03 Driveline Vibration

[Briman]

When I'm at 75 mph there is quite a vibration. I can put in the clutch and let the engine idle down and it is still there. So somewhere from the trans to the tires lies the problem. I have an appointment with the dealer on Tuesday morning and will take the service manager for a ride. My truck has another anomaly as well. When starting out in 2nd gear I can feel a definite wobble in the seat of the pants all through the gear. It is not there in 3rd gear and up. If you let your hand lay on the gear shift during the 2nd gear run you can feel the wobble. If you put a bit more pressure on the gear shift than your normal hand/arm weight you can really feel and see the wobble. The gear shift wiggles back and forth a couple of inches. I don't recall this with my 2000 6 speed. The gear shift does not wiggle like this in 3rd and up either. I'll be heading out across Wyoming and Nebraska in about a month and hope to have this resolved by then. The speed limit in those two states is 75 and I like to take advantage of it.

 

[Steve M]

Briman,

That's interesting. Your truck has the vibration worse at 75mph? Mine is worse right at 66-67mph. The driveshafts in our trucks are both turning right at 3,000rpm at those speeds. Yours being a 3. 73 ratio and mine a 4. 10.

74mphX3. 73X336/30=3091rpm

67mphX4. 10X336/30=3076rpm

If this reflects a constant with others, I'd have to believe it eliminates tires and focuses on the driveshaft again.

 

[Briman]

Has any one pulled the front driveshaft and gone for a drive yet?

 

[Briman]

Steve, I couldn't finish previous reply, had to go to dinner. You may be on to something with your drive shaft calculations. My front drive shaft clanks when I push on it. At first I thought it was coming from the trasfer case but instead, may be play in the slip joint. Does yours make noise when you push sideways on it?

 

[PCline]

The driveshafts in our trucks are both turning right at 3,000rpm at those speeds.

Ditto for me. The dealer has even used the Chassis Ears to measure the vibration frequency in the range of 50 - 56 hz (that's 3000 - 3360 rpm, or 67 - 75 mph).



The only parts turning at those speeds are the pinion gear, driveshaft, T-case (with a 4X4) and the rear output shaft of the transmission.



Interesting... .

 

[Steve M]

I ran my truck up to 75mph on the interstate today. It's smooth as glass at any speed but 65-68mph/2100rpm.

It's going back to the dealer for a rim and tire this week. While it's there, they're going to look further into it. Going by what the book says, I'm hoping some pinion angle adjustment will cure it. If not, it's not any worse than the drone zone vibration of my previous trucks at 2100rpm. Just enough to slightly blur the rearview mirror and buzz my backside.

 

[PCline]

Dealer ran my truck yesterday without the Front driveshaft - no change. Still vibrated between 67 - 74 mph.



Next, removed the REAR driveshaft. Had to install a plug at the rear seal to keep the fluid in T-case. Still no change.



Now they're taking a T-case out of one of their trucks on the lot to swap with mine. New Venture wouldn't send them a new T-case until they proved that was the problem.

 

[Steve M]

That's strange... I'd still like to swap all four wheels with a truck that doesn't vibrate just to rule out the tires. Tread squirm can cause vibration. The only reason I'm focused on that right now is I don't have the resources to try anything else. In my travels I ran thirty miles one way with the tires at 60psi front and rear. On the return I ran at 80psi front and rear. The vibration was still there but felt different and alittle less. It could be that the ride was rougher and made the vibration feel less in comparison.

Mine is 4X2, yours is 4X4, one is 6spd and mine's automatic... Whatever it is must be a common component of our trucks. I assume they all come with Michelin's, AAM axles, the same exhaust and fan etc...

 

[MCummings]

Looks like yall need to run these ???



#ad




I found them browsing through a magazine,, chck thier website @ www.drivetechnologies.com

 

[PCline]

I hear ya on the tire issue. I wish I could swap them out too.



