I have a 97 4x4 ext cab XL. This model does not have a tach so its kind of hard to pinpoint when and how long this vibration occurs. Its very noticible in third around 55 mph. I can watch the 4x4 shifter and its vibrating like crazy! I can feel it in the seat as well as the steering wheel. You let go of the accelerator and it pretty much chills out, but when you stomp on it...very annoying. Maybe U-joints? I guess this is what happens when you abuse your truck.

 

Could be ujoints, rear axle bearings, transfer case, transmission, etc. You'll just have to start with the cheapest and easiest and work up from there. Start by checking/changing the transmission and transfer case fluid if it hasn't been done in a long time or looks burnt/dirty. From there then check the ujoints in the rear axle. From there then check out the rear axle lube and look to see if you can visually see any problems with the bearings. Ideally you would check for proper backlash with a magnetic dial indicator. Also check for tightness and condition of the transmission mount.

 

What type of tranny is in the truck? A few things. I would like powerstroke suggested start cheap and easy and work your way up. I would go with u joints first. Have you lifted the truck or done anything that would change the driveline angle. What you are describing sorta reminds me of what would happen if your drive shaft is too long. When you accellerate the axle wrap causes the driveshaft to be shoved into the tranny further and if it bottoms out then there would be a transfer of vibration up through the rest of the truck.

Here are some things to try:

Is it speed related or RPM related. If you put it in another gear and run it up to the speed it does it in does it still do it?

Is it a tire? At highway speed is it a buzz or is it a slower cadence? The driveline to the rear diff turns 3-4 times faster than the wheels so that can help start narrowing it down.

Rotate the tires. I know it may sound crazy but you would be amazed at the things a tire with a bad belt can cause you to think and feel.

If you have over 40-50K on the truck I would change the u-joints just on principle. It is a cheap and easy thing to do that you would have to do eventually anyway.

Check for fluid leaks. If the vibration is really bad then chances are it could cause a fluid leak somewhere. If the driveshaft or u joints have been bad for a while and are really going south then the seals around the tail housing could be leaking. Check the pinion seals and axle seals. And this should go without saying but check to make sure everything has enough fluid in it and like powerstroke said changeing all the fluids is a good idea. Check for metal etc. in the fluid. If there are broken components then that should show up.



Driveline vibrations are a real pain to diagnose and correct. Stick with it and do the obvious things first. I hope these things will get you started.

Mike

 

Well thanks guys for giving me some tips and what to look for. My truck has 130,000 miles so I guess it wouldn't be a bad idea to go ahead and change the u-joints. At first I was thinking it was the tires, since they were almost gone, so I bought some new ones. My truck is still in stock form, no lift of any type. I'll probably do the u-joints some time this week and see how it goes.

 

Ever thought of putting the truck on jackstands and have someone run the truck thru the gears.
With you outside, looking up at the drivetrain/wheels, you might be able to eyeball the problem

 

Well it would be a good idea to lift it and check out for any visible problems. I prolly try that at the Navy's hobby shop this weekend if swapping out these u-joints doesn't fix it. Well I have the driveshaft off and did the u-joints but was wondering what people use to lube the splines at the slip yoke. I read in one of these forums to use teflon grease but no one sells it. Whats the alternative? I definately need to lube it before I throw it back on and see if the u-joints fixed this vibration.

 

I was having a driveline vibe on my '99 sc with 38000 miles. The trans extension housing was also leaking a little.

Today, I took it to a drive shaft specialist and had a new seal and bushing installed in the extension, the drive shaft ends cut and re-welded (the front was .050 out of round, the rear was .025 oor). There were lots of weights welded on from the factory. They removed those and re-balanced the shaft. New Spicer u-joints.
It now runs smooth, like new. Just over $300.

 

Well I changed the 130,000 mile u-joints and made no difference. Its pretty hard trying to diagnose these types of problems. When I have a chance to go to the Navy Hobby Shop on some weekend, I'll do what one of you recommended and run it while its up on a lift. That way it may help in the diagnosing process.

 

The Teflon grease you a looking for should be availiable at a Ford dealership. That is where I got mine. Mine came in a Tube the size of tooth paste for around $10, and it is light blue in color. Perhaps other places have it but call it by the Chemical name for Teflon (PTFE: Polytetrafluoroethylene, Dupont owns the name Teflon)

This grease is recomended because if some of it migrates up into your transmission, it will not contaminate your transmission fluid.

I Know it is to late now but I hope it helps.

Dpostman

 

I have the same problem....the manual 4x4 shifter vibrates and ticks? when you are on the gas. Not as much when you lay off of it. You can see and feel the floor mounted 4wd shifter moving. It is a pain because of the sound in the cab, as well as the thought of damaging my tranny. At one point I pulled in to a rest stop to shift through the 4wd gears and back to 2wd to see if it would help. At the time I thought that it helped a little, but the sound is definitely still there.

I recently changed my front transfer case fluid. .......maybe it is an unbalanced drive shaft as mentioned??

 

i just changed the rear u joint on my '99 sd dumptruck...at 25 mph the coffee was shaking out of the cup while in the cup holder!...at 55 it rumbled really bad...i did'nt notice it 'till i was out plowing with the window down(windows allways up diesels are noisey enough)...against snowbanks it really was squwaking....now its smooth as glass...zap!

 

My truck will start vibrating once I have about 30,000 miles on the tranny fluid. I change the fluid, it goes away.

 

I'm definately going to replace the fluid to Mercon V. Now that I think about it, this vibration graduallly got worse after I drained the tranny to replace the gasket. I refilled with dextron.