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Juddering

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rwb   
Thu Oct 31 2019, 09:06am
Joined: Dec 22 2014
Member No: #1988
Location: Telford
I've got really quite bad juddering both when accelerating and when being pushed, e.g., down hill. I.e., when there is torque in the drivetrain.

Seems to be worse if not in a straight line.

Noticed pulsing whir on corner at low speed.

Noticed a clonk when reversing into a parking space, and sometimes the same clonk when setting off, e.g., from lights. Not reliably repeatable.

Current hypothesis:

* not an out of balance wheel because it's not at specific resonant speeds and because it's not particularly noticeable through the steering wheel

* not a wheel bearing because it happens in a straight line as well as corners

* not the torque converter lockup clutch because it happens at all speeds and in all gears

* driveshafts

Any more suggestons?

The long driveshaft seems to be hard to find. Can the joints be replaced or does it need to be a full driveshaft?
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Dan595   
Thu Oct 31 2019, 10:00am
Joined: Nov 26 2010
Member No: #299
Location: Wiltshire
Front suspension FRIP joints, wishbone bushes?

Anything odd showing on tyre wear (e.g. inside edges)?
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 rwb (31 October 2019)
rwb   
Thu Oct 31 2019, 10:26am
Joined: Dec 22 2014
Member No: #1988
Location: Telford
The long one seems generally to be out of stock.

Found these, though.

- Click Here -
- Click Here -

(Irritating since AutoDoc has an SKF short one at a slightly better price.)
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rwb   
Thu Oct 31 2019, 10:29am
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Good thinking, but I think they can be ruled out because yt's just MOTd and not even an advisory on suspension or drivetrain parts or tyres, and because the 407 doesn't shake like this when it's got worn out bottom swivel joints.
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C6Dave   
Thu Oct 31 2019, 11:01am

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
I had a 'knock' / judder when pulling away from standstill in my previous C6 and it was the subframe bushes not located properly.
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cruiserphil   
Fri Nov 01 2019, 02:19pm

Joined: Jan 24 2010
Member No: #38
Location: Celbridge
Hello rwb,

CV joint or loose wheel nuts?

Best regards,

Phil C.
1 User said Thank You to cruiserphil for this Post :
 rwb (01 November 2019)
rwb   
Fri Nov 01 2019, 03:32pm
Joined: Dec 22 2014
Member No: #1988
Location: Telford
The wheel bolts were frighteningly tight; I sheared one off trying to undo it. Wire brushed and copper slip applied so hopefully they won't be so bad in the future.

I'll get some drive shafts ordered then...
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1 User said Thank You to rwb for this Post :
 cruiserphil (04 November 2019)
speedfix   
Fri Nov 01 2019, 03:51pm
Joined: Sep 28 2012
Member No: #1043
Location: south west
Engine, gearbox mounts?
rwb   
Sat Nov 02 2019, 10:20am
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Hmm. Not much consensus.

I think I'm going to have to throw some driveshafts at it.
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321dave   
Sat Nov 02 2019, 02:28pm
Joined: Sep 09 2011
Member No: #614
Location: Dublin
rwb wrote ...

Hmm. Not much consensus.

I think I'm going to have to throw some driveshafts at it.


On the topic of engine mounts and judder. If your sitting in the drivers seat and car is at idle, then put it into drive and blip the throttle can you feel a wobble but your not really driving away yet? And then all is smoother again until you blip or put a lot of torque to the engine?

Again the engine mounts have an adjustment for torque etc.. the little pipes can be off or the wiring bad or simply the rubber bushes worn out from age. They are not simple rubber blocks for sure and worth a second look if you have an inspection camera.
rwb   
Sat Nov 02 2019, 05:51pm
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Definitely no shake on blip.

I can't reliably reproduce the clonk when setting off.

There's something funny when easing off and so going from accelerating to coasting. Feels a bit like it's changing gear (it isn't) but then changing its mind and changing back again. Again, I can't reliably reproduce.
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rwb   
Sat Nov 02 2019, 08:09pm
Joined: Dec 22 2014
Member No: #1988
Location: Telford
Driveshafts ordered.
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rwb   
Thu Nov 21 2019, 05:16pm
Joined: Dec 22 2014
Member No: #1988
Location: Telford
It was indeed drivehafts.

The inner joint and the intermediate bearing were absolutely knackered. It had got hot and got itself stuck and took a bit of getting out.

Replaced hub with wheel bolt sheared off in it.

Juddering now gone...

...and on to the next problems:

* Mechanic says that brakes don't look too good.
* Bleed nipple has bust off the front passenger side caliper.
* Needs a brake pedal switch.
* Had a BEEP for "suspension fault". Diagbox says "front axle average movement (value inconsistent)" and "front static pressure signal (value inconsistent)".
* I can now hear what I think is drop links.


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2 User said Thank You to rwb for this Post :
 cruiserphil (21 November 2019) , 321dave (26 November 2019)
Ruccey   
Mon Nov 25 2019, 02:42pm
Joined: Nov 23 2019
Member No: #4155
Location: NYC
What was the mileage on those parts? They do seem rough.
1 User said Thank You to Ruccey for this Post :
 321dave (26 November 2019)
rwb   
Tue Nov 26 2019, 11:08pm
Joined: Dec 22 2014
Member No: #1988
Location: Telford
110k miles
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1 User said Thank You to rwb for this Post :
 321dave (02 January 2020)
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