406 shaking

5

505604

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Fellow Frogger
Joined
Jul 12, 2002
Messages
1,173
Location
Junee, NSW
I'm out of ideas. My mechanic is out of ideas.

My 406 HDi has, since about 380 000 km, had a shaking which seemingly comes from the rear end.

The shaking starts quite mildly at a little over 50 km/h and becomes really pronounced at about 70 km/h. It goes away (completely) at about 75 km/h.

Suspected was the trailing arm bushes and so these have been replaced. Also replaced were the rear suspension link bars. On the front, all subframe mounts have been replaced. The right hand side engine mounts have been replaced - separate story.

The car has had new tyres and wheels and has also had a front wheel alignment. The rear tyres aren't wearing in a manner which indicates that the rear needs aligning. (I'm not even sure if they can be aligned.)

After all this, the shaking still remains, but the car feels really tight, and the mechanic says that he's been under the car and pushed, prodded and shaken everything that he can and there isn't any movement.

If you have any (sensible!) ideas as to what could be causing this shaking, I'd love to hear from you :)

Cheers,
Andrew
 
First go to Pedder's and get the $28 dollar suspension check done, even for fresh eyes on the problem. Road trip to Albury or the next nearest branch after that, surprise them as such.
Second check rear brakes; rotor thickness and runout both inside and out (Ford problem but you never know!), pad wear and pistons being sticky to return.
Finally, Are the tyres/wheels round? No joking here, I've not seen it all but feck me I've seem most of what can happen. Tyres not seated in the bead, bent rims (easy to spot), radial runout in the wheel or tyre ie buckle, incorrect weighting and the CSI favourite failed tyre sealant or the lack of removal.
:cheers: Brendan.
 
Thanks, Brendan.

I've changed from steel wheels to alloys and put new tyres on. Surely, even if both sets of tyres and/or wheels had problems, the shaking would at least have changed in some respect. But still worth checking those things again.

Thanks for the ideas about the rotor thickness etc. and yes, a fresh set of eyes isn't a bad idea, either.

Cheers, Andrew
 
The rear end alignment should also be checked. It's easy for the tyre place to adjust. If the rear drop links need to be replaced, get that done first.
 
Hi Gerry,

The drop links - as you call them - have been replaced.

If the rear alignment was out, wouldn't that cause uneven rear tyre wear? My tyres are wearing very well/evenly.

Thanks for responding.

Andrew
 
505604 said:
Hi Gerry,

The drop links - as you call them - have been replaced.

If the rear alignment was out, wouldn't that cause uneven rear tyre wear? My tyres are wearing very well/evenly.

Thanks for responding.

Andrew
Click to expand...

In that case this probably isnt the issue.

Sometimes a wheel out of round or out of balance will produce a front end shake. Other than that, I'm out of ideas!
 
Have seen tyres out of round many a time. Spin rear wheels whilst mounted on hub with a screwdriver or ruler up close to the spinning tread but not touching. If the tyre/rim is out it will be really obvious.
 
I've changed tyres and wheels (as per first post). Nothing changes.

Someone (not on here) suggested driveshafts. Anyone know if and how a driveshaft could cause this problem?

Thanks,
Andrew
 
Yes it is possible, we had a 406 HDI Auto that began to rattle items in the driver's door pocket at about 70 kph. Very strange. Car was traded soon after but followed up with the dealer who spent lots of time tracing the problem. Eventually swapped a driveshaft from another 406 and the problem vanished. Cause? During our ownership the car was shipped away for work on the Al4 as part of the extended warranty. It transpired that an original driveshaft boot had been replaced with a non original one. New owners still in love with the 406 three years later.
Geedee
 
A bent driveshaft/axle can certainly give a car the shakes. Doesn't really sound like your problem since they tend to get worse with speed. What speed does the shake seem to be at? Drive shafts will run at wheel speed. At 60kph that's something like half a dozen bumps per second, and will vary with road speed, but not with gear. Does anything change if you knock it back a gear when the shaking's happening?

I know you say it seems to be coming from the rear, but these things can be deceptive.

Have fun,

Rob.
 
Driveshafts usually are balanced by design or balanced on the manufacturing line, but it would have to be some extra weight or dent that is large enough to cause the thing to actually go out of balance.
 
Worn out cv joints could do it. Specially the inner on the right hand shaft.

Via the aussiefrogs App
 
If you are certain it's the rear that's shaking - could it not be the handbrake drums in the rear discs?

Perhaps after 380,000km they are no longer optimal roundness, or something :)
 
I reckon you should pull out both front driveshafts, get the inner joints apart and check for wear patterns in the grooves. It appears to me it could be a drive line shake under high torque. A pattern of wear can occur where under higher load the cv ball will travel up and over a wear ramp in the ball grooves in the inner joints. This makes the engine shake side ways across the car. That then feels like the arse wobbling. Any sign of rusty grease is a tell tale.
 
Thanks for the input, everyone. Very interesting and helpful.

I'll get to these things in the coming weeks and report on progress/outcome.

Cheers,
Andrew
 
stew said:
I reckon you should pull out both front driveshafts, get the inner joints apart and check for wear patterns in the grooves. It appears to me it could be a drive line shake under high torque. A pattern of wear can occur where under higher load the cv ball will travel up and over a wear ramp in the ball grooves in the inner joints. This makes the engine shake side ways across the car. That then feels like the arse wobbling. Any sign of rusty grease is a tell tale.
Click to expand...

Daughter's 2000 XSi 306 auto had same problem, very similar symptoms to 505604s. The 306 had only done 120000km. Reco drive shafts fixed it completely. 505604s, 380000km is big mileage from a drive shaft!!!

Also the 605 would do a similar shake if you drove it and forgot to take the handbrake completely off. Could be related to hand brake?

And ... I have noticed on all the Pugs fitted with ABS that the back pads wear before the fronts???? Pull the ABS shunt and test drive?

Why do we drive bloody Pugs?? :)
 
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robs said:
A bent driveshaft/axle can certainly give a car the shakes. Doesn't really sound like your problem since they tend to get worse with speed. What speed does the shake seem to be at? Drive shafts will run at wheel speed. At 60kph that's something like half a dozen bumps per second, and will vary with road speed, but not with gear. Does anything change if you knock it back a gear when the shaking's happening?

I know you say it seems to be coming from the rear, but these things can be deceptive.

Have fun,

Rob.
Click to expand...
Hi Rob, sorry I missed your questions earlier.

Yes, I realise that things - location - can be deceptive.

Shaking starts at a bit over 50 km/h, is really bad at about 70 km/h, and goes away completely by about 75, maybe 80 km/h.

Driving yesterday, it seemed that the shaking was worse under load. Again, it seems that it is speed related. I'll have to try coasting in neutral and also with the car in gear but the foot on the clutch.

Have fun, you say? I'm not!

Andrew
 
Get someone to follow you and see if the shaking is evident from the rear .At least it could show which wheel is shaking. I have the same problem on a Merc 380 SEL hire car I drive [I don't own it] .It was shaking in the front at 80 km/s ,even after wheel balance and after swapping wheels from front to back .The problem is still not resolved.
 
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