Drive Shaft: Angle & vibrations...

[Noxnabaker]

I've noticed I've got vibrations above 60km/h & I wonder if these angles could be the cause?
(the car is resting on its rear wheels)

Front from right/passanger side:
(impossible to take picture straight from the side,
this is slightly from rear)


Rear from left/driver side:

[junior]

tough to tell from the photos nox. basically if the engine/trans center line is pointing downwards 4 degrees for example, then the pinion center line needs to be pointing down 4 degrees too, or 4 degree up will work as well...the basic rule is equal angles. from the photos it looks like both the engine center line and pinion center line are pointing down...referred to as broke-back. once you measure the angles if they are more than about 1/2 degree off then adjust them. this is easy to do with wedge shims under the spring pads on the rear axle. This assumes that your engine and pinion centerline are parallel to each other in plan view as well. drivetrain vibes are sometimes a bugger to chase down, and all bushings, bearings, and joints need to be in tip top shape too. cheers, junior

[62champ]

There was someone who chased a vibration and replaced/checked everything. It ended up being a drum that was out of balance. Good luck.

[Alan]

Yes, Nox. Those look to be some gnarly angles there. Better get out your bubble protractor and Google some sites for angles. I can't see the front, but that looks nasty.

[Neal in NM]

You may need a cardan joint.

[studegary]

In the picture, it does not appear that the front universal joint is in alignment (not put together squarely) with the shaft out of the transmission.

[Jeffry Cassel]

Is the u-joint retainer ring on front drive shaft broken? The angle in rear is not good at all . It is 100% non-original which makes it very difficult- - assorted parts thrown together. If not broken , dial indicate drive shaft; bet a nickel it is bent or, more likely, someone made it --crooked. You have a serious challenge.

[Noxnabaker]

The shaft is proffesionally ballanced by the best workshop for that in Holland & the joints were new when put in, it's all MoPar stuff.
Thanx for all the quick answers! Gonna get down to it now...

[DEEPNHOCK]

At ride height....
Whatever angle you have at the trans..
The opposite angle should be at the pinion.
Performance guys add a degree or two down for racing (pinion down), but the numbers should match at cruise speed, ride height.

Lots written about this all over the internet.
It is not Stude specific.

[Noxnabaker]

Yes ofcourse Jeff, that's why the car is on stands on the rear axel.

[StudeRich]

Not having a Stude. rear axle or driveshaft make it very hard for us in the U.S. to relate to it or help.

[bensherb]

Not really: Our '53 Coupe has a Chevy trans, and Ford axle and has been working great for thousands of miles over thirty years with no problems at all or drivetrain vibrations.

Deepnhock is correct. If the trans angles down X degrees, the axle pinion should angle up X degrees. They should be on parallel planes. Same in the left to right, parallel. Some times even when everything is correct, driveshafts vibrate. In the past GM has run U-joints slightly out of phase, meaning they are not in the same relation to one another. This is incorrect by conventional wisdom, but, it keeps the u-joints loaded all the time and curbs harmonic vibration at the cost of slightly shorter U-joint life.

[DEEPNHOCK]

And to add...
The reason for not having things perfectly in line is the u-joints.
"If" the crank centerline, the driveshaft centerline, and the pinion centerline were all 'perfect'....
Then the rollers in the u-joint would not roll, and they would 'brinnel' (pound grooves) into the trunion and the cap.
U-joint life required the rollers actually roll a little bit. And roll more than just the amount caused by suspension movement.
The comment about intentional off phasing is also true (in certain circumstances).
Sometimes it is a band-aid to solve a harmonics issue.

Read up on it here.. (318,000 links..)

https://tinyurl.com/Driveshaft-Vibration

[Jeffry Cassel]

Anybody out there ever had anything screwed up by the "best shop in town" ??? Why is the u-joint cup sticking out of the driveshaft seemingly unsecured? Yes, that shft -diff angle will vibrate. I reiterate, you have a serious challenge.

[DEEPNHOCK]

Anybody out there ever had anything screwed up by the "best shop in town" ??? Why is the u-joint cup sticking out of the driveshaft seemingly unsecured? Yes, that shft -diff angle will vibrate. I reiterate, you have a serious challenge.

Yessir... While not OE Stude, here is what I found on my initial inspection of 'The Black Car' for the rear U-joint.
Wrong u-joint installed. No problem! Add some washers to 'center' the caps.
Wrong sized caps. No problem! Just smash 'em in there with a $50 aluminum u-joint cap (that the wrong size, too).

Once you put the correct u-joint in, things work a lot better.