I don't have any personal experience with the SPEC single mass flywheel or SPEC clutches, but if I was considering a conversion to the single mass flywheel this recent thread would have caused me some concern:

http://forums.swedespeed.com/showthread.php?179455-volvo-s60R-2004-M66-transmision-problems!!!!!

From what I can tell from that thread, both the thread starter and TheApache are currently having shifting problems with their SPEC setups. I know that there are other people running this setup without reporting any problems (Trav8832 and DavenRuth, amongst others if I recall correctly), but I still thought it was a bit strange.

 

Any issues related to the flywheel, clutch or slave cylinder will be present in all gears, and not just in gears 1-2 like in that thread. The issue in that thread is most likely an internal gearbox component failure (as reported by the thread starter in his posted on 8/31. The synchro's of the M66 are designed off the M56 synchros, which can fail. I won't be surprised if more M66 synchro failures start appearing as these cars start accumulating more and more mileage. None of the M66 gearbox components are service items by Volvo, FYI.

 

I like my SPEC single mass from viva, no issues and it spools so quickly!!! At idle my R does sound like a diesel tho...

If quiet is your thing you might not like it but if you're after performance then it's a very worthwhile mod.

 

Hey Phil, Hope your feeling 100% ! The single mass will spool up quicker, but along with that it will also dive off much faster too. So if you throw it into a corner & get out of the throttle you may very well see the back end come around.

I'm going to be doing my clutch soon. . . . . . .I'm looking at going with a single mass along with the factory clutch. Simply due to the fact that the dual mass 9 outta 10 time's Can't be turned & reused. the thin rubber usually deteriorates, or get's shaving's in between & fail's shortly after reinstall. dual mass is around 900 I believe & the single mass is around 600.


...........Dave

 

I just did a SMF conversion in my car, I have some sort of rattling or chatter now, usually at low rpm. If the windows are down you can not hear the noise but if the windows are up and AC is on you can tell something is up.
Not sure what the noise is, could be trans internals, however it seems to be the same noise other people have reported. Some did report that their noise went away, I have my fingers crossed now.
06 100k

 

The noise is from the flywheel not muffling the engine noise anymore.

 

I have a Viva SMF with an OEM clutch. check my sig for other mods i have.
when i first drove the R i always felt the clutch and the engagement had an odd feeling. not what i was used to in other cars, but then every car is different.

Shifting the R gave me a feeling of being dis-connected with the motor. The SMF really brings the feeling back. Sure, the motor spins up and down quicker and there is less engine braking but FOR ME, after 3 months with the SMF, that's not what makes this mod shine.

the drawback is the noise. MountainR summed it up pretty good. My car sounds like a diesel at idle with the clutch out. bogging any gear makes a bit of noise too. From what i understand the noise is from the tranny - the individual cylinder pulses are transmitted to the tranny gears. there's less weight and no rubber to round the pulses out. But the noise is not bad at all... not for me anyway. it simply reminds me that i have a Volvo that is rather unique. I mean, everybody does exhaust mods...how many cars our there do you hear with turbos that whine and gearboxes that chatter?

 

the drawback is the noise. MountainR summed it up pretty good. My car sounds like a diesel at idle with the clutch out. bogging any gear makes a bit of noise too. From what i understand the noise is from the tranny - the individual cylinder pulses are transmitted to the tranny gears. there's less weight and no rubber to round the pulses out. But the noise is not bad at all... not for me anyway. it simply reminds me that i have a Volvo that is rather unique. I mean, everybody does exhaust mods...how many cars our there do you hear with turbos that whine and gearboxes that chatter?

That's got to affect the longevity of the transmission, right?

And anyone have a video or recording of what the chatter sounds like?

 

I'm talking outta my ass here, but single mass flywheels have been around for a long time. I think we have other things to worry about than this, such as the synchros that George mentions. And like he said, it has little if nothing to do with the clutch.


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Oh, somebody on here mentioned that the dual mass was for comfort and noise reduction only. Now that i have a SM, i have to agree.

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I dont have experience with the SMF in the volvo but I had it in my e36. It made that car easier to rev and more responsive. If I was going to be doing the clutch on the R I would certainly entertain the option and probably go the SMF route. The flywheel chatter in neutral and very low rpms really wasnt that bad for me and I didnt mind it.

 

Just as an FYI. easier to rev and more responsive has nothing to do with single or dual mass, it's all about the weight of the flywheel. And the distribution of the weight. With the same rotational mass, a single and dual mass flywheel will rev just as eagerly. Most single mass setups are light weight, hence they rev easier. Note that a lighter flywheel makes the chatter and gear lash worse as well.

 

Maybe relevant

I have not change flywheel (or clutch) on the Volvo but did it recently on my M5. With a single mass flywheel you gain four things:

1. You have one less component that can break (the dual mass mechanism - springs and all)
2. If need be you can resurface the flywheel later. Yes, some guys will tell you they find a shop that can resurface a dual mass flywheel, but it's very, very hard.
3. Generally you get a more precise take-up point.
4. For the same performance grade, it's cheaper than a dual mass setup.

Nothing in life is free, so you pay:

1. You will have gear lash in neutral and clutch out. Depending on the weight and design of the flywheel it is a lot or a little. Some sounds terrible, some are close to stock. But there will be gear lash.
2. There will be chatter, especially in the beginning (1,000+ miles) and it is worse the more aggressive you go on the friction material.

That's about it.

 

I'm looking to replace the clutch and go with a SM flywheel soon, but want opinions on Stage 2+ vs. Stage 3+. I won't be even close to the torque rating of the Stage 2+, so I'm wondering how smooth the engagement & pedal effort for each is (vs. stock) and/or if the cost of Stage 3+ is worth the extra $$$. Thanks!

 

Stage 3+ is a really nice clutch talking about smooth engagement and pedal travel.

 

@aggrorider1, the SM replacement flywheel is a few lbs lighter than the OE DM one.
@volvos60t5x, thanks for the feedback! George @ViVA has expressed the same.

 

I changed mine for a viva and came back to the garage thinking there was something ready to break but finally learned its the single mass.

I was a bit disappointed of the sound since it cover the nice 5 cylinder sound only when you don't drive
But combine it with a 3" downpipe gas pedal to the floor and it make a demoniac sound!

Also power is really improved I was surprised a lot...was...need more...damit!

 

Flywheel noise... Like when you push the clutch pedal in, you hear a fairly high pitched metallic squeaking noise?