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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006   
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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. |
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21st Oct 2012 7:01am |
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| tolley Member Since: 07 Nov 2011 Location: gloucester Posts: 1117  
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any play in the diff
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21st Oct 2012 9:09am |
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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006
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As in pinion or back lash? Rhubarb and custard let fly with their secret weapon.
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21st Oct 2012 9:16am |
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| tolley Member Since: 07 Nov 2011 Location: gloucester Posts: 1117
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back lash.
i had similar when i replace bushes ,uj etc just seem to i light play else where 
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. |
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21st Oct 2012 9:40am |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6318 
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any thing to do with the beach boys
 sorry that was good vibrations.
...here I am  myself (simple things .... simple mind) |
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21st Oct 2012 9:53am |
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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006
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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.
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21st Oct 2012 10:00am |
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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006
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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.
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21st Oct 2012 5:44pm |
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| Retroanaconda Member Since: 04 Jan 2012 Location: Scotland Posts: 2684 
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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. |
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23rd Oct 2012 5:30pm |
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| yostumpy Member Since: 01 Aug 2010 Location: n/kent Posts: 327 |
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?
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23rd Oct 2012 5:34pm |
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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006
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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. |
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23rd Oct 2012 6:08pm |
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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006
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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.
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23rd Oct 2012 7:05pm |
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| Retroanaconda Member Since: 04 Jan 2012 Location: Scotland Posts: 2684
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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! |
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23rd Oct 2012 7:35pm |
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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006
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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.
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27th Oct 2012 10:09pm |
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| yostumpy Member Since: 01 Aug 2010 Location: n/kent Posts: 327 |
Glad you're all sorted!
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31st Oct 2012 6:58pm |
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