Signs of impending dual mass meltdown?

I hooked up to my 32ft car hauler last week and was pulling out and it felt like the clutch was slipping under load ( rpms climbing, speed not , was able to make the run without incident by staying down in the gears and keeping the rpms up , had to go retrieve wife.govs car after she hit a deer), which seems pretty absurd since it has less than 10k miles on a kevlar lining and I'm not a clutch rider, in fact I usually get more miles out of a clutch than just about anyone, and I got under there and looked for signs of oil or fluid contamination and it looked good.

Is this a sign of impending dual mass flywheel doom or do I have something freaky going on in the clutch department or possibly a dragging brake on my trailer?

THanks--------Robert

I'm by no means an expert but if the clutch is slipping there is either fluid contamination or the pressure plate is not doing the job right.

The DMF has a built in overload clutch that if it has ever slipped once there is a chance it may never hold right again. It is a spring (I'm searching for words here) with friction material on it sandwiched under tension. If it gets hot it looses the spring tension and causes problems. Other than that are you sure your clutch is completely engaging, no pressure holding it disengaged slightly?

1dieselman said:

The DMF has a built in overload clutch that if it has ever slipped once there is a chance it may never hold right again. It is a spring (I'm searching for words here) with friction material on it sandwiched under tension. If it gets hot it looses the spring tension and causes problems. Other than that are you sure your clutch is completely engaging, no pressure holding it disengaged slightly?

Click to expand...

I went under there and checked it over real carefully, still freeplay in the pedal. the disc is under full compression until the pedal is fully pressed .
Something definitely did get hot while I was attempting to pull out of the driveway, I got in at a bad angle and had to row back and forth uphill a bunch to get wriggled out, but I've never had the clutch get hot. Old truck driver here, I don't rev it, I idle as the peddle goes out. The DMF is pretty old and has a lot of miles on it. It was checking out within limits when I put the new clutch and engine back in , but I'm beginning to think that was a mistake.

The thing is unless you completely disassemble the flywheel you can't see this spring steel band. Its only 1" or so wide and less than 1/8" thick. I have have one in the shop if you want a picture of it tomorrow

1dieselman said:

The thing is unless you completely disassemble the flywheel you can't see this spring steel band. Its only 1" or so wide and less than 1/8" thick. I have have one in the shop if you want a picture of it tomorrow

Click to expand...

That would be interesting to see. It is sounding like the culpret

My DMF sounded like tin cans being drug on a string down the road behind the truck. It also rattled and sqeeked like heck on shut down.

DMF internals picture's

Okay, here's pictures of the inside of a DMF. The two small round pieces are the overload clutch. Made of spring steel they are convex and clamped in the center of the clutch face and backing plate. Once these spring plates have been slipped enough to overheat they are shot. You can buy the bearing, springs and bumpers to rebuild these if you clutch face is good but I'm not sure about the spring plates, I don't remember seeing them separate anywhere. I have been thinking of rebuilding this one and selling it, its not the right one for my 94.

Thanks for the pics. What I'm gathering from this is that you really do not want to mate anything other than a stock clutch up to a DMF, because if you put a super stout clutch up against a dmf, you instantly make that little slip goodie a functional safety release that you don't want to happen ( the weaker point of friction releases where I bet it's calibrated to be the stouter of the two with a stock clutch).
Kind of sounds like I'd better go with a solid flywheel, as much as I'd not like the noise. I pull too many heavy trailers and just getting them parked at my place can be an interesting chore.

You are correct, and going to a SMF sounds like it may be a good ideal in your case, and yes the rollover noise is obnoxious.

Oh well, I need to pull my front seat bracket to mount a new center seat, and I have a bunch of this nifty insulation to put under the carpet, maybe that'll keep the gear noise down

Some will overfill the tranny or use 30w oil instead of ATF to quite it. The first one I did many years ago I notched the ends of a 2x4 to fit between the seat bracket and depressed clutch pedal so I could hear the engine if I needed to do something on it. Maybe you should wrap that insulation around the tranny.

I've actually already got a 30 wt synthetic ATF in the thing already ( regular ATF is 20 wt ) When I was matching up a lube for the spicer aux tranny I'm fixing to put in this thing, it worked out to be the 30 wt and I wanted to have the same thing in both boxes and it crossed nicely so I went ahead and put it in the ZF as well so hopefully it won't be too bad.

I think the only time you will notice the gear clatter is below 1500 RPM. If you like to gently lug the truck around in 2nd gear in parking lots, then you will hear it. Once you are in the power band and pulling properly, there should be no noise. If there is noise under those conditions, then something is wrong.

I did a SMF conversion on a 1995 powerstroke last year. The springs flew apart in the flywheel and it sounded like a bunch of fresh shreaded pop cans were getting torn up in there. After the conversion, there was a little groaning noise in neutral with the clutch out, but it was not enough to compete with the engine noise.

When test driving the truck the only time I noticed the gear noise was when I was a little clumsy with a low RPM downshift to 2nd gear and the truck lurched back and fourth a little. Sounded like a pile of bolts rattling around in the oil pan. Sounded a little funny, but it wasn't loud. I orderd a SMF converion kit through Valair in texas. Last I heard the truck was still doing fine with it.

One other thing is the SMF is usually lighter than the combined weight of the DMF, so shifting might be a little faster after the conversion.

I don't think the rollover noise is as bad on the powerstrokes because of the lower compression