well I understand if I want more power Im gonna upgrade. could someone explain tom cause people are asking me "what are you talking about how do fly wheels go bad"? what happens to the the dmf and or how does it work?

well I understand if I want more power Im gonna upgrade. could someone explain tom cause people are asking me "what are you talking about how do fly wheels go bad"? what happens to the the dmf and or how does it work?

Well the DMF is a two peice flywheel, hence Dual Mass Flywheel. It's design was to make the truck as quiet as possible. When the Duramax was first released it was by far the most silent diesel on the pickup truck market. Well when you have a really quiet motor everything else seems to make much more noise. The problem arose when GM was testing the ZF6 with a single mass flywheel, it made a sssshhhhhhhh sound when placed in nuetral with the clutch out. Naturally this would be a big problem to the general public because one of the big selling points at the time was how quiet the truck really was. So some engineer that must have been getting paid too much came up with the brilliant idea to make a dual mass flywheel that would eliminate the ssshhhhhhh sound by obsorbing the pulses that the diesel motor produced.

They way they go bad is the constant torque from the motor and weight of the truck has a direct impact on the flywheel itself, the flywheels clutch contact surface is separate from the part of the flywheel that bolts onto the motor. It can rotate approx 1 inch in either direction from it's center axis via compression springs, so everytime you hit the accelerator it compresses the springs in one direction, then when you let off it returns back the other direction, over time the flywheel, springs and other components start to wear out due to excessive heat a pressure thus causing the flywheel to start to rattle and squeak and course causing the clutches to eventually slip and fail.

Sorry for the long explanation but figured it was some good ZF6 101!!!

Cheers, Wade

Very well said. It's to bad you have to be right.

dont appologize I really appreiacte you taking the time to explain it to me thanks for the info no I get it. to bad it a p.o.s. lol have a good one! hope to hear about your kit sooon!!!!

Since this is a new thread on The Infamous DMF setup, I thought I would post here...
I have a 93 k3500 6.5 4x4 with just over 200,000 on it. At 140,000 the pilot bearing went out causing significant damage to the tranny. It took the input shaft out and some bearings.....While at the garage they asked me to come in and check the flywheel. They said it wasn't too bad and suggested just a new clutch and pressure plate because the DMF was about 800.00.

All has been fine for just over 60,000 miles, which after reading some of these threads, I consider myself lucky to have gotten 200,000 out of my dmf. The other day I started my truck and let it run for a few minutes and shut it off. It shut down rather different than usual and very abrupt...When I restarted it, it sounded like a rod knocking in the motor! I thought, surely that didn't just happen!

I restarted it and pushed in on the clutch for some reason and the noise went away! Whew...Relief! After checking it all out, I found that a spring had let go in the flywheel which was hitting the block....Thus the knocking sound....

My question: After doing some research, I found that there are several conversions available for my truck. The only problem I have in switching to a SMF, is that one website I found required you to purchase a dampener that goes in between the tranny and the transfer case. At a cost of an additional 250.00. The garage I am going to have working on this, said their vender on the SMF package didn't suggest any kind of dampener to be installed.

Does anyone here on the forum have any info on this? I don't want to do the conversion if it is going to damage something else down the road unless it is done right....

Thanks in advance...

Since this is a new thread on The Infamous DMF setup, I thought I would post here...
I have a 93 k3500 6.5 4x4 with just over 200,000 on it. At 140,000 the pilot bearing went out causing significant damage to the tranny. It took the input shaft out and some bearings.....While at the garage they asked me to come in and check the flywheel. They said it wasn't too bad and suggested just a new clutch and pressure plate because the DMF was about 800.00.

All has been fine for just over 60,000 miles, which after reading some of these threads, I consider myself lucky to have gotten 200,000 out of my dmf. The other day I started my truck and let it run for a few minutes and shut it off. It shut down rather different than usual and very abrupt...When I restarted it, it sounded like a rod knocking in the motor! I thought, surely that didn't just happen!

I restarted it and pushed in on the clutch for some reason and the noise went away! Whew...Relief! After checking it all out, I found that a spring had let go in the flywheel which was hitting the block....Thus the knocking sound....

My question: After doing some research, I found that there are several conversions available for my truck. The only problem I have in switching to a SMF, is that one website I found required you to purchase a dampener that goes in between the tranny and the transfer case. At a cost of an additional 250.00. The garage I am going to have working on this, said their vender on the SMF package didn't suggest any kind of dampener to be installed.

