Vcu Vibration

roshe25 · Jun 11, 2015

Hi
I had a recon vcu fitted a short while ago with new bearings and I have nothing but trouble with vibrating,It has been in my local garage about three times for them to check different things.I have got so fed up with it I have had the prop taken off and it is running fine so the prop is staying off and I will inform my insurance.

chris51 · Jun 11, 2015

Are ya tyes the same size, brand etc. I hat the same problem with mine turns out the passenger side front tyre was a smaller size so i had 2 new ones on the front and it solved the problem. Mybe tyre pressure perhaps worth a look. HTH

Chris

Alibro · Jun 11, 2015

I had a vibration from mine after refitting it. Turned out the problem was the damper! I turned the damper one bolt hole and the vibration stopped.
I kinda knew the damper might cause a problem because after refurbing my VCU I tried spinning it to make sure it had no wobble. The VCU was fine but the damper was off centre by around 5mm. If none of the three positions had worked I was going to cut it off and try without.

roshe25 · Jun 12, 2015

Hi
The tyres are the same make and their pressures are all ok I was going to see if turning the damper would make any difference but the garage checked it and said it was ok.
I can't keep paying out so I have a complete prop and a nearly new vcu sitting in my garage,I am going to remove the rear part of the prop so it is easier to store.

Alibro · Jun 12, 2015

roshe25 said:
Hi
The tyres are the same make and their pressures are all ok I was going to see if turning the damper would make any difference but the garage checked it and said it was ok.
I can't keep paying out so I have a complete prop and a nearly new vcu sitting in my garage,I am going to remove the rear part of the prop so it is easier to store.

How did they test it? Did they run the car with all four wheels off the ground checking to make sure it was perfectly centred cause if they didn't then they didn't test it. My guess is they checked to make sure there was no play or slack and then fobbed you off. Mine had no slack or play but was off centre by a large amount. Turning the damper will take at most 15 minutes and most of that will be jacking up one side of the car to get access. I drove mine onto a couple of wooden planks so I think it took me around 5 mins to do it.

Arctic2 · Jun 13, 2015

If you are changing the whole lot front rear prop shafts and VCU can it really be fitted on the wrong way, also will the damper being out one bolt hole make such a difference, asking as I seem to still be having a bit of vibration after full change over.

clarkkent · Jun 13, 2015

Had new vcu and bearings fitted and yes it appeared to be more vibration noise, though not excessive. When I asked garage they said its cos its working properly now, fair point.

Nodge68 · Jun 13, 2015

roshe25 said:
Hi
The tyres are the same make and their pressures are all ok I was going to see if turning the damper would make any difference but the garage checked it and said it was ok.
I can't keep paying out so I have a complete prop and a nearly new vcu sitting in my garage,I am going to remove the rear part of the prop so it is easier to store.

If you leave the front propshaft and VCU fitted the car, the vibration will continue. In some cases the vibration can get worse as the plates inside no longer turn at different rates, distributing the fluid. I'd put money on the bearings being pattern parts. The original bearings had very soft rubber bushings to damp out vibration. Many pattern bearings have hard thick rubber bushings, adding to the vibration.

Hippo · Jun 13, 2015

Arctic2 said:
If you are changing the whole lot front rear prop shafts and VCU can it really be fitted on the wrong way, also will the damper being out one bolt hole make such a difference, asking as I seem to still be having a bit of vibration after full change over.

We've had peeps in the past undo then tighten bolts holding the props to the ird/rear diff and this has stopped high speed vibrations. Also turning the prop round. We're talking the difference in the bolt moving in the hole I guess. Tolerance is slim but it may be enough to balance out a vibration from somewhere in the prop/vcu setup. Those who have had success with this have come back and said so. Not many, but not many have those sorts of problems. There are some who don't agree this is possible.

Alibro · Jun 13, 2015

Arctic2 said:
If you are changing the whole lot front rear prop shafts and VCU can it really be fitted on the wrong way, also will the damper being out one bolt hole make such a difference, asking as I seem to still be having a bit of vibration after full change over.

No and yes
The damper in my car for whatever reason was off centre. Like a record with the hole off centre (if your old enough to remember that

) but the VCU was fine so I figured the problem must be the damper.
I tested it on the bench before attaching to the prop shaft so that is how I know I'm not talking rubbish.
Why turning it one hole made such a difference is another question which I can't answer but it did. In theory it shouldn't have made any difference if the VCU was OK as the damper fits a recess on the VCU so there is no way it can be fitted wrong.
As I said before this is a ten minute job If there is any possibility it might work why have you not already tried it?

Alibro · Jun 13, 2015

clarkkent said:
Had new vcu and bearings fitted and yes it appeared to be more vibration noise, though not excessive. When I asked garage they said its cos its working properly now, fair point.

Sorry this is not a fair point. There shouldn't be any vibration when it is working properly.
This is just a Fob off from a garage which doesn't care.

tonytherunner · Jun 13, 2015

Clean propeller shaft flanges and mating faces.
With assistance, fit propeller shaft assembly in
position, support front and rear propeller shafts
at each end.
Align viscous coupling support bearings, fit
bolts but do not tighten at this stage.
Position propeller shaft to rear axle and align
reference marks.
Fit and tighten nuts and bolt securing propeller
shaft to rear axle to 65 Nm .
Position propeller shaft to IRD flange, align
flange reference marks.
Fit nuts and bolts securing front propeller shaft
to IRD flange and tighten to 40 Nm .
Correctly position support bearings at 90 to the
centre line as shown at points 'A' and 'B' ,
tighten rear then front bolts to 28 Nm .

Arctic2 · Jun 16, 2015

Fingers crossed looks like I have got it sorted, one of the rear break cylinders was sticking, managed to free it up and all seems ok now but I am going to changed them for sure.

will report back in a few days etc thanks for all the info appreciated Arctic2

Vcu Vibration

roshe25

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chris51

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Alibro

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roshe25

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Alibro

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Arctic2

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clarkkent

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Nodge68

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Hippo

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Alibro

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Alibro

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tonytherunner

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Arctic2

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