Drive Shaft Vibration 40-50 mph

I am experiencing a mild (but annoying) vibration from 40-50 mph. It comes from the rear of the truck and resonates like a driveline problem. It is not tire. I think it may be driveshaft?? No lift. leaf springs are about a year old factory replacements. Any thoughts?

Pinion angle:

 

Why do you believe it isn't a tire imbalance related issue ?

9 times outta 10 it is done poorly or just plain wrong.

The '95.5 - '04 Tacoma are lug centric
and requires use of a backing plate that has studs positioned correctly.
Lot's of tire shops do not have the proper backing plate for spin balancing
1st gen Tacoma that have a lug centric wheel mounting.

More commonly the majority of vehicles these days are hub centric...
and the standard spin balancing technique utilizing cone adapters works fine.


Did you rotate the rear tires to the front and see if there's any change ?

Have you checked to be sure all the bolts securing the driveshaft/Ujoints are tight ?

Have you greased those Ujoints on schedule ?

Have you greased the slip shaft as well ?

Could be the leaf springs themselves are tired and could be of fault.
Make sure the Ubolts holding the axle are still tight.

There's a million things that can cause vibration in the drive line.
Hard to diagnose something over the internet.

 

New oem (fj cruiser) wheels and tires, problem persists as before the new tires/ wheels.

I will argue that my truck is hubcentric. i have never seen a backing plate used with toyota shank-style oem lug nuts/ oem toyota alloy wheels. Aftermakets on a toyota would be lug centric. Anyway....

Highway speeds 60+ are smooth as glass. I doubt tire very strongly.

Ubolts were just replaced and torqued. problem persists.

Driveline flanges are tight.

I greased the u joints and slip joint. no change.

 

Oh, leaf springs are only about a year old. aftermarket replacements.

 

I don't know squat about FJ cruiser wheels.

Argue away... modular (shank type) lug nuts or tapered...
'95.5 - '04 Tacoma hubs are still lug centric.

I'd make sure your wheel balance is correct
before venturing on to more costly repairs.

Not saying it can't be another issue.
But wheel balance seems to be an issue
with many '95.5 - '04 owners.

I don't know what the 'crusier wheels are designed to be
they could be hub centric by design.

 

New wheels and tires would have rulled out tire and wheels anyway. The problem existed before. Oem toyota alloys (stock taco, or cruiser) are hub centric, others will back me up. Shank lugs do not center the wheel as the clamping face has zero taper. There is no such thing as a vehicle that is lug centric. Centricity is determinded by the wheel. Most any aftermarket wheel will be lug centric.

I failed to mention that the vibration is at its best under acceleration and worst when off the gas and the engine is slowing the truck. this leads me to believe pinion angle is to blame and it is exacerbated by axle wrap. i would like somebody with drivline geometry experience to weigh in on my picture posted above. Accordng to level the app on my phone, the pinon angle is 1 degree.

 

Angles are fine. Have you taken the drive shaft off to look at it? Sounds like a typical U joint failure. Might also examine your rear shocks.

 

Very well then... believe as you wish.

 

Rear shocks are brand new. No detectable play u joints. I may replace the rear u joint and see what happens. I dont mind replacing a low-cost wear item where the truck is almost 20 years old.

 

If only one of the needle bearings has failed it will be hard to tell while the shaft is still connected. Have you taken it off and examined it?

 

Are you saying the vibration is not felt, or is not as apparent under acceleration? From your picture, the pinion angle looks fine under no load, but when you accelerate the pinion will tend to raise, due to the weak stock springs (brand new or otherwise). When the pinion raises and the rear u joint angle is increased, that is when I would expect you would feel vibrations.
I set my pinion angle about 0.5 degrees below the driveshaft at static ride height, so under hard acceleration the angle will still be within acceptable limits. It rides smooth at all speeds/rpm's.

And you are correct that stock wheels are hub centric, sometimes cheap aftermarket lug centric wheels can cause an apparent imbalance, but that shouldn't be the case here.

 

I would recommend greasing your u-joints first, then checking your carrier bearing, then checking your transmission mount. if not the tires, these 3 sections can cause imbalance in the driveshaft and cause a "vibration"

 

Vibration Relative Severity:

Acceleration: Slightly noticeable
Cruising: Annoying
Deceleration: Very annoying (resonating vibration)

Note, this is only between speeds 40-50mph

 

I have a single cab, therefore no carrier bearing and a single piece driveline.

No noticeable difference when i greased the u joints.

I will check the transmisson mount. Great thought.

 

If you have a one piece drive shaft your pinion angles at the differential and at the transmission need to be parallel. Based on your picture your differential pinion angle is too steep. It should be closer to horizontal, assuming your transmission is also horizontal.

 

OP says "single cab, no lift". Some single cabs came with one piece shaft with a double cardan joint.

 

Agreed, pinion flange and transfer case output flange need to be parallel for a one piece driveshaft. If you have the center double cardan joint, they don't have to be perfect, but the closer the better.

 

I have a one piece drive shaft, double cardan at the tcase. this is my setup:

 

Interesting, that would explain why your pinion angle is so much higher than the two piece driveshaft setup on xtracab or double cab tacos. I would look to other culprits then, as others have said - u joints, trans/motor mounts, possibly axle bearings, etc.

 

I have the middle one. Thanks for posting.