405 Vibration...

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fastandfurryous
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Post by fastandfurryous »

this does sound very much like the engine/box assembly is moving about rather a lot in reference to the body. I would check all 3 mounts. The gearbox one has probably seperated, and is soaked in oil, and I would check the top engine mount too, as these can seperate, and then split apart. I've had a number fail on me now.

With the bonnet open, have an assistant apply load (slip the clutch) in both 1st and reverse, while you watch the engine/box for movement. anything more than about 10mm or so is excessive, and I have a feeling it's going to be worse than that.
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stevieb
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Post by stevieb »

Cheers F-and-F, the clutch trick is how I confirmed the lower mount was fubar'ed.

The top mount was new two years ago, when I had the head gasket done, but I think may have split since, probably when I last did my timing belt.

The gearboc mount was bone dry, and very clean when I last checked it, but after my battery went flat on me on Sunday, I'm wondering if it may have a tiny leak. That would split the rubber, with the mount being directly beneath an' all.

I shall have a proper look tomorrow. I have a gearbox mount here. Another spare part purchased some time ago and never fitted... :roll:
stevieb
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Post by stevieb »

Right, I didn't get as much time to check this as I'd hoped (i.e. got home after dark).

However, waving a torch at the offending area in otherwise complete darkness has answered my own questions. There is a clear gap of around 2mm between the rubber of the gearbox mount and the gearbox itself. So it seems the gearbox end is flailing about in the wind, so to speak.

Trying the clutch trick beforehand revealed quite a bit of movement, which is why I decided to dig further into the darkness.

My theory is that maybe the transmission end of the left hand driveshaft is getting out of position, and under suspension compression the driveshaft doesn't have enough spare lateral movement. I imagine the driveshaft compresses a little when the suspension is compressed due to the angle of the struts. This might explain the vibration at speed, which is exaggerated under gentle turning, and of course only there when under power. I guess it makes sense that the car sits a little lower when running at speed - downforce an' all.

My theory on roundabouts is that maybe the sideways forces that should be soaked up by the mount are getting the driveshaft output points out of line, and causing a "cranking" effect between the two - each driveshaft trying to mimic feet turning push-bike pedals. I imagine the sump doing a marching action - left, right, left, right. This would explain why the car, and not the steering, feels as if it's wiggling when negotiating roundabouts.

Alternatively, this might all be nonsense, and it might just be as simple as a wobbly transmission end that's causing things to shake rattle and roll...

Either way, it looks like that might be my culprit.

Quinny, I hope you're taking note.
Quinny
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Post by Quinny »

Quinny, I hope you're taking note.
Indeed I am young man. :lol:

As I'll have a bit of free time this weekend,and the weather looks good,I'll take a butchers at the gearbox mount,and see if it has the same problem,I may even take a quick peek before I go to work this morning.

If it turns out to be the gearbox mount that looks suspect,is there a place,other than Peugeot,where I can get a replacement,ie:an independent,or will it be just as cost effective to go to the dealers,which wouldn't be a problem,as I live within 3 miles of 2 such places?

Ken.
stevieb
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Post by stevieb »

Quinny wrote:
If it turns out to be the gearbox mount that looks suspect,is there a place,other than Peugeot,where I can get a replacement,ie:an independent,or will it be just as cost effective to go to the dealers,which wouldn't be a problem,as I live within 3 miles of 2 such places?

Ken.
Mine was a main dealer part. I think it was only about ten or twenty quid. Not too bad, and they had it in stock, so it might be a common part across the range.

If not, it might be worth looking for a good Motaquip dealer in your area. They'll probably have them in stock too.
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Post by stevieb »

Right, I've taken the car for a blast.

The roundabout wiggle has gone - completely.

The vibration at speed when travelling over undulations in the road is still there - just. Now it definitely feel like it's coming from the front.

