Correct, Spec is the brand name. It is a popular aftermarket clutch & pressure plate company. They also do lightweight flywheels and etc. Their stage 2+ kit is FI compatible and is good for roughly 500-600 HP and will allow for quicker shifting. Also, the engagement should be much sharper than the stock unit (a must for me).

They said they would do a lightweight flywheel for us but would need commitment of 10 owners, which is nearly impossible. Naturally, I dropped the pursuit of the LTW flywheel (especially since it doesn't seem to do that much on our cars anyways).

You can get the special lightweight pressure plate option which reduces the pressure plate assembly by about 3-4 lbs around the outer edge supposedly. It costs about $150 more I believe (if memory serves me correct).

I plan on just getting the regular Spec stage 2+ instead of the lightweight option because the lightweight option uses an aluminum backing plate with a steel pressure plate surface where as the regular just uses a solid steel disc all the way through (obviously it can handle more power and I would assume have longer life). Also, the pressure plate is cross drilled (similar to a brake rotor) in order to shave the weight down in addition to the aluminum base plate. Most of the reviews have stated the lightweight pressure plate option does not really do that much and is not nearly as beneficial as a lightweight flywheel. If you are going to go that route, better off just getting the regular pressure plate option and lightweight flywheel.

Either way its about $2200-2400 depending on which stage you want plus $150 for lightweight option (if you chose to go that route). I don't see the point in replacing the clutch with a stock unit if you can get a much nicer/stronger unit for the same price (if not less).

 

I vote for V12 front bumper

 

That's a much better explanation than the one I gave. Thanks for clarifying...I'm still interested in the lightweight flywheel, but really I need to get my traction issues sorted out before I do anything else.

 

I would think that any shop who knew what they were doing could replace the clutch - its not a difficult job. The most awkward part of the job is removal of exhaust manifold required to gain access to be able to remove the torque tube.
After rebuild it is possible to do a clutch kiss point learn and gear position learn without needing bespoke diagnostic equipment - just follow set procedures to initiate self learn..

If the shop is well practiced at Vantage clutch changes the duration is about 6 hours... book time / dealer time is about 8 - 10 hours depends if the BBQ'ing of the friction plate ridged the flywheel - in that case extra time is needed to remove and re-surface, or remove and direct replace flywheel.

So, RRP of clutch kit plus, say, 9 hours tech time should be the basis to calculate the final price...

 

Hi 007.

A couple of points you made caught my eye...

There are over 100 N24 / GT4 owners + me that would disagree that a lightweight flywheel don't seem to do that much.... There is no argument to counteract the fact that the engine will and does spin up faster as a direct result of inertia reduction - and this improvement in rate of change of engine acceleration is noticeable to driver as perceived improvement of performance feel.

Also, be careful to suggest deviating away from std. clutch for sportshift trans applications as the cal for clutch control might not adapt correctly. I was having a conversation with a guy last week who had a 'different' clutch fitted to his sportshift resulting in catastrophic failure....

 

Mike,

I think you are taking my comments out of context. I never said they don't do anything, obviously lightweight flywheel will always help. However, the perceived improvement is not nearly as much as it is on other applications. The problem with lightweight flywheel is it exchanges the sensation of torque for the improve revving feel ... and on our cars, the last thing I want is even less sensation of torque. For that reason I am trying to see what other alternatives there are. The stock flywheels on our cars are not that heavy either (I believe stuart weighed the whole assembly in at 42 lbs, 22lbs for clutch/pressure plate combo, and 20lbs for the flywheel). 20lbs for a stock steel flywheel is actually pretty light by OEM standards (many are in the 30+ range). So even if you go from a 20 lbs to a 13 pound (which is as low as you should go in a car as nice as ours) ... its only a 7 lb difference, where as on other applications the mass reduction can be 15+lbs.

I do agree on your sport shift statements. Never do lightweight flywheel on sequential transmission unless you have the appropriate software update (and even then its usually best not to touch it).

Thanks for the input

 

Hi.

