If it were driveshaft related, wouldn't the vibration stop or change when in neutral?

Maybe engine mounts?

 

I think engine mounts can be excluded as there is no vibration at stop and also no change in vibration when driving and changing RPM/gears.

A driveshaft related vibration won‘t stop when in neutral as the driveshaft is always spinning in a steady ratio to the wheels. Rear differential ratio is 2.87 meaning that the driveshaft makes 2.87 revolutions for 1 revolution of the wheels.

 

I think wheels or driveshaft. But check motor mounts.
Need a friend to watch engine. Put in drive with brakes on firmly. Raise rpm to maybe 1500 rpm. Have watcher check for motor movement. If it lifts more than 1 cm it looks like bad mount. Do the same in reverse.
If you only have small motor lift the mounts are fine.

 

Good advice (above)...

About Driveshaft Balance:

- Unbalanced driveshaft will generally "Lob" (move in an oblong) when spinning, especially at unbalanced end. (Lobbing is allowed by trans and rear subframe rubber mount compliance. If driveshaft is defective - eg, running out of round at slow speed - then fix u joint, etc and retest)

- Put the car on a lift with helper and run up to vibration speed. (It helps to remove rear wheels to isolate driveline vibration)

-- If vibration seems to be at middle of shaft, check center support bearing and bearing mount. rubber bridle. Rough bearing can be heard with a screwdriver

- Typically, holding piece of chalk so lobbing drive shaft skims it will show problem and mark "heavy" side. (If this is opposite the square rust mark, bingo)

- Old school solution is to mount a pair of hose clamps with heads 180 opposite "heavy" side (mark heavy as 0 degrees). Carefully adjust clamps toward 90 and 270 degrees until shaft runs smoothly (ie, chalk skims evenly around shaft)

(Note: I like that you measured vibration frequency as an integral of prop shaft RPM. Hope these tips help)

 

Thanks very much for your input, hisport. Thats exaxtly what I wanna do next: Put a hose clamp on the propshaft near the rusty mark and see if there is any change in vibration.

Watched this very good video on Youtube before:
I‘ll keep you updated guys.

 

Tios:

- Adjust clamp heads exactly like you'd adjust two weights when manually bubble balancing a wheel. Progressively move each clamp head equal distance from 180 mark

- If weight is insufficient, use two pairs of clamps - keeping each pair of clamp heads together per above

- Like bubble balancing, trick is to begin at 180 with a bit too much weight, then move heads equally toward 90 and 270 until balance is achieved

- Trick is to just barely skim spinning shaft with chalk. (eg, tape chalk to piece of 2x4 and hold against driveshaft tunnel, move slowly toward spinning shaft)

- Paint clamp heads when done (the clamp screws will rust otherwise)

- OE balance weights get knocked off by road debris, etc

- Remove rear wheels first and be super careful around spinning shaft

 

Hello Guys, I'm about to replace the transmission mount, following this great explanation about how to do it.

The symptoms:

Some vibrations at low speeds that could be feels on gas and brake pedals.

Slightly knock sound/feeling on the floor, mostly around the center console area but that's when there is any little bump or road imperfections, the feeling is like something lose underneath.

If I turn right and left sometimes I can feel and hear that slightly knock on the floor.

Note: Engine mounts were replaced like a year and a half ago but not the transmission mount.

I went under the car this morning and took some pictures so I would like that some of you guys with experience in this could tell me if this is the way that a bad transmission mount looks like.

I bought the car almost 6 years ago with 128,000 miles on it and today has 177,000. According to the seller (dealer) the car have a transmission rebuild, I haven't had any issues with transmission or engine during theses 6 years, just regular maintenance. So I don't know if when they rebuild the transmission they also replaced the transmission mount and it's not as old as the vehicle (2005)

Thanks for your help.

 

Thumps against the floorboard seems extreme. The mount LOOKS okay. Try levering the tail shaft to see how much it moves?
Were the crossmember bolts tight?

 

Thanks for your help, I'm gonna check that and I'll update as soon as I do it.

The floorboard is not that hard, but could be feels on your feets but that's the most confusing thing about the issue, because sometimes it's hard to tell where it's really coming from, some times seems like it's under the dash.

I just found this part that was extremely lose, I was able to loose the bolts with my fingers. That lose it was but I don't really know what is the function of that bar.

