Drive-line vibration

[andyborris]

My MK1 has developed a very bad drive-line vibration. Car is mostly MK2 in the drive-line

It's not the wheels, because it stops in neutral or with the clutch pedal down, but road surfaces do seem to affect it and it's worse on the overrun.

Feathering the gas, i.e. neither accelerating or slowing down greatly reduces the vibration.

Rear differential is only 12 months old and came from a reputable supplier.

I'm thinking prop-shaft? Am I right?

Thanks

Andy

[valencia]

Check the propshaft by all means but how about the gearbox mount for security and overall condition.

[Allen Walker]

I would say you are likely correct to investigate propshaft first.

[CAR]

I would say you are likely correct to investigate propshaft first.

Is yours all sorted now Allen?

Colin.

[Allen Walker]

No, propshaft has been sorted with a donated second-hand good 'un, but I still need to get under the car and replace the quill-shaft bearing which I believe to be shot.

Clutch is also not happy. Hydraulics are okay I think. As far as I know it is the original clutch and as it's fast approaching 90,000 miles I think it's due to be replaced. I'm wondering how to approach this job. I may need to put it in to a garage, I can't see that I've got the time or space to do it myself.

The car and I are not best buddies at the moment, but then I guess I didn't endear myself to it by dragging it 2500 miles around Britain with a buggered propshaft.

Things to do:
Clutch
Quill Shaft Bearing
Radiator
New controller on Kenlowe fan (bought, ready to go on)
Ignition fault-finding
AOB

[Jonathan Lewis]

My MK1 has developed a very bad drive-line vibration. Car is mostly MK2 in the drive-line

It's not the wheels, because it stops in neutral or with the clutch pedal down, but road surfaces do seem to affect it and it's worse on the overrun.

Feathering the gas, i.e. neither accelerating or slowing down greatly reduces the vibration.

Could be propshaft, driveshafts or mountings, but I'm a little confused as to why the vibration would disappear with the clutch down...

One thought - you don't have a viscous-coupled fan fitted, do you? If the coupling begins to fail, these can cause precisely this sort of vibration problem, usually under conditions where the fan speed differs from that of the crankshaft...

Regards,

[TedTaylor]

Propshaft vibrations usually occur at a specific road speed - if you are saying only 60-70mph this does suggest prop.

Check bolts then check UJs. Move them in all directions - by rotating prop and up and down/side to side. Even the slightest play indicates a UJ that needs replacing.

I remember many many years ago when a friend had a Spit with a specific road speed period vibration. Classic prop problem but our local main dealer could find nothing wrong - after 3 attempts. I was asked to have a look, targeted the UJs, and found just the slightest play in one yolk bearing. Replaced joint and problem solved.

Ted

[Mike Stevens]

Like Jonathan, I'n not sure why there's a difference with the clutch down.

When you do check the prop, you really have to remove it (or each end in turn) as a failing UJ can also go stiff or notchy. This you won't find by checking for play with it still on the car.

Viscous coupling is a possibility. I've had one of those go and the symptoms were a horrible sickening 'crunch' as you took up drive or changed gear. The noise goes right through the transmission and sounds very expensive.

I hate to say, but excessive play in the diff could also be a possibility. The changing nature with drive must give a clue though.

Gearbox mounting (as mentioned) as well as engine and diff mounts come to mind too.

Cheers,
Mike.

[tony]

One further thing occurs to me, but I hope I'm wrong !
Some years ago when using my TC as an everyday driver, she developed a similar vibration.I thought to myself "thinks" I must have a look underneath in the weekend.
Unfortunately it didn't last that long. When going over a railway crossing, a load bang and no drive. The flange on the diff nose piece had parted company from the rest of it.Obviously it had starting to fail when the vibration began.
Fitted a suitably reinforced one and no further trouble.
Don't know how you would pick this fault up without removing the diff and inspecting closely.
As I said, I hope I'm wrong.

[andyborris]

Of the usual suspects, the gearbox mounting has gone to the top of the list!

Can hear/feel the thump of the gearbox moving as I lift off or accelerate.

Luckily, Rimmers have this part on special!

I'll start there.

Andy