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lambert.the.farmer



Member Since: 11 Apr 2012
Location: harrogate
Posts: 2006

England 1998 Defender 90 300 Tdi PU Rutland Red
vibration

Hi all.

My car has developed a fine vibration. When under load in 4th at about 40-50mph and also in 5th between 50-60mph. It is a very fine/high pitch vibration and is not constant. It can be felt on the dash and through the steering. However when on the flat or driving down grade it becomes undetectable but I presume it is still there. It is almost like when you are in slightly too high a gear and you get that buzz before it starts knocking but it is never that bad and I'm not in the wrong gear.

It has had a new rearmost uj fitted, new trailing arm to chassis bushes and new radius arm axle bushes.

It has become a lot better for having the bushes settled in climbing about on a couple of lanes but it does persist. All bolts on all bushes and all prop joints are tight and show zero play. If it were a wheel balance issue I would have expected it to be constant and not engine load dependent.

As there is a feud between me and the shop that did the work I wand to be able to prove a fault before I take it back as otherwise they will just say it has always been thus and is not their problem.

Unfortunately I don't have a dti so I can't tell if the props are out of true beyond a visual inspection that said the welded on weights seem to be intact and the new uj seems to be seated correctly.

It also had new front brakes but it stops fine no juddering or pulling.

So any ideas? Cheers. Rhubarb and custard let fly with their secret weapon.

Post #177587 21st Oct 2012 8:01am
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tolley



Member Since: 07 Nov 2011
Location: gloucester
Posts: 910

United Kingdom 2006 Defender 90 Td5 CSW Oslo Blue

any play in the diff

Post #177629 21st Oct 2012 10:09am
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lambert.the.farmer



Member Since: 11 Apr 2012
Location: harrogate
Posts: 2006

England 1998 Defender 90 300 Tdi PU Rutland Red

As in pinion or back lash? Rhubarb and custard let fly with their secret weapon.

Post #177634 21st Oct 2012 10:16am
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tolley



Member Since: 07 Nov 2011
Location: gloucester
Posts: 910

United Kingdom 2006 Defender 90 Td5 CSW Oslo Blue

back lash.
i had similar when i replace bushes ,uj etc just seem to i light play else where Mad

i did find a had seized wheel bearing, did they but the props back facing the right direction ,is they any play if you hold both ends of the prop and try and twist they.

Post #177642 21st Oct 2012 10:40am
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Caterham



Member Since: 06 Nov 2008
Location: Birmingham
Posts: 5411

England 2011 Defender 110 Puma 2.4 XS CSW Stornoway Grey

any thing to do with the beach boys

Rolling with laughter



Embarassed sorry that was good vibrations.


...here I am Censored myself (simple things .... simple mind)

Post #177645 21st Oct 2012 10:53am
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lambert.the.farmer



Member Since: 11 Apr 2012
Location: harrogate
Posts: 2006

England 1998 Defender 90 300 Tdi PU Rutland Red

There is some back lash but not much. Not able to detect any movement when twisting prop all seems suitably tight. Rest of car seems in quite good order for its mileage. I suspect I may end up chasing this back through the entire transmission and not really finding too much wrong, it would just be nice to find it then I can leave it or fix it as I see fit. Rhubarb and custard let fly with their secret weapon.

Post #177649 21st Oct 2012 11:00am
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lambert.the.farmer



Member Since: 11 Apr 2012
Location: harrogate
Posts: 2006

England 1998 Defender 90 300 Tdi PU Rutland Red

I think I might try putting my all terrains on as one I know they are balanced and two the off chance it is related to the tyre pattern. Rhubarb and custard let fly with their secret weapon.

Post #177745 21st Oct 2012 6:44pm
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yostumpy



Member Since: 01 Aug 2010
Location: n/kent
Posts: 266

One thing to remember on coil sprung lrs, is that the propshafts HAVE to be 'out of phase'. if they took one part of the prop off to change the uj, and left the other half on the truck, ie pulled it apart on the slide joint, then when put back they should be out of phase. This essentially means , well you would think to balance it all the flanges would line up, or be at 90 deg,to each other. This is 'in phase' but these should be almost random and not equally spaced circumfrencially. If that makes sence. This would cause vibration. i have a sheet from an old magazine explaning this. If you want to pm me your e-mail, I'll try to scan it and e-mail it, not sure I can post it on here. Thumbs Up

Click image to enlarge


wonders of modern science. This was from an old AWDC mag.

Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated Mr. Green

Post #178350 23rd Oct 2012 6:19pm
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Retroanaconda



Member Since: 04 Jan 2012
Location: Scotland
Posts: 1546

Scotland 

yostumpy wrote:
One thing to remember on coil sprung lrs, is that the propshafts HAVE to be 'out of phase'. if they took one part of the prop off to change the uj, and left the other half on the truck, ie pulled it apart on the slide joint, then when put back they should be out of phase. This essentially means , well you would think to balance it all the flanges would line up, or be at 90 deg,to each other. This is 'in phase' but these should be almost random and not equally spaced circumfrencially. If that makes sence. This would cause vibration. i have a sheet from an old magazine explaning this. If you want to pm me your e-mail, I'll try to scan it and e-mail it, not sure I can post it on here. Thumbs Up


That is true for the front propshaft, but the rear should be in phase.

The reason is to do with the difference in the angles of the transfer box output flanges and the diff nose flanges, and the fact that universal joints are not constant velocity - they introduce a variation in rotational speed through their rotation. The level of this variance is proportional to the angle the UJ is working at.

Both transfer box outputs are on a plane roughly parallel to the chassis datum. Ie. they are parallel with the ground if the vehicle is on flat ground and sitting level on its springs.

The rear differential flange is also on a plane parallel with the chassis datum. This means that, for normal "vehicle suspension level" operation - ie. general road driving - the angle at the transfer box end is equal and opposite to that at the differential end of the propshaft. This means that the two 'variances' in rotational speed cancel each other out.

On the front axle the differential nose points upwards slightly towards the transfer box, which creates a discrepancy between the angles, and therefore rotational variance induced, at each end of the shaft. The net difference results in a vibration felt through the vehicle. In order to limit this, the front propshaft is "out of phase" slightly, by an amount which cancels out the discrepancy of rotational speed as best as is possible.

So rear prop in phase, front out of phase. I think it's by about 1/3 on the front, though don't quote me on that. Should be markings on the shaft.

Post #178357 23rd Oct 2012 6:30pm
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yostumpy



Member Since: 01 Aug 2010
Location: n/kent
Posts: 266

I was assuming that when the op said rear most uj and steering wheel vibrations that it was the rear most uj on the front prop. Could be wrong , Pray tell which one was it that was replaced?

Post #178361 23rd Oct 2012 6:34pm
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lambert.the.farmer



Member Since: 11 Apr 2012
Location: harrogate
Posts: 2006

England 1998 Defender 90 300 Tdi PU Rutland Red

Right this is interesting. The replaced joint is the rear rear or pinion end back axle. That said closer inspection reveals that the front prop has been undone at the axle end as it has new nuts at the axle but not at the transfer box end. It is also "in-phase" ie both yokes are in the same plane. Could it be that someone at the garage has seen them off-set and thought they were wrong? I would not be surprised. All this said I have asked a third specialist garage and they seemed to think the sliders would only fit in one place not many?

Cheers. Rhubarb and custard let fly with their secret weapon.

Post #178378 23rd Oct 2012 7:08pm
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lambert.the.farmer



Member Since: 11 Apr 2012
Location: harrogate
Posts: 2006

England 1998 Defender 90 300 Tdi PU Rutland Red

Cheers both, just been looking at pics of front props and all are the same but different to mine. I will rectify in the morning cheers. Rhubarb and custard let fly with their secret weapon.

Post #178402 23rd Oct 2012 8:05pm
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Retroanaconda



Member Since: 04 Jan 2012
Location: Scotland
Posts: 1546

Scotland 

As above there should be alignment marks on the tube of the propshaft to allow you to set the phasing correctly. The slider will be splined so there will be several possible positions. I have never seen one with a master spline, which would only allow one.

Usually two arrows, which need to line up. Though you may need to give it a damn good clean to see them!

Post #178414 23rd Oct 2012 8:35pm
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lambert.the.farmer



Member Since: 11 Apr 2012
Location: harrogate
Posts: 2006

England 1998 Defender 90 300 Tdi PU Rutland Red

No visible marks so last wed I put it two splines out of phase with the grease nipple corresponding to a plip on the sliders yoke. This improved matters no end. However it still felt odd but not in a precise way just not quite there. More research found that the box yoke should lead the axle yoke anticlockwise so I took it off again this lunch time and moved it again back to straight then minus 2 and it is smooth. I can now appreciate the difference all the new bushings have made its lovely to drive now. Cheers again for the help. Rhubarb and custard let fly with their secret weapon.

Post #179641 27th Oct 2012 11:09pm
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yostumpy



Member Since: 01 Aug 2010
Location: n/kent
Posts: 266

Glad you're all sorted! Thumbs Up

Post #180736 31st Oct 2012 7:58pm
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