transmission banging
 

I have my lovely 240 estate back as of today and she is stopping much better than she was - thank gawd for that!

But, you know what, there's still some grumbling going on under the floor...

Here's the history as brief as I can:
1 Bought at 98k miles - transmission smooth as you like in all aspects except a weird vibration in top gear 45-60mph. No clutch judder and no banging
2 2nd hand g/box fitted and clutch changed. Much vibration. Undriveable
3 f/wheel skimmed (allegedly burned). Better but still bangy
4 use car. Banging gets better
5 original g/box vibration investigated - turns out to be shagged main shaft/top gear - so a genuine fault (but no longer relevant)
6 car still banging (low speeds - especially reversing)
7 s/h (111k mile) propshaft fitted. Better but still bangy

So what's the deal? It's had new suspension bushes all round (3 months ago). The clutch itself new 18 months ago

Possible centre bearing on prop? Possibly still the flywheel being a bit rough?

Any thoughts folks?

Hi- couple of questions...

I assume the connecting doughnut between the gearbox and propshaft was replaced when the propshaft was changed?

Does it only bang in gear- what about if you shift out of gear into neutral down a hill- does it bang then?

Where in London are you?

Cheers

Hi Bugjam

In reverse order - Teddington, SW London

The banging occurs notably in reverse and at low speed (parking etc). You can get judder changing gear in lower gears - especially if changing down

I don't think that anything was changed two years ago and nor this time. Go back to my timeline above: when I bought the car the transmission was smooth with no problems. The transmission banging has only started since the gearbox was changed (and the gbox was changed because as I now know, it was defective)

I haven't tried the freewheeling in neutral trick - I will try to remember to do that some time. Like I say tho', the banging only occurs at low speeds and once on the move, by and large the transmission is fine...

I’ve reread your timeline- sounds like something is wrong with the replacement gearbox, since it hasn’t ever worked without noise. Where did you get it from?

M47 gearboxes are so cheap now that if you could swap the gearbox yourself you could replace the gearbox you have with a known good one for little money. Perhaps not so appealing as a test if you’d be having a garage do the work though due to the extra cost of labour...

Are your engine and gearbox mounts in good condition? Propshaft ujs?

Cheers

Re the old messed up shaft in the previous gear box, let us not ignore that, just in case. Incidentally in general I'm curious or possibly concerned how that happened.

The replacement gearbox, who fitted it, skimmed the flywheel and refitted the gearbox?

Does the banging sound and feel like something internal to the transmission, or like knocking against the body of the car? I get the impression you are talking about knocking against the car body? Can you get the use of a mechanic's stethoscope and would that help?

If the engine is ticking over, and by laying down on the ground to listen, is there any knocking even a gentle tapping sound? If so can that sound be relieved by say slightly supporting the gearbox on a jack?

Looking also at the timeline, and with experience of a similar problem on a car of a different make, my hunch is engine and/or gearbox mounting[s]. That is even or perhaps especially if the mountings or any of them were replaced recently.

Perhaps replace all the engine and transmission mountings. Using genuine Volvo parts. Try to do it by supporting the entire engine/transmission assembly so the mountings are not under strain during the process. Then, with little or no weight or stressors on the mountings, tighten them up incrementally. Tighten each mounting a little at a time, in turn one by one. If any sort or form of resistance is encountered, try to check it out before continuing. Get the whole situation as stress free for the new mountings as possible. Do it thy self or see it done.

You have mentioned to me a vibration of a different component at or about a particular road speed. It does sound unrelated. But ... I suggest always keep an open mind.


.

What exactly do you mean by banging?
A mechanical, metalic sound from a gearbox, as if something has broken or come loose?
Or a suspension-related sound, as if something is moving about too much on its mountings and causing a thumping noise or vibration?

If it wasn't that you've said all the suspension bushes have been replaced I'd have said worn reaction arm bushes, letting the rear axle tramp excessively in low gear, and bumping the front of the diff against the rubber bump-stop.

Or a very worn rubber prop doughnut, letting the prop whiplash around under low speed torque or oscilate at certain revolutions.

Hi all

Crikey so much help and thought Bugjam, Clifford & Stephen. Thank you

Ok let me try and be more precise:

1 The rear suspension has indeed been poly-bushed (about 150 miles ago) and at the moment I have eliminated axle tramp as a possible source
2 The gearbox in the car now has 210k miles on it being a s/h one fitted about 5k miles ago. I recently changed the oil in it; it drives sweetly making no strange noises
3 The car has just had a s/h propshaft fitted (no replacement bearings/UJs etc) and the banging is no better - slightly different, but no better

So that leads me to:
4 Engine/gearbox mounts have not been changed but appear fine. I am not aware of excessive movement in either, when starting or whilst running. I guess it is possible that the g/b mount is a 210k mile fitting and maybe suspect so there's a thought...
5 Two propshafts with very similar mileage on them, may both be presenting the same fault. I think that that is unlikely
6 Lastly the clutch/flywheel. Ok, huge saga here. When the s/h g/box was fitted, a new clutch was fitted against the car's original flywheel. Allegedly this was totally undriveable as the flywheel had heat spots on it. From recollection, the car currently has a 5k miles clutch in it with a flywheel that had been skimmed...

Clifford - by banging I mean a sound you can feel (like a trembling) and the noise is a booming or rumbling-like noise - it would be consistent with vibration in the propshaft setting up a drumming sound. (it's not graunchy, metallic or a whine from the gearbox which as I say is pretty sweet considering it's mileage). The sound is not that loud, but someone standing outside the car can hear it as well as the driver. It only occurs when you are taking up the drive through the clutch, generally from stationary (but also you can induce a slight trembling (no sound) sometimes when changing gear, especially changing down and the engine and gearbox speed aren't matched so the clutch is acting as a brake). I haven't tried, but I suspect that I could induce the banging by lifting the clutch against the handbrake with the car in reverse or first

Any further thoughts? And thanks again

Nick

You have reminded me I did once experience a slightly similar noise on a previous car, which after trying umpteen things finally went away by itself, so I never knew what had caused it.

(Read the saga here - https://www.volvoforums.org.uk/showthread.php?t=229118
but mixed up with another unrelated noise)

Another thread did highlight a soft gearbox rubber mounting, causing the box to jump about under starting torque. It was hard to spot until it finally collapsed and the box was sitting on the cross member.

I've just remembered another similar noise, caused by the gear lever carrier banging on the side of the bodywork turret.
Despite new engine and gearbox mountings I could see when lying directly underneath that the back of the box was not central in the space, and could move enough to touch the metal on one side.
In the end I removed the mounting bracket and elongated the fixing hole to a slot so that I could centralise it properly.

Clifford, your comment re a gearbox mounting on a cross member mirrors an experience I had with a Triumph 2000 mk1. And I have wondered if that transmission might have been not quite correctly aligned in the tunnel, causing the mounting failure.

Bit of a long shot: ~ have you checked the exhaust system for clearance against the body? Just had it on my car- tail pipe required adjustment?
Good Luck.
Bob