Vibration/ Seat of your pants, not felt on shifters

[Mikldom]

84 GL, dual range, 4inch lift, 15inch pug alloys 205/75/14 all terrains..

 

Been running great for quite some time..

 

did a passenger axle change last weekend, all WAS well.

 

Ran it from NC to PA/NJ, and all over over last week with no problems until almost 100 miles from home (400 miles straight through with no stopping 'cept for gas)..

 

It started getting what felt like a bad vibration from under my A$$. I do not feel any vibration on the 4speed stick or the 4wd shifter..

 

I did notice tho, that at slow speeds, and the clutch pushed in, it felt like the tranny would 'jump' only at idle.. under power nothing.

 

high speeds, no vibration when pushing in the clutch or going out of gear, only during acceleration or under power.

 

The new axle could possibly be bad, who knows, I did manage to feel it and it felt hot, but I think all cv axles get hot when driving.

 

it did start to 'feel' better right before I got home.

 

No unusual clicking or ticking or binding in turns.

 

could this be bad front axles? bad back axles? center driveshafts? or bad front wheel(hub) bearings? I know, could be all of them, but what/who has expirienced this, and what did it turn out to be?

 

thanks in advance.

 

/mike

[ScottG]

Since you fell the vibrations in your butt & not the steering wheel, I will begin by assuming the problem is in the rear axle or rear tires. (This is a BIG assumption on my part).

 

Start with the easy stuff - the tires. Jack up one side of the rear & carefully go over the tire tread. Make sure there have been no belt separations, etc. look for lumps or bumps. Check the sidewall, too. While the wheel is off the ground, grab the tire at the 12 o'clock & 6 o'clock positions & see if there is any play. Try the same thing with hands holding the tire at the 9 o'clock & 3 o'clock positions.

 

Now lower the car & jack up the other side of the rear & go through the same process. Does the movement (if any) of the tire with hands at the 6 & 12 o'clock postions & hands at the 3 & 9 o'clock positions feel the same as the other side?

 

These little checks & tests should provide some clues as to the problem. I'm not all that familiar with the 4WD system since my GL wagon is FWD. If these checks yield no answers, I must defer to knowledgeable brother members.

 

ScottG

[Durania]

I had a seat of the pant issue when my Toyota threw the weight off one of the back wheels. Might give that a look.

[edrach]

Vibration under acceleration that goes away is almost always a bad DOJ on one of your axles. Frankly, I would suspect the one you just installed. Not likely the rears; they just never seem to go bad; and when they do it's not with those symptoms.

[TomRhere]

Another cause of "seat vibrations" is u-joints going out. Drop the rear driveshaft and check u-joints for any binding and/or sloppiness. By sloppiness, you'll be looking for movement of the cross in any of the bearing caps.

 

Just went thru this with both the '85 and '86 BRATs. The '86 had siezed a rear u-joint bearing, and the '85 had way worn bearings in one cap.

 

 

Not sure on the shifter jump issue. At first I was thinking bad tranny mount, but if that was the cause, it would do it more often than just at low speed.

[Mikldom]

Brand new axle just installed last sunday, is bad.. I took it out, and the inside pressed on cap on the tranny side of the axle came out, and is flopping around in there, and likely mucked it up..

 

I made Autozone eat it, since it was only a week old, and was very specific I DID NOT want to use my warranty.. I know, Autozone axles are complete crap, and they usually click as soon as they go in, but they are convienent, and I can usually do an axle in about 2 hours.

 

I am working on getting a ball joint out, and will start another thread for that.. being a pain.

 

/mike

 

 

Vibration under acceleration that goes away is almost always a bad DOJ on one of your axles. Frankly, I would suspect the one you just installed. Not likely the rears; they just never seem to go bad; and when they do it's not with those symptoms.

[edrach]

Brand new axle just installed last sunday, is bad.. I took it out, and the inside pressed on cap on the tranny side of the axle came out, and is flopping around in there, and likely mucked it up..

 

I made Autozone eat it, since it was only a week old, and was very specific I DID NOT want to use my warranty.. I know, Autozone axles are complete crap, and they usually click as soon as they go in, but they are convienent, and I can usually do an axle in about 2 hours.

 

I am working on getting a ball joint out, and will start another thread for that.. being a pain.

 

/mike

Judging from what you found it confirms that the DOJ (inner) was bad. Good to make Autozone eat it.

 

Just a comment, the clicking noise indicating a bad axle is always from the CVJ (outer). A bad outer joint will click under full lock conditions indicating failure.

 

A DOJ failure is almost always silent (NEVER clicking in my experience). Vibration under acceleration which goes away instantly when you let off on the gas is the hallmark indication of a bad DOJ. The vibration can be very minor or so bad you think the transmission is about to fall out of the car.