MGTF PolyBush compliance bushes

my thoughts too, its only on certain bumps like speed bumps that seem to cause it.

At least from what I can see from the design of the bush it seems more of an issue of the suspension design. As all of the lateral arms allow rotation in more than one direction, the job of constraining the rear Hub's rotation around that axis is also one by the trailing arm, and as the arm is only fixed at on place this also doesn't fully constrain it. that is in my mind why there is a flat plate on the trailing arm where it sits on the bush to stop it from 'complying' left and right as it were. this naturally over time wears down the rubber it sits on till it reaches the metal.

Are you sure the bush is the cause of the noise? It maybe that although the bush looks suspect and that’s what you found when you looked, that’s what you found that didn’t look right, but the cause of the actual noise is something else? Like a shock absorber perhaps?

I’m a F’er not a TF’er so I’m not all that familiar with the TF suspension, so I’m only really guessing 

I have been looking into it for a few months and I have changed the rose joint style bushes on the upper arms and shocks and the ball joints on the hubs. I cant find it at he moment but there was a youtube video that detailed the same noise in which he put a rubber disc on top of the bush that fixed the issue, so I am considering removing a trailing arm to ensure that is whats causing it, but that's quite a big job in itself

EDIT: link to suspension diagram https://www.16vminiclub.com/forum/general-public-area/rover-chat/20901-anyone-used-a-mgtf-frame-including-suspension

Don’t forget the small cross-bar that sits on top of the compliance bush. As far as I am aware it is prevented from metal to metal contact by a rubber/polymer additional component that is like a thick washer sitting on top of the bush that is pressed into the metalwork of the compliance bush assembly.
Could it be that polymer washer that is missing/damaged?

I did a complete front and rear suspension rebuild just over a year ago, the subframes were replaced with galvanised ones and every wheel bearing and ball joint bar the rear track control ones. Poly bushes were fitted all round with the idea of making it maintenance free for a few years. I think that replacing the rear compliance bushes are down to if they are worn out, but it is also down to where and how you drive. We drive over Exmoor quite a lot, especially from now until Easter while the roads are very quiet. At times we do push the car to its limit and that is where the polybushes all round and the big brake discs come into their own. If you are just out for a normal drive then I wouldn’t bother, the ride is much firmer, not uncomfortable but firmer. 

I believe that rubber part on top of the compliance bush is what has worn through allowing for metal to metal contact which causes the noise.

EDIT: found the video here you can clearly see how it wears through

That certainly looks like a solution to the compliance problem on a TF. The only comment I would make would be the material he used to make the doughnut didn't look like a "permanent" fix.
I would probably use a harder plastic material rather than rubber. As I did when I fixed my compliance bush issue with the F.

2mm thick ABS plastic.
 
I fitted these over 10 years ago and they are still in A1 condition. They are 60-61mm outside diameter;25mm internal diameter. I used a number of them as shims to take up the worn space on the compliance bush, which is the issue on the F.

I see that the TF polybush kit uses a separate poly doughnut
 

thats correct and they do look to be quite thick on the polybush ones, given my schedule Ill likely be looking at doing something in November, if I do end up replacing them with polybushes I will try to document it for a how to guide.

Made some stainless rings with HDPE shims to get the play out. 

    I changed mine to poly bushes roughly at the end of 2013 or beginning of 2014. No problem with the old ones, just an upgrade.
Now I wish I hadn't. They literally disintegrated. I have just changed them again. They had actually disintegrated at least a couple of years ago but I very rarely use the car so it wasn´t something I needed to do.

The same happened to the ARB bushes and ARB droplink bushes. I have replaced the links with the ball joint type and the ARB have gone back to rubber - interestingly the VW part 6Q0411314 is compatible with the rear ARB bushes so I have fitted those (as they are very available without silly postage and import duties - thanks Brexit..)

 

That bush is fairly fornicated, it must have been a very hard grade of poly to do that! Not all poly bushes are equal some are much harder than others.