Maniflow LCB manifold fixing to gearbox?

[1071bob]

Interesting posts about this bracket! In my defence the Maniflow LCB came with three clamps, two for the downpipes to Y piece and a smaller diameter one for the primary pipe. In the Minispares advert it recommended the two bolt bracket as in the photo. I did change to longer UNC bolts to allow for the thickness of the bracket so I'll see how I get on with it.
Another problem with the manifold was the centre pipe manifold flange fouls on the standard Cooper inlet manifold, most of the problem was the weld but I also had to grind the chamfer for clearance. Very hard to see when fitted but you should be able to slide a piece of cardboard to check for clearance. I think 'Coopertune USA' mentioned this a while back.

[NZmember]

Somerford do the three bolt bracket for a very reasonable price.
https://www.somerfordmini.co.uk/bracket ... diff-bolts

[BAD942B]

Interesting posts about this bracket! In my defence the Maniflow LCB came with three clamps, two for the downpipes to Y piece and a smaller diameter one for the primary pipe. In the Minispares advert it recommended the two bolt bracket as in the photo. I did change to longer UNC bolts to allow for the thickness of the bracket so I'll see how I get on with it.
Another problem with the manifold was the centre pipe manifold flange fouls on the standard Cooper inlet manifold, most of the problem was the weld but I also had to grind the chamfer for clearance. Very hard to see when fitted but you should be able to slide a piece of cardboard to check for clearance. I think 'Coopertune USA' mentioned this a while back.

Your mods to the centre pipe weld & flange are how my original LCB was, which I assume was ST because the PO was a BMC agent, I'll need to replicate it & take your advice, thanks Bob

[mab01uk]

I've always found that any bracket that bolts up to the gearbox, in time, only pulls the threads from the gearbox. I stopped bolting up any of these brackets here nearly 40 years ago and never looked back. I've repairs load and loads of gearcases that have had damaged threads here all from the exhaust being bolted up here.

Same here, always found any combination of brackets more trouble than they are worth so stopped using them around 40 years ago with no problems, at least with the extra stability of a remote gearchange (or a rod change gearbox with the later factory or extra engine/gearbox stabilisers).

The original Minis with a magic wand gear change were I believe designed to use the exhaust downpipe to further stabilise the engine/gearbox...until the gearbox bracket eventually cracked, followed soon after by the exhaust to manifold flange once the engine mounts/steady bar rubber bushes had gone a bit soft! This was so common back in the day that you could buy from local motor factors a short replacement section of the Mini exhaust downpipe to clamp on complete with a new manifold flange, to repair your otherwise ok exhaust system. (some came with a built-in section of more flexible downpipe).

I remember watching Russ Swift doing his stunts at Mini shows in brand new Rover Minis, where you could see the strain on the exhaust system moving below the car, as he did his sudden changes of direction under full acceleration and with wheels spinning...

[Spider]

Same here, always found any combination of brackets more trouble than they are worth so stopped using them around 40 years ago with no problems, at least with the extra stability of a remote gearchange (or a rod change gearbox with the later factory or extra engine/gearbox stabilisers).

The original Minis with a magic wand gear change were I believe designed to use the exhaust downpipe to further stabilise the engine/gearbox...until the gearbox bracket eventually cracked, followed soon after by the exhaust to manifold flange once the engine mounts/steady bar rubber bushes had gone a bit soft! This was so common back in the day that you could buy from local motor factors a short replacement section of the Mini exhaust downpipe to clamp on complete with a new manifold flange, to repair your otherwise ok exhaust system. (some came with a built-in section of more flexible downpipe).

I remember watching Russ Swift doing his stunts at Mini shows in brand new Rover Minis, where you could see the strain on the exhaust system moving below the car, as he did his sudden changes of direction under full acceleration and with wheels spinning...

Exactly.

I recall seeing1 drawing for the 850 from a time prior to it's release and after the Orange Box's were used in road tests where the exhaust pipe was the only engine steady !

[timmy201]

Why hasn't maniflow or someone come up with a nice flanged header/exhaust??? That connection kills me...I can never get it to seal, and when I try to separate it, it's always a torch job.

I can separate an r53 header in 2 minutes, throw in a gasket and be on my way again in no time.

Guess that's outside the OPs question, but thanks for letting me vent.

Happy Easter?

Pat

The best alternative I’ve seen is a double slip joint with a spring like this. As mentioned earlier, adding a flange or V band would make it tricky to install into the car, and you also need the room between the pipes to install them

[minstix]

On the manifold to gearbox fixing issue, I tried the official two bolt bracket from Mini Spares.

Having read and taken on board all the comments in this thread I had decided to fit a fixing at the front but thought that, however it is fitted, it mustn't in any way be putting a strain on the manifold, exhaust or fixings to the gearbox casing. So I tried to avoid clamping anything up and bending even slightly the manifold pipes.

The two threaded holes are much deeper than the standard 1 inch 5/16 UNC set screws had ever used before and they're threaded deeper as well. In fact the lower one of the pair has been drilled and tapped right through to the outside world, as it was when it left the factory. So I could use a 1.5 inch screw in that one and a 1.25 screw in the higher one. So I thought if I use the two hole bracket with those longer screws, what could go wrong? Hmm...

