Vibration at speed

[Colin RedGriff]

Noticed today on the way to Sunday Service a vibration in the Griff.

It doesn't happen when I am am accelerating but once I am at say 50mph and I lift off it becomes apparent. I can feel it at part throttle but not as much. Seems to be coming from the front of that car rather than the rear.

It seems to be engine speed related rather than purely speed related. On the way home I tried a few things to isolate it.

If I dip the clutch and keep the revs up I can still feel it but if I dip the clutch and take my foot of the the throttle it goes away. If i put my foot down it goes away too.

I feel it through the steering wheel and also through my right foot on the throttle and through the transmission tunnel.

My initial thought is an engine mount so I'll check but they are less than a couple of years old. Could be but if anyone has any ideas -

[Barreti]

If it's any use to have a second opinion I'd be looking at the engine mounts too Colin

[QBee]

I had a vibration in my Chimaera but that's another story returning from a track day. Was at about 3000 rpm.Turned out to be a loose pipe in the silencer, solved by changing the exhaust.

[Colin RedGriff]

Had a bit of a poke around underneath and in the engine bay - the engine mount bolts are all tight and the engine doesn't rock or move significantly when I rev it, so I think the engine mounts are OK.

Had a look further back and I think the drive shaft CV joints might be worn.

I can turn the wheel and there is about 5mm of rotation at the wheel rim before the driveshaft turns and it certainly sounds a bit clunky if I grip the driveshaft and twist it back and forth.

There shouldn't be any play in the joint should there?

Also noticed oil weeping from the nearside of the diff. There appears to be a pin hole which i assume is a tell-tale for a worn output seal, oil seems to be leaking out of that. Offside has a hole too but no oil coming out.

Can the seal be replaced in situ or is it a diff out job?

[QBee]

Obviously I haven't heard your noise, and that leak from the CV boot definitely needs inspection by an expert. The slight play is something I have noticed, and I have had mine inspected recently, so maybe it is standard?
Going back to the exhaust theme, have you checked that all the bolts holding it in place are tight, and that it is not touching anything. It is a common source of unwanted harmonic vibrations.

[Colin RedGriff]

QBee said:

Obviously I haven't heard your noise, and that leak from the CV boot definitely needs inspection by an expert. The slight play is something I have noticed, and I have had mine inspected recently, so maybe it is standard?
Going back to the exhaust theme, have you checked that all the bolts holding it in place are tight, and that it is not touching anything. It is a common source of unwanted harmonic vibrations.

The vibration is felt, not heard, and it's a fairly high frequency vibration like I'm going over rumble strips almost but not as severe as that.

The leak isn't from the CV joint itself. On the underside of the diff just underneath the output flange there looks like a small hole drilled in the casing and the oil seems to be coming from there. There is matching hole on the offside of the diff too but that one is dry. I checked all 4 of the CV joints and the boots are all intact

I checked the exhaust mountings and they are all tight, the exhaust doesn't move on it's mountings and I can't see anywhere that it has touched the chassis. Its not rattling around although I did notice a couple of places where it is blowing slightly.

[roseytvr]

Colin

I had a similar issue on my Griff and there were two contributing factors:

1 the bobbins attaching the exhaust to the underplate had been over tightened and squashed
2 the pate had a slight bow in it

Net result was the exhaust box was actually touching the underplate. Net result is a vibration through the plate into the chassis. Check that there is a gap between the exhaust and the plate

Good luck

[PeteGriff]

Colin RedGriff said:

Noticed today on the way to Sunday Service a vibration in the Griff.

It doesn't happen when I am am accelerating but once I am at say 50mph and I lift off it becomes apparent. I can feel it at part throttle but not as much. Seems to be coming from the front of that car rather than the rear.

It seems to be engine speed related rather than purely speed related. On the way home I tried a few things to isolate it.

If I dip the clutch and keep the revs up I can still feel it but if I dip the clutch and take my foot of the the throttle it goes away. If i put my foot down it goes away too.

I feel it through the steering wheel and also through my right foot on the throttle and through the transmission tunnel.

My initial thought is an engine mount so I'll check but they are less than a couple of years old. Could be but if anyone has any ideas -

Colin, it sounds very much like transmission vibration to me from what you are saying. The propeller shaft will have a bit of 'slack' when rotated, but if a UJ has gone you will feel slop in the movement rather than rotational 'slack' (which with a good setup should not be that much). Have you lubricated the prop UJ's and slider at all? They need checking at least once per year by pumping grease into the grease nipples! Does it vibrate when say slacking off acceleration and driving along at a no load speed? Also, the leaking oil from the diff is not good, check your oil level as soon as you can because a replacement diff or worn crown wheel & pinion is a lot more than a couple of seals! Best of luck, Pete

[Colin RedGriff]

Thanks for all the ideas

I dropped the exhaust this evening to check the propshaft and that all looks good. UJ's look lubricated and there's no play in them. Bolts on the propshaft are tight as well.

Checked the ideas on the exhaust from QBee and roseytvr as well, but that all looks good. There's at least 1cm of clearance between the exhaust and the plate that bolts to the chassis. Can't see anywhere that it is touching the chassis either.

I'm going to get the wheel balance checked I think so I can rule that out.

I've wiped down the diff to make sure it's not just overspill from when it was topped up at the service in April. I'll check the level and top up before I drive it to the tyre place to get the wheel balance checked I think

[PeteGriff]

anonymous said:

[redacted]

Hi Anthony, no did not get the lift, but did have a good look at all the 'car lift gear' whilst at the NEC Classic car show last November. I have carried out a 'full survey' of my garage/workshop and have deduced that I cannot fit in a 2 poster (not enough ceiling height)! Because my garage/workshop has a storage area/additional room on top (it was an outbuilding years ago) the ceiling inside cannot accommodate a 2 poster. So, my decision is to buy one of the 'Strongman Tools' Clifton Scissor lifts! They lift a car just over a metre, with clearance down the middle, all fitting nicely in my building. That is a project for later in the year. All the best, Pete

[Colin RedGriff]

To bring this to a close (hopefully)

I spent some more time today checking under the car again and took the car over to a local tyre place and had them rebalance the wheels. They weren't wildly out of balance but on a test drive afterwards the vibration seems to have gone. Here's hoping