Vibration help please

[jvisions]

So I haven't crawled under my 94 4 runner yet to look around, but maybe one of you guys has had this problem before. I have put LC springs in the rear and 1.5" bj spacers in the front, 4" panhard drop bracket, and shocks all around. It seemed to be running good at lower speeds. Yesterday we took it for a 1.5 hour trip and hit the freeway. It gets up to speed and sounds fine until you let off the gas, then there is a sound coming from the rear end or mid truck that is not good. I think it could be bearings, but not really sure which ones. Maybe a u joint. I just don't know, and its frustrating.

 

[77'911]

Yes, you might check the drive shaft and drive line mounts. If you raise the truck, you have changed the geometry of the suspension(and drive line). The bushings, mounts, and joints will need to be of decent nick to with stand that change.
regards

 

[jvisions]

Yes, you might check the drive shaft and drive line mounts. If you raise the truck, you have changed the geometry of the suspension(and drive line). The bushings, mounts, and joints will need to be of decent nick to with stand that change.
regards

Thank you, i will check into that.

 

[fourwd1]

The title says vibrations, then you talk about a sound, which is it?
Specifics make a difference when trying to diagnose a problem over the web.

 

[dewiseman]

I put LC coils on my 95 4r and got the same thing (vibration ) it produced to great of an angle on the drive line. There is a way to correct that by changing the positioning of your rear axle. Thats what a shop told me anyway...( transmission shop ) said they could adjust the axle position somehow to change the angle. Hopefully someone can chime in on how to do that. Or take it to a good transmission shop. good luck.

 

[fourwd1]

Exactly why I was asking him. The lift springs change the drive shaft angle and the pinion angle. Correcting the pinion angle will usually eliminate the vibes. That means rotating the axle housing. Much easier to do on a leaf spring suspension than a coil spring suspension. Another possible solution is a custom drive shaft with a double-cardan joint on the t-case end.

 

[dewiseman]

Exactly why I was asking him. The lift springs change the drive shaft angle and the pinion angle. Correcting the pinion angle will usually eliminate the vibes. That means rotating the axle housing. Much easier to do on a leaf spring suspension than a coil spring suspension. Another possible solution is a custom drive shaft with a double-cardan joint on the t-case end.

How do you rotate the axle housing?

 

[4runnertank]

well you're going to have to make your coil mounts sit at a different angle if you twist it up. So pretty much you can turn the axle up towards the middle but your mounts will still be level with the ground. I was thinking about making new mounts for my leafs so my rear dif and drieshaft are in line, but i think i'm making a traction bar. I've never done this but i'm sure fourwd1 knows how

 

[fourwd1]

well you're going to have to make your coil mounts sit at a different angle if you twist it up. So pretty much you can turn the axle up towards the middle but your mounts will still be level with the ground. I was thinking about making new mounts for my leafs so my rear dif and drieshaft are in line, but i think i'm making a traction bar. I've never done this but i'm sure fourwd1 knows how

Exactly, you have to move the buckets (coil mounts), and the rest of rear susp parts. Not a simple thing on a coil spring susp. The object is to get the pinion angle back to stock (ie, horizontal (parallel with the ground)). A suspension lift makes it point upwards, which screws up the geometry.

On a leaf spring susp it's easier, you can get some degree shims to stick between the spring and axle perch to correct (if the angle isn't too bad).

 

[dewiseman]

Thanks guys...I was thinking about a blazeland LT in the future, sounds like the rear will be alot more complicated than the front.

 

[jvisions]

Sorry, I should have been more specific. It is a vibration that is felt in your butt, not the steering wheel. The vibration was enough to produce a sound anyway. I haven't solved the problem but greasing up the zerks made it much more quiet. I think it may just be a u joint, but haven't had a chance to change them yet. Thanks for your help guys.

I was talking to someone who said that the suggested max angle for the pinion joint is like 8 degrees. I kinda want to check and see what mine is at.