How Much Louder is a SMF Over a DMF

[Macrobb]

I am using and AMS clutch and flywheel, single mass; and once the truck is moving, there is some typical rumble/growling which doesn't bother me at all....but at idle with trans in neutral, wow...sounds like the through out bearing is about to grenade. Loud rattle especially once its warmed up.

One thought - grab the clutch fork with your hand and see if it quiets down.
I had an odd rattle on one of my trucks with a SMF; it would go away if you rested your foot on the clutch.
I ended up adding a spring from the clutch fork down to the frame, to hold it "down" and keep it from moving around. Quieted it right down.

 

[franklin2]

I am using and AMS clutch and flywheel, single mass; and once the truck is moving, there is some typical rumble/growling which doesn't bother me at all....but at idle with trans in neutral, wow...sounds like the through out bearing is about to grenade. Loud rattle especially once its warmed up. Tried every type of fluid in the trans. Overfilled and otherwise. My timing is set at or near 9, can't remember now. I have read that the timing and/or the way the injectors are performing can effect noise. I have new BB codes and a baby moose pump. No issues there. I will try playing with timing some more, I have a bit but didn't make much difference.

Next ZF swap will bet getting a DMF....in fact I may even do a DMF swap back into the truck that I am referring to if the clutch wears out

Step on the throttle slightly when it's noisy and see if it helps. Like was said, raising the idle speed a little bit really helps sometimes. If it helps you can go out and turn the screw in some.

 

[Kevin 007]

Yes, increased idle does quiet mine down. I have my fast idle on a manual switch and when idling for more then a few mins, I engage my fast idle. But I don't think that is a long term solution for the rattle as its also makes for more clutch slippage every time its engage from a dead stop.

I will try the spring on the clutch fork. However it only becomes fully quiet if the clutch is fully disengaged, (pedal depressed).

 

[Macrobb]

I will try the spring on the clutch fork. However it only becomes fully quiet if the clutch is fully disengaged, (pedal depressed).

I really wonder if something's not quite square or true and is out of balance here...

 

[Kevin 007]

My first thought a while ago, was maybe a broken spring? I have been driving the truck this way for some time now and its not getting worse..just haven't had the time to drop the tranny again and check it out. But I thought I would mention as I came across this post

 

[pelky350]

The luk 12.25 clutch works very well so far holds up my 90cc r and d pump and stage 1's injectors and almost 20psi boost no slips so far, the dmf stock set up didn't handle it though pulled a trailer up a hill one downshift almost at the top and clutch was no more 10mph the rest of the hill, I thought I had felt it slip before towing and then it wouldn't even hold highway speeds a couple days later while limping the truck around awaiting the arrival of my new clutch setup. Having a smooth running truck is the key to keeping the clutch/transmission quiet, when it's cold it will make a little noise at idle but once warmed up it's no louder then the dmf setup. It did seem a little louder when I first installed it and quoted down some after some miles on it

 

[franklin2]

If you didn't know, the factory DMF has two sections to it. One that we all know about is the friction discs and springs to dampen the noise. But the other one some people do not know about, there is another clutch section in the flywheel down in the center. This cuts loose when the engine output is too high, I presume to protect the transmission/driveline. And this was factory with the dmf and normally aspirated engines.

 

[reklund]

I fought the same issues with mine before I figured out that it was all in the disc. I'd just pull it and see which disc you have. Seriously.

If you look at the pics I posted earlier, the 10 spring disc is the standard duty that is currently in the truck and working well.

The 8 spring disc is the HD Sachs that sounded really noisy. It worked great, engaged great, but was just real loud at idle.

 

[AZ6point9]

tbh I'm not sure if my truck has a worn out dmf or is converted to sm, as the PO did a zf5 swap over 10 years ago but i do know its loud.

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[franklin2]

tbh I'm not sure if my truck has a worn out dmf or is converted to sm, as the PO did a zf5 swap over 10 years ago but i do know its loud.

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It's a little hard to tell over the computer, but that does not sound like the SMF rattle I am familiar with. That is more of a clunking sound. The SMF rattle is a higher frequency and is more "filled in". In other words, the SMF noise is caused by the engine firing, which would be 4 times each revolution, At 500 rpm idle speed that would be 2000 little noises per minute. Versus your (guessing) clunking of about 500 clunks per minute(one each revolution)..

 

[BrianX128]

That sounds like a dmf that's super worn out from another video I've watched on YouTube before where the owner confirmed he had to replace it. That's a crazy noise whatever it is.

 

[AZ6point9]

It's a little hard to tell over the computer, but that does not sound like the SMF rattle I am familiar with. That is more of a clunking sound. The SMF rattle is a higher frequency and is more "filled in". In other words, the SMF noise is caused by the engine firing, which would be 4 times each revolution, At 500 rpm idle speed that would be 2000 little noises per minute. Versus your (guessing) clunking of about 500 clunks per minute(one each revolution)..

Appreciate the info. I plan on pulling it apart before too much longer because it annoys the **** out of me.


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[AZ6point9]

That sounds like a dmf that's super worn out from another video I've watched on YouTube before where the owner confirmed he had to replace it. That's a crazy noise whatever it is.

It doesn't make a sound past 40mph. Just annoying as **** putting around town. That truck isn't my daily though so I've just lived with it.


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[catbird7]

When I bought my truck it still had the original dual mass which was extremely quiet. After several years of driving the clutch started to make noises similar to the video which is when I changed to smf. SMF eliminated the noise while idling in neutral however roll-over noise was terrible when "lugging" the 300,000 mile engine & trans. Couple years later I had the transmission rebuilt and the amount of noise was drastically reduced. Therefore it seems transmission condition might play a significant role and directly related to the "roll-over" noise.

 

[needlenose]

tbh I'm not sure if my truck has a worn out dmf or is converted to sm, as the PO did a zf5 swap over 10 years ago but i do know its loud.

FWIW, I pulled a failing DMF from my truck. It had one broken spring and at least 2 more that were severely worn and on the verge of failure. I have no idea where the pieces went. It sounded like a slight rod knock at idle.

Mine sounded similar to yours, but no where near as bad. I would bet you have a DMF with several springs missing. I forget how many there were.(6?)