Odd vibrations at 1,500- 2,500 RPM VE Commodore Ute 2009

[WhiteCommie]

Hi all, hope everyone is having a great day.

Specs:
I've got a 2009 VE commodore Ute:
- V6 3.6L engine (can take Ethanol or Petrol)
- M82 Automatic Gearbox is currently installed AKA (5L40E)
- has a sporty trim with the red dials and red LCD display for the centre console (not sure which custom package it is)


Problem:
When I'm driving at rev and speed ranges specifically (70-80kph) (1,500 RPM) and (80-120kph) (2,500 RPM) i get this really weird vibration (similar to highway rumble strips "brrrrrrrrrrrrruuuummmpp"). As soon as it changes gear all the vibration disappears and then comes back again when i reach those rev ranges (sometimes at higher speeds too).

Additionally, it also happens when there's a load occurring e.g. driving on a slight incline, turning left, turning right or bumpy roads.


Attempted Fixes:
Things I've checked and completed:
- Changed the donuts and the centre bearing. (donuts were cracked and centre bearing rubber was cracked at the top) Installed them as they should be considering the positioning of the bolts where the thicker part is in compression, thinner part compression.
- Wheels have been rebalanced and fitted, (all of them).
- Parking brake shoe has been reset (originally it was so tight it wouldn't move in neutral or automatically in reverse with no throttle on even ground).
- Automatic transmission fluid has been changed with new filters and new fluid filled properly (drained and re filled, engine on for a bit though the gears, refill till you get wet fingers etc.)

Notes:
1) previously, the gearbox has been swapped, along with a new torque converter which I was told at the time "fitted with a stally, and now has the correct one"
2) The installation of the centre bearing is adjustable slightly, as per this forum on 08-09 pontiac G8's (similar driveline system) Check out "#PIC4989: Drive Line Boom Noise And/Or Vibration - (Oct 2, 2008)"

3) when I was installing the new rubber donuts, I notice that I had to buy larger ones. although through every website i've used to configure my vehicle into their product recommendation system for a '09 Commodore Ute everyone recommends a smaller donut.

- VE commodore rubber coupling size: 96mm PCD, Outer Dia 134mm , Centre Hole 50mm.
- Current ones installed: 105 PCD, Outer Dia 141mm, Centre Hole 55mm.

Question:
Does anyone know how to fix this issue and have any experience? I've looked at posts all across the forum and still can't find the problem, I've tried to adjust the centre bearing today and "re-align" it using adjustment holes but no avail, still happens. Also, have I got the wrong coupling donuts? Why is my donuts larger? should I consider the smaller ones?

Thank you all.

 

[WhiteCommie]

Also just wanted to add, these are the parts I bought for the coupling and centre bearing:

- https://www.supercheapauto.com.au/p...-ba---4.0l-i6--petrol---manual/SPO422102.html
- https://www.onlineautoparts.com.au/...B980-suits-Holden-Commodore-2009-VE/ZPN-09485

Yes i know, the couplings are for a "falcon" and stuff, but they're exactly matching the ones ive pulled off from my original. (previous owner has changed maybe?)

 

[losh1971]

V6 and V8 use different couplings AFAIK. This is what I was told when I bought mine. The Centering bush wears on these and will cause vibes. The other thing can be a stuffed uni. Depending on how the bearing was changed you can sometimes damage the uni.

 

[WhiteCommie]

Interesting, I'm wondering if i should try and switch back to smaller drive shaft couplings and see if that changes it since ive got a V6. I also checked the Uni-joints which were perfectly working and smooth as butter.

Thanks for your reply though!

 

[WhiteCommie]

Would anyone be able to dumb this right down for me?

#PIC4989: Drive Line Boom Noise And/Or Vibration - (Oct 2, 2008)

Subject: Drive Line Boom Noise and/or Vibration

Models: 2008-2009 Pontiac G8
--------------------------------------------------------------------------------
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
There may be a either a boom noise or vibration and in some cases both a noise & vibration detected in a very few 2008 & 2009 G8's. This condition may be detected by customers at speeds of 55-65 MPH on either 08 or 09 G8's. The noise could be described as a low frequency boom or moan noise (not a whine) coming through the body. The vibration is generally felt in the seat or the floor pan. The condition could be caused by either a misaligned center support bearing assembly or the prop shaft mounting to the differential yoke.

Recommendation/Instructions:
The prop shaft center support mount is slotted left to right and can be adjusted by loosening the bolts which are accessible through holes in the metal shield between the prop shaft & the floor sheet metal. After loosening the center support bolts you can use a pry bar between the prop shaft & floor to adjust the center support. If the alignment isn't correct the prop shaft will usually "snap over" into proper location with very little input.

If the condition is both noise & vibration felt through the floor, re-indexing the prop shaft to the differential yoke may have to be performed:

Mark the relative alignment of the propshaft, rubber coupling, and differential in the original position.
Number the nut and bolt pairs and their hole in the rubber coupling which join the rubber coupling to the differential (silver) and the nut and bolts which join the propshaft to the rubber coupling (black).
Remove rubber coupling from differential and propshaft, ensure the nut and bolt pairs are kept together.
Re-assemble indexing the rubber coupling and silver bolts clockwise (relative to differential), and the propshaft and black bolts counter clockwise (relative to differential).
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.


So, do I attach the bolts on the diff with the bolts positioned in the direction of the arrow markings on the rubber couplings? (silver bolt heads facing engine side) and black bolt heads facing diff side? or is it telling me to install the bolts (all heads facing the same direction) but silver bolts torqued clockwise and black bolts torqued though each bolt in a counter clockwise pattern?

Also, has anyone attempted this fix before? how do i align the centre bearing properly (i still dont get how to with these instructions). Thank you!

 

[WhiteCommie]

Update for the 11/04/2024.

Ignore the post about the centre bearing, i was able to rotate the centre bearing slightly by twisting it and then bolting it into place due to the slots on the centre bearing holes.

However, doing all of that is nothing and did not stop the vibration. Turns out the vehicle was suffering from transmission shuddering. definitely learnt a lot about those M82 5L40E's.

Note: If you are driving at 5th gear, whether in sports or in normal driving and experience a sensation in your ass similar to the feeling of driving over highway rumble strips its possibly gearbox related.

When I drained the fluid and refilled, I noticed that I made several mistakes on my part here's some key pointers.

1) ensure that the trans oil temp is 30 - 50 deg centigrade if you are replacing the transmission oil.
- trans fluid expands when hot and thus this allows the fluid to flow nicely out of most of the passages in your transmission.

2)When you fill the transmission do it in these steps:
- Fill the drain pan with oil until it hits your finger or gushes , seal the filler hole with that bastard plug
- Start the engine and with the foot on the brake, cycle through all the gears P,R,N,D ensuring that you are stopping minimum 3 secs for each one.
- Turn the engine off, and refill the transmission again, you'll definitely notice that the level is down. reseal with the plug.
- Start the engine again, cycle through the gears
- with the engine on, put more oil into the transmission again, until its slowly leaking out.
- seal the plug.

With this, you should have roughly used about 7~9L worth of transmission fluid.
As per the service manual, a total transmission overhaul takes about 9L of fluid, dropping the pan only takes out 6L.

Highly recommended that you change the filter and pan gasket (which I have) and possibly even another fluid transfer using the trans cooler lines, which I will be doing next month cause fluid isn't cheap and I want to ensure I'm really getting a good mix of the old **** inside.

Now the car is shifting smooth like butter and does not shudder.

Have a great holidays everyone.