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Which Single mass flywheel with which clutch?

996lee

Well-known member
Joined
26 Aug 2014
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748
Hi guys
My clutch is on its way out so thought I'd take the opportunity to get a bit more performance out of the old girl so planning to put a single mass fly in and possibly an updated clutch if that's recommended over a standard clutch?

So which clutch and flywheel combo works best for a fast road set up?
As always your advice is much appreciated

So far from reading aasco seems to be the result that keeps coming up and cheapest I've found it was 693 at the porsche shop
 
Watching with interest Lee as my car is going for IMS seal flipped open hence new clutch, in a month or so.

It's all a bit vague re the single mass flywheels. Apparently they have to be balanced with the clutch as one unit to stop vibrations putting strain on your crankshaft and bearings, which I'm sure you already know.

It's finding out who does it etc and if they'll do it with the new clutch I already have here or if they insist on supplying the clutch and flywheel.

I'm still wary about it to be honest. These engines are so hitty missy that introducing new stresses could be opening a can of worms. I also only like to do easily reversible mods to my cars, however the difference in feel a LW flywheel makes is great. I loved it on my GT3.

Maybe Harv, Popop or the other engine guys may know. I did touch on it on Kens (9e) project car thread but he didn't really answer to say he'd balanced it all. That could mean he didn't do that. I don't know.

:popcorn:
 
I have actually had quotes from Ken and also rpm technic
But wanted to price up buying the parts myself
And then get quotes from Indies to fit them as a second option
 
Ah right. So do they balance the parts then or just bolt them on?
This is the part I know nothing about.
 
I can point you in the direction of TTV racing's single mass lightweight flywheels via coordsport which is where I got mine, made in the UK and I have heard it's the same unit rpmtech fit to their cars.


This works with the oem clutch kit but you will then need a different sprung centred friction disc as the oem one is solid, I have found a supplier for that also in techniclutch.

For the best result you should balance the front pulley, crank, flywheel and clutch cover plate but you can just have the clutch and flywheel checked. My take is it will reduce stress on the crank as you are loosing a very heavy old dual mass flywheel which have dubious balance out of the box let alone after 75k and nicely reduce the weight/stress induced on the those last main crank bearing shells (a known design flaw).

True it's not a five min job to swap back agin if you decide you dont like it but no problem if you can live with a little chattering at idle, I think you stand to gain more than you'll loose.

Hope this helps
 
Hi harv that's right it is the type rpm use
Theirs was 828 quid with the sprung friction plate

@marky 911 to be honest non of them has actually mentioned balancing
That's not to say they don't but it's all info I want before commiting
 
Use Richard at Coordsport, about £385 when I purchase mine, the centre disc is £110 from the place mentioned who buy up lots of un-used stock but you'll need a clutch cover plate and release bearing anyway so try them for the lot.

Out the box I'm convinced it's better balanced than a DMFW but put it in somewhere and have it checked.
 
I'll admit I don't really understand the balancing bit

As I just assumed the flywheel was balanced on a computer similar to as per what your wheel is when that's balanced
So no idea how it's balanced with the crank etc
 
That's the bit I don't understand either Lee. :dont know:

Even though I'm a precision engineer by trade and have fitted clutches/flywheels to road cars and track cars for my hobby over the years, I can't picture how they do it.

The prices seem good though. I expected it to cost the thick end of £1000.
I may be pushing it to gather the parts and get them balanced as my car is due at my Indy in a few weeks time.

I may knock it onto next years list as he only charges £250 to remove box, clutch and flywheel (and change RMS/IMS if necessary), then refit. So it's no biggie to have it done next time.

Interested to see how you get on though Lee as it's definitely something I want to do.

Great info Harv, the best info I've seen on the topic to be honest. Everyone is a bit vague usually.
:thumb:
 
Needed to get the ball rolling as my summer holidays are nearly over so purchased rpms flywhà¨el along with sprung friction plate

Will report back with my thoughts once it's all fitted
 
Nice one Lee. I'm sure you'll love it.

I must admit I knew I'd read negatives about it a while back and that post of 911munkys has refreshed my memory. Good link munky, thanks.

I think I'll leave it for this year. If I was having an engine built and could have the crank, LWFW and clutch all balanced then I would, although that still doesn't sort out these "harmonics" people go on about.

I'll revisit my flywheel once the rest of the car is as I want it, but with wheels and calipers to refurb, Aerokit to fit etc, I don't want to be throwing in a part that could cause me trouble. There are cars running them without issue but there's no smoke without fire, so I'll look into it again next year.

Report back with your thoughts Lee. Like I say you'll love the way the car revs and picks up. :thumb:
 
I stand to be corrected, but.....

The point about balancing is: The flywheel will be balanced by the manufacturer before it leaves the factory, as will the clutch cover, and of course when the engine was built the crankshaft etc was balanced too.

BUT - All these components were all balanced separately and to varying degrees of tolerance. ie to within 1 gram or 0.25 grams, or 5 grams? Then you bolt them all together which means that the chance of the rotating assembly now being in balance (Or within tolerance of what is considered balanced) is tiny. Chaos theory comes to mind here!

So, what do you do?

If your building your engine yourself, you can get the whole rotating assembly balanced from front pulley, crank, flywheel and clutch cover. Rods balanced end to end, and pistons matched etc. Plus you can get a real expert like David Brown at Swaymar's to do it (Credit to Harv - thanks) to within 0.25 gram. Beautiful and perfect and lovely.

If your fitting to an existing engine, you can get the flywheel and clutch cover balanced to each other, but they will still not be balanced to the rest of the crank etc. So not perfect. What tolerance is it balanced to within, or how much is it out of balance?

So is a Lightened and balanced Single Mass flywheel better than a Dual Mass flywheel? Is the Dual Mass flywheel likely to be worse, or better in this regard? Well you do your research, listen to the good advice, pay your money and take your choice!
 
Pretty much that James....

But there's one more point that no amount of balancing will solve...

Harmonics.
After reading the above thread and many others most 996 engine builders seem to concur that the dual mass flywheel acts a big damper for engine harmonics and removing this for a single mass item leaves all these to transfer to the crank.

Forged balanced cranks can handle this but sintered cranks (which a 996 has) cannot, hence stories of snapped crankshafts on some engines.

I don't believe the likes of RPM would just bolt them on ignoring this, so on the one hand I still think some of it is hot air. On the other hand I can understand the principal and after owning a GT3 which sounded bloody awful at tickover
(In neutral with clutch out) I can see the argument for the damping effect of a DMFW.

I'm going to fit my standard gear next month then look into it again in a years time, if I can find out some concrete info by then.
 
Yep, +1.

I did that last month. The bottom line was I felt I had more to lose with the LWFW through unreliability, (Broken crank, potential extra strain on the valve operating chains / IMS, and gearbox internals) than I had to gain with a freer revving engine.

If I was doing what Harv. is doing though, no question I'd fit the lightweight single mass item.
 

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