Vibration

[Wick]

I have a 1999 Century Class Frieghtliner that we had Show Hauler convert with a 32 ft box. We looked at 7 different manufacturers before I stumbled onto Larry's Photo's. We then went to Show Hauler and hammered out what we wanted. It was finished last June and we have since put 41,000 miles on it. It has been absolutely great with one exception. We have a chassis vibration that appears when the road speed gets up close to 65 and then it gets more severe as the speed goes up. I started with the tires. I replaced all ten and had them balanced. This had no effect. I went under the coach and checked the drive line. All looked fine. I removed each shaft assembly and inspected them. They appeared to be no problems. When the chassis was streched all the shafts were built then. They do appear to be a degree or so off from the rear looking forward to the front yoke at the transmission, but I was told that the tolerance was something on the order of 2% per shaft. I then took the coach to a good alignment shop but they also found nothing amiss. Next I jacked the rear wheels off the ground and attempted to run the drive train at 65 mph, but I could not get the autoshift to go up to that speed, I think that the computer for the Detroit and the transmission had something to do with that. I did detect alot of noise coming from the back rear. We pulled it and found it a bit out of adjustment. after re-installing the rea we took it for another drive. But the vibration is still there. I do not know what I should do next and would appreciate any help. I am contemplating removing the transmission next and going thru it and then the front rear, but I don't want to do that if I do not need to. The coach has 543,000 miles on it and I bought it specifically for this conversion. Any suspension parts that were showing signs of wear were replaced at that time. We pull a 32ft trailer with about 20,000 lbs of sporting clay traps and accessories in it.The vibration is there pulling a trailer or not...
Thanks for the help
Wick

[RICHARD PHELPS]

Wick:
Two quiestions, what trans are you running and is it single axle or tandem? I went thru the same routine 2 years ago and got most of the drive line vibration out of mine.

[Wick]

We have a 10sped Eaton autoshift. It is a Tanem axle.
Thanks
Wick

[OLDphoneman]

Wick --

You had the conversion done -- Did it vibrate before the conversion?

If not -- It's most likely drive line.

An out of alignment will usually only cause accelerated tire wear. A severly mis-alligned configuration will cause crabbing.

But -- An out of balanced drive line will cause vibration. Also a dry/worn out carrier bearing will cause noise/vibration.

I'd suggest -- Either taking it to a drive line speciality shop and have them re-balance each drive shaft -- Or you take them off and take to a drive line shop for this work.

If the vibration just happened one day -- You probably just spit a balance weight off one shaft.

As far as noise goes -- What you attempted to do is neither valid or safe -- That being -- Jacking it up and applying power to the drives.

Dave

[onezman]

If the suggestions above dont solve the problem, you might check the motor and transmissin mounts. Make certain they are tight. Front dampers can also go bad, that can cause vibrations.

onezman

[Warpath]

I know your getting alot thrown at you, but I also had a vibration that began at 55 mph. Very annoying! I was in a rush to cure this since it was going to Show Hauler for the Conversion. Since it had not been stretched I leaned towards a wheel/tire problem.

I went with all new Aluminum rims front/back and new front tires. The guys at the tire shop thought it was a slightly bent rim,(no broken belts in the tires) and said most truckers wouldn't have given it a second thought.

That fixed it. You would have thought I could determine if it was front/back related or wheel/drive-line but I could not pin point it. Although there was no fluctuation in vibration when I was on or off the throttle so I pretty much put the tranny/motor on the bottom of the list.

Let us know if you get it figured out, when you do your going to love that thing again, I know I did.

[Wick]

Thanks for all the info. I have had the vibration since the conversion and I did not have the truck before it converted. The first time I drove it was when we picked up the finished product.
Dave,
we have a full service truck shop and I can assure you that we had the truck properly locked down before running it with the wheels off the ground. I have had it at a drive line specialist and they have determined that the drive shafts are ok. We are going to change the air ride height in the morning and check a couple of other things....I'll keep you updated.
Wick

[Reluyog(Damian)]

You might check the shimming at the power divider input, or possibly a bad bearing there. The slip joint splines on the drive shafts might be bottoming out, or a bent yoke? A couple of long shots might be the fan clutch or water pump, or a cracked or broken engine bracket or bolts that hold the alternator, air conditioning compressor, etc. Good luck.
Damian

[This message was edited by Reluyog on March 24, 2004 at 10:06 PM.]

[Patrick]

If the pinion angle is off it will vibe going down hill. When they did the build they should have swapped in new perches to get the pinion angle correct. One easy way to test it is raise the ride height in the rear by straightening the vertical rod on the diff. If it gets worse your angle is off.

[Patrick]

Wick! Please keep us updated...inquiring minds want to know!

[Wick]

The weather has not been very good but we have made some adjustments and do not see any improvement. We will have a closer look this week of the front rear.
Wick