Driveline vibration

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m99roadster

m99roadster

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Hello all, I'm still fighting a driveline vibration in my 68 Dart four door with a 340 and 904 transmission. I've replaced and checked everything I can think of. Is there suppose to be a dampener on the tailshaft of the transmission, if so does anyone have one for sale or know where I can purchase one? Thanks
"I'm at wits end"
 
Can you tell us if anything at all has been done to try to resolve it yet?

Step one would be a balance shop.
 
8.75 rear housing
New axels 5.25 bolt pattern
New 10 inch rear breaks
All new bearings
New 323 gears
New pinion
New custom made driveshaft made locally balanced then re balanced
New front slip yoke and bushing
Pinion angle checked and rechecked

I'm waiting to hear on price far another custom driveshaft from Mark Williams driveshafts in California.

Vibration is from 60 to 65 mph
I believe I've changed everything I can, not sure what to do next. This is why I'm asking about a dampner on the rear of the transmission

New motor and transmission mounts also

Driving me crazy
 
The vibration occurs between 60-65. Does it happen if you are accelerating and go above 65? Does it happen while slowing down from 70-60? Or does it only occur while driving steady in this range?

Have you checked and had all four tires balanced?
Is there any vibration in the steering wheel, or just in the seat of your pants?
My 904 tranny does have a heavy weight that hangs from the tail shaft. I have driven it with it on and with it off and couldn't really tell any difference at all.
C
 
m99roadster said:
8.75 rear housing
New axels 5.25 bolt pattern
New 10 inch rear breaks
All new bearings
New 323 gears
New pinion
New custom made driveshaft made locally balanced then re balanced
New front slip yoke and bushing
Pinion angle checked and rechecked

I'm waiting to hear on price far another custom driveshaft from Mark Williams driveshafts in California.

Vibration is from 60 to 65 mph
I believe I've changed everything I can, not sure what to do next. This is why I'm asking about a dampner on the rear of the transmission

New motor and transmission mounts also

Driving me crazy
Click to expand...

I would for sure quit throwing money at it until you find the issue.


Did you assemble and install the rear?

Was the axle end play adjusted properly when it was done?

What is the pinion angle at?

When the driveshaft was balanced did they check it for run out?

Have you try flipping the driveshaft end for end?



What about wheels and tires, have those been checked, have you tried other wheels and tires?

Maybe borrow some for a minute from a buddy?
 
Troubleshooting vibrations can be frustrating unless you break down into sections.

First things to try are the easy stuff:

If you have a tach installed at what rpm going down the road does it do this?
Next, with the car in neatrual and not moving try running the engine up to that rpm and see if the vibration occurs. if it does, the vibration is in the engine/flywheel area. If it doesn't then try putting the car up on jackstands and see what happens with the wheels on, still vibrates? Take the rear wheels off and try it again (put lug nuts on the wheel studs so your drums don't come off).

If it still has the vibrations you may want to try another driveshaft/take it to another shop for balance verify. U-joint angles? Are those new mounts made out of Poly? Still running twin V-Belts if you have factory air? They can vibrate like crazy.

I chased a "driveshaft/wheel vibration" on a Mustang only to find out it was the flywheel.

NVH troubleshooting requires patience and a disciplined approach.
 
goldduster360 said:
I chased a "driveshaft/wheel vibration" on a Mustang only to find out it was the flywheel.
Click to expand...
I was gonna ask: manual or auto trans? Flywheels and even new pressure plates are known to be a source of this type of vibration. I am getting ready to pull them out of a /6 for this exact reason: a vibration at 50-55 mph that showed up after changing clutches with an engine rebuild.

Fairly easy to confirm a flywheel/PP vibration: the vibration will occur with the car in neutral and revved to the offending RPM range while just sitting still.
 
nm9stheham said:
I was gonna ask: manual or auto trans? Flywheels and even new pressure plates are known to be a source of this type of vibration. I am getting ready to pull them out of a /6 for this exact reason: a vibration at 50-55 mph that showed up after changing clutches with an engine rebuild.

Fairly easy to confirm a flywheel/PP vibration: the vibration will occur with the car in neutral and revved to the offending RPM range while just sitting still.
Click to expand...

Yep, same scenario about 15yrs ago, really frustrating to have to pull it all apart again because someone else didn't do their job. Nothing like doing the same job twice. It was a 5.0 5spd.
 
My car had a nasty vibration at road speed, so one day just for kicks and something to do I pulled it and swapped the yoke 180 degrees.
It had new joints and it occured to me that some people don't know that when swapping ujoints they are supposed to mark the line and yoke so they go back together the same way as they originally were.
After turning the yoke 180 the vibration all but disapeared completely.
Obviously it could go the other way and be worse, but I thought it would be worth a try and it paid off.

Just a thought.
 
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