Driveline vibration

[Scott C]

Okay,
I am contemplating a test to try and sort out a source of vibration that I thought was gone. Thinking of removing the halfshafts (from rear wheels) to see if the vibration is present at 55 - 65 mph indicated speed. Is there any risk that a "system" either engine control, ABS or tranny will prevent this test from being conducted? ie, remove the halfshafts then run the engine in drive (autotrans) to see if vibration present? I need to do the differential seals anyway so why not try? I am curious as to if the center bearing went south so exhaust and driveshaft will likely come out next.

Thanks,

Scott

Before anyone asks:
New tranny and engine mounts within 2 months, rebuilt driveshaft (50miles) with center bearing, new front end components include thrust and control arms with M5 (within 3K miles), shocks/struts within 25K miles, inspected front wheel bearings and passenger rear bearing - all fine. Tires were just rebalanced 3 days ago.

[632 Regal]

shouldn't be any issues since the speed sensor is in the differential. Shut the engine off before you put it into park.

[bmwrp8]

Okay,
I am contemplating a test to try and sort out a source of vibration that I thought was gone. Thinking of removing the halfshafts (from rear wheels) to see if the vibration is present at 55 - 65 mph indicated speed. Is there any risk that a "system" either engine control, ABS or tranny will prevent this test from being conducted? ie, remove the halfshafts then run the engine in drive (autotrans) to see if vibration present? I need to do the differential seals anyway so why not try? I am curious as to if the center bearing went south so exhaust and driveshaft will likely come out next.

Thanks,

Scott

Before anyone asks:
New tranny and engine mounts within 2 months, rebuilt driveshaft (50miles) with center bearing, new front end components include thrust and control arms with M5 (within 3K miles), shocks/struts within 25K miles, inspected front wheel bearings and passenger rear bearing - all fine. Tires were just rebalanced 3 days ago.

I have the exact same problem as you and did the same thing that you did and replaced almost everything like what you did. My next is i'll replace my subframe bushing and diff. bushing since there's nothing more i could think off

[Scott C]

shouldn't be any issues since the speed sensor is in the differential. Shut the engine off before you put it into park.


Thanks - that will be this weekends work ;)

Do need to check on the passenger subframe bushing but the drivers looked great.

Scott

[Scott C]

I have the exact same problem as you and did the same thing that you did and replaced almost everything like what you did. My next is i'll replace my subframe bushing and diff. bushing since there's nothing more i could think off

It is really frustrating - not much logic to it. My son says "buy a new car", I remind him that we all make choices and if he wants to go to college, he should be helping me ;)

[whiskychaser]

It is really frustrating - not much logic to it. My son says "buy a new car", I remind him that we all make choices and if he wants to go to college, he should be helping me ;)
Education: The only thing they cant take away from you. I wonder if our grandchildren will even know what a spanner is though.

[Scott C]

Education: The only thing they cant take away from you. I wonder if our grandchildren will even know what a spanner is though.

Actually I did make progress with one son - his first car was a $500 Plymouth neon that required all new brakes (I "let" him rebuild the calipers for $2 seal kit) as well as he had to pull the engine (yes!) and put new seals and a headgasket in. He spent one summer working on that car and now regrets selling it to his younger brother because he "needed" to buy a jeep...

Now, my second son is more of a talker than a doer....

[Scott C]

Halfshafts are out - both units, the CV joint by the diff seems very dry and notchy. Boot is fine. Checking on replacements...

Haven't spun it up to 55mp with halfshaft out (yet), but don't think I will see a problem.

Scott

[Scott C]

Okay,
It was not the halfshafts...

Running the car without them results in much vibration between 50 and 60 mph. I took a video but it really doesn't show the problem.

Out comes the exhaust to check how things are with this rebuilt driveshaft. I suppose I screwed up on the preload which will be the first thing I check. Did I ever mention how much I hate working on this exhaust?

One thing I did notice is that there is some notchiness in the differential when (driveshaft locked) I spin one end of the output shafts (both halfshaft are removed). I can definitely feel repeatable gears which may or may not be okay. Will have to check with driveshaft out and then move the front pinion.

Scott

[632 Regal]

that gear feeling when turning the outputs in opposite direction would have nothing to do with a vibration. I think your right back at the driveshaft. Is there a chance that the driveshaft is in there out of phase?

[Scott C]

that gear feeling when turning the outputs in opposite direction would have nothing to do with a vibration. I think your right back at the driveshaft. Is there a chance that the driveshaft is in there out of phase?

Driveshaft out of phase (you mean front and back sections not installed per original balance?) - Not by me, it came fully assembled (with center bearing installed). I installed it out of the box... I will look for some type of markings to see if maybe they assembled it incorrectly when putting center bearing on. I sure would like to get it silky smooth without having to send this back to texas.

All I did when I received this unit was check to make sure that the U-J and CV joints were free (and clearly the CV had new grease) and popped her in being careful not to overangle the CV joint.

[Scott C]

Well,

The center bearing was not preloaded as much as I would have liked, so retightened it. Low and behold, vibration STILL persists in the driveshaft. (again with half shafts out). Peak resonance is right at 55mph - interesting eh?

I validated upon removing the shield that the driveshaft was assembled correctly (at least the way the rebuilder had put on tags that showed where the two halves join).

So now, back to texas it goes....

Scott