Finally given up!

[Lingen]

Mike. From your information at the start, you have shown that it is nothing to do with the engine, and there simply isn't enough inertia in the internals of the gearbox,diff, or the driveshafts, to cause the problem. If it is a high frequency vibration, then I still think it has to be something associated with the propshaft. If it is a slower one, like an off balance wheel, then in my case, after numerous unsuccessful attempts at getting them balanced, I found that the rear brake drums were the culprits. A pair of new ones made an amazing difference.
Mike.

[andy2stags]

Hi Mike
I have a most parts from a manual stag including the complete running gear if you wish to do a swap around to identify the culprit.
Let me know if I can be of assistance.
Andy.

[mike@thenook]

Hi Mike,

I think on the basis it does it without the drive shafts connected it has to be as you say propshaft related;

Talking to Peter at LD he says the alignment of the output shaft from the gearbox is crucial to the input at the differential. These two have to be running parallel to one another and also the wheelbase between axles should logically be the same both sides - mine having ,measured this afternoon seems to be 100" on the LHS and 100 5/8" on the RHS so there appears to be a front to back alignment issue which could mean the diff is not sitting at right angles to the prop'.
So I'm going to take it to Elite in Rainham so they can check the whole alignment (they have the gear to do it) I can then (knowing the wheelbase is square) check the prop is running parallel and adjust that if need be.

Maybe i'm getting there.......

And thanks Andy very much, I may well be in touch (will you be at Rye House for the November meet or the SOC Windmill..?

Cheers,

[andy2stags]

Yes Mike I should be at the Windmill all going well.
As for Racing we done Beccles Yesterday and had a great day.We are not sure if we are doing Rye as Jack is asking to do Red Lodge which is the Saturday before.

Andy.

[mike@thenook]

Hopefully see you at Windmill then - cheers

[jleyton]

did someone say bacon yup I'd be there if asked .

Ditto

Hi Mike,

I think on the basis it does it without the drive shafts connected it has to be as you say propshaft related;

Talking to Peter at LD he says the alignment of the output shaft from the gearbox is crucial to the input at the differential. These two have to be running parallel to one another and also the wheelbase between axles should logically be the same both sides - mine having ,measured this afternoon seems to be 100" on the LHS and 100 5/8" on the RHS so there appears to be a front to back alignment issue which could mean the diff is not sitting at right angles to the prop'.

Cheers,

Hi Mike,

Peter makes a very valid point and bear in mind that the correct location of those two giant washers under the bolt head that holds the big front subframe mounting can have an effect. It's very easy to get these muddled up

Oddly perhaps, but I wouldn't be so concerned about the wheelbase difference. Some time ago I found mine differed by over 1" but when I posted on here about it it seemed that many had the same issue and some with even greater difference without any obvious adverse effect !

Good luck.

Cheers

Julian

[mike@thenook]

Hi Julian,

weird isn't it, I can see exactly what Peter is getting at and it does seem to make sense - i'll just have to get the whole set-up checked properly and go from there but if it ain't the prop itself it seems it must be something to do with the way it is locating. The noise emanates from under the floor where the diff sits, unfortunately the exhaust can also cause problems in that area but it even does it without the engine running at 65 + in neutral.

Something for the winter nights.....

Cheers

[wilf]

uj orientation.jpgMike - UJ orientation as per the attached?

[jleyton]

Wilf is, of course, quite right as was one of our German contributors (can't remember which one) who originally posted that diagram that I, too, have saved.

However, if correctly assembled, the Stag propshaft cannot be orientated incorrectly as kind Mr Triumph or, more likely, Mr GKN gave us markings to ensure we got it right. However I suspect many people don't realise this as the markings are not immediately obvious. I wonder how many would notice them without the highlighting (sorry about the poor photo )

Cheers

Julian

prop marking.jpg

[mike@thenook]

Thanks for that Wilf and Julian but sadly I can discount this as the problem because I've had both the original prop balanced - it made no difference and now I've had a new one made with TV tubing like the original and fully balanced -that's made no difference either.

I had a long conversation with Faversham's this morning and went through everything that has been replaced/checked and also relayed Peters thoughts too on the possibility of some alignment problems.
What they said is that as the diff location is by the two main locating pins and the rear of the car, unless the bodywork is seriously out of alignment forward of that point (which I know it isn't) it shouldn't be possible for the diff to be taken out of alignment with the prop. The suspenion arms and their respective rubber mountings at each corner bolt up to the floor and then the straps have elongated holes to allow for any adjustment of the mount depending on where the whole unit sits - this seems to make sense..
Moving on they came to the conclusion that as everything else has been (mainly) replaced or checked and that it does it with the half shafts disconnected it could only be the actual diff.
Bearing in mind (excuse the pun!) it only occurs at 65/70 + they wonder if a bearing in the diff could be breaking up or sufficiently worn to allow enough free play at high speeds to introduce the vibe's.
So - they have offered me the option to borrow a 2nd hand diff to see what happens but given it whines anyway and has done since it was fitted I am tempted to have it re-built by someone that can actually show me if there is anything seriously wrong inside. I reckon if I've got to take it out anyway I may just aswell try a rebuild.
So - looks like another day under the car and a trip to diff builders - i'm not too tempted to get recon one as some seem worse than what is taken out or am I being a little sceptical...?

Thanks again for all the input, its just what this fine forum is for!