I had also bought the official clamp to go on the main pipe. It has a longer reach with elongated holes to allow for adjustment. When it arrived I realised it was made for a smaller bore pipe. So that was scrap! It should have rung warning bells at that stage. Anyway, I went ahead and fitted the two hole bracket with the longer screws. It fitted perfectly. However, there was an issue when the Maniflow manifold was fitted.

I had fitted the two hole bracket while the exhaust and inlet manifold brass nuts were loose, which gave me access to fit the bracket. Then I temporarily slid on the Y piece to ensure the two pipe ends were in the correct position. It fitted like a glove. Then I tightened the brass nuts, bit by bit until fully tightend (at that point I checked that I could slide a piece of paper through under the inlet manifold as mentioned earlier in this thread, and I could).

Back under the car I noticed an issue. The main pipe was now rammed hard against the new two hole bracket. It's obviously designed for a smaller bore pipe. That didn't look ideal, with engine vibration I could see long term issues there. I realised that I could remove the bracket and shave off a few millimetres and refit it. I then removed the bracket, after slackening off the brass nuts again. I now realise that if I do modify the bracket and put it all back, the pipe will now be rammed against the head of the upper of the two screws that hold it on. If fitted with no bracket at all, the pipe only just clears that screw head. At least there's a bit of air between pipe and head now, all beit only about a millimetre.

So I've ditched the bracket and clamp and will have to think again!

Steve

Exhaust front mounting bracket hitting down pipe.jpg

[twc641]

A intermediate flex pipe perhaps this will reduce the stress to the bracket at the gearbox?

[minstix]

Maybe if there were such a thing. I'm trying a fixing without using the two hole bracket. If it works as I hope I'll come back with some pictures.

The trouble is, minis were never designed to have such a big wide exhaust fitted I guess and so there will be issues and compromises.

Steve

[Spider]

,,,,, I had decided to fit a fixing at the front but thought that, however it is fitted, it mustn't in any way be putting a strain on the manifold, exhaust or fixings to the gearbox casing. ,,,,,,

I apologize here as while I did say these break brackets, and pull threads from the gearbox, I don't think I mentioned why. The engine is on rubber mounts and there's also rubber in the steady bars, so the engine assemble will and does move relative to the car's body. I can see here you're going to some trouble to ensure that in a static position, that it all fits up neat and tidy, some nice pride of workmanship for sure.

For a different project, I measure how far the engine moves on the mounts and found that on hard acceleration, it'll move forward up to 18 mm, though, on more normal driving this was generally around 12 - 13 mm. On over-run, it can move back up to 17 mm in the lower gears, though more usually 10 - 11 mm. Along with this movement, the engine also tilts. It's this constant nature fore, aft and tilting movement of around 24 mm that reefs on the brackets and threads that does the damage.

[BAD942B]

,,,,, I had decided to fit a fixing at the front but thought that, however it is fitted, it mustn't in any way be putting a strain on the manifold, exhaust or fixings to the gearbox casing. ,,,,,,

I apologize here as while I did say these break brackets, and pull threads from the gearbox, I don't think I mentioned why. The engine is on rubber mounts and there's also rubber in the steady bars, so the engine assemble will and does move relative to the car's body. I can see here you're going to some trouble to ensure that in a static position, that it all fits up neat and tidy, some nice pride of workmanship for sure.

For a different project, I measure how far the engine moves on the mounts and found that on hard acceleration, it'll move forward up to 18 mm, though, on more normal driving this was generally around 12 - 13 mm. On over-run, it can move back up to 17 mm in the lower gears, though more usually 10 - 11 mm. Along with this movement, the engine also tilts. It's this constant nature fore, aft and tilting movement of around 24 mm that reefs on the brackets and threads that does the damage.

Is this on rod change engine / gearboxes, surely not on remote change gearboxes

[Spider]

Is this on rod change engine / gearboxes, surely not on remote change gearboxes

Rod and Remote, though, remote doesn't tilt as much.

[minstix]

All food for thought. Thanks for your input everyone.

Steve

[InnoCooperExport]

I was looking at this very bracket the other week while working on my Inno. In the end I decided that the best fitting place was on the lower steady mount in the subframe. I'm wondering now if I've maybe not thought this through properly



Not once did it cross my mind to look at the gearbox for a mounting spot, but considering how this is a rod change I'd rather not rip a stud out of my box. Maybe I'd be better off removing it entirely.

[minstix]

It seems to me that if we take into account that the engine will move during use, backwards and forwards a little, but also tilting with acceleration and braking, if the manifold is firmly attached to the gearbox, the manifold itself won't be stressed that much between the head and the gearbox bracket. Most movement however, would have to be accomodated by the rear rubber mounts and flexing of the exhaust system between between gearbox mount and the back rubber mount. The Y piece and the thinner section that goes between the Y piece and the RC40 may be more likely to flex more than the RC40 itself. The Y piece is known to fail in time, perhaps as a result of this?

With no gearbox mounted bracket, then the movement and flexing would then be accomodated to include the manifold as well. I would be concerned about attaching that bottom manifold bracket to the front subframe as it would mean that all that movement would have to be accomodated in the manifold over quite a short distance. Especially with a rod change car.

All food for thought anyway,

Cheers,

Steve