Makes good sense to start with the obvious, Brian. I’ll get that checked - thanks

It could be a combo of the new tyres and road surface. I drove a piece of road regularly which had long indentations worn in it, from having queuing trucks stood on it. On the previous tyres, I'd notice the steering tramline and grab as it encountered these surface dips.

Then I got a deal on some new Pirelli P6000s and first time on this road, I too had to pull over and check there wasn't a bulge or a flat. Something about the tread pattern gave a real "brarrp" and vibration that wasn't present with the previous tyres. But only on tramlne-y surfaces like this.

I've avoided Pirelli since (and they were oem on that car, a 9-5 Aero)

Your rear bushes definitely need doing Jim, but I've personally not seen bad ones behave like this. Usually they give a loose feeling at the rear on cornering and really bad ones make the car quite unsettled on turn-in. Interesting that Mark has experienced something similar though.

A thought - is the problem in specific places? On the way back from Germany last year I had to stop in Belgium to make sure all my wheels were still attached! The odd road surface had set up a very unpleasant resonance in my car because of the specific combination of components in it, whereas the other D2s were all fine. Jimster may be on to something with the road surface if it only happens on some roads.

Now Spannerrash has found aftermarket bushes for the rear arms we can look to get yours done some time in 2020 once I've caught up on my backlog.

I really appreciate the input on this guys! But, no, it’s not on specific stretches of road; there was no issue yesterday on roads where it has ‘wobbled’ or ‘juddered’ or whatever previously. But I’ve also fitted Pirelli P Zeros!

But a date to get the rear subframe done would be great Michaela! Just so long as you’re not going to overdo it again!

Looks like Jim has mislaid his

1. Shudders,
2. Wobbles,
3. Judders.

Could anyone finding any of these please return them to Jim.

With the various terms used already to try and explain Jim's plight, I'm reminded of the scene in Airplane II where they're skimming through Roget's thesaurus looking for new words to describe how the shuttle was behaving.

Hopefully he can sort it out before we all run out of synonyms.

As some of you, those of a certain age, will understand, shudders, wobbles and judders, as well as shakes and various other unsteady descriptions, are not restricted to our cars!

Another possibility (if you have the 5HP24A transmission). The torque converter lock-up clutch is susceptible to wear once the transmission exceeds 100k miles. The LUC was designed without torsional vibration springs/dampers to save on installation length and instead relies on software control at low speeds to allow it to slip at around 3% to absorb torsional vibration. It only locks solid at higher engine speeds where TV isn’t an issue. The total LUC piston movement is only 1mm, so wear in the friction plate means the controlled-slip mode becomes harder for the control system to manage and the result is a vibration at lower engine speeds that sounds a bit like driving over a cattle grid. If you look closely at the rev. counter you can see the engine speed wavering slightly (usually only by a couple of hundred rpm) in sympathy with the noise.

Phil

Did you ever get to the bottom of this Jim?

It’s still happening, and I’ll try to check the rev counter next time it happens. But it happens quite rarely and only for a couple of seconds, so it’s hard to check what else might be going on. Hopefully, I’ll be fit enough in the New Year to start investigating, but I’ve still not slept through the night since the op at the end of September, so I’m permanently knackered!