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Jackzi
Silverstone


Joined: 30 Aug 2015
Posts: 122
Location: Sussex


PostPosted: Mon Apr 15, 2019 9:02 am    Post subject: Lightweight flywheel (RPM Technik - CSR) Reply with quote

Hi everyone,

I'm looking at a car that has a lightweight flywheel fitted. It's from RPM Technik and the one they use in their CSR builds.

I've done some basic research about the mechanical side of things and have read that it can cause increased stress on the crankcase. So I'm not sure if it's a good idea if you're not doing a comprehensive engine/gearbox lightening programme.

But here's my question to those who have one/have driven one: does it feel any different?

Is the clutch more sensitive? Is it 'daily driveable' (city traffic, etc.)?

The owner says it makes more noise, but that's all he had to say about it really.

The car is a far way's away from me. So I was hoping to get an impression from the good people on here before I drive it myself.
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MisterCorn
Dijon


Joined: 08 Jan 2011
Posts: 7068
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Mon Apr 15, 2019 9:19 am    Post subject: Reply with quote

Yes it will feel different. Immediately noticeable. The engine revs will rise and fall much more quickly and you will have up to 20% more power at the wheels in first gear.

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Jackzi
Silverstone


Joined: 30 Aug 2015
Posts: 122
Location: Sussex


PostPosted: Mon Apr 15, 2019 9:23 am    Post subject: Reply with quote

That in itself doesn't sound too bad at all.

But I would imagine some driveability will be sacrificed as a result, right?

If the revs fall quickly that would theoretically mean you'd have to give it more revs when driving in first in stop start traffic.
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MisterCorn
Dijon


Joined: 08 Jan 2011
Posts: 7068
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Mon Apr 15, 2019 9:37 am    Post subject: Reply with quote

I run one on my turbo with an upgraded clutch. It takes a bit of getting used to at first but not really a big deal. There is more of a chance of stalling the engine if you are a bit ham-fisted with the clutch. But no downsides as far as I'm concerned. I will be fitting one to the engine for my C4 project.

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FRP
Albert Park


Joined: 30 Apr 2014
Posts: 1637
Location: Middlesex


PostPosted: Mon Apr 15, 2019 12:53 pm    Post subject: Reply with quote

I have a 996 turbo and have fitted along with a custom clutch,,,,,all good !
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Jackzi
Silverstone


Joined: 30 Aug 2015
Posts: 122
Location: Sussex


PostPosted: Mon Apr 15, 2019 2:18 pm    Post subject: Reply with quote

Doesn't sound that bad then.

There are a bunch of naff videos on youtube where people try to show the difference, but they're not very helpful.

The clutch is standard in the car I'm looking at.

I'm not a 'driving God' who heels and toes everywhere and the standard cars I've driven up until now were just fine for driveability.

So I'm only worried it might be a pain.
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MisterCorn
Dijon


Joined: 08 Jan 2011
Posts: 7068
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Mon Apr 15, 2019 2:23 pm    Post subject: Reply with quote

You don't need to be a driving God. In fact it is even easier with a lightweight flywheel as there is less requirement to heel and toe since the engine spins up so much more easily when changing gear.

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Albert Park


Joined: 30 Apr 2014
Posts: 1637
Location: Middlesex


PostPosted: Mon Apr 15, 2019 2:25 pm    Post subject: Reply with quote

I cannot or dont need to heel and toe, just keep the boost on bar and hold on LOL

I really dont think you need to worry about anything
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Paz
Trainee


Joined: 06 Jul 2014
Posts: 99
Location: Leicester

1998 Porsche 996 Carrera 2

PostPosted: Mon Apr 15, 2019 5:09 pm    Post subject: Reply with quote

I've got a lightweight flywheel in my early 996, yes it's a bit noisier but it's not hugely intrusive.
The more immediate throttle response more than compensates for it and I find it easier to modulate the clutch too.

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PGN
Trainee


Joined: 07 Feb 2010
Posts: 61



PostPosted: Wed Apr 17, 2019 9:52 pm    Post subject: Reply with quote

Best mod for driving sensation imho.

First thing I get done on my 911’s
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Spinner
Newbie


Joined: 26 Jan 2019
Posts: 5



PostPosted: Fri Apr 19, 2019 6:17 pm    Post subject: Reply with quote

I drove an RPM CSR last year when hunting for my first 911. It had the LW fly wheel and was absolutely fine both as a daily and in anger. A touch more revs needed pulling away from standstill needed. Gave the impression of a more motorsport engine.
 
