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nickdav80
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Joined: 28 Apr 2012
Posts: 59



PostPosted: Wed Oct 30, 2013 9:32 pm    Post subject: Reply with quote

I got front B6 PASM shocks from Rose Passion in France for £250 each. Depending on the age of your car budget on replacing top mounts as well - mine were both rusted solid to the struts. Indeed this problem may prevent a refurb of the original shocks. Incidentally when I enquired I was told Bilstein can't refurb front B4 PASMs so beware you don't end up really testing the goodwil of your garage!

Nick
 
  
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clarkey979
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Joined: 10 Aug 2011
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PostPosted: Wed Oct 30, 2013 9:50 pm    Post subject: Reply with quote

nickdav80 wrote:
I got front B6 PASM shocks from Rose Passion in France for £250 each. Depending on the age of your car budget on replacing top mounts as well - mine were both rusted solid to the struts. Indeed this problem may prevent a refurb of the original shocks. Incidentally when I enquired I was told Bilstein can't refurb front B4 PASMs so beware you don't end up really testing the goodwil of your garage!

Nick


That's very helpful info, thank-you. B4 fronts,,are they the PASMs fitted to the 997? It's the fronts I need to do. Car is a 55 reg, so I guess top mounts are worth doing as well.

I have just prepared myself for a week of cycling to work, mines a daily driver, but I figure if its saving £800 it's worth the trek.
 
  
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nickdav80
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PostPosted: Thu Oct 31, 2013 6:57 am    Post subject: Reply with quote

B4 PASMs are standard fit, B6 PASMs are the same length but uprated and B8 PASMs are uprated and shorter for lowered cars. At risk of shrieks of disgust from purists I'll confirm there's no problem with B6s on front and B4s on the back. I only chose B6s as they are cheaper on the front and would gladly have saved more money if I could.

Best of luck with the fix and please update the forum when it's done so others can see what's involved.

Nick
 
  
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clarkey979
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Joined: 10 Aug 2011
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PostPosted: Thu Nov 21, 2013 8:15 pm    Post subject: Reply with quote

nickdav80 wrote:
I got front B6 PASM shocks from Rose Passion in France for £250 each. Depending on the age of your car budget on replacing top mounts as well - mine were both rusted solid to the struts. Indeed this problem may prevent a refurb of the original shocks. Incidentally when I enquired I was told Bilstein can't refurb front B4 PASMs so beware you don't end up really testing the goodwil of your garage!

Nick


Just to update, thanks Nick, yes confirmed the B4s can't be rebuilt. I bit the bullet and stuck with oe shocks, also had to do bump stops, top mounts and drop links all in its just over £1,600 from an Indy.
 
  
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MaxA
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Joined: 11 Oct 2015
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Location: Helsinki


PostPosted: Mon Aug 12, 2019 7:28 am    Post subject: Reply with quote

As it turns out that was a helpful revival of a dead thread.

I have a slight clonk in the right hand side front suspension, and as much as I hope it might be a drop link bush (I've done about 63,000km on a 2010 car), it might well be time for a set of Bilstein B8 PASM front dampers... at least I now know what I'm looking for.
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NLW73
Barcelona


Joined: 27 May 2014
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Location: Yateley


PostPosted: Mon Aug 12, 2019 8:10 am    Post subject: Reply with quote

these dampers give up at anytime and there are no real warning signs nor is it related to mileage or usage.

mine just gave up one day and I noticed a load of oil and grease on the inside of the front wheels. PASM failure and no warning. they were 13 years old so done pretty well.

they can go at 30k or 60k or 90k.

I went for OEM replacements as its a daily road car.
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Robert SausageTrousers
Monza


Joined: 02 Apr 2018
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PostPosted: Mon Aug 12, 2019 8:38 am    Post subject: Reply with quote

How much were the OEM replacements, if you don't mind me asking?
 
  
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The return of Marty Wild
Kyalami


Joined: 04 Nov 2016
Posts: 1776



PostPosted: Mon Aug 12, 2019 8:51 am    Post subject: Reply with quote

clarkey979 wrote:
then quite eary/unnerving when cornering as you dont have PASM adjusting all the time. I really dont like it, cant wait to get fixed up!


I should say that’s psychological, the OEM PASM doesn’t adjust on the fly. Just literally gives you two damper rates. Unless you have an aftermarket controller. You are riding around in the harder setting which I can imagine isn’t fun, but you’ve not lost any other functionality other than a softer damper setup.
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The return of Marty Wild
Kyalami


Joined: 04 Nov 2016
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PostPosted: Mon Aug 12, 2019 8:52 am    Post subject: Reply with quote

Just seen the dates Laughing
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deMort
Dijon


Joined: 21 Mar 2015
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PostPosted: Mon Aug 12, 2019 6:30 pm    Post subject: Reply with quote

Some info as it's not just hard or soft i feel but a predetermined map based on road conditions and which setting is selected ..

We could do with a report button .. these Norton / Mcafee .. virus links i expect are starting to get annoying .
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Kyalami


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PostPosted: Mon Aug 12, 2019 6:39 pm    Post subject: Reply with quote

So as far back as the 9x7 era, the PASM was doing more than just two damper stiffnesses?
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deMort
Dijon


Joined: 21 Mar 2015
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PostPosted: Mon Aug 12, 2019 6:44 pm    Post subject: Reply with quote

I've always assumed as its an active system that they adapt to various road condition .. it's not something i really need to know in depth so haven't investigated it ....

i had a brief read of this file and it mentions a map based on conditions along with various other things it alters for ..

