Crankshaft harmonics with solid clutch disk??

[3rdstrikedsm]

I have been having a decel noise since I put my unsprung 6 puck in my evo and I am now remembering a conversation I had with an Exedy rep years ago and he said since I am using an unsprung disk that the harmonics tends to be transfered to the rest of the driveline since there is no springs in the center hub to help absorb some of this,
Now I also remember him saying the front 2 cyls harmonics/vibrations are mainly absorbed by the harmonic dampner and the rear 2 cyls are mainly absorbed by the clutch disk.

I know a lot of people have had decel noise and maybe this is the root problem for some of you, I know it won't hurt anything but it does get annoying some times.
My question is, If I were to invest in a better dampner such as Fluidamper help absorb some of these harmonics?

Just an idea at this point but I really don't want to switch back to a sprung disk as I hate them.

Curtis, You got any input?

 

[Brianawd]

Quote:
Fluidamper help absorb some of these harmonics?



It works about the same as a factory one. The reason people go with after market ones for our cars is because of the stock one likes to fall apart.

 

[jepherz]

Keep in mind that the dampner pulley is there to protect the crank from the accessories. Vibrations produced in this fashion won't be felt/heard by the driver; think of the give in the belts that connect these devices, that's quite a 'bushing' in the first place.

I don't know much about harmonics at all, but the balance shaft description sounds far fetched to me.

 

[3rdstrikedsm]

Balance shaft? What are you refering to?

 

[curtis]

I had a long talk with the owner of PTT about this topic the fuildamper actually eliminates more than a stocker and way more that a aluminum pulley. As the motor spins down the crank is twisting, they all do aftermarket or not. The clutch is engaged and and on a unsprung hub the drivetrain it locked up to it. If I had to bet your disk has a warp or you have a out of balance situation going on somewhere if it just started after the clutch install. The way the fuildamper works is a ring is suspended in goo and and spins inside so it has more movement that a ring vulcanized to rubber.

If you ever have a chance to talk to the guys at PTT and see one of there units in person you'll never buy anything else. I would give them a call inquiring about one of there dual disks and swap it out because it can't be good on you main bearings and thrust in the long term, harmonics can screw up alot of stuff, stress risers on gears and shafts etc.

Now back to the twisting effects I had a friend that was looking at building a small dampener for his cam in a V8 once. test had proven at 8K and above the cam was twisting about 12 degress or so, from front to rear, and was playing havoc with cam timing durations and total lift. I think he ended up rifle drilling the cam to lighten it and since a tube is stronger that a solid rod may have solved the problem, engine was sold before the car ever made a clean pass anyway.

 

[3rdstrikedsm]

Well the noise is very minor and if I give it over 10% throttle it goes away but it could have something to do with the fidenza flywheel as well since I have heard they are out of balance right out of the box /ubbthreads/images/graemlins/dunno.gif

I have a line on a quartermaster twin disk that I was thinking of but in my opinion this is not needed for a high 11sec car that rarely sees the strip but does get run hard on the streets.

 

[jepherz]

Quoting 3rdstrikedsm:
Balance shaft? What are you refering to?



Whoops, I read what you wrote wrong. Don't pay any attention! /ubbthreads/images/graemlins/wink.gif

 

[3rdstrikedsm]

I talked to the guy a ptt and what a wealth of info that guy is!!
I picked his brain for a good 45min and we came to the conclusion that an ATI damper is what I need since it is tuneable and should cure the problem so I was on the right track.

I just love to talk to people like him since it seems as if he has a good logical answer for every question I threw his way, The crappy part is I did not even catch his name /ubbthreads/images/graemlins/frown.gif

In short he said not to worry about it and to invest in the ATI if need be.