DMF to solid flywheel conversion?

Further to this, been chatting to a guy on TDOC about it and how the DMF exactly performs during operation.

First talking about how it dampens not only on clutch engagement but also under load too... well to a point.

nutron said:
The spring force is obviously progressive, the manufacture would design the springs to be strong enough to no be fully compressed when cruising, to allow for more damping if you put your foot down suddenly. They may design the springs to be strong enough to resist without fully compressing, any torque load the car would normally produce (unmodified of course). In a heavily modified car, you may well be fully compressing the springs before even reaching peak torque. Mine was only designed to put out 230lbft, so 400lbft would probably flattern the springs on full load.

DMFs on mine are only £230 and fitting in some places as low as £200. I would rather pay £430 every 100K miles than have to recon or replace the gearbox. That's my reasoning.
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edk said:
Ah interesting. Yeah I've found a similarly price DMF for mine on buypartsbuy. If it really does last 100k then I'd be happy to do that too. The DMF on this engine doesn't seem to be a weak point like say on some Fords so I could get away with it.
Clutch upgrade would be cheaper too as I could just buy the pressure plate from the kit I was looking at (ACT do sell parts separately :)) and buy and OEM solid clutch disc.
Cheers for the info Karl, gives me food for thought.
-phone-
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The thing with buying a new DMF is that the cheapest is £337 from buypartsbuy.co.uk. Then the cost of the pressure plate would be about £185 delivered. Then a new solid clutch disc too. Easily £600. But the argument would be that the gearbox is kept safe.
So with the SMF and sprung clutch disc option being cheaper I'd really like to know more. Like does the sprung clutch disc perform a similar operation? Or do the springs only work on engagement.

Some insight would be most welcome! In the mean time I'm going to trawl Google.
 
The springs in the clutch plate will do the same job...
But there's another issue, If you imagine, the DMF dampens anything after the central part of the flywheel (outer mass of fly, whole clutch setup then tranny, drivetrain etc)
A SMF and sprung clutch disc will only dampen from the clutch disc centre (clutch disc centre, tranny etc).
This is another thing you need to think about because converting to an SMF may make the engine run rougher especially on startup/shutoff you will notice more vibration as there's going to be probably in excess of 30lb's weight that is now smoothly dampened, that will be fixed if you get what I mean??
The DMF broke in my stapdad's Focus, and when it was worn, you could feel the play in it, wobbling and effecting the engine's idle smoothness etc.
Joe
 
Cheers for the reply Joe. Pisht, well the car's a daily and I drive it in traffic a lot so I really don't want to be making my life in the car more difficult. I'd hate to start hating the car and loosing the love.

I guess with the DMF it's dampened both directions of force, whereas the clutch only dampens one way, on engagement, and certainly not while it's engaged at idle in neutral?

Looking at the design of the DMF I see what you mean about if it was solid it would be all 30lbs undampened. But I think the weight itself performs a level of smoothing of the engine running. but I guess the flywheel face part is probably a 1/4 of the total weight and is the bit that sits in springs that absorbs any vibrations from the engine/flywheel so it's not passed onto the clutch disc.

$(KGrHqEOKjsE6Jkd5NF)BOu8PDghVw~~60_12.JPG
 
thought about tk's ed?

also if your clutch is slipping then replace the pressure plate and friction plate but, as it is id leave the pressure plate on and just buy a really good friction plate, def give cambridge motor sport a call, as they made mine, just give them the input shaft spline teeth number and clutch diameter (maybe send them an available one to copy) and they will get one made to order where high enought performance parts are not availble. remember my one they made for me, cant remember what lbft it is rated for but made extremely well, with the plates being alot thicker than others ive seen, holding the spring in stronger,

basically what your doing is transfering the springs from the flywheel to the clutch, things ive thought about are;

how strong are the springs in the flywheel?
there will be more pressure n the friction plate springs as the friction plate springs are closer to the center of the disc, compared to being further away from the center on the flywheel making them take more load safely?

:) stu
 
These are the things I've brought up in this thread, about whether the clutch will take the absorbing over the flywheel. But not knowing if the DMF's springs compress fully when under normal driving means I don't know what affect changing it for a SMF will have.

As for the clutch, it would prefer a strong pressure plate and better clutch disc, not just the disc. But I don't need to go to anyone for a custom clutch as the RB25DET (Skyline GTS-T) and VG30DE (300ZX) clutches fit, so just need an uprated one of those, which I've found made by ACT. It's all in this thread dude.

Cheers for the input though. I did ask TK's a while back about the possibility of welding the Flywheel but they said they don't really know and couldn't guarantee it. So it really needs to go to someone with experience with that type of thing.