I think its fair to say the standard OE single plate clutch is weak from the amount of owners across many forums complaining of early life failure (<20k miles).
However, the single plate clutch is weak ONLY in specific modes of operation. For example, when on the move thrashing around a race track up and down the gears - no problem - the clutch will last as long as any other.
The problem is when moving off from standstill and an amount of clutch slipping is done. If the clutch is slipped excessively whilst moving backwards and forwards, and especially on inclines, the wear rate will be high - associated by the tell tale clutch BBQ smell.
So, wear rates really depends on the user / conditions, and using RPVantage as an example - 41k miles is pretty good going from a sportscar clutch. And seeing as RPVantage driving style clearly does not drive in a manner to cause premature failure (from slipping) - the obvious conclusion then, IMO, is that a standard clutch replacement is the best option for this user as there is no problem from premature failure from how they operate the car. And only if during a normal service life clutch replacement consider an uprated clutch if the driver wanted better clutch pedal feel - as reported by owners who have upgraded to a twinplate clutch.

However, whilst a manual gearbox driver can drive in a manner to reduce clutch slip and extend service life, the sportshift owner can not - as the TCU will control clutching - and often slips the clutch horrendously..! This application does need a well developed alternative that works with the OE transmission control calibration robustly.

 

So wait, Mike, are you suggesting that it is better to dump the clutch more abruptly at a stoplight (as jarring as that could be) than to gently ease off? I'm sure if I did that, my passengers and onlookers would suspect that I don't know how to drive a stick smoothly.

 

Didn't mean to quote you out of context... As always... my comments are in the interests of a good discussion.

Not that i agree with your comment anyway, but your feeling of torque sensation doesn't matter... The position of the car on the road after accelerating away from standstill is all that matters as it is this performance benefit we are all trying to achieve. And seeing as the torque at the road wheels will not be reduced by lightweight flywheel, and the fact the engine spins up faster on the car with lower flywheel inertia, means it will be this car ahead of the car with the higher engine inertia in terms of road position.
To be blunt but nonetheless respectful - if you don't grasp this concept dont apply for a job at a race team anytime soon...

 

Again ... taken out of context Mike, there appears to be a language barrier ...

Yes its obvious the torque is the same, thats automotive 101 stuff Mike ... however, the sensation of torque is less, at the end of the day nobody wants to feel like their car has less torque than it already does. With that said ... when the cam phase changes you feel it a lot more with a lightweight flywheel than a standard flywheel. Essentially increases the lack of torque sensation off cam, but pronounces the acceleration once the cams finally open up. Trust me I know how bad this can be running 288 race cams w/ 10lb flywheel on an old bmw race car of mine. It felt like the car had a turbo lag on the bottom end but once cams opened up it screamed to redline.

The point I am trying to make is there are always drawbacks to doing the lightweight flywheel (worst of which is gearbox chatter). I feel there are better ways to improve the acceleration without having to make such drastic sacrifices on our high end luxury sports cars.

At this point though its all conjecture as nobody really even produces a standard single disc lightweight flywheel anyways so there is really no point in discussing it. (yes I am fully aware a dual clutch smaller diameter unit has been made but it is a bit aggressive for a street setup).

 

ha ha.... yes - for clutch life it would be better to dump clutch at low revs, you have me thinking now.... the price of clutch replacement versus a course of neck treatments with doc.... probably more cost effective to dump the clutch and wear a neck brace.

Because the clutch is 'weak' in this condition, driving around the problem is quite an art - smoothly take-up of drive in all conditions without slipping clutch too much (engine revs too high for too long), or other end of scale jarring passengers necks. Whereas, you could slip a twinplate clutch to your hearts content and the clutch BBQ whiff will never be smelt.

Best advice is to keep the engine speed as low as possible whilst disengaging clutch as fast as possible but enable smooth take up of motion without jarring passengers necks. Simple? but as everybody will know, whilst this might be quite easy to achieve on straight and level movement, it does require some forethought before attempting moving on inclines (don't roll back and slip clutch to commence moving forward) or quickly (whilst parking for instance or pulling out of junction rapidly). A slight lapse in concentration is quite easy and each time you smell the clutch BBQ whiff means another few microns off the thickness of the friction plate...doohh...

