Dual Mass Flywheel?

[NickBarrFishing.com]

I was hoping to know if I have dual mass flywheel or solid? How can I tell? I am looking at replacing the clutch and so I need to know which one I have and what clutch kit do you guys like?

thanks,
Nick

 

[schiker]

iirc a 95 is dual mass. I think they switched back to single mass during 96 production year early so some 96 and 97's are single mass.

Can't resurface the DM it has to be rebuilt $$$ or replaced. Most go back with single mass kit. There are few threads down in the other drivetrain or transmission forum.

 

[BigBlueChevy]

Even if you have a dual mass flywheel, I recommend replacing it with a solid mass.

If you starting changing HP / TQ numbers you will throw off the DM flywheel as its set operate at a "set power level" They don't have as much vibration transfer as a Solid mass, but are easier to break.

 

[6.2 turbo]

If it rattles every time you shut it off you have a dual mass.I had a hays super brute truck clutch that worked good, I now have a spec stage 3 , its a little jumpy,valair makes good clutches for the cummins,dont know about the 6.5, luk pro gold would be ok for a stock application. I'm using a hays steel flywheel from a sbc ,it don't have the big opening in the center, which gives me a lot more clutch options.

 

[SmithvilleD]

Believe my truck came OEM w/ the DM, but the clutch/flywheel had just been replaced right before I bought the truck & they used stock delco parts (clutch was new enough the white silk screened "Delco" label was still clearly showing on the friction surfaces.

My transmission shift well & feels tight. However, it will make a bit of a rattling sound when put in 1st (granny) & the truck is idled along low rpm, w/ no load. Apparently, this relates to the strong diesel power pulses that had been taken out by the DM flywheel.

When GM went back to single mass flywheels, they also added a little dampener on the tranny tailshaft (at least on the 4x4 trans). Believe Slim found one of these dampeners at a trans shop & had it added to his tranny when he went to SM flywheel. I haven't added this part to mine yet, but would like to in the future. Behind our modestly powered 6.5's, this tranny should be tough enough to outlast the truck.

I've attached a GM document detailing the DM to SM switchover details, & a few pics of the little dampener that can be added in the tranny tailshaft. If I interpret the GM document correctly, it appears this damper added to the trailshaft compensates for what was lost in the DM to SM switch.

Here is a link to a website w/ lots of good NV4500 info & this little dampener is about halfway down the page the link takes you to.

http://quad4x4.com/NV4500 Parts.htm

 

[625fireman]

I would stay away from the dm flywheels no where as strong as sm. As for the dampner i dont have one in mine and i dont have any vibrations that are noticed. I looked into getting one when I did the swap but could only find it at the stealership. It was $480. So i told them to keep it.

 

[chevyCowboy]

my truck has the SM by one of the 3 PO and another one of them probabley the last one must have put a dm clucth in pics in the manual tranny area

 

[SmithvilleD]

I would stay away from the dm flywheels no where as strong as sm. As for the dampner i dont have one in mine and i dont have any vibrations that are noticed. I looked into getting one when I did the swap but could only find it at the stealership. It was $480. So i told them to keep it.

Yeah, I don't know if the dampener is necessary. Mine's been swapped to SM w/o it for quite a few miles. Just thought I'd bring it up as you don't see it mentioned very often, so folks may not be aware it exists.

Mine has the rattle the GM document talks about. It's the only obvious symptom I hear/feel. It's just in 1st/granny @ low rpms/no load. Feels like it's an ocillation bouncing btwn the front & back sides of the gear because there's not enough drivetrain load to keep it seated against the driven side of the gears.

I've seen NV4500's that look to have some type of obvious/external damper on the back end (see attached pic). Is this maybe an NV4500 for a 2WD that came behind a Cummins?

 

[NickBarrFishing.com]

I do get a rattle/clunking sound when I start off in 2nd gear, with very little in 1st gear. Could this be something?

 

[625fireman]

Yeah, I don't know if the dampener is necessary. Mine's been swapped to SM w/o it for quite a few miles. Just thought I'd bring it up as you don't see it mentioned very often, so folks may not be aware it exists.

Mine has the rattle the GM document talks about. It's the only obvious symptom I hear/feel. It's just in 1st/granny @ low rpms/no load. Feels like it's an ocillation bouncing btwn the front & back sides of the gear because there's not enough drivetrain load to keep it seated against the drive side.

I've seen NV4500's that look to have some type of obvious/external damper on the back end (see attached pic). Is this maybe an NV4500 for a 2WD that came behind a Cummins?

That would be a pic of a 2 wheeler so the balancer is outside the tailhousing. That is also a GM setup too. The Dodge ones have alonger input shaft and the shifter tower is almost straight up.

 

[625fireman]

I do get a rattle/clunking sound when I start off in 2nd gear, with very little in 1st gear. Could this be something?

Kinda hard to be 100%. It could be a few things.
1 long miles on the clucth could be springs
2 long miles on a DM colud be springs
3 could be bearing in trans
4 or nothing - normal...
IDK

 

[SmithvilleD]

Mine has a fresh SM flywheel/clutch & front bearing carrier. Haven't checked, but assume it doesn't have the rear damper.

The chatter in mine is only at very low rpm. Seems like it could be a resonant vibration/chatter in relation to each diesel combustion pulse & limited load thru the driveline. You don't hear/feel it except idle/low rpm no-load in 1st, or low rpm starts in 2nd in summertime temps. No unusual noises above say ~ 1200 rpm or other normal driving conditions.

Don't know that this additional damper the GM document suggests would eliminate the chatter. Seems possible/likely it might - for GM to recommend the part w/ going back to SM, but guess I won't know unless I add the damper. Believe SlimShady did add this damper; don't know if he'd driven the truck w/ SM & no damper first, so he'd have experienced the comparison? Guess if I decided to drop the trans to consider adding the damper, I'd prolly also go thru the tranny looking for any obvious signs of dmg or excessive endplay/tolerances.

I've only gone thru a couple automotive manual trans. The ag/tractor trans I've been into seem to tend towards opposite ends of the spectrum: either in good shape/wear patterns, maybe just reset endplay tolerances w/ shims or new bearings - OR - things went very wrong, something broke (seems to always either fall into the works, or clearance is tight enough on the bottom that a gear somehow re-grabbed a broken bit & fed it thru the works more than once), & some expensive/initially tight clearance parts are now junk.

 

[schiker]

I have the factory SM and dampener ('97). It also growl/groans some in low rpm low speed situations in 1st moreso than 2nd depends somewhat on load. I get it the loudest if I idle up a hill on a dirt road where traction and bumps vary. But it is probably quieter with dampener say on level no load low rpm. Some clutch shops recommend it and others say most customers don't add the dampener.

The single mass has almost as many clutch hub failures as the DM flywheel failures. Its been theorized that the needle pilot brg fails first and leads to hub failure. So SMF by itself is not the end all solution. Read South Bend website about pilot bearings.

 

[6.2 turbo]

I never use the needle bearing pilot,the bronze one is much more forgiving,and won't gouge your input shaft,a sealed ball bearing would be best if you want to machine the crank.

 

[Odlaw]

I was hoping to know if I have dual mass flywheel or solid? How can I tell? I am looking at replacing the clutch and so I need to know which one I have and what clutch kit do you guys like?

thanks,
Nick

If you have a lot of miles on the current setup I would buy new 1 piece flywheel and clutch kit (regardless of what you have in now). In hindsight I wish I had replaced my DM with a solid. The springs are shot on the DM and it has that rattle when I shut it off and everytime I shift. I really get tired of hearing guys that ride with me say "you got a universal joint going out?"