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Folks, my exhaust is trying my patience a bit. I seem to be unable to clamp the LCB to Y piece tight enough and after a bit of use it seems to work out of the Y piece and rubs the rubber coupling, seemingly without blowing out too. I have the gearbox to downpipe steady, but that is the other branch of the manifold.
Everything has been hung on now with the real Maniflow brackets. System is genuine but the LCB is some no-name thing, although good quality IMO, quite heavy and nice welding at the flange/tube joint.

Thanks in advance for any ideas.

Hi,do you have a remote or rodchange?
My guess is the engine is moving just a little to much.
The only cure with the rodchange is to fit a thermostat extra strut.
If it's a remote ,it good be that the whole exhaust is under stress,and it pulls itself out .

I also had rubbing with a genuine maniflow lcb and QL5000 drive couplings which are slightly smaller than rubber couplings.

Solved it by installing the maniflow lcb made specifically for rubber drive couplings. Cost more but no more breathing exhaust fumes from the joint getting knocked loose. I've read that some people have bashed a dent in the lcb to make the necessary clearance but I didn't want to interfere with the exhaust path.

I used to have this problem when I was rallying a Mini in the 80s, solution was to drill a hole in the y piece and into the lcb down pipe, and then put a self tapper through and then to keep the self tapper in place put a jubilee clip around it, a little crude , but it works !

Don't think its under stress, I had it all just hanging with the brackets in the right place before anything was tightened up. Yes its a remote car. What about tweaking a bend into the branch of the lcb? Pipe already dented and it can't go that far from the driveshaft because of the subframe.

If it's already dented give it a squeeze to miss the joint. Maniflow do an exhaust specifically to miss the older cross joints, but as yours has has a flew whacks, I would just make it fit now.

Sorry for confusing you, I mean I put a dent in it in purpose beside the cross joint. Thinking about using a spring from down pipe to Y piece. I'll make it pot joint eventually I think.

This seems to be a common problem these days, for reasons I do not understand, given that an LCB manifold which will fit a Mini with rubber drive couplings, will fit later Minis with ease, did manufacturers change the tooling with the advent of pot joints to ensure that their manifolds would only fit later Minis? If so, why? If I go to buy an LCB, no one ever asks what driveshats are on the car I have had the problem with the LCB rubbing the rubber coupling, but that was long before pot joints were invented & I cured it initially in the way that billycooper suggests, it does work! Eventually, I used oxy-acetylene to re-shape the pipe. The problem you have here, the Y-piece clamps will not hold the pipe away from the coupling, it needs to be clear when bolted to the head without the Y-piece, unless you do the billycooper mod, or something similar. Although not regarded as the best, I have a Sportex LCB on my car & there is loads of room around the pot joint, more than enough for a rubber coupling.

A dent in the pipe works, but looks gash, an LCB for use with rubber couplings is a good option. I also weld 3 7/16 nuts to the Y piese & the same to the down pipes so when it is all assembled I can wire the two parts together this also seems to reduce the occurence of the original problem.

I've found many of the LCBs, particularly those from (sorry to say) Maniflow, to be over-bent or twisted, there have been some set that have been OK, but after paying for them and then spending sometimes a couple of hours to get them right, I'm put off ever buying them again. We have a couple of local manufacturers (I think they are still local!) and while not being a name brand, I've found theirs really good, every time.

I never EVER use that silly bracket that bolts to the side of the gearbox, good way to wreck the threads there and in some cases, wreck the case. It also causes them to come apart as the OP has found. Only in few cases the engine has been steady enough that they don't come apart (or probably not really driven). I let the exhaust system 'swing free' at the bottom end of the engine, but fasten the upper and lower sections together with straps welded to each section, then bolted together so they can be taken apart. Never had a leak or a dropped system when done this way.