Lagondaforum

Subject: Uneveness/vibration

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Has anyone had any experience of worn engine mountings on an LG45 causing an uneveness/vibration ?
I have checked all the other usual suspects with no success.
It occurs at about 65mph ie in the Meadows "Death Zone" but I am sure it is not the engine or bad tuning. I have renewed the crank damper with a nice new LMB one.
It is not back axle. The clutch and propshaft have been balanced. I have rebuilt the gearbox and aligned it properly.
The problem is annoying rather anything else.
I wonder therefore about engine mountings or even possibly a poorly designed exhaust (back pressure ?).
Anyone got any ideas or suggestions ?
Thanks in anticipation.

Subject: Re: Uneveness/vibration

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Morning Bill,
Difficult question. You seem to have checked all the usual suspects but there is one more. The later LG45s had a funny spring damper in the front engine mounts, if this is not wound up tight it can cause what you describe.
However if your vibes are from about 2400 to 2600 revs I would suspect engine harmonics and a possibility of worn main bearings although the LG45 does not suffer anything like as much as the earlier Invictas and M45s.
If not the front mounts then perhaps give me a phone and we can talk through the symptoms better and try to solve this.

Best regards,
Julian

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Subject: Re: Uneveness/vibration

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Julian, Thanks very much for that. Never heard of these spring damper engine mountings. I have had a very close look at mine again and they appear to be a conventional silentbloc type secured by 4 bolts - with a very large vertical bolt through the centre securing the engine mounting itself. Is this the type you are referring to ? If they are presumably it is just a question of making certain that the large vertical bolt is tight - or is there something I have missed ?
Nothing in the Revised Handbook !
Sorry to everyone that this topic should have been under LG45 not V12. Dont know how this happened. Is it possible that the Moderator could move it as I dont know how !
Many thanks.
Bill

Subject: Re: Uneveness/vibration

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Bill

Julian is referring to a long bolt that runs horizontally front to back through the upper part of the front mount. There is a coil spring on one end. Early LG45s may be different.

I have a diagram I could look out if you need more info.

David

Subject: Re: Uneveness/vibration

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David
Thanks very much for that. I think I have the early LG engine mounting so unfortunately that does not seem to be my problem - unless any one else has any suggestions.