 

I drive an x351 with the same transmission mount as the OP.

Had my transmission mount changed because of a growling/ vibration noise as I went on or off the accelerator at around 2000 rpm.

There was no obvious/ visible damage to my transmission mount. But changing it eliminated the noise. So unlike the engine mounts, the transmission mount may not show obvious wear.



Old mount looks fine

Rubber flexes easily. Limited resistance.

When I cut the old tranny mount, you can see the oil filling leak out.

 

That one looks good and that's a perfect example, if you wouldn't see it once you removed it you wouldn't even notice with your eyes how it was.

Since the engine mounts were replaced a year ago, i think that I must replace not the transmission mount even if that's not the problem, but for sure there will be some improvements on the driving experience.

Thanks for your help and sharing your experience with this.

 

Those engine compartment braces just stiffen the car chassis. They could cause some noise being loaded and unloaded by the body as you drive over bumps but I would think any noise it would make would be in the engine compartment area?

Yes post back with any changes from the replaced transmission mount. That may be the problem?
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Yes, I'll do that. I'm gonna order the Mount and a few others tools that I need.

QUESTION:
My transmission mount show on pictures looks different than the one that Nedoerr, there are different shapes for the same vehicle?

 

My transmission shop recommended replacing saying that there was little play around 3k mi ago. Car has 108k mi. They said it isn't urgent but something to keep in mind. They are ok with me ordering the parts myself. My question is:

I don't hear or feel any of the symptoms in this thread other than the "classic" ZF- gear whine. Should I consider doing it soon? Also the car is on original engine mounts; should I do those as well at the same time?

Finally, what is a recommended place to buy the parts?

 

Anymore, where you can find them is best place. I put in an Eurospare brand. Still fine. But those are not 100.00 anymore. Try dealer, might be close to aftermarket in cost.
I ordered my cheapo from Amazon.

 

I know this thread started in 2015 but, THANKS XJ8JR!

My 2006 VDP a.k.a. Jinxie had those very same symptoms, and I quote:

Symptoms:
-vibrations at idle
-vibrations at initial acceleration which would disappear until around 30 mph and then again just before 70mph
-loud hum like the inside of a jet
-loud whirring noise upon acceleration
-occasional slight bump sensation when decelerating
-when nose down on a steep incline, like a hill or driveway, engine would sometimes get super quiet and all vibrations would stop. I used to think the engine was about to stall, but now I realize that at those moments, the engine/transmission would sort of rock back into its proper position, and then when the car righted itself again, the engine/transmission would go back to its broken-mount incorrect position, whereupon the vibrations and noise would return.

Now all those symptoms have disappeared completely. Incredible.

My mechanic changed the bracket and now Jinxie feels and drives like a real Jag! Amazing.

The car has 120k miles, bracket look ok at first sight.

The core was completely loose, you can move it 1/2" each side. I'm leaving Abdi's info, great mechanic, well, he's the same one that let the car fell from the lift arounf three months ago. There is a long thread in this forum about that odyssey.

 

Mine had a few issues, mainly when accelerating or decelerating. But back then the Eurospare were around 99.00 with free shipping.
Looking at it showed nothing. Once new one arrived, thought it was the wrong part. Looked way bigger installed. This mount fits in my hand.
But saw the oil was leaking out once removed. Did not notice any side to side.
Drove much better.
I thought only S/C engines killed these mounts. Time is showing they fail on N/A engines too. Just not as soon.

 

I never imagined that such a small spare part will make such a difference. It is smooth as silk now, a real Jag.

 

The aftermarket appears to be out of stock other than I buy it from the dealer. Again; I barely experience any symptoms mentioned above and my mileage is 108k. I only heard about this problem when I did my 105k oil change\brakes\ fluids at a transmission shop (they started working on my car since I change the tranny fluid at 85k) Is there any visual test that I can do while the car is on a lift? I really don't know if it is necessary or not. What age and mileage have most X350 owners replaced theirs?

 

No visual test. Sounds like yours is still good. Follow the symptoms posted above. The car will tell you when it's worn out. Of course if you have ANY vibrations as you say I would change it and be done with it. No real mileage or time requirements. It just depends on your car.
Also be aware it's common to replace both engine mounts and the transmission mount when chasing down these types of vibrations.
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