Shudder possibly from the exhaust

[bobfather]

I have a shudder that appears to be coming from the exhaust, starts at about 90mph and shudders for a about 3 second then no shudder for 3 seconds then shudder again and so on. I overheard someone discussing a flexi joint that is fitted around the bottom of the down pipe, I don't appear to have this and wonder whether this is why I have the shudder.

Any thoughts? and if this is available where's the best place to acquire one?

[Milky400]

yeah, slow down........

[AV8]

Mine doesn't have a flexi and never shudders. I might be wrong but I thought only 500's had the flexi.

Is the bonnet flapping up and down by any chance?

[bobfather]

Bonnet doesn't wobble any worse than it always has, this shudder is central and low down in the car. I'm doubtful that it's an out of balance in the drive train or wheels because of the way it cycles on and off over several seconds, out of balance mechanicals normally shudder constantly when at harmonic rpm.

My engine mounts are originals so they are likely to be significantly weaker now, possibly replacing those would tighten things up enough to stop the shudder

Edited by bobfather on Monday 28th April 15:15

[Chuffmeister]

Well that's the thing I'm looking into and I' have my exhaust off and am awaiting new UJ's for the prop shaft. The engine mounts will be done after that.

[Milky400]

Does is disappear when you gradually accelerate? I have exactly the same on my daily drive, but it stops when you speed up, it there when cruising at 60-80mph.

[bobfather]

It's gone by about 100mph but obviously I don't get to pprove that very often. It's only present between 95 and 100 so I doubt it would show if I was accelerating. It occurs when cruising at those speeds. Because of the speeds that it's present it's not easy to demonstrate to anyone

[bobfather]

It's gone by about 100mph but obviously I don't get to pprove that very often. It's only present between 95 and 100 so I doubt it would show if I was accelerating. It occurs when cruising at those speeds. Because of the speeds that it's present it's not easy to demonstrate to anyone

[HENRYKS CHIM]

Im getting the same symptom as you. I would call it a repeating drone about the same every few seconds.Mostly when crusing on the motorway at a steady speed.
Similar to a friends Merc SL whos problem was a small tear in the soft top.Im wondering if its caused by the 6 air holes in the floor by the fuel tank? Possible increase /decrease of air pressure in the boot through the vents into the cockpit maybey. Try it with the roof down. Tape up the holes and try that as well. Thats what im going to do when i get the chance

[Dodsy]

I had something like this. Vibration but only at speed (in my case anything over about 60) but it was cyclical , about every 2 seconds while driving. Also accompanied by some thrumming.

Turned out to to be the UJ on the propshaft. Dont know if they are all the same (being TVR!) but mine needs greasing and it hadnt been done for a very long time by the previous owner and their mechanic. Once it had been stripped down repacked with grease the problem was solved. I now make sure its greased at every service. I think it gets overlooked as I think the exhaust has to be dropped to get to the grease nipple.

[bobfather]

Propshaft UJ sounds right, low down and central. Mine hasn't been greased for several years. I guess I'll try that though I'm not looking forward to manhandling the exhaust

[StarmistBlue400]

I used to get similar at motorways speeds, thought my wheels needed balance but turned out one of the rears was bent and buckled