At the moment I've got two spare sets of clutch and flywheel. One set from an old P12 that's pretty worn and the DMF is spare parts really. The second set form the grey car that's done 77k so still good. Then the stuff in the black car at 60k. If I can get away with just changing the clutch for an ACT one and keeping the current DMF until it does go, then swap it for the grey car's one that'll be cheaper. But until I know more about my DMF I'm going to hold off as my clutch has probably got several thousand miles left in it yet.
 
http://moodle.student.cnwl.ac.uk/moodledata_shared/cdx etextbook/dswmedia/trans/clutchMan/clutches/dualmassflywheels.html

http://www.google.co.uk/url?sa=t&rc...pb2sCA&usg=AFQjCNEpRsio9ujdccy1RgzhFcV2FygqzQ

It's good to go back to school :D

While it says it dampens all the time, it does say that it works most at startup and shutdown:

"
DMFs are designed to provide maximum isolation of the frequency below the engine’s operating RPM, usually between 200-400 RPM. The time that the DMF works hardest is during engine startup and shutdown."​

So dipping the clutch at both these times should be enough to save the transmission damage? As in normal running RPM never goes bellow 800rpm.

From what I gather from it all is that the weight of the fly helps smooth out torsion spikes from the high CR engine, and the springs/second mass help at low RPM to protect the transmission. I think the springs still help at higher RPM but it's not as important.
 
I've got a solid centre clutch disc in my car Ed and I hate it, smooth starts are almost impossible. I would stick to a sprung centre. But my UK shipment of bits will solve that and due in a couple of weeks. I'll be moving to the Di clutch and flywheel.

DMF's are a wear item, I think they are worth the trouble, it takes a much heavier single mass flywheel to run as smoothly. I don't see your extra torque causing earlier death though, it's extended idling and very low rpm driving that works them hard.
I wouldn't lighten up any diesel flywheel as it makes low rpm torque unusable due to vibrations. I have the issue on my 4wd that I need to roughly double the flywheel weight to make the lower half of the rev range usable with my current torque levels. Currently I can't use full torque below 1800rpm in higher gears, it shakes everything.

Honestly I can't see any benefit in trying to weld up a DMF. Just like the clutch, run it until it fails, see how many miles it took and what it's worth to replace.

Have you checked Navara DMF/SMF parts? The difference between Di and DCi seems to be the number and location of trigger flags for the crankshaft position sensor.
 
Did wonder about the Navara D40 but don't have any info on their clutch and fly so no idea if it would fit the my YD22.

Never would have got a solid clutch disc, that was only if I was keeping the DMF. My stock clutch is solid. If I was changing to SMF in some form then it would have to be a sprung clutch for me.

Can you explain a bit more when the DMF exactly serves its purpose mate? Still a bit in the dark with it. I was thinking that if I went SMF then to avoid damage to transmission at when tje shudder is the worst, on start up and shut down just dip the clutch. Then as long as I keep the weight up on the flywheel and use a sprung clutch it'll be safe and smooth?

-phone-
 
The shudder I get is the clutch plate on the flywheel. This is taken care of partly with a sprung clutch disc (those four, six or so springs on the plate itself), it is so much worse with a solid centre clutch plate like I currently have.
Is that the stock clutch plate you have with the solid centre or an aftermarket? You probably won't be able to tell the state of your flywheel until you split the engine and box to take a look. I presume you've got a spare from your gray car.

The primary purpose of the DMF is to minimise noise, vibration and harshness at low engine speeds and idle. IMO the only reason not to use one is cost. That is the cost of replacing them when they wear out.

Got any pics of the spare flywheel?
 
As I said, my stock disc is solid. And running is smooth. But I would not use a solid disc if I went SMF.

No pics of the actual spare one but pic of which one looks like above.

-phone-
 
No idea I'm afraid. Why?

But I think that wouldn't work on a DCi anyway due to different clutch dimensions.

-phone-
 
I've got one coming with engine/box and have no idea either.

The clutch dimensions are the same (240mm disc, 1" centre, same spline count), but the triggers for engine position are very different. That much I know, but I never actually found out if it was single mass or dual.
 
So what's your train of thought? That it could be an SMF replacement if the crank sensor teeth are the same?

-phone-
 
I'm thinking if it is DMF, I've just screwed myself. The one coming with the engine/box is probably close to worn out. I should have bought a new DMF when I had those parts shipped.
 
Arse, I hope not Dougal so you can just get cracking with it when it all arrives.

You mentioned in a post that the flywheel springs do not transfer torque, can you elaborate of link to a source? I really would like to have a complete understanding of the DMF, especially it's sprung parts and function.
 
edk said:
Arse, I hope not Dougal so you can just get cracking with it when it all arrives.

You mentioned in a post that the flywheel springs do not transfer torque, can you elaborate of link to a source? I really would like to have a complete understanding of the DMF, especially it's sprung parts and function.
Click to expand...

Ignore that, they definitely do transfer torque on your type of DMF, I have since deleted that comment. Boat arrives March 31st. But it'll be a few weeks before everything is out and collected.
 
Where did you find what type it is? is it torsion springs and dampers, or is it of a planetary gearing type?

Hope the packages find their way to you ok!
 
On the one above (which I presume is the same as yours) the clutch cover is attached to the sprung side, which means it has to transmit the torque through the springs. I wouldn't expect to find any planetary gears inside, feel free to strip yours down if you change it.

The irony is previously people have bought automatic cars secure in the knowledge they will never have to pay for the huge labour in a clutch change. But these days many automatic cars run DMF's, so you can be up for the labour of a flywheel change which isn't much different.
 
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