The other problem seen too frequently is damage from drivers keeping their foot rested on clutch pedal - this overheats release bearing and often trashes the flywheel as well as the clutch - an easy fix to cure..!

it is clear from the evidence that some drivers return acceptable clutch wear rates (40k+ in my book), whilst drivers experiencing clutch failure at <20k miles could extend clutch life by driving differently - I wont say they are driving incorrectly..

But that would be for manual cars, for sportshift however - in theory, as a computer controls clutch slip and pullaway- sportshift pullaway / clutch slip should always be perfect?? yeah right...! so any failure <40k IMO would always be hardware related and never the drivers fault, in a sportshift application...

 

Are there vendors in the USA that sell twin-plate clutches? If so, I assume no dealer would install them as they tend to shy away from installing 3rd party stuff (except perhaps exhausts). Prolly have to go to an indie shop, I suppose.

I really don't like the non-linear feel of my stock clutch. It feels like it slips to a very high point in the pedal throw and then grabs suddenly and jarringly in the last 10mm of travel. I've never driven any other V8Vs so I don't know if this is normal for these cars, but it makes it very difficult to make a smooth take-off. Of course, based on your comments, maybe I should not be worrying so much about smoothness if I want long life out of my clutch.

 

conjecture... no - there are ROAD cars out there at that spec reporting no gear chatter = no compromise in luxury car attributes / therefore not aggressive for road use.

Your anecdotal BMW tale is your tale on that application, it does not translate - we are talking very specifically about Aston Martins, and i trust the performance data of lap times of race cars under precise development for the last 6 years either with or without the parts we are discussing here.

lost in translation or plain not understanding your rationale i dont know? but less inertia whilst complying with luxury car attributes = faster car and I really dont comprehend your reluctance to acknowledge this. but hey ho...

 

I never said there were no cars are running 288 race cams ... AGAIN ... taken out of context completely. The 288 race cams have absolutely NOTHING to do with gear chatter. Gear chatter has to do with the flywheel being single mass vs. dual mass, with/without sprung hub clutch and etc. I never said it was slower on the track b/c on the race track you are always in the upper portion of the power band (hence cams have opened up as I mentioned).

HOWEVER, Lightweight flywheels in high end luxury application are always a tough mod to accept due to the unacceptable noise of gear chatter when running a lightweight single mass flywheel. There are ways to minimized the chatter (heavier gear oil, sprung hub clutch, etc etc). Ultimately it is an issue. Furthermore, off cam performance does feel like its not nearly as good as with the heavier flywheel (talking purely feel here). 99% of the vantage owners will never even take their cars to a race track, much less put it against a stop watch so for all intensive purposes any such discussions are a complete waste of time with context to this subject. We don't own GT2s or GT4s or N24s so trying to make such comparisons is apples vs. oranges.

For the street we want improved performance without any sacrifice in refinement, its hard to find a lightweight flywheel that will do that without gear chatter or other downsides, whether it be much harder engagement, more difficulty engaging clutch, etc etc.

"I really dont comprehend your reluctance to acknowledge this. but hey ho..."

 

I think you guys are misunderstanding each other. Mike wasn't talking about the cams when he said "road cars out there at that spec reporting no gear chatter." He meant that there are Vantages out there on the street using lightweight flywheels and not having gear chatter. His reference to your BMW analogy was basically saying that was a different animal altogether, so your experience there doesn't mean that a lightweight flywheel won't work in this situation.

I think what you're saying is that because of the intertia of a heavier flywheel, going to a lightweight flywheel will make it seem like you are not carrying the power as well especially off cam, whereas Mike is saying that the benefit of the lightweight flywheel is faster revving (including off cam) to get you into the power band faster.

I do think that a lightweight flywheel could be done for the 4.3 that adds performance without sacrificing drivability. AM did that themselves when they went to the lightweight flywheel on the 4.7 and I've never heard anyone complain that there is excessive gear chatter on those cars. I've driven one myself and if anything the drivetrain was a bit more refined. It's just a matter of using the right flywheel that will be good for a street car.