I’m starting to experience some juddering at around 15mph in my P38. Tyres seem ok and braking seems alright - any help or ideas would be greatly appreciated.

Thanks in advance.

Milage?
Any vibration at idle
" " reving constant speed in park?
Hold it in 1st gear does it vibrate at a constant 15mph?
Could be the viscous fan coupling
Does it do it when cold or hot?
Under brakes or on brakes?
Could be hand brake drag?

At 15 mph unlikely to be wheel balance
Could be a bung universal joint or a CV joint

Mileage is 135k, no vibration at idle or speeds below 15mph. It kicks in around 15 and then stops again at about 20mph, regardless of gear/revs - I'll try locking it in 1st and see if that's any different.

I don't use the handbrake much so probably not that. My first guess was a warped disc/sicky calliper.

I’ll probably get shot because this relates to an L322 not a P38..........but Just in case it proves helpful, I had a judder between about 15mph and 25mph. Everybody said “classic torque converter break up”. One gearbox refurbish and new torque converter later. The judder was unchanged. Then PCourtnay on here said check the rear prop shaft centre bearing carrier. Which proved to be the culprit.

Good luck tracking down the issue. I’ve learned the hard way that an accurate diagnosis is vital.

Tom 2004 L322 4.4 V8 Vogue Bonatti Grey
(205,500 miles and counting.......)

Milage is moderate, what sort of transmission servicing has it had
Engine idling nicely?
Has the vibration just started recently?
Try rolling at your speed and knock it into neutral
Take a look at all the visible stuff drive belts universal joints tires rims harmonic balancer fault codes wheel alignment

Last edited by RR P38 on 6th Jun 2020 11:14am. Edited 1 time in total

Seriously guys hold on a minute you dont even know what engine it has in it

Petrol or dev. Auto or manual ?

/\ what he said!

Apologies, it’s a ‘96 auto derv.

Gsxr1250dave wrote:

Seriously guys hold on a minute you dont even know what engine it has in it

Petrol or dev. Auto or manual ?

I managed to test it a bit more today - wobble kicks in at about 15-20mph where it is at its worst, then gets better as speed increases and then it’s gone above 50mph.

I tried knocking it neutral and the wobble remained. It is also present under braking within the speeds above.

I’ll try and get underneath it and check out the propshafts etc when there’s a gap in the rain...

Yes he says p38 in his post but now we know the engine and drive train it's a big help.
Iv got a p38 my self.

1st and cheapest thing to check are the prop ujs front and rear, steering damper, etc.
Worse case it's your flex plate

Turns out it was the propshaft UJs - all replaced now and going to pick it up this afternoon.

Unfortunately, the EAS compressor died last week so that also had to be replaced! Again, all sorted now, though!