoying thing as it is not consistent.
15 March 2007, 11:24 PM
#29
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I've got AST's also and mine makes a bump kind of noise too from the rear passenger side. Seems like it's a bit of a common thing.
I was also having a creak coming from the front at slow speed but some grease on the ARB sorted it
I was also having a creak coming from the front at slow speed but some grease on the ARB sorted it
17 March 2007, 05:46 PM
#30
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Its not a problem to live with but when you pay approx £1500 for a suspension you expect perfection. Great guys at Powerstation and dont want to be seen saying anything untoward regarding them but just want to add that I have the same problem on my 2001 classic !!!!!