vibration

yep even all 6 shocks

 

Yah, sounds like you have a tire that is out of round. Look at the centering tabs of the hubs were they touch the rim and see if any of them have a jape. If there is, that tire is out of round. Tires are so heavy when they spin at highway speeds that they will shake the whole truck!

 

I even got all boned up and put the Centrimatics on after I bought new drives but that didn't change much, only took out the...inconsistancies...I guess.

The thing I've always wanted to do is drive a couple other guys' trucks for a day just to see what/if they put up with as far as how it drives...and to see if I've got it better or worse. The handful of us on here CAN'T be the only ones...

 

If the tire, or rim is mounted off center making the whole wheel out of round then you can balance the tire with whatever trick you can think of and it still won't fix anything. Centrimatics, or tire sand, or whatever only works with tires that are spinning round and true first. We have an excellent tire guy. Never has a problem. Here is what he does...

When he goes to mount a tire, you have to check the rim for wear where the bead of the tire sits. Some tires will wear into the rim and cause the surface to be mis-shaped. This will cause the tire to mount off center. Anyway, the rim has to be in good shape to begin with, and CLEAN. For guys that pop a tire off and slap a new on without cleaning anything aren't doing a good job. The rims actually do get pretty dirty after a while. When mounting the tire use plenty of tire lube - and follow the directions for the lube correctly! Some types of lube have to be mixed with water first. When in doubt, use more lube, you can't use too much. Always start with a quality tire, none of this J A Pan company crap. Mount the tire, but NEVER use one of those tire cannons to set the bead. There is too much pressure and tire is always forced unevenly to the side of the rim opposite of the cannon, you will not get a good tire mount this way. Tire guys use it because it is faster and gets you off the side of highway quicker, that's it! Air the tire up to whatever the rated tire pressure is on the sidewall. If it says 105 psi, then air it up to 105! Not 85! After it is remounted you have to spin it up to make sure it is mounted properly. If it spins nice and smooth you are good to go! If you can see it going up and down as it is spinning the tire is out of round somewhere either between the tire and rim, or the rim and hub. Every tire has a bead set line moulded into the rubber that is very close to the outer edge of the rim. As the tire is spinning, if the tire is mis-mounted on the rim you will see the space between the set line and edge of rim change. You need to check both on the outside and inside too! If the tire is mis mounted, deflate the tire and spin it on the rim 180 degrees and re-inflate, try again. If the space between the set line and rim is good then the tire has a highspot because the rim is off centered to the hub. Spin your tire up, hold a tire crayon real close so only the high spot hits, stop the tire, move your high spot to the top, loosen all your wheel nuts and let the wheel settle, retorque your nuts, try again. So here is the thing... If a tire is installed properly and spins smooth and true you should never need balancing. If a new tire needs more than 6 oz of weight to balance it then something is wrong with that tire, don't use it, warranty! Anything under 6 oz is normally too little to be able to be felt by most drivers. Centrimatics and tire sand only provide around 6 oz of balancing effort and are more for "fine tuning" final balance. If a new tire is installed improperly, only takes about 8-10,000 km/miles before they are ruined for ever.

 

We had a similar problem a truck and had everything checked and the shop couldn't find anything wrong with it. We ended up taking the truck back and then later found out that it was just a bent rim.

 

If it has an air ride rear check your leveling valve. I have seen the arms come just a little loose and vary the ride height during a trip, wich changes pinion angles and will cause an intermittent viberation. usually if it an angle issue it will be worse under accelleration/load.

 

I had the same problem with my 88 freight. It turned out to be the pinion angle, coming from the carrier bearing to the power divider.

The spring pads on the front drive were wore and that allowed the pinion angle to climb causing a terrible vibration.