trying to find source of vibration

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2 fast z28

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hi guys I know its not an a body but still a mopar what im working on it a 1961 Chrysler imperial four door with push button trans and a 413 in it. the story starts out with the car had a really bad vibration but found out the center bearing was shot it a two piece drive shaft so sent out shaft to get a new center bearing put on, drive line shop called me and they told me that the second part of the shaft the rubber was damage so the drive shaft was junk so we just had a hole new one made, got the shaft back still 2 piece and put in car drove vibration was gone at 45 to 50 but still had a vibration at 20 to 30 mph, called shop they said we can recheck the balance of the shaft but they said they had a very good balancer had it done still only vibrates at 20 to 30 and after the smooth as glass check all motor mount trans mounts, and it doesn't matter if you step on gas pedal or just touch it 20 to 30 it vibrates im lost any help would be great
 
Photos?

Not familiar. I would guess? That somewhere "in there" was a ball and trunion U joint. Was it repaired, replaced, replaced with something else?

Does the two--piece have a spline slip joint? You have to rotationally clock those,

You sure it's drivetrain and not wheels / tires?

How 'bout rear wheel bearinngs?

What have you done, IE wiggle test, looking at rotational wheel wobble, stuff like that?
 
What he said, check tire balance/wear on fronts esp. Can you throw it into neutral at that speed?
 
If vibration varies with acceleration or deceleration, suspect joints in drive shaft. Otherwise, check for bent axle, bent wheel, front end alignment, tire out-of-balance, or tire/wheel not concentric. If vibration can be felt through steering wheel, suspect front end alignment or front wheel issues. If vibration is felt primarily though the seat, suspect rear end and driveline issues.
 
A vibration at speeds that low is often times a separated tire. Take a close look @ all 4 of them....
 
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here is a pic of how the drive shaft is not actually car but good example yes the driveshaft is splined with a slip yoke after the center bearing all the u joints are brand new and the drive shaft was balanced as a whole unit to me its not a tire vibration its to fast of a vibration and its felt in the floor and sound to me like the rear area of the car I have a pretty good knowledge of tire vibes and driveline vibes I work on car for a living but one thing that I was thinking is the rear wheels bearing could they just make a vibration with no noise ? and yes you can still feel hear the vib if you coast around 20 to 30 thanks guy so far
 
oh yeah this car never had a vibration problem till the center bearing went out and the back half of the driveshaft failed if this helps
 
I'll take a stab. If the back shaft was deemed to be "junk" then I would have expected a vibration long before it was total junk. Maybe the real problem is the rear end is failing. It could be many other things. Maybe put it on stands and take the rear tires off and let it spin, see if it shakes. You'll have to just keep looking. It may be as stupid as a broken brake drum.
 
1.........Do you understand rotational clocking of the slip yoke? I cannot tell from that photo, but either of the caps on the one--piece part of the shaft MUST be "inline" just like rifle sights, if not, welded wrong

Also, the front joint behind the spline must ALSO be lined up with either cap inline with the very front joint. That is, they cannot be rotationally maligned say, 20, 30, 45, whatever degrees.

2.....I would spend some time, get it on jacks and see if you can tell anything by first watching the wheels and tires for wobble. You will want to jack it under the rear axle tubes to keep the weight on the suspension. Watch or have someone watch the wheels / tires for wobble and other out of true, and try and "feel" for shake

Then remove the tires and see if you can still feel it

3.....Spend some time gently and more firmly wiggling and feeling the rear bearings. This probably has the adjustable rear taper bearings, so there should be NO play

Here's a problem I had with mine that threw me for a loop. I had "thrown" in a temporary 3rd member. This is a Ferd 9" but it could happen to a Mopar

This pumpkin was an "open" (no limited slip) and soon began making weird noise, a little click or clunk ad 25-35 mph. It also made a strange noise on the highway. I probably only drove it 150 miles or less

Jacked up and "thought" I could feel plain in one tire AS IF THE FAR END of the axle was loose in the 3rd member.

Finally tore it down and that's EXACTLY what it was!!!!

Either the guy who had it was a "single track burn out king" or else a Jeeper / Mudder who liked to spin up the tires in mud

The side spider gear for that axle had been spun so much IT HAD WORN A CAVITY in the carrier!!!! There are no bearings in any of them, they are gear against carrier.

Anyhow just an example of "weird $sheet whut cun happen"
 
2 fast z28 said:
oh yeah this car never had a vibration problem till the center bearing went out and the back half of the driveshaft failed if this helps
Click to expand...

This tells me that the problem is in the driveshaft, intermediate bearing, or u-joints. Check to see if the new shaft is exactly the same length as the old one that went bad. Check to see that the u-joint crosses are centered in their respective earworks and that the straps on the pinion connection and evenly snugged down.

If it is possible to do so safely, try running the car with the wheels off the ground supported at the axle. Use a mechanics stethescope and listen for clunking noises around the intermediate bearing and in the area around the pinion in the rear end. You can do the same thing with your hand and try to feel the vibration.
 
67Dart273 said:
1.........Do you understand rotational clocking of the slip yoke? I cannot tell from that photo, but either of the caps on the one--piece part of the shaft MUST be "inline" just like rifle sights, if not, welded wrong

yeah think I know what your talking about I call it u joint phasing when you look at the shaft the joints are inline

I think my next step is to put the car on jack stands and see if or hear and issues with the car on them when running thanks again for the input guys
Click to expand...
 
I had a limofied '64 Chrysler once which had kinda similar vibrations I think as yours.
It would shake the car at low speeds when accelerating.

This car also had a 2-piece driveshaft, and, as with yours, while the intermediate support rubber was shot, it turned out later the transmission mount was soft and mushy aswell.
Replacing this mount aswell cured the low speed vibrations. Might be worth checking into.
 
I HAD A BALANCE WEIGHT FALL OUT OF A FRONT ROTOR ONCE. tOOK A LONG TIME TO FIND THE VIBRATION! I GOT LUCKY AND A OLDER FRIEND OF MINE HAD ONE OF THE OLDER ON THE CAR WHEEL BALANCERS WITH THE STROBE LIGHT. that's HOW WE FOUND IT. JUST A THOUGHT.....
 
2 fast z28 said:
67Dart273 said:
1.........Do you understand rotational clocking of the slip yoke? I cannot tell from that photo, but either of the caps on the one--piece part of the shaft MUST be "inline" just like rifle sights, if not, welded wrong yeah think I know what your talking about I call it u joint phasing when you look at the shaft the joints are inline I think my next step is to put the car on jack stands and see if or hear and issues with the car on them when running thanks again for the input guys
Click to expand...


Thats not correct, you can have the joints in line and out of phase.

Did the shop have the front and rear section of shaft together ?

If yes then there should be a mark at both shafts how it needs to be indexed to each other.

If no then that shaft isn't right, the front and rear shaft MUST be together when ever any balancing is done.

,.
Click to expand...
 
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