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Discussion Starter #1
Faced with the prospect of installing a new clutch to cope with the 311bhp my 9000 Aero is pumping out, I’ve been thinking about the options.

The Sachs pressure plate seems to be the preferred option for Swedish tuners, but it costs a whopping £491 from Speedparts. The route BillJ has gone down is an Abbott drive plate at £295, which, I understand holds up perfectly well. A third option is an AP Racing competition drive plate (part no. CP2583-24) which, at just £200 including delivery from Demon Tweeks, is a bit of a bargain.

Does anyone know anything about the AP drive plate? Has anyone got one fitted? Any other comments on the options are very welcome!

Thanks,

Alanb
 

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Alan,

There is only one AP plate- basically you pay a premium to Abbott cos they keep them on the shelf whereas the lead time from other AP distributors is circa 6-8 weeks. It depends on how long you can wait... if Tweeks have one in stock, you're lucky.

List price from most AP dealers is around £160 plus VAT.

Mark

Forgot to say- I've got it fitted too. The AP clutch is lighter in operation than the standard but does suffer from judder on take up, which gets worse in stop start traffic . Many tuners do not recommend it for day to day use, and certainly if you do a lot of driving in congestion it could be wearing.

As your torque output isn't massivley over standard (and it's torque that cause the slip, not hp) I suppose your other option is to clean up the flywheel fully, and use a standard plate but stiffen the pressure up slightly. I know that the pressure fingers can weaken over time and it may well be that it's a lack of pressure causing your slipping
 

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Discussion Starter #3
Cheers Mark,
Well, I've just gone and ordered the plate for £145+vat from Tech-Craft. I was told 2-3 weeks delivery. Not bad eh? I only hope this finally fixes the clutch slipping woes.

Alanb
 

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Discussion Starter #4
PS Re-reading your post I didn't realise the Abbott clutch = the AP racing clutch. 80% mark-up ain't bad!

Alanb
 

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Discussion Starter #6
Mark,

Although the torque isn't up by that much (314 lbs) it's the way that it comes in very sharply with the Dawes Device which is the real problem. I'm actually getting a bit tired of the all boost/no boost operation of the DD but it gives such instant acceleration when I need it that I don't want to go back to the more gradual boost rise of the Speedparts ECU just yet

Alanb
 

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You guys may want to check out the comparison I did of the AP, Swedish Dynamics Kevlar, and OEM clutch plates on my web site under engine. I decided not to go with the AP plate, while clearly being the best made of the three. The reason being that I was also going with the Sachs Sport pressure plate and did not want a digital clutch, two modes only - on / off. I first tried the Swedish Dynamics plate and could not get that thing to work at all. The plate was slightly thicker that the standard plate and thus it would not release from the pressure plate. So, in went with the OEM plate which has worked well with this combination. Given that I am pushing around 425 lb/ft of torque at the flywheel, the clutch is doing its job. However, with all this swaping about, I did get it so that I could remove and install the transmission in about 2 hours.

There seems to be the two schools of thought on this: higher rated pressure plate with stock friction plate or stock pressure plate with higher rated friction plate. My though was that there would be less shock to the transmission going with my set-up because it would still allow some slip before the clutch would engage (mostly dependant upon how you release the clutch) and it seems to be the approach used by the Swedish tuners. However, you have to keep in mind that the tuners also have the benefit of the tools and knowledge to be able to frequently rebuild their transmissions. So, in the end, I am not really sure which approach will prove the best.

Cheers
 

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I've got the four puck copper disc for Saabine and I must say clutch engagement/disengagement is pretty smooth - similar to what I had with the both the stock and the AP Racing relined disc (although the lining on that looks about the same as stock). More positive, but by no means on/off. An uprated pressure plate with the given OE hydraulics will mean higher pedal efforts - could be a good or bad thing depending how the OE set up is in this respect on your particular car.

Another thing that springs to mind is that I've always learned that from a driving/technical point of view there are only two proper positions for a clutch - engaged and disengaged - and that any transitional phase between them should be kept as short as possible. Thinking that through - I'd tend to say the shock loads would only occur if you were back on the throttle before the clutch is fully engaged again - or am I talking utter b*ll*cks now (wouldn't be the first time)?
 

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Originally posted by Eric van Spelde:
[qb]or am I talking utter b*ll*cks now (wouldn't be the first time)? [/qb][/b]
Nope, Eric, I'm with you on this one (what's that about fools seldom differ? )

The only time I find any difficulty with the AP is on take up in to first gear or if I get the revs seriously wrong on a higher gearchange in which case it just goes with a bit of a thud.

In particular, when I'm really caning it, I make sure that I don't put the power on before the clutch is fully engageed.

The downside of all of this of course is a reduced 0-60 time because to get the best sprint on a 9000 IMO requires you to slip the clutch in first gear to avoid useless wheelspin
.
 

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You guys and your British made stuff (Eric aside, who probably deep down wants to swim the channel away). Just kidding!

One thing that we just briefly started to touch on was application. If the car is intended for track days mainly, then an application like the AP would probably be the best. However, it appears that neither of you are advocating an AP plate AND a higher rated pressure plate. I think this would be a bit over the top.

If the car is intended to daily driving, some slip might be preferred with frequent stops and starts. This comes down to a matter of choice and preferred feel as long as the clutch is holding the horse power, it really does not matter. As to the comment about additional clutch pressure, I have not noticed additional pressure or a "stiff" clutch, but I have noticed that the engagement point has shifted slightly to where it disengages at the end of the pedal throw.

Hasta la vista baby
 

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Originally posted by KevinY:
[qb]If the car is intended to daily driving, some slip might be preferred with frequent stops and starts.[/qb][/b]
Well, I do use my Aero for daily driving, but I suppose it depends on the type of driving. I find the AP clutch a bit tiresome in traffic but then I find traffic tiresome anyway, so I try to avoid it. If I lived in a big city, I would probably have gone for the standard plate and stronger pressure-plate. I would have been wary of the extra pedal pressure required, and I'm surprised to hear that this isn't apparent in your experience. Hmm...
 

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Originally posted by Mark E:
[qb]The only time I find any difficulty with the AP is on take up in to first gear or if I get the revs seriously wrong on a higher gearchange in which case it just goes with a bit of a thud.[/qb][/b]
I find that if I inadvertently get on the power a bit too early, I can make the clutch "honk" which I suppose must be simply high-speed judder since it doesn't like to slip. I'm still adjusting to it and it "honks" a lot less frequently now than when I firsat had it fitted.
 

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Is a clutch "honk" similar to a shudder? As to the Swedish Dynamics disc, a recent post on TSN noted that they were having issues with clutch slip at higher HP using a standard pressure plate.
 

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And roughly how much HP and torque can the stock 9-3 tranny take? I've got the original clutch plate, pressure plate, and gearbox but I'm now running ~260 hp and around 280 torque (estimate). I've got no problems now, I think, but soon I'll be increasing the power to around 280, at which point should I be concerned?
 
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