Juddering under mild load.

[fourwheeler]

Hello all

A quick question, if you will..

I've narrowed down a juddering / vibration in my S212 E 350 petrol last evening on a late drive home.

Slowly accelerating from 40 to 60mph, at about 2k RPM under mild load and throttle just eased on.... i.e. Very careful driving... I get a real judder and vibration on the underside of the car. If I set the car at cruise control it runs fine, but any bit of an incline that puts load on the engine and it starts vibrating again.

I'm going to say it feels like the driver seat is vibrating and not the steering wheel... I say this because some people specifically say the CV joints cause the steering wheel to vibrate - not sure if that applies to RWD cars too.

A bunch of people have said it is usually the driveshaft couple (donut).

What's a solid way to check this and diagnose? Get underneath and check it? How do I check CV joints.. when jacked up, try to move the wheels at 12 and 6 o'clock and then 3 and 9 o'clock?

I should probably also come clean and admit that my transmission has had the same fluid for around 200k miles... I've had the kit ready to go for longer than I care to admit :/

Thank you.

[stevieturbo]

Go to a mechanic.

But "judder" can mean many things, from a drivetrain problem, an engine problem....it is extremely non specific.

You could try checking for rubber donuts on the propshaft.

[fourwheeler]

I see where you are coming from but I am cutting my teeth on this car. I bought it literally 4 years ago have maintained it 100% on my own over the 35k miles i've had.

I'm more than happy to work through these issues and fix it myself.

Admittedly a lot of people will come on here and look for a diagnosis based on a single line of fault description.

For me i'm more than happy for people to go into as much detail as possible on various points to check and troubleshoot. Noises in a car can be some of the most difficult things to track down I get that.. but isn't it all part of the fun, eh?

[E-bmw]

First port of call would be any joint/support in the drive train.

So driveshaft UJs, gearbox mounts, driveshaft couplings, driveshaft rubbers etc.

[Demelitia]

Try loading the engine against the brakes if possible.
Have the bonnet up and check for any odd movement of the engine that might imply you have a knackered engine mount.
After that it’s physical inspection I suppose. Torch and big pry bars to check for slop.
Anything that receives torque from the engine will need going over.

Have you ruled out or are you happy enough that it’s not a misfire happening for some reason?

[camel_landy]

E-bmw said:

First port of call would be any joint/support in the drive train.

So driveshaft UJs, gearbox mounts, driveshaft couplings, driveshaft rubbers etc.

^^^ FWIW - This is where I’d be starting, especially if you have the rubber donuts on the prop UJs.

M

[Steviesam]

Torque converter?