I was told that the flywheel in the 6.7 has springs in it. Ian about to change the clutch and was told that I would have to get a new flywheel, can someone please elaborate on the situation.

Thanks,

Dayton

 

the stock clutch is a dual mass flywheel. it's also total crap! go with a good aftermarket such as Valair or Southbend. yes, you'll need a new flywheel and possibly the hydraulic upgrade as well, depending on the clutch you choose. I love my Valair. Put it in a few months ago and it holds everything i've thrown at it.

 

Thanks for the help. I am gonna go with valair, did you get a regular old flywheel or another dual mass

 

no, no dual mass. it's a billet flywheel that came with mine.

 

FWIW, I brought my truck to a local, highly competent diesel mechanic for a clutch evaluation. I asked him about upgrading the clutch (yes, I'm considering Valair, too). He mentioned something interesting regarding changing the dual mass flywheel to any other type. He said the purpose of the dual mass flywheel was to prevent vibrations from reaching the transmission. Changing that flywheel to any other type could possibly cause long-range problems with the tranny (I'm talking about a G56 here. I don't know if that applies to the automatics). Whether he's correct in his assessment or not, I'm just passing this info on so others can comment.

 

what did he think it would damage? i've talked to many people with lots of miles on aftermarket clutches, and have heard of no problems. the dual mass will stop vibrations. and yes the single (heavy) flywheel does let the vibrations be known. sounds just like a big rig at idle. clutch chatter.

 

Here is my take on my Con OFE: At idle, with the clutch out, I get a rattle from the throw-out bearing; push the clutch in and it goes away.

The gears in the transmission (G56) rattle at low RPMs, however that goes away after about 1400 RPMs. I can avoid it by not lugging it at low RPMs. These trucks are louder and less refined without the dual mass damper flywheel and OEM clutch, but at least the clutch doesn't slip.

Will this cause long term damage to the transmission? My take is that it probably isn’t good for it, but I have no supporting data. It won't kill the trans in 10K miles. For example: maybe it will reduce transmission life from 500,000 miles to 400,000. I don’t really care because I wouldn’t mind installing the newer G56 with taller gears anyway.

 

The newer SB clutches ship with most of the coil springs replaced by neoprene dampers (in G56 apps) which allows more of the CTD's harmonics to affect the transmission.
Jury's still out on how much of a problem that is... probably isn't significant for most trucks.

The new noises in the cab at low RPM under load are quite noticeable, but the DMF's shutdown death-rattle is gone.