Vibration

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kevin s
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Vibration

Post by kevin s »

My son has used minor for around 250 miles this weekend, towing a trailer.
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rps20220529_203423.jpg (64 KiB) Viewed 959 times
It performed well, did the whole lot on one tankfull with some left over as well.

There is one issue though, it has always had a vibration at around 60mph, which he says is getting worse ( may just be more noticible on a long run) it seems to come through the structure, all 4 wheels have been balanced so I'm thinking propshaft, we'll change the U/J's and see how it goes, but I seem to remember it looked like a balance weight had dropped off when I painted it, does anyone know somewhere in essex who balances them?
simmitc
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Re: Vibration

Post by simmitc »

Any tyre dealer will do it for you, chargeable.
philthehill
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Re: Vibration

Post by philthehill »

I could be wrong but I think that the balance weight mentioned refers to a balance weight on the propshaft.
If that is the case it may be easier to change the propshaft assy.

kevin s
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Re: Vibration

Post by kevin s »

Yes it was on the propshaft, good idea, get another one fit new u/j's the its a 10 minute job to swap it over.
panky
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Re: Vibration

Post by panky »

Try a big jubilee clip around the prop shaft with the screw positioned where you suspect the weight has dropped off. Not a permanent solution but it might prove if it is the prop or not.
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kennatt
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Re: Vibration

Post by kennatt »

as above had same on an HB viva couple of clips and test drive moving clips till vib stopped, were stll on car 5 years later when sold.Worth a try.
kevin s
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Re: Vibration

Post by kevin s »

Thanks all, looking at the above and some old posts, i think I will do the following.

Get it on the 4 post lift
Check the u/j's for play fix if need be.
Jack back axle up strap front wheels down with chocks.
Check run out on diff flange fix if need be.
Run it up to 60 check it it reproduces when stationary and wheels spinning.
If so play around with jubilee clips till hopefully it goes.
oliver90owner
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Re: Vibration

Post by oliver90owner »

Talking about balance - that overhang cannot be good!
kevin s
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Re: Vibration

Post by kevin s »

The canoe weighs next to nothing so despite appearances the balance is towards the front, given it's so narrow it also tracks within the width of the car on corners.

Not sure on the legalaties, we did stick a reflective triangle on the end though.
JOWETTJAVELIN
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Re: Vibration

Post by JOWETTJAVELIN »

I might have read it wrong but I would not run any car with no load on the driven wheels.
oliver90owner
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Re: Vibration

Post by oliver90owner »

As I see it there are only two(?) possibilities for problems with the balance of a prop shaft.

1) A balance weight has fallen off. Usually there is evidence of where it was welded on, if this is the case.

2). The UJ has been changed and the yoke has been turned round. Unlikely to cause much trouble, I would have thought, as that part is securely bolted to the differential.

The prop shaft cannot be mis-aligned, surely? Is there not a spigot on the shaft yoke, to align it with the differential?

If no faults are found (including the UJ joints, I would think a substitution is the best way to determine if the vibration is prop shaft related
philthehill
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Re: Vibration

Post by philthehill »

The prop-shaft is located centrally to the diff flange by a spigot on the rear prop-shaft flange which fits into the diff flange.
The rear prop-shaft flange can only be rotated by 180 degrees to the diff flange as the PCD of the flange bolts is not equidistant. Whilst fitting the prop-shaft 180 degrees to original orientation is not to be recommended in my experience it would not lead to excessive vibration. It is advisable to mark the prop-shaft and diff flanges before dismantling so as they to go back in the same orientation.

kevin s
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Re: Vibration

Post by kevin s »

That's another thing to try, turning the prop 180 degrees but really if it's balanced and the diff flange runs concentric it shouldn't matter which way round it goes.

Had a quick poke around just now, no play in the joints, only thing I did notice is the diff looks like the nose points down slightly giving quite an angle on the back joint, not sure is this is normal, other cars I've had have it pointing slightly up more in line with the prop . Car was on level ground with about 30mm between the bump stop and axle and has original spring seats and springs, if this isn't normal the only thing can thing is the springs have deformed or it's like this to compensate for the nose of the axle rising as torque is applied to the wheel.
oliver90owner
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Re: Vibration

Post by oliver90owner »

philthehill wrote: Tue May 31, 2022 9:43 am The prop-shaft is located centrally to the diff flange by a spigot on the rear prop-shaft flange which fits into the diff flange.
The rear prop-shaft flange can only be rotated by 180 degrees to the diff flange as the PCD of the flange bolts is not equidistant. Whilst fitting the prop-shaft 180 degrees to original orientation is not to be recommended in my experience it would not lead to excessive vibration. It is advisable to mark the prop-shaft and diff flanges before dismantling so as they to go back in the same orientation.
Let’s be clear - I was very specifically, in my post, suggesting the yoke may have been fitted 180 degrees to its original orientation on the shaft at a time when the UJ spider had been changed. Not just by un-bolting on the prop shaft and bolting it on the other way (a “ten minute” job).
kevin s
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Re: Vibration

Post by kevin s »

I've not changed the joints, they were smooth with no play, but they are sealed for life ones so I guess must have been changed at some point, it's the front balance weight which is missing so I will have a go with Jubilee clips on there.
oliver90owner
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Re: Vibration

Post by oliver90owner »

it's the front balance weight which is missing

Now he tells us! Should there be one? Can you discern its size? They would have used the same thickness of steel for the weights used.
kennatt
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Re: Vibration

Post by kennatt »

think he mentioned a lost weight in original post.
kevin s
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Re: Vibration

Post by kevin s »

No idea what was there originally, it had been stored outside for some time when we got it so was all fairly rusty, the back has one is around 30 x 20mm and about 2mm thick.
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