At the moment my dealer isn't looking at the tires. Since I've actually felt the transfer case shaking during one of my own "tests", I'm go to let the dealer change it out. If that doesn't fix the problem I'll have some different tires installed.



My biggest fear is that I have two problems (tires and t-case). I don't want to fix the easy part of the problem and then have my dealer try to tell me "that's the way the trucks are and it isn't going to get any better. " I'll let him change out the t-case and then I'll pursue the tires.

 

[Dean Upson]

Steve,



My wife's Acura had a bad vibration and we tried just about everything. Our tire dealer finally just swapped out the tires (Goodyear Eagles) and the vibration just went away.



Dean

 

[champspa]

I've had the vibration also , in 96 , tried everything the tires were swapped out and it went away , one wheel had about a 4mm run-out . I used that one on the spare.

 

[Vaughn MacKenzie]

PCline, do you have the steel or aluminum wheels? Steel wheels often don't run as true as the aluminum ones and any of them or a combination of them with a bit of runout could easily cause vibrations that seem to come from the driveline or somewhere else.



Vaughn

 

[PCline]

I have the aluminum wheels. And coincidentally, one of the rear wheels had to be replaced because there was a leak through the wheel itself. Porosity in the casting. The vibration didn't change after that single wheel replacement.



I'm not ruling it out, and after the t-case replacement I plan to look into wheels/tires, but wouldn't vibration caused by poor wheel runout be at a much lower frequency than the driveline? The vibration in my truck was measured at 50 - 56 Hz (3000 - 3360 rpm).

 

[Prairie Dog]

I guess I'm one of the lucky ones here as my truck doesn't seem to have this problem. The only thing I did have was what I would compare to the feeling of a bad rod knock at about 2000 RPM when cold and when it only had a few miles on the clock. After it broke in a little it was as smooth as silk. For you guys that are local to me, if you want to make some kind of comparison test drive or something just let me know. Maybe I could drive next to you on the highway and watch for bouncing tires or some other obvious defect. I'd be happy to help.

 

[Steve M]

I just ran accross this site. I thought it was interesting. It shows that a tire can cause a higher frequency vibration but not from being out of balance. But the chart they give as an example point right at the driveshaft. 2100rpm 6cyl 3. 73 with a 3,000rpm vibration.

http://www.vibratesoftware.com/vibsoft/diagnose.htm

 

[PCline]

Prairie Dog... my t-case gets swapped out next week, if that doesn't fixt the problem I'll definately take you up on your offer!



Still trying to get the diagnostic page to load from vibratesoftware.com.

 

[Steve M]

This is very far fetched and probably wishful thinking. I sucked some fluid from the rear axle to about 3/4" below the fill hole. While I was at it, I know... do one thing at a time so you know what does what, I reduced the tire pressures to 55psi front and 60psi rear. We took a ride down the interstate and the vibration is "almost" gone. Could it be possible that the oil level being high in the rear end could cause the differential to paddle the oil and resonate into a driveline vibration? Looking at the spider gear housing shows that a high oil level would no doubt paddle the oil and cause foaming but... I have a severe case of wishful thinking going on here. Tires are still a possibility...

 

[D808]

Steve, I couldn't finish previous reply, had to go to dinner. You may be on to something with your drive shaft calculations. My front drive shaft clanks when I push on it. At first I thought it was coming from the trasfer case but instead, may be play in the slip joint. Does yours make noise when you push sideways on it?





The drive shaft center bearing support on my quad cab has quite a lot of circumferential free play. It's not from the bearing, but from the rubber the bearing is mounted in. However, after reading that others have also noticed this free play, I believe it was engineered that way for some reason.

 

[Prairie Dog]

PCline (or anybody else), PM me if you wan't to get a hold of me as I may not get back to this post in a timely manner.

Steve, I've topped off my fluids so I doubt it's the cause. I haven't tried uping my tire pressures though, their at about 60 fr and 55 rear. As soon as it stops raining I'll check my driveshaft for movement.