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Road Vibration where to look?

U-711ipmc

U-711ipmc

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OK. I've got an '88 Suburban that has a bad vibration starting at about 35-40 MPH. 50-55 it's almost unbearable. Hood is shaking in the center worse than a shaker hood scoop and the whole vehicle shakes BAD and annoying!

Now the back story...I bought it like this. Replaced a few small parts and drive it around my property. It's a 3/4 ton on 38 TSL's w/ 6-8 inches of lift.

I am looking at replacing u-joints and taking the tires to get balanced (or as close as possible).

My question is where else should I look? Wheel bearings (since I don't know how old if ever been replaced)? Wheel joints? What else?

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scottsdale86 said:
Driveline angles and U-joints would be my first guess.
Click to expand...

^This, and also, it's probably just the 38" TSL's. Are they the bias ply or radials? If bias ply, then that is the nature of the beast. And most tire shops won't do a tire that large unless you know a place that will. I just put a whole bunch of airsoft BB's from walmart in each tire and it makes it manageble going down the road. I can go 65 or so with no vibs (after the flat spots work out of corse :haha:)
 
Eliminate the easy stuff first. Go to the junkyard, or the used tire store. Grab a set of cheap standard size wheels and tires.
Have them balanced at a tire store, and put them on.
Tires that big generally do not run smooth. The vibration from them ranges from mildly annoying to undrivable.

If you still have a vibration with standard tires, then you can start hunting the other stuff.
After you get it smoothed out, then you can put the big tires back on and see what they are going to need.

Most of the time, some shaving and/or airsofts will get them to the point that you can be comfortable.
But like he said, bias belts are usually going to be bumpy.

Also, if you have not washed them after that mud trip, that is going to be a problem.
A couple pounds of mud stuck to the inside of the rim is never conducive to smooth driving.
 
Ya the mud was all cleaned off this last time I took it out. I may look at getting a different set of tires and wheels and trying that.
 
A word of caution about the Cherokee steering shaft. If you got the shaft by melting the plastic isolator and collapsing the shaft you will most certainly have a little play in your steering wheel. I do because of the way mine was collapsed to get out of the donor vehicle. That plastic isolator is what minimizes the vibrations and annoying clunky noise during low speed driving and parking.
 
It's the tires. Anything that makes the truck shake like that at those speeds has to be heavy and slow moving. Obviously it increases with speed. Tires/wheels are the only thing moving at that speed with that kind of weight to shake a truck.

A driveshaft or bad u-joint is spinning at higher speeds (3-4 times) than a tire and will result in a buzzing kind of vibration or simply a noise.

How old are your tires? Dry rotted? Cracking? The tread could be starting to separate from the carcass which results in a shifted belt or a bubble in the tread. Impossible to balance and it will get worse and ultimately fail if not replaced. This may be the case if your tires are old, even if they have plenty of tread left.
 
If your wheels are balanced, your u-joints are good, and you're still having the problem, pull your driveshaft and take it to a drive line shop. They can check to see if it's balanced or not, and re-balance if necessary.
 
Is it death wobble? Check all the ball joints, tie rod ends, wheel bearings, spring/shackle bolts and everything up front. Is it really consistent once it starts or does the shake kind of fade in and out? How are the tires balanced?

You might lift each corner and spin the tire to look for obvious out-of-round or runout issues (put some fixed object near the tire so you can judge how far out the rubber is). You might have one tire or wheel that is bad and the rest are OK. It's hard to find a round bias Swamper. I actually just got rid of my 38" TSLs because of the shaking. I had tons of air soft pellets in them, but some were like 1/2" out of round.
 
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