All,


I've been away from the forum for quite a while. long story. built my truck, sold it, then got it back. So, I apologize if I haven't responded to questions about my build recently.


Anyways, I'm in need of some help. I have this harmonic vibration that I can feel in the floor of the cab up through the steering wheel at speeds of 50mph +. I can't really notice it putting around town.


I was told to check my custom exhaust. maybe too tight? causing binding? I know there wasn't a lot of space for it.


Also, to check driveshaft balance. I had it balanced once before, anything is possible.


These two would be the easiest to fix.


The engine doesn't shake at all. While at speed I can put the transmission in neutral and it goes away.


My tires are junk, probably, but they are in similar condition when the 360 magnum was in. No shake then..


The Hemi sits right where the 360 was. The drive angle should be fine.


It's maybe more pronounced when I engage the overdrive. It's hard to tell it still rides like a truck built in 1992.


Any thoughts? Thanks a lot!!

 

Couiple thoughts,

First I would check the Rims, by that I mean, based on the photos you have Aluminum rims, when they balance those they usually use stick on weights, they can and do pop off.

Second, even though you had the drive shaft balanced, it is possible for the weight to come off, look at the drive shaft for a discolored area where the weight might have been, if it was the stock weight it will be rectangular with 2 little projection weld spots. If the weight is there, take a hose clamp, the kind with the "worm gear" and the little slits all the way around it. put it on the drive shaft close to the balancing weight with the adjustment screw opposite the weight. Take it for a test drive.

If the Tires check out, and the driveshaft is good, you may have something "Tweaked" in the tail section of the Tranny, possibly the tailshaft bearing, if the previous owner was giving the truck a "workout", with those large tires and the hemi engine, something may have bent.

Jake

 

Ok thanks. I'll check them out this weekend and let you know.

Jeff

 

the wheels and driveshaft check out fine. Something is causing it while the drivetrain is under load. It won't do it while in neutral at the same speeds.

 

Is It just at 50 odd miles or so it does it or just any thing over? Sounds like my problem too. Mines just around 45-50 mile an hour mark it turns into a margarita maker.

 

That eliminates the easy stuff...

Put the rear end up on good jack stands, check for free play in the drive shaft that might indicate a U joint issue. grab the tail shaft yoke and check for play in the output shaft.

with the tranny in park, have someone rotate the tires while you watch, the drive line, put your hand on the differential yoke when the tires are turned forward and back does it feel like the yoke is moving any direction other than around. if the bearings that support the pinion gear are worn, that would cause a load only vibration, usually you will hear a clunk if you let off the throttle while going down hill. with the throttle on the yoke is being forced down while the pinion pivots on the bearing and is being forced up when you let off the throttle or slip it into neutral, the pressure is released and the wheels drive the drive line.

while the truck is up on the stands and,If you are comfortable with it, and the parking brake is in good working order, set the parking brake, have someone you trust get in the drivers seat while you watch the driveline. put the tranny in reverse. Does anyting move? put the tranny in forward, does anything move?

Hope this helps.

Jake

 

thanks, Jake! I'll have a chance to mess with it again next weekend. I'll let you know.


Jeff

 

Cooreman,


the vibration gets worse at highway speed. I can still feel it around 45mph though. It's very subtle. I did notice my 8 3/4 had puked some oil on the garage floor...not good. I still haven't been able to inspect the driveline yet. Going to try tonight. It does clunk when I put it in gear. It's been doing that since way before the vibration but maybe that's how it started.


Thanks

 

Clunk going into gear, vibration at 45MPH?

U-joints.

I didn't have the vibration, but was almost without one of the spiders on my U-joints (!!)

RwP