Does anyone here on the forum have any info on this? I don't want to do the conversion if it is going to damage something else down the road unless it is done right....

Thanks in advance...

my dealer told me about a required damper but did not say much about it

I have been checking out some other forums on the net, and have found mention of the dampener between the trans and the transfer case. Some install it and some don't....Nothing concrete as to whether it ABSOLUTELY NEEDS TO BE DONE or whether it really doesn't matter. My local GM dealer wants $450.00 for it and told me he never sold one....I found it online for 250.00....Since the conversion is going to be about $1500.00 installed, I don't want $250.00 stop me from doing it right. But if it doesn't need it, then I wouldn't mind saving the money!

Just giving this thread a bump....Has anyone done this conversion and messed with the dampener?

Just giving this thread a bump....Has anyone done this conversion and messed with the dampener?

Sorry I didn't get back to ya bizzy but I thought you had it figured out. When I called around for you I was told it was more of a precaution then a "Need". It is possible with the diesel vibration caused by your motor with a SMF over a very long period of time could have an effect on some of the internal bearings and gears, but it has not been a big enough problem to call it a "Need", it would be more of a "Want". I would say if you have the $250 to spend on taking every precaution then do it. If the $250 is a big deal then you could always wait to see how bad it vibrates and if needed do it down the road.

Just my .02

Cheers, Wade

Sorry for the confusion...I was just wanting to hear from someone who might have done the conversion. It's in the garage right now getting the SBC clutch kit! I decided to wait on the dampener to see how it reacts when I get it back. Will post the results later...

Thanks, Wade, for checking that out for me! :)

I talked with ZF directly over a year ago before I purchased the SMF from CPMac and they (ZF) never indicated anything about a dampener requirement or that the SMF would hurt the ZF tranny. I can probably dig up the email.

Thanks,
Tim

Just thought I would post a quick reply to let everyone know how the conversion went. I didn't install the dampener like the dealer suggested. I only get a little trans chatter if I don't give it enough gas (diesel...LOL) when I let out on the clutch...Probably not that much more than before really...My suggestion, after converting to smf....save your money on the dampener....You don't need it.

I talked with ZF directly over a year ago before I purchased the SMF from CPMac and they (ZF) never indicated anything about a dampener requirement or that the SMF would hurt the ZF tranny. I can probably dig up the email.

Thanks,
Tim

I think a lot of use would like to see it if you can find it.
Thanks.

The Dodges and the Fords are both using SMF Flywheels in their setup without serious longevity issue's, I don't think that the ZF tranny's are much different. I also haven't heard of too many ZF's having internal problems with the syncro's or internal's due directly because the owner installed a SMF. I to have talked with ZF on this issue and their tech informed me that it didn't seem like a problem that would ever create enough problems to be addressed. In theory it makes sence to have a dampener, but I don't think it's something that is ever going to create a bunch of problems for the ZF owners. The only reason that it creates problems in big rig trucks is because they see millions of miles and have much more stroke and diesel spike then our tiny duramax motors in comparison. You should better spend you time thinking about finding a new motor after you rebuild your current one a couple times.

Cheers,
Wade

I asked the question in an email to which I received a reply within 24 hours, something you don't typically see from a large US company or any large company. My hats off to ZF, they seem like a real class act all the way.

To paraphrase what was said:

I asked specifically why GM used a DMF and what would happen if I were to replace my DMF with an SMF, would it damage the tranny?

The response was that GM wanted a DMF for reduction of NVH. ZF indicated that if the tranny were to be used with an SMF instead of a DMF, they would use a part with "the 3 tabs on the dual cone synchro ring hardened". But, they also indicated that since GM purchased the same tranny for their medium duty truck line, which uses an SMF, they (ZF) opted to not have two different parts visually identical and so instead put the hardened tab version into both which means the tranny we have is SMF ready.

Deadeye -- If you want a copy of the note, PM me.

Tim

That's good to hear that our ZF's will be ok with SMF's. The Ford tranny is a ZF too isn't it?

That's good to hear that our ZF's will be ok with SMF's. The Ford tranny is a ZF too isn't it?

yas ford has the ZF but they have a built in oil cooler.

yes the ford tranny is the same.

Actually, there was a post on this forum a while back about a guy who busted his input shaft twice (ZF6). The dodges do also, that is why SBC makes an aftermarket input shaft for them.

Tim sent me the e-mail from ZF and it seems to be a good explanation of their position. Hopefully, they are more honest about their products than GM seems to be about their DMF! However, reverse torque will eventually have an impact. Everything on this planet breaks eventually !!