One thing I was a little confused about was the gap I mention above, between the gearbox mount and the gearbox. Even with the new mount the gap remains. I would've thought the lower section of rubber should be snug against the gearbox, after all there's a "cup" there which looks as though it's designed to accommodate the rubber. The spacer on the gearbox stud just stops the mount clamping down enough. Surely this allows the gearbox to bounce up and down without too much resistance...??? Which might be the vibration on the bumpy stuff...

I might shave a few mm off the spacer tomorrow and see what happens.

My alternative suspicion is now turning to the top mounting. It just seems that the buffers are sitting a bit too low (I can see where the paint has rubbed through, so I guess the point of impact is now about 5mm lower than previous), so maybe I've got a problem there too. A top mount isn't too bad a job to do, and they're quite cheap, so I might fit one on Monday.
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Post by Quinny »

Keep us posted Steve.

Ken.
stevieb
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Post by stevieb »

Right, I still haven't had a go at the right-hand mount, mainly through lack of time. Nor have I tried shaving the spacer on the gearbox mounting down to size.

But I do know it's one of the types which the Haynes

Book
Of
Lies,
Lies,
Oversights,
Codswallop,
Knickers, and
Something else not very nice,

manual suggests I should fabricate a tool for. Is this necessary? Or can another bodge be successfully used? I guess a cold-chisel could be used to creat a "nick" in the metal surround, and then that could be knocked away at to get the thing turning (a bit like bashing a screwdriver into an oil filter to turn it). Does anybody else have any suggestions?

One other thing, is a question regarding the plastic hex which sits on top of the RH mount, just beneath the plain metal bracket, which I presume stops the engine jumping out of its rightful place. Is the hex supposed to rest against the underside of the bracket? I'm sure mine did when I'd had the mount replaced a few years ago, but can't be sure. As it is now, it sits about 5-10mm below - roughly the same as the buffer-rubbers are against their surround (see post 29/10/05).

Whatever I do, I'm going to have to do it soon, because the car is making all sorts of weird and not-so-wonderful noises now, when I maneouvre round car parks. It's a case of fix it, or scrap it. Which would be a shame because I've had the car six years now (I'm only the second owner). :shock:
stevieb
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Post by stevieb »

For those still following the saga, here's the latest.

The car happily travelled 310 miles today, but vibrated reasonably badly for half of that (when it had warm up - again).

One thing I hadn't mentioned after Saturday night was the opinion of two friends. We went to another friends house for a bit of a bash, and I drove (soberly of course). On the outward journey I had the heavier of my two friends (14 stone-ish) sat behind me (O/S rear), with my lighter friend (11 stone-ish) alongside me in the front. The vibration was pretty bad, and both said it was coming from the O/S rear.

On the journey home they swapped places, with the heavier friend alongside me in the front, and the lighter friend immediately behind me. This time the vibration was a lot less unpleasant, though still very noticeable under power and when cornering - but probably only half as bad as previously. Again, both friends said O/S rear was the source. In fact they both said it seemed to be directly beneath the rear seat on the drivers side.

Now, considering the fact that the source was previously thought to have been N/S front, and I've only changed a couple of engine mounts, does anybody else reckon it's an engine mount problem? The R/H engine mount looks reasonably okay to me, so I'm doubting that that's the last remaining culprit.

Am I back to thinking it's dodgy driveshafts? I'm starting to get a bit of grumble from the front end at very low speeds - especially when touching the brakes in 2nd, without dipping the clutch enough (like you do in traffic). It sounds like something is chattering, but whatever it is sounds reasonably exposed, unlike the innards of a gearbox.

I'm looking for another car, but I'll be jiggered if I'm gonna be beaten by this problem first...
Quinny
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Post by Quinny »

The mystery deepens........

Just a suggestion Steve,and it's something I keep meaning to do,but have a memory like swiss cheese at the moment,would it not be worth ringing the local Peugeot dealers service department,mentioning what you've done already,and see if they can shed any light on it?

