6.7 w/ 6spd manual, Clutch vibration?

[professor39]

Hey guys With a heavy load I am getting a vibration when I start letting the clutch out in 1st or Reverse. It feel like axle wrap up but when I have a friend watch the drive line there is nothing happing. It gets so bad that you have to stop. It will be a real problem when I start hauling horses. Any Ideas?

 

[Jeff Knight]

It might be a problem with the DMF.

 

[professor39]

I'm Sorry what is a DMF

 

[GCroyle]

DMF = Dual Mass Flywheel

Trucks equipped with the G56 transmission have a DMF. These have the possibility of vibrating as they age, they go out of balance. Test in neutral, increase RPM, if no vibration it is not out of balance. Might let someone else drive under the same conditions and see if it happens to them also.



Keep us posted, how many miles on truck?

 

[professor39]

There is only 2000 miles on the truck. I notice it more in reverse than in 1st but it is still there. I will try the test later this afternoon. I have always noticed a little vibration/pulsing on the pedal when the pedal is released. Maybe this has something to do with it also.

 

[GCroyle]

I would be very suprised if a 2,000 mile truck had the DMF vibration problem.



It is easy to check, but it is an RPM dependant vibration.



Chatter is a series of uncontrolled engage/slip/engage/slip cycles that occour rapidly and out of the drivers control during 1st and Rev engagements from a standing stop.



Might want to focus on "it does this, when I do this" and get back to us.



I rode in one of our trucks (trailer attached) with an employee and he engaged the clutch in such a way that I thought the dash was going to pop out. I got his foot off of the fuel and tried again from a stop, smooth as silk. He set up a "leg resonance" with everything going back and forth, it was nasty.

 

[jelag]

Gary is right... . HI Gary... ... I might add, that when you start out... the design of the truck, transmission is such that you are to not add throttle on a level road until the clutch is fully engaged... The engineers have designed the system to allow the torque of the engine at idle to pick up the load and start to move it... once the clutch is engaged you add throttle and than shift as needed... .

Todays inexpensive clutch facing tend to glaze up, allowing them to chatter like Gary mentioned above... . once this occurs there isn't much that can be done but change the disc.....

Hope this helps... .

 

[Regcabguy]

No chatter.

Gary is right... . HI Gary... ... I might add, that when you start out... the design of the truck, transmission is such that you are to not add throttle on a level road until the clutch is fully engaged... The engineers have designed the system to allow the torque of the engine at idle to pick up the load and start to move it... once the clutch is engaged you add throttle and than shift as needed... .



Todays inexpensive clutch facing tend to glaze up, allowing them to chatter like Gary mentioned above... . once this occurs there isn't much that can be done but change the disc.....



Hope this helps... .

Ditto on this post. Zero throttle input in 1st,2nd and reverse yields me a smooth launch every time and I'm carry 2,000# around all the time.

 

[GCroyle]

Jim, greetings to you from beautiful SC.



It may sound crazy, employees of clutch companies giving advice to engage the clutch at idle, instead of at higher RPM, one of the two choices sells more product, but Jim and I are not recommending it!