Vibration - AGAIN!

[Brian]

I seem unable to cyre a vibration om my previously smooth MK1. When I replaced the subframe mounts (nothing touching body etc) a propshaft type vibration set in. I have replaced the propshaft with a brand new item and the vibration is considerably worse. Flanges are clean, quill shaft bearing seems ok. Running in gear with one driveshaft disconnected eliminates them. Any ideas??
Many thanks

[Alan Chatterton]

Now, this is strange, but after I replace the rear trailing arm bushes as documented in the article in six appeal, I have got an awful vibration that I had put down to propshaft, I was about to replace it.
It may be the same.
 
Any thoughts anyone??!
Rgds
Alan
 

[Alec]

Hello Brian, <br>
<br>
how you run with one&nbsp; drive shaft I don\'t know? However, something
comes to mind of a vibration discussion in Six Appeal a long time ago,
(from a New Zealand member if my memory is correct?) about the maximum
angle allowable for the propshaft to run, i.e the difference in height
between the gearbox output and differential input. Presumably the new
mountings will have dropped the input relative to the gearbox output
and so may have exceeded that angle. (Particularly if the differential
rear mountings were not also changed. <br>
As this is rather vague and I have not first hand experience of this,
and indeed would imagine that the shaft could run at quite an angle
before it would start \'mangling\' the suggestion is all I can come up
with?&nbsp; And doesn\'t affect your problem Alan?<br>
<br>
By the way Brian, I sent you an E Mail, did you receive it?<br>
<br>
Alec<br>
&nbsp;<br>

[Brian]

Hello
Thanks Alec. I\'ll check my email now!! The only theory that I can come up with is that the vibration was always there and was being \'taken up\' by the slackness in the old mountings. I have put my old propshaft back on today and the vibration has improved. The new propshaft must be faulty.....
I ran with one driveshaft disconnected over the pit with me underneath and the car stationery.....didn\'t explain that too well.

[Peter Douglas W]

A very stupid one is:- has the prop shaft been&nbsp;separated at some time by mistake and it has not been put back together in the same place? I did this as a young lad not realising that prop shafts are balanced as a complete entity.

[Dion]

Very interested to hear and learn more about this vibration issue.
My car (automatic) vibrated badly from about 50 - 70 mph. To try solving that, I changed&nbsp;the driveshafts for the Nissan-ballbearing type that were on my Mk1 (which did not vibrate). No improvement. Then, reading the Top Tips in the Tips manual, I put in shorter distance pieces to the rear gearbox mounting so that the gearbox did not hang so low anymore (lessen the angle gearbox-driveshaft). No improvement.
The&nbsp;car sometimes also made a light grinding noise when accelerating (starter ring gear touching the starter motor). This probably&nbsp;means the flywheel is too flexible or broken.
Now, I think these two things (vibrarion and&nbsp;grinding noise) could be related. If the flywheel flex too much, then also the torque convertor shimmies about and this might cause the vibration??
Anyway, I now have located&nbsp;a good flywheel and main drive&nbsp;shaft (been busy all day yesterday getting them out of a rotten dirty car, aargh!) so will&nbsp;exchange the flywheel first. This will solve the grinding noise issue&nbsp;(I hope) and possibly the vibration issue too. I fnot, I will exchange the axle and hope&pray this will solve the vibration!
Cheers
Dion.
75 2500 Mk2 auto / 66 2000 Mk1 O/D&nbsp;&nbsp;&nbsp;

[Clifford Pope]

Let me get this right - replacing the old propshaft improves the
vibration, but does not cure it? Is it back to how it was before you
changed anything?<br>
This would seem to suggest that the propshaft is part of the problem, but not the whole.<br>
You say running with one driveshaft disconnected stops the vibration? You mean either driveshaft, or a specific one?<br>
<br>
On the propshaft maximum angle theory, I read recently (in connection
with installing a new engine in my boat) that Hardy-Spicer joints
ideally should have an angle of less than 15 degrees across any one
joint, and for perfection any offset at the first joint should be
countered in the opposite direction at the second - ie the input shaft
and the final output should ideally be parallel, and no more than 15
degrees to the intermediate&nbsp; shaft.<br>
<br>
I believe it is also the case that a worn, or incorrectly aligned,
shaft/joint will exaggerate any play and vibration in adjoining
bearings - eg gearbox rear bearing or the quill bearing. The same would
apply at the driveshafts, but of course they don\'t rotate so fast.<br>
<br>
So just possibly fixing one problem in a whole train of mildly worn components would exacerbate one of the others?<br>

