Rig Vibration

[pl521sss]

Hey folks

Experiencing vibrations in my truck at various speeds.

I don't think it's the wheels not balanced cause their new and had them balanced it. Weights are there.

Just replaced U-joint, it was busted.

It helped but I still experience vibrations.

 

Could bad king pin be a culprit? Lots of free play on front end.

How about pinion angle?

I put 3 " blocks but it's not the angled blocks.

Rougly about 5 '' drop from the rear.

Curious if other factors can cause my rig to just shakevibrate at certain speeds.

[]2eDeYe]

Probably pinion angle from the drop blocks.

Did you check all of the ujoints while you were at it?

There are 3.

Could also be a worn carrier bearing.

 

I doubt it's the kingpins, but you may wanna tighten the frontend anyways ;)

[pl521sss]

2eDeYe;32907']Probably pinion angle from the drop blocks.

Did you check all of the ujoints while you were at it?

There are 3.

Could also be a worn carrier bearing.

 

I doubt it's the kingpins' date=' but you may wanna tighten the frontend anyways ;)[/quote']

 

 

I did check the other 2 U joints, it looked ok.

Carrier bearing looked ok also.

 

Have you heard if pinion angle is not corrected, I'll get vibrations?

 

Not so much the front end having loose bolts.

The king pin is shot and has lots of play.

[datsunaholic]

I've had plenty of worn out kingpins. They've never caused vibration, just really bad tire wear.

 

Is the vibration speed specific? Meaning it always happens at the same speeds- then it's a balance issue of some rotating component. Wheels, tires, driveshaft, brake drums/rotors.

 

Oh, just because wheels are new and balanced doesn't eliminate them. I've seen brand-new tires blow a belt (causing a tread bulge) on the drive home.

 

Also, a broken U-joint could have bent the driveshaft- not enough to see, but enough to feel. Or, the bent driveshaft could have caused the U-joint to fail- excaberated by the static drop, which without wedge put undue stress on the rear driveshaft.

 

I've also seen vibrations caused by bad shocks, but that was road-specific (had to hit the right harmonic, then the whole axle started bouncing off the road).

[Pacific coast Datsun]

Does it ever vibrate when braking? Worn steering bushings may cause vibration or wobbling too. Maybe the driveshaft isnt balanced...:rolleyes:

[makya]

Is the front end lowered? If so, did you have the front end aligned afterword?

 

And is it vibrating the truck, or is it showing at the steering wheel?

[laniadude]

I put 2" drop blocks on the rear...I didn't touch the front end....Is there something I was supposed to do after I put the blocks on?? Or are they bolt and go??? cuz I noticed vibrations too...mainly at about 55-65 Mph...at 70 mph...It goes away..I can't remember if the vibrating was there before I put the drop blocks on...lol

[pl521sss]

I've had plenty of worn out kingpins. They've never caused vibration, just really bad tire wear.

 

Is the vibration speed specific? Meaning it always happens at the same speeds- then it's a balance issue of some rotating component. Wheels, tires, driveshaft, brake drums/rotors.

 

Oh, just because wheels are new and balanced doesn't eliminate them. I've seen brand-new tires blow a belt (causing a tread bulge) on the drive home.

 

Also, a broken U-joint could have bent the driveshaft- not enough to see, but enough to feel. Or, the bent driveshaft could have caused the U-joint to fail- excaberated by the static drop, which without wedge put undue stress on the rear driveshaft.

 

I've also seen vibrations caused by bad shocks, but that was road-specific (had to hit the right harmonic, then the whole axle started bouncing off the road).

 

 

 

Only happens at specific speeds and consistent.

So I'll check with the tires if they balance correctly or not.

Drive shaft being bent will be a tough one without having a spare to swap it out with.

So even if pinion angle is not corrected it will NOT cause it to vibrate but would wear out the U joints faster than usual, correct?

 

There's a slight steering wheel vibration but not bad at all or not enough to cause a noticeable vibration to the whole cabin area or whole truck really.

No vibrations on breaking, new shoes and drums.

[pl521sss]

Is the front end lowered? If so, did you have the front end aligned afterword?

 

And is it vibrating the truck, or is it showing at the steering wheel?

 

Front end is lowered.

I still need alignment, but wouldn't that be just tire wear issue not vibration?

Also front suspension has king pin, it didn't look like it altered the suspension geometry like the 510 front suspension does.

I'm still new on this truck suspension to know it all yet.

[pl521sss]

Does it ever vibrate when braking? Worn steering bushings may cause vibration or wobbling too. Maybe the driveshaft isnt balanced...:rolleyes:

 

I didn't tamper with the drive shaft.

Are they suppose to be balanced time to time?

 

I never did on any of my Datsun unless I cut them down for a longer tranny swap.

 

Does not wobble pulls to the left on very heavy breaking.

Brake shoes needs adjustment again.

[71-521]

if only the wheel is vibrating then I would bet on a tire/frontend issue...

usually you would have to raise the carrier bearing if you dropped it 3" but you might want to try spacing it up an inch or so just to see if it cures your problem...

[datzenmike]

If you were to look down the center line of a drive shaft at a U joint while it is turning you would see that it's only turning in a circle when there is no bend between the two drive shafts. As the bend becomes greater the U joint actually follows an ellipse or oval path, and because it is forced to spin at the same speed, actually has to speed up and slow down at to top and bottom of it's turn. This is the cause of vibration. There is a way to minimize this vibration by using two U joints, one at either end with the same angle and they will cancel their effects.

 

Just remember to get the same angle from the rear end to the drive shaft as you have from the drive shaft to the tranny. (or other drive shaft)

http://i138.photobucket.com/albums/q251/datzenmike/driveline.png[/img]"]

 

Here is another way to remove vibration by using two U joints at the same bend. It is spring loaded to force the same in and out angles. It's called a double Cardan joint.

 

http://i138.photobucket.com/albums/q251/datzenmike/doublecardanjoint.jpg[/img]"]

 

 

Props to BEEBANI (I think, for the top picture and the explanation, I hope I got it right)

[pl521sss]

If you were to look down the center line of a drive shaft at a U joint while it is turning you would see that it's only turning in a circle when there is no bend between the two drive shafts. As the bend becomes greater the U joint actually follows an ellipse or oval path, and because it is forced to spin at the same speed, actually has to speed up and slow down at to top and bottom of it's turn. This is the cause of vibration. There is a way to minimize this vibration by using two U joints, one at either end with the same angle and they will cancel their effects.

 

Just remember to get the same angle from the rear end to the drive shaft as you have from the drive shaft to the tranny. (or other drive shaft)

 

Here is another way to remove vibration by using two U joints at the same bend. It is spring loaded to force the same in and out angles. It's called a double Cardan joint.

 

 

 

If this is true, I can't be the only one having this issue with lowering the rear end to a point and cause the driveshaft to vibrate.

Hence the pinion angle I suppose.

They offer 2 or 4 degree, now which one :confused:

It does make sense on your explanation here.

[VRTSid]

Oh, just because wheels are new and balanced doesn't eliminate them. I've seen brand-new tires blow a belt (causing a tread bulge) on the drive home.

 

+1 happened to me. caused a nasty sidewall bulge on the inside where I didn't see it. they were kumho extas, I think it was a manufacture defect discount tire replaced it with the same tire and it rides fine.

[]2eDeYe]

Sounds like you need to raise your carrier bearing or get some angled wedges for your drop blocks.