Vibration at highway speeds

[mrw1108]

A lot of great feedback and I really appreciate it. This is much more than what I was getting from the dealer. Just to recap the diagnostics that has been done;



1. At highway speeds (50-70 mph) when the clutch is depressed vibration is reduced DRAMATICALLY however I can still feel some mind vibration. At lower speeds under 40 mph is hardly noticeable

2. Dealer installed a new set of stock rims & tires for road test only. Problem still there.

3. Rear DS UJ's (both) replaced.

4. Upper/Lower Ball Joints Replaced - They were bad but didn't resolve problem

5. Stock tires Balanced and rotated - No change in vibration

6. Check for vibration while parked, run engine RPM's from 800-2500 - Smooth no vibration

7. Dealer replaced last year front uj on one side and outer wheel bearing on other side. Can't find receipt, but work was performed.

8. No missing weights on drive shaft.

9. Dealer checked Front & Rear brakes and rotors checked good

10. Dealer checked front inner/outer wheel bearings checked good

 

[sag2]

OK, time to quit guessing and find a dealer with a vibration analyzer. Some of the Chevy dealers had it (EVA) as a required special tool. Some Chrysler dealers were part of a pilot program and got one for free, others purchased one. You are looking for an "EVA" (electronic vibration analyzer) or an MTS 4100.

 

[mrw1108]

I have already spent over 500. 00 dollars in diagnostic fees at the dealer and still no clue to what the problem is. So at the advice of my brother "SWithrow" setup a Trial Membership in the hopes to get some real advice from Dodge truck owners and mechanics. So far I have received a lot great suggestions and will start with the drive shaft checking for balancing issues, then to the transmission - Clutch possibly. The dealer does have something similar to what you are suggesting, measures vibration changes through frequency. It may be the same not for sure.

 

[sag2]

That sounds like a vibration analyzer. It measures the frequency of the vibrations and the EVA needs you to calculate what part is rotating at that speed. The MTS 4100 does the calculation for you and says right on the screen "first order driveline" etc.

 

[Prairie Dog]

I wish you luck in finding your vibe. I've had a vibration at 40 MPH for years and no one can find it (posted on the TDR a while back). I've replaced drive shaft, tires and wheels (w/stock parts) and clutch. Checked front bearings too. Tire shop ran it on lift in 2WD, 4WD and it's smooth. Does same thing clutch in or out. I've given up but I recently mounted much heavier 285/75/17 Toyo AT's and the vibe is greatly reduced. Must be a brake rotor or something but I've just learned to stay away from 40 mph.

 

[Loren]

... When I push the clutch in vibration goes away...

I’m stuck on this interesting bit of information. It seems to me that if the vibration goes away when the clutch is disengaged it cannot be a driveshaft, brakes, axle, or any of the other parts that continue rotating with the clutch disengaged.



Actually, I suppose it could be the engine itself if the engine is allowed to change RPM’s when the clutch is disengaged.



To me, mrw1108's statement above points strongly to the clutch itself.



– Loren

 

[seafish]

At highway speeds (50-70 mph) when the clutch is depressed vibration is reduced DRAMATICALLY however I can still feel some mind vibration. At lower speeds under 40 mph is hardly noticeable

While I have NOT read this entire thread, this statement alone would indicate to me that the dual mass flywheel (DMF) on your truck is going bad. This is has been previously observed on the 3rd gen trucks with the g56 transmission. Chrysler engineers selected the DMF to help REDUCE NVH (noise, vibration, harchsness) but the DMF they selected is apparently NOT up to the task of doing so while coupled to the mighty CTD, and some early failures are being reported. Unfortuneately, I am pretty sure that it is NOT covered by the warranty, even though it should be, as it is part of the driveline, but NOT a wear item. Do a search here on TDR for DMF and read more about it. Sorry if I am repeating or denying what others have said earlier, but didn't have time to read the whole thread.

 

[mpaulson]

If it is a clutch issue, then wouldn't the vibrations happen at a specific engine rpm and not matter what gear the transmission is in and not matter what speed the vehicle is going at?

The 50-70mph would have me thinking of things from post clutch rearward. Are the transfercase mounts in good shape? Bearing issues in the diff???? If it is in the diff carrier, you wouldn't see any leaking like you would with the pinion. Has the pan been of the rear diff?

 

[HBarlow]

Yep, I agree with CFish and MPaulson both. The original poster may not be mechanically inclined and may think that because he feels it at in a certain speed range in sixth gear that it is speed related when, in fact, he could slow down, gear down, and duplicate the vibration at any road speed in a specific rpm range.

IMO, the most likely cause in a truck with a DMF, made even more likely by the op's statement that it diminished when he declutched and allowed the engine to drop to idle rpm, is dual mass flywheel and clutch assembly.