Transmission mounts

Themoog2 · Post by **Themoog2** » Tue Jun 29, 2021 6:16 am

Has anyone got experience of transmission mount failure symptoms and/ or engine mount failure symptoms?
Was there a noticeable change after replacement?
Ive got a vibration that I'm determined to chase down.. Its at about 2k rpm as pressing the accelerator. Sort of a booming harshness. Difficult to explain.
I swapped the engine mounts a few years ago but it was even worse - especially at idle. Possibly because the replacement parts were cheaper ebay bits- so I put the old ones back on.
So I'm thinking of replacing the transmission mount and driveshafts flex discs. Maybe the centre bearing too. I'll look at the diff mounts and also put in new subframe bushes.
I think after 165k and 20 years they may be a bit worn out..
All this is because I've been car hunting and everything I look at is not as good as the old 4.4 so I'm sticking with it.

Leslie · Post by **Leslie** » Tue Jun 29, 2021 8:38 pm

I doubt the transmission mounts will have failed as its usually the passenger engine mount that takes a pounding due to the way the engine flexes it . The new engine mounts would have be stiffer just because they are new so that would account for it being a bit more harsh.

henrym3 · Post by **henrym3** » Wed Jun 30, 2021 6:50 pm

I changed the engine mounts because of a small vibration in the drive line, one was completely shot (passenger side) new ones made bugger all difference other than more vibration at idle. When I changed the rear subframe bushes the drive line vibration went away.

Themoog2 · Post by **Themoog2** » Wed Jun 30, 2021 10:21 pm

Ah.. That could be it. I've been told the subframe bushes are knackered.
I have no knocking tho - maybe a wallowy feel to the back of the car.
That's on my list.

Themoog2 · Post by **Themoog2** » Sat Jul 03, 2021 12:59 pm

Interesting. Nathans bmw workshop on YouTube has just replaced the main drive shaft on his mother's X3. Ive been in contact and the symptoms on his were very similar to mine.. Something to look at I suppose.

Themoog2 · Post by **Themoog2** » Wed Jul 07, 2021 2:14 pm

I think I may have found one of the contributing factors to my driveline harshness. Either the prop shaft UJ is worn (it has no radial play) or the centre support bearing is worn. When I thump the shaft with my fist just in front of the bearing there is a knock or rattle coming from either of the two. It’s not much but it’s there.

Themoog2 · Post by **Themoog2** » Sun Aug 08, 2021 1:31 pm

Just finished replacing the rear subframe bushes..
What a palaver - dodging rain showers, drinking beer and getting dark do not go together.
I made the mistake of doing one side and tightening it all up then doing the other side whilst slightly drunk - the bushes didn't line up with the location pins on the body but I didn't notice and banged the bolts in with my torque gun. As they were at an odd angle the threads picked up and made a mess of the bolts..
Anyway, this morning with much harsh language and some engineering (and sober) I undid the first side and lined it all up. I rethreaded the bolts and now it's all back together.
I can report that the vibration in the drive train has virtually gone, although I've only driven it 200 metres.
I shall report back when properly assessed.

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