I know they'll probably be insistent on you bringing it in,but stand your ground,and see what they say.

If I remember,I'll ring mine tomorrow,and post back with the result.

Ken.
stevieb
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Post by stevieb »

Unfortunately, our local Pug dealer is a crooked outfit (I know, I've used them before).

My sis used to go out with one of their mechanics, and his opinion was that they were nothing more than fitters, who couldn't diagnose a cold.

We have a good local breakers yard. I might try them for a couple of driveshafts.

Even if they're not 100%, at least the problem might move/change. That way I can be sure where the problem lies.
alan s
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Post by alan s »

I'll try a silly suggestion; could it be a tyre with an air bubble under the tread by any chance?
I had this on a CX years ago and blamed everything else but the tyres but eventually it started to shred after a 1000 klms drive on hot roads.
Another option is the rear bearings in the rear axle/swing arms. Could they be on the way out?
Try a tyre swap first, by swapping the rear tyre for the spare. One side then the other, then even try the front as my CX was on the front yet it was hard to pinpoint the problem area.


Alan S
RIP Sept 19th 2008.

She said "Put the cat out" She didn't mention it was on fire!!
stevieb
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Post by stevieb »

Well the sensation is exactly like a flat-spotted/bubbled tyre - the whole car shakes, but the steering sends back no sign of a problem at all. The snag is the fact I've changed all four tyres since the problem started, so I can safely eliminate the tyres as a cause.

I've pondered the rear arm bearing idea, but haven't managed to carry out a proper test on it yet. Mine's an estate, so I plan on getting a couple of people to sit down on the boot lip and stand up a couple of times while I watch the back wheels.

But would the arm bearings cause the vibration at speed in a straight line and only under power?

As an example, there is a road not far from home. A nice dual carriageway with a long downhill stretch. It starts on a gentle bend, then straightens up. Overall the downhill run is about a mile long, with the bend accounting for the first quarter.

As I head downhill and apply any amount of power. the vibration starts. Even when I'm going at such a speed the engine has no grunt left (up near 4,000rpm). The vibration is worse on the bend, with a small amount of lock applied. As soon as I lift off the throttle the vibration goes. But the tiniest re-application of power causes it again - even just gently touching the accelerator pedal.

Coming back up the same hill the vibration is constantly there, presumably due to the constant load on the engine/transmission/roadwheels, though a temporary lift-off sees it disappear again.

So although it feels like the rear end is vibrating, it's clearly related to power application, which is obviously front end... :?

Something has definitely moved since I've changed the gearbox and lower mounts, as the exhaust now vibrates on the rear bumper when reversing, so I'm guessing the engine is flapping about far too much. The occasionally dodgy gear linkage is also a pointer in this direction. Though we all know Pug gear linkages are dodgy to start with... :roll: I guess the fact the vibration has reduced after each mount has been changed, only to return once it's bedded-in, also suggests front end/engine/transmission area.

I am clutchin' at straws now, but I've bought a top mount, so I'll get that fitted and shorten the spacer mentioned above and see what happens.
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Post by stevieb »

The right hand engine mount is split.

The cone attached to the top stud has parted company with the rubber, though it is remaining seated in the right place.

The rubber is VERY soft though - a lot softer than that on the new one - so I want to replace it and see what happens.

But, how the hell do I get the old one off?

I can't get anything at it to get a grip on it, or bash at it, or anything. I've dropped the engine as far as I dare, but I still can't get a clear run at it.

Any suggestions? Please :roll: .
alan s
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Post by alan s »

If it's the same as a BX (I know the Mi16 and BX are the same) you get access to it through the tower it's mounted in from the engine side and working from over the mudguard looking back towards yourself (if that makes sense) and you need an openended spanner to get onto it.


Alan S
RIP Sept 19th 2008.

She said "Put the cat out" She didn't mention it was on fire!!
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