mopartruck

hey everyone

My 2006 4.7 6 speed has developed a vibration. it comes on at about 40 mph in 3rd. I had it in to my most trusted mechanic thinking it was suspension or tire oriented. It was not. He said it is something motor or transmission oriented. I guess what I am asking is has anyone else encountered anything like this? or does anyone have any ideas on what it might be?
Any help would be Greatly Appreciated

thanks
Sean

440roadrunner

A good mechanic should be able to differ between wheels / tires and driveline in no time at all.

So is this a lower speed vibration IE tires or related, or a high speed buzz, more like U joints, bent driveshaft, etc?

That would be the first thing.

Second, get the thing "up into" the vibration range, and push in the clutch. Any change? Shift gearbox into neutral? Change?

If the vibration goes away in neutral and or with clutch in, slowly bring engine RPM up to match what you had "in gear" but with the vehicle coasting in neutral.

If this is inconclusive, try bringing up RPM to "that speed" (RPM) while sitting still

These procedures may not FIND the trouble, but they might give you a good idea where it is NOT

Last you can NOT investigate U joints by "wiggling them in place." You MUST remove the shaft and slowly work the joint around feeling for roughness, dryness, etc. and inspect for damage, both to the joint and to the shaft.

You get "off road?" Possibility of damage or impacted mud and dirt?

mopartruck

44roadrunner

thanks - I will give that a try today
the mechanic said he checked in and out of gear, said when he felt the vibration, he expected to see serious damage to the drive shaft or u-joint, but found none.
Today when I was on the freeway I tried varying some speeds but pretty much from 40-65 it was present. I will say the vibration was not as severe at the higher speeds. I did pass someone at about 70-80-ish then there was no vibration in the gearshift at all.
This is all felt pretty much through the gearshift - if that means anything.

thanks again
Sean

Boat Guy

What exactly did your most trusted mechanic do to diagnose the problem? You said it is limited to a speed range, that usually indicates an out of balance condition. As mentioned, you need to test if the condition goes away by shifting up or down at the same speed, and taking the truck out of gear completely. If the problem doesn't go away, recheck the balance points, tires, drive shafts, wheel out of round, ect. If it goes away immeadiately, then suspect u-joints, trans input/output shaft, clutch or something along those lines.

You also might have them check the alignment. As strange as it sounds, the vehicle can pick up a vibration if it is out of alignment enough. My Challenger had the toe out and was vibrating at 70. It wasn't out that much either but it was eating up the tires.

TVLynn

Have you done a compression test ?

mopartruck

I took it for another drive and noticed the vibration both in and out of gear -

I do notice it more through the gearshift than the steering wheel - if that helps?

it definitely worse at 38-40 mph

I don't know if this matters or not but it does have an aftermarket exhaust on it that has a bit of rumble as well

I know my mechanic checked the drive shaft and connections

does any of this point at anything more specific?

Boat Guy

Vibrations felt through the gearshift tend to be rear axle/drive line related. Through the steering wheel would most likely be front end related. The in gear and out of gear being the same pretty much rules out u-joints as unloading them usually removes the vibration. The speed range you are saying screams tire out of balance or out of round. Especially if the vibration starts to go away once you go faster than those speeds. I'd take it to a tire store and have them check the balance on the tires.

mopartruck

I am leaning that way as well - it really feels and acts like that

I just want to make sure its not something more serious that breaks and leaves me out in no man's land - or worse leads to an accident where someone gets hurt.

I bought the extended warranty with it just in case -

thanks again

Sean

440roadrunner

Sorry this is ABSOLUTELY incorrect. "Up here" where we have fairly wet / sloppy winters, and when I was younger, had many people living on muddy, dirt roads, some of them hardly roads, it would be VERY common to have a U joint "show up" as bad by vibrating

with LITTLE significant difference as to loading.

THE ONLY WAY you can check a driveshaft and U joints is by removing it

mopartruck

that seems to be the common consensus so far with people that have commented or that I have asked - u-joint or tire balance. my understanding is that the extended cab trucks had an extra connection as well to make up the distance and angle (?) one more connection that could be a problem as well?

thanks everyone

Sean

Boat Guy

Physics must work differently up there. I have done a lot of off roading and we eat up u-joints and they all pretty much act the same. In fact I have a 85 Chevy K10 with a bad rear U-joint that I haven't had time to change. If I let off or put it in neutral the vibration from the U-joint goes away. And no I didn't need to drop the driveshaft to know that rear U-joint is bad. The best way to check them is to drop it, it's not the only way.

The extra shaft is usually connected with a carrier bearing. The carrier bearing doesn't unload when you push the clutch. A bad front U-joint could allow the shaft to drop and pole vault the truck causing significant damage. If it is under warranty, I'd have the dealer fix it since it should be covered. Make sure they call you once the find the problem so you know it's covered.

440roadrunner

I doubt like hell that this is true



Yeh. OK. whatever you say. I was not talking about the ones that are so damned bad that they rattle your teeth. I've seen lots of them that rust up and "seem tight" but don't make noise. They just simply vibrate at high speed.

Boat Guy

I doubt it to, just trying to give you the benefit of the doubt. We check them by applying leverage to see how much play they have. When they are falling apart loose even Ray Charles can see them. The truck's U-joint won't move by hand but will with a screwdriver.

RacerHog

Shoot us up a video Sean.... Will get this hashed out....

mopartruck

thanks everyone -
racerhog thanks - I don't have the ability to do that -

I did have it in to dodge - thankfully along the way they found a water pump pulley that was rather loose and we were both surprised we did not see fluid everywhere. They did disassemble the u-joints and they checked out to be ok. The previous owner had put on some type of dual exhaust that may or may not have been made for the truck. They had it buttoned down too tight and did not use the stock hangers. It is also beginning to rust quit a bit(a new adventure to come).
The service tech felt that the exhaust may be causing the problem vibration. he said he would drive it and coast in neutral then coast with the motor off. The motor off he said did not produce the vibration. So he reworked the connections. So far not too bad. I still think the vibration is there around 40 mph. But overall the vibration did get better.

I am going to keep an eye on it, I still think there might be a tire problem - balance - it behaves like that to me but who knows? He did think the tires on the truck were not the best for regular highway driving but . . ..
someone else had mentioned maybe brake or alignment as well?

thanks again everyone

Sean