55mph vibration (1 Viewer)

[powthief19]

I was doing some highway cruising over the past few days. Everything is working great that I know of except when i get up to speed of around 55mph there is a slight vibration/shake but if I keep accelerating to about 60/65 the ride smoothies out to buttery smooth.

Rig is a 77’ FJ40, fresh rebuilt engine, transfer case, transmission. Fresh front axle rebuild. Drivelines were freshly balanced. Tires were balanced when mounted via a road force balancing machine.

Wheels are stock steel, tires are 35/10.5/r15

It drives smooth all the way up to 55, then is “shaky” between 55-59ish then smoothes our right around 69.

Steering is electronic power steering and I tried it with the power off, mild assist, and high assist. Same thing..

What am I not thinking of?

Pic was taken today on my way back to Nevada from the wine country.

 

[coonassjohn]

tire balance? Right speed range for this to be the cause. Nice rig.

Tire balance is only as good as the person doing the work.

 

[Solace in Solitude]

Reaching...

Warped wheel?

Alignment?

Check wheel bearings/knuckles for proper tightness.

U-joint?

 

[Travis 76]

I had similar problems years ago, turned out to be bad wheels. They balanced but would not ride right at a few speeds like you are saying. Maybe swap your fronts to the rear, or see if you can try another set.

 

[FJ4013]

Sounds like a tire out of balance. I had the same issue at 50 mph. Found my right front weight had dropped off. Spun and re balanced and problem solved.

 

[shawnfj40]

Yep balance your tires. If that doesn't do it the next thing to look at is your drive shaft.

 

[73tlcv8]

oversize tires can cup and vibrate at normal highway speed. Try swapping front to back, that will fix the problem if that is it.

 

[4x4veteran]

Have you tested for the vibration on different highways?

 

[65swb45]

All good suggestions here Chris. Also try getting the tire off the ground and spinning them to check vehicle WMS. I had a bent rear axle years ago (yeah, I wheel my junk hard) and didn’t know it until a guy behind me coming off the trail noticed it.

 

[4x4veteran]

Another thought....Does it do it with or with out the bicycle mounted on the back?

 

[Hack]

Drivelines were freshly balanced.

Is the rear drive shaft operating angle correct?

 

[pondjumpr]

Tires/wheels are the first thing to check. I had a bad steering wheel vibration and front shake around 50-55 and could drive through it at around 60. I didn't like going past 60. I swapped front with rear and the vibration stayed but I could feel it in the rear. It was definitely tire/wheel related and not driveshaft related. I made sure the wife knew it was a safety issue. A few thousand dollars later, new wheels and tires, and the vibration was gone. Simple enough fix...

 

[powthief19]

it would appear the number one recommendation is having the wheels re-balanced. I'm now sitting at LesSchwab getting them checked. Will report back!

 

[powthief19]

Left les Schwab and the vibration was still there. The employee said they were off roughly 1oz per wheel.

However, they only spin balanced them apparently... I’m going back to have them road force balanced and maybe a different outcome will arise.

They only road force balance them if you ask them to!!! Argh!

 

[powthief19]

Have you tested for the vibration on different highways?

CA highways were rough but NVs are a bit smoother. Same same vibration.

One update... if I get up to speed to cause the vibration and take it out of gear and coast, the vibration is still there.

 

[powthief19]

oversize tires can cup and vibrate at normal highway speed. Try swapping front to back, that will fix the problem if that is it.

tires are brand new.

@65swb45 i will check this tomorrow.

 

[thebigredrocker]

Are your drivelines in phase?

Did you add lift springs or longer shackles? Perhaps you need to check pinion angles.

Quote from a similar vibration thread.

This is far more important that you have been lead to believe.

If you do not own an angle finder, purchase one and post up what your rear output on the transfer case is sitting at and what the rear differential companion flange is sitting at.

 

[69LC]

Do you feel the vibes in the steering wheel, your feet or seat?

 

[powthief19]

Are your drivelines in phase?

Did you add lift springs or longer shackles? Perhaps you need to check pinion angles.

Quote from a similar vibration thread.

Yes, drive lines are in phase. Lift is 2.5” OME with OME shackles. Nothing exotic here.

Will throw the angle finder on the driveshaft if the road force balancing doesn’t work.

 

[powthief19]

Do you feel the vibes in the steering wheel, your feet or seat?

Everywhere!