[Brian]

Hello
Well, I have found out that the new propshaft is probably faulty, ie balanced wrong. So another new one is on its way....!!
also I have just fitted a sport exhust from Chris Witor and this SEEMS to have cured the low speed vibration.
Thanks for all tghe replies. I\'ll let you know how I get on.

[Bazzamech]

Hello Brian,
I have the same vibration problem on my mk2 auto. Have changed the driveshafts, trailing arm bushes. Next job is to change the gearbox mounting and crossmember bushes, with polybushes supplied by Chris Witor. Then I,ll road test again to see if there is any improvement!
If you can, get hold of a copy of SIX APPEAL, JUNE 1995 edition. There,s an article by P. ROEBUCK, called \"BAD VIBES.\" it says that vibration could be caused by DRIVESHAFT INNER FLANGE PLATE. If this flange is not perfectly flat, the U.J does not spin concentrically with the output shaft.
Could be worth looking at, I,ve not looked at mine yet, but will try this if no improvement after changing gearbox mountings.
Let me know how you get on please.
Regards,
Barry.

[Dion]

An update on my problems / experiences regarding vibrations on my 2500 Mk2 auto. There is a vibration from&nbsp;55 mph onwards,&nbsp;its peak at around 70 mph then getting better again (which is not very useful).
Replaced: driveshafts, propshaft, flywheel,&nbsp;wheels/tyres, decreased&nbsp;the angle from the rear of the autobox - propshaft by fitting shorter distance pieces to the rear gearbox mounting. I checked the driveshaft&nbsp;flanges on the diff for irregularities, they are perfectly straight. The driveshafts & propshaft now fitted gave a rumble free drive on my Mk1, as did the wheels/ new tyres borrowed from my brothers 2000 Mk2.
The new flywheel, from a scrap&nbsp;car,&nbsp;has been installed with a reinforced plate from Chris Witor. This has eliminated the grinding noise which the car had when accelerating in D. The old&nbsp;flywheel&nbsp;was cracked and slightly \"bubbly\" (not completely flat).
An interesting finding was that the&nbsp;starter gear rings on both flywheels were fitted the wrong way! The ring does have&nbsp;chamfered edges on&nbsp;the teeth to ease in the gear from the starter motor, but these&nbsp;edges were on the gearbox side! That would be fine for inertia starter motors as fitted to Mk1s (and possibly early Mk2s?) but not for the pre-engaded starter motor fitted to my 1975 car. As an effect, the gear wheel on the starter motor has worn and the engine side of the gear ring shows hammering to the straight gear. This may&nbsp;have had its effect on breaking the flywheel considering the forces used by seeing the damage done to the teeth.&nbsp;I am considering fitting an old-style inertia starter motor with a starter relais (what is the disadvantage of having that, or in other words, why have they been replaced by the pre-engaged version?). As an aside, years ago I&nbsp;had to replace a&nbsp;gear ring from a 1972 2000 Mk2 (overdrive) for the same reason. The ring has been moved (hammered) backwards on the flywheel by the starter motor because the ring had been the wrong way fitted.
None of these replacement did any&nbsp;good for the vibration. A test drive showed that only&nbsp;in D the bad vibration is there - it comes and goes like a wave. When in 2, there is a vibration but very different - much less and constant, not wave-like. This finding would point the source of the vibrations&nbsp;to&nbsp;the automatic gearbox. If something else in the drive line would be the cause, why then would there be a difference in the gears?
The next thing I will do is to replace the box for another one. I have a spare one, came out a running car years ago. Before fitting, this box will probably have to be checked over, I will have to leave&nbsp;that to a specialist. But this will take a few weeks,&nbsp;I do not particularly look forward of again a weekend work of replacing the transmission!
Dion
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