My engineer did say not to go overboard with the strength (ie thickness of my my pipe) as he said a lack of flexibility would have a twofold effect. The engine being held too rigidly would transfer the engine stresses too directly to the chassis (which it technically wasn't designed to take). And in the event of a headon, if the chasis did not bend at all then a soft squishy thing would (me ).

Having said that 2.8 to 4mm makes little difference

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225hp atw on 14psi. 1/4 Mile no idea. Take one 1971 Mini Clubman, one Starlet GT Halfcut, Simmer over a warm MIG Welder, and Voila Minstar! www.mpdesign.id.au

If you wanted to engineer a crumple zone in the mini, it would take alot more than a thinner walled subframe. You would need the thickness or material to change within the subframe so that the front of the car would crumple in a way that absorbed energy in the right way. You would probably need to model the subframe on a computer to analyse the behaviour upon impact.

Just go with the thicker stuff, and maybe put a rollcage if youre worried about crashing it

Just a thought
Pierre

later model mini clubmans were desinged with a crumble zone in the engine bay... Have a look at any post 74 clubman and it will have 2 holes (about the size of a 50 cent) in the tops of the inner guards right on the bend....This was to allow the inner panels to squash in 1/2 taking some of the force in an impact.

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1974 Moke - 998cc
76 Clubman B16a2 Vtec AWD Turbo 12.9@105mph
https://www.youtube.com/watch?v=V9PW49e1hYs

Hey matt,

Different story - my ginger-beer said that there should be zero movement of the subframe under all loads, and that stresses due to engine movement should be taken up in the mounts. Once the frame starts moving, things start wearing and then, things start breaking.................

Andrew

Cars manufactured after 1971 had to comply to crash tests
My engineer was worried about making the sub frame too stiff ie wouldn't crumple in a crash but wasn't as worried when he figured that mini's didn't have much of a crumple zone still don't make it too rigid

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4efte powered Clubman
supercharged 998 race car

Andrew I can pretty much guarantee that neither of our subframe will "move". The stresses of the engine are alot less than that of a car impacting at 60kph. I fully agree with your statement about the engine being held rigidly, I just think load flex differential over 12 inches (distance of back of subframe to furthest mount) would be miniscule. I am just saying that I think you can overengineer things.

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225hp atw on 14psi. 1/4 Mile no idea. Take one 1971 Mini Clubman, one Starlet GT Halfcut, Simmer over a warm MIG Welder, and Voila Minstar! www.mpdesign.id.au

interesting...

I like the way your subframes don't have anything solid bracing under the motor - IE from the tie bar mounts to the point where the bottom suspension arm extends from. Having this 'gap' would mean the subframe would crush back to there before pushing into the cabin. Question about that strategy though, does it rely on the body being stiff for rigidity at the tie bar mounts? if so, I'm guessing a flip front wouldn't be advisable... I liked the idea of a clamshell bonnet as Gafmo posted a pic of a little while ago

SK. I can see your point but especially on the left hand side of the engine the engine itself just prevents putting a spar underneath or one wide enough to provide any strenth. Plus the tie rods pretty much sit exactly where you might want to join it on. The starlet itself runs gaping holes on either side, but does have upper and lower wishbones...One of the reasons I put the spar across the back was to provide a little more protection but mainly to stiffen it up.

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225hp atw on 14psi. 1/4 Mile no idea. Take one 1971 Mini Clubman, one Starlet GT Halfcut, Simmer over a warm MIG Welder, and Voila Minstar! www.mpdesign.id.au

SK,

I dont think the body provides very much in terms of additional stiifnesss to the tie-rod mounts at the front. With Matt's and my design, the tie-rods mount directly onto the vertical tubes off the main lateral spars.

Andrew

Yeah definitely Andrew it locates it to some extent but for torsional forces I think it makes bugger all difference. The fact is like anything where you transplant and engine from a completely different car there are always compromising, the trick is to minimise them!

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225hp atw on 14psi. 1/4 Mile no idea. Take one 1971 Mini Clubman, one Starlet GT Halfcut, Simmer over a warm MIG Welder, and Voila Minstar! www.mpdesign.id.au

the civic I got my running gear out of actually had 2 seperate pieces to the subframe, basically connected by the tie-bars and the engine (via mounts) but there was a little more body to it than a mini

the honda has some scope for lower bracing bars, but nothing more than about 1" square

With my subframe I have the main braces under the engine then ones over the top bolt on holding the engine this was to distribute the weight of the engine a bit better not just hanging off the supension towers. Put some of the weight underneath more like a standard mini.
Right hand side veiw

Left hand veiw

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4efte powered Clubman
supercharged 998 race car

Wow 92, it never ceases to amaze me how many different ways there are to skin a cat. Great effort...

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225hp atw on 14psi. 1/4 Mile no idea. Take one 1971 Mini Clubman, one Starlet GT Halfcut, Simmer over a warm MIG Welder, and Voila Minstar! www.mpdesign.id.au

yeah 92 - good work!

There ya go, two different designs. Yours is more of a cradle while mine and Matts are more of a cantilever principle.

Looks good though, cant wait to see the finished product.

Andrew

Very interesting. I was originally thinking of building my mini with a roll cage that mounts to sub frame bolt up points. With the idea that my engineer could design the points ie bolts to break when a heavy front impact occurs so the engine subframe is pushed under the car dispersing the load (such as in the A series merc).