i'm getting a pretty noticeable vibration in the rear of my 93 toyota pickup. the weirdest part about all this is that it starts at about 50mph and its a perfectly tune vibration...every other second its shutter. i can look at my rear tires from the mirror and see both of them moving in sync.

i checked ujoints and thats good..also wheel bearings. could the diff be bad?
i have a reman 3rd member from jaws gear with a detroit trutrac.

also another weird thing is i noticed the vibration only after putting on bigger tires..BUT..i dont want to say its the tires because bad tire vibration will be a constant vibration..not on and off at 55mph.

sometimes the left side will stop too and just fell the right side moving it all. help!

 

Put on the smaller tires and see how it goes. Also, does it go away if your doing 70 or so...or does it increase?

 

EAsy! dont drive between 50 and 55mph!

Check your tires...make sure they are balanced...you could even try switching the tires up (rotating them) and see if that helps...

also check all your spring bushings and shackle/spring bolts

 

Ya it sounds like a tire problem.

What kind of tires are you running?

 

i went from 225/50/15 to 265/50/15 in the rears. the fronts are still 225/50. i'll try replacing the tires at les schwab and go from there.

the problem starts at 50-55 but it does increase...i usually dont go past 60mph so i dont know if it continues.

 

are the tires balanced? Why are you running 2 different size tires? that could very well be the problem

 

shocks!

 

Sounds familiar but mine is coming from the front left wheel. Mine starts around 60 and gets worse as you go faster. It will only happen when im coasting though. I'll be getting larger tires tomorrow so hopefully when its balanced and aligned it will fix it. I had it looked at and the mechanic said my lower ball joint was bad so will see. If it does not fix it expect a thread on here lol.


/Thread Jack

 

If your truck really does have a worn lower ball joint, there is no way to accurately align the vehicle. That ball joint will have to be replaced first.

 

Yep your right and thats why I'm getting one today.

 

i'm running 2 different tires because 225/50/15 doesnt hold up to 400+rwhp too well. that is not the problem, i know that for a fact. i havent ruled out the tires themselves being bad...but i know that running two different sizes will not and should not effect balance issues. tons of stock cars run staggered and hot rod guys do it all the time.

shocks are newer and i just took them off to test them..even if they were bad it wouldnt cause a high spead vibration..just will make me bounce a crap load.

i did further checking and realized that before i took my lowering blocks out, when i launch or put a semi heavy load it'll rub my right rear tire..so i think because part of it is slightly rubbed off it throws the whole tire dynamic off.

 

to me it sounds like either the carrier bearing is going out on the drive shaft If you have one) or that the shaft itself is out of balance.

 

i have a one piece drive shaft...i did think it might be out too..

 

sounds like a tire issue... mine does the same exact thing; right at 50 it starts, and it just gets worse the faster you drive; no real noise, just vibration and shuttering. mine does it up front and in the rear, and I know I need new tires... I also want to replace all the ball joints and tie-rod ends, so that'll all be done at the same time... and if that along with new shocks doesn't stop it, then I'm just gunna live with the vibration, lol

 

check the u joints, but it sounds like a tire balance problem.

tire rub has nothing to effect like that, my mustangs rear tires are chopped to hell from the fenders but never throws a balance problem.

 

I raised the air pressure in mine to 29psi and noticed mine was doing that in the rear today around 60.

 

when the tires were installed, were they balanced?
if so, did the shop use the sticky weights inside the rim or the clamp ons?
and get it fixed soon or the tires will start wearing funny and you'll never get rid of the vibe.

 

Pull off one of your rear shocks and see if it still has some resistance. If not, and they are empty of oil, there's your problem. I had the same problem with my '93 4X4. One of the rear Rancho shocks lost all of the oil, made a mess, and then broke off at the weld on the bottom eyelet. I was experiencing the same symptoms around 63mph. Check and see. It's easy, you only need 5min., and a ratchet w/ a 17mm socket.

 

i checked the shocks already and it still has alot of resistance. ujoints all checked out good. no play at all.

i'm going to say its the right rear tire/rim for sure. i notice that its not even really the left rear..because its solid axle i think it just looks like the left rear also..but i feel my right ass cheek vibrating more then anything.

the wheel weights are hammered on the inside lip with sticky center weights.

thanks for all the input guys and giving me your experiences. much appreciated.

 

Vibrations that come and go are usually caused by tires. If both are out of balance or not round, then they will go in and out of phase with each other alternately amplifing and canceling out the vibration.

this is usually most noticeable around bends in the road as the speed of the tires are diferent from side to side.