To me that would indicate it continually alters and is not a set soft or hard .
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Hertsdriver
Spa-Francorchamps


Joined: 12 Nov 2018
Posts: 262
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2004 Porsche 997 Carrera 2

PostPosted: Mon Aug 12, 2019 7:12 pm    Post subject: Reply with quote

I doubt they could have got away with calling it ‘active’ if it were just running off of a set map.
 
  
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jonttt
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Joined: 20 Aug 2012
Posts: 5966
Location: Liverpool


PostPosted: Mon Aug 12, 2019 7:28 pm    Post subject: Reply with quote

My understanding:

Oem PASM Controller = active adjustments but same for all 4 corners

DSC PASM controller = active adjustments to individual wheels and its programmable with provided PC software

I've been playing with the DSC software and it's great fun. The only real thing you have to be careful with is not to set a range past softest setting or you can overheat them
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deMort
Dijon


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PostPosted: Mon Aug 12, 2019 7:53 pm    Post subject: Reply with quote

As below .. i'm afraid i don't know this system inside out so just post what Porsche have said ..

My guess is the aftermarket unit and the Porsche unit just have different maps Dont know
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99pFlake
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Joined: 24 Jun 2018
Posts: 48



PostPosted: Mon Aug 12, 2019 8:20 pm    Post subject: Reply with quote

PASM is a semi-active suspension setup as it allows variation of the damping characteristics in response to the vehicle's dynamic changes.

Fully active systems can adjust both the damping and the spring rate of the vehicle. Off the top of my head, the only fully active suspension setups available today are Mercedes' Active Body Control and the setup on the Audi A8 (the former uses hydraulic pistons to effectively move the suspension top mount while the latter uses electric actuators that apply a force to the lower suspension knuckle at each corner).

In the case of PASM on the 997, there's a solenoid in each strut that varies the bypass around the main damper valve. I'm not sure if it's continuously variable or whether it just permits a firm and a soft damper setting.
 
  
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jonttt
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Joined: 20 Aug 2012
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Location: Liverpool


PostPosted: Mon Aug 12, 2019 8:27 pm    Post subject: Reply with quote

Thumb looks as though the oem does have individual wheel adjustments then using a predefined input maps

They must use different inputs as well as maps, at least in pre 9x7.2 cars, as you have to fit an accelerometer for the dsc (already fitted to .2 cars)
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99pFlake
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PostPosted: Tue Aug 13, 2019 9:12 am    Post subject: Reply with quote

A little update - it looks like PASM in the 997 is continuously variable (as opposed to some other systems which allow switching between a set number of damper settings).
 
  
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jonttt
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PostPosted: Tue Aug 13, 2019 12:41 pm    Post subject: Reply with quote



These are the variables used for the aftermarket DSC PASM unit, programmable by PC software......

In simple terms it works from the main table "Shock Calibration" which you set 2 maps for eg Normal / Sport. This sets a "min" and "max" damper setting for each wheel with a gradient between eg what setting at 10%, 50%, 80% etc......

You then use the other tables to alter how those "inputs" relate to the "shock Calibration" table eg G force, if you going around a fast right hander and the G force is X how should each damper be set left front 50% = look up 50% on the "shock calibration" table........ it gets complicated when you the factor in the other inputs eg braking..... but in practice it seems the main thing to tinker with is the main "shock calibration" table and rely on the default factors already set of for the variables, probably unless you are fine tuning for track when you can record the results and compare etc......

So with the DSC you can "see" how the dampers will work and the variable factors, with the OEM its a sealed box you can't tinker with. Most seem to think the OEM "normal" is too soft and "sport" too harsh. The DSC makes the "sport" more useable on the road but I think "normal" is now too harsh (for a 987) and so thats why I'm playing around with it. THe beauty is the way the "shock calibration" table works means that you don't need to have an even gradiant between the softest and hardest setting and so you can setup a sporty mode which is more compliant at lower variables and changes more as the variables get more extreme ie best of both worlds. I think that is probably the main difference with OEM ie can offer a more compliant ride until its really needed and then it can automatically offer a more sporty ride within the same map.
Great fun playing around with it (any excuse for a fast road run lol)

My car has 64k on the clock, has a clean OPC bill of health and the suspension seams spot on. Its good to know from this thread that you can buy a full replacement system which is slightly improved for reasonable money when / if needed...

The one thing I have not really had chance to research is how the PASM damper control actually works physically. What I have established is you have to be careful in what you set as the "softest" damper setting ie it is 1500mA ie if you set 2000mA there is a risk the damper can overheat. It therefore assumed that the damper was therefore controlled by passing an electric current through some form of magnetic damper fluid, that current influencing the viscosity and thefore the damping ability of the fluid ie infinitely variable between its "softest" and "firmest" viscosity ?????? a post above implies is via a mechanical mechanism ??????

Every day is a school day and I'm getting as much out of learning about PASM as I am from driving the car Grin
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99pFlake
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PostPosted: Tue Aug 13, 2019 3:01 pm    Post subject: Reply with quote

On continuously variable dampers there's usually a solenoid that varies the size of the flow restriction on the valve at the bottom of the damper piston. The overheating is caused by the solenoid being switched too quickly.

What you're describing is closer to the magneto-rheological dampers that Delphi originally offered - they have an electromagnet that surrounds the oil passages in the piston valve and have a ferrofluid instead of conventional oil. Applying a magnetic field causes the fluid to become more viscous and thereby restricts flow.
 
  
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