  
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996lee
Hockenheim


Joined: 26 Aug 2014
Posts: 706
Location: Nottingham


PostPosted: Tue Apr 23, 2019 3:19 pm    Post subject: Reply with quote

Ive got the RPM LWFW on mine with their sprung clutch
loved it as a modification that much that even after a freak incident of a stuck starter motor damaged the teeth on mine
i went and purchased another

i live in Notts if thats closer to you your welcome to have a listen and passenger ride in mine Thumb
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Jackzi
Silverstone


Joined: 30 Aug 2015
Posts: 122
Location: Sussex


PostPosted: Fri May 03, 2019 6:04 pm    Post subject: Reply with quote

Thanks for the opinions and the offer of a listen Smile

I'll check out the car in question myself in the next few days and report back.

From what I can tell it makes a fair bit of sense on turbos, as the engine doesn't rev as freely as its naturally aspirated cousin.

Best thing about it all though is that it can be replaced for a dual mass if I don't like it, as the car ticks a lot of other boxes for me.
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deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6783
Location: Brighton


PostPosted: Fri May 03, 2019 7:01 pm    Post subject: Reply with quote

Jackzi wrote:
Thanks for the opinions and the offer of a listen Smile

I'll check out the car in question myself in the next few days and report back.

From what I can tell it makes a fair bit of sense on turbos, as the engine doesn't rev as freely as its naturally aspirated cousin.

Best thing about it all though is that it can be replaced for a dual mass if I don't like it, as the car ticks a lot of other boxes for me.



I'm starting to get a little excited here .. a possible purchase on the cards Question
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Jackzi
Silverstone


Joined: 30 Aug 2015
Posts: 122
Location: Sussex


PostPosted: Sat May 04, 2019 12:25 pm    Post subject: Reply with quote

Maybe Very Happy

I'll be in touch mate.
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Jackzi
Silverstone


Joined: 30 Aug 2015
Posts: 122
Location: Sussex


PostPosted: Thu May 09, 2019 7:10 am    Post subject: Reply with quote

I had a go in the car with the flywheel.

The good: didn't make it any more difficult to drive. In fact, the free-spinning nature made it easy to blip the throttle on a downchange (if so inclined) and drive quite smoothly.

The bad: the noise. It sounds awful. Like something is about to rattle itself loose and fall out of the car when it's sitting at idle. It's fine when the clutch is in though.

Question: it's also noisy at times when underway. It's hard to describe the sound but it groans or grumbles when engaging the clutch at low revs (like setting off in second, for example) or when accelerating hard (only for a moment)

Is this normal?
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sp1ke
Trainee


Joined: 07 May 2009
Posts: 54



PostPosted: Thu May 09, 2019 10:34 am    Post subject: Reply with quote

I'm by no means an expert, but I'd wager it's not normal. I recently drove a 996 C2 with a LWFW, clutch & LSD & didn't notice any significant increase in NVH over my own C2 without these drive train mod's.

Perhaps the car you drove needs refreshed transmission &/or engine mounts OR perhaps it has the original powerflex transmission mount inserts which several people have reported added NVH.
Might be worth enquiring about that cars history to see if these were done when the LWFW was fitted.
 
  
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MisterCorn
Dijon


Joined: 08 Jan 2011
Posts: 7068
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Thu May 09, 2019 10:52 am    Post subject: Reply with quote

On my turbo there was definately a bit more chatter at idle until the clutch was pressed. When I changed to RSS engine mounts this largely went away. It certainly shouldn't sound like a bag of spanners.

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Jackzi
Silverstone


Joined: 30 Aug 2015
Posts: 122
Location: Sussex


PostPosted: Thu May 09, 2019 11:07 am    Post subject: Reply with quote

Interesting.

According to the history, the flywheel was fitted as part of a clutch service as a small additional extra by RPM. No mounts were done at the time.

It's really quite a bit noisier at idle than stock. It sounds almost like the chatter from a diesel engine if that makes sense.

Here are a couple of vide examples that came close:

This is a 996 GT3, but sounded pretty similar: https://www.youtube.com/watch?v=aMIZAm9qWKw

And this one's on a Boxster:
https://www.youtube.com/watch?v=vAVb_vPUHaE

It's mostly worrying accelerating from low revs as that's when it makes quite a pronounced sound to start with and then goes away.

It's a tough call this one...
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Martin996RSR
Spa-Francorchamps


Joined: 08 Dec 2016
Posts: 333



PostPosted: Thu May 09, 2019 11:34 am    Post subject: Reply with quote

That boxster sounds like the release fork is loose. Maybe there is something in the way it goes back together that means the clutch assembly is fractionally shorter with a LWFW, meaning the release fork mechanism has slop in it that allows it to rattle. Just a thought.

I don't subscribe to the school of thought that a solid rather than standard flywheel will always be rattlier and it should just be put up with. Plenty of cars out there have a solid flywheel and a sprung centre plate and manage to not rattle. I reckon that the way it goes together has a lot to do with it, and better selected parts may well improve it.
 
  
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