Where I used to work, they had a dirty big hot dip galvanizing tank for doing street light poles. On weekends us workers used to take boat trailers and box trailer bodies (or whatever) in and dip em. A lot of this stuff was 1.5mm or less in thickness. I reckon hot dipping a rear subby without distorting it would not be a problem.

Somewhere I have pictures of a Group 44 Jag (XJR 5 or 6 - or something like that) backbone.  Basically a lump of alloy about 6'x3'x3 or 4 inches all hogged out and looking like a huge space age butterfly... They bolted the engine/suspension on one side and the rest of the car on the front....

Can't help but think that a plasma sprayed standard frame would be the best (and cheapest) option though ...

Cheers, Ian

Yeah, I usually keep quiet on this forum, but the planets must have been aligned properly or something last night (No beer though!).

Terry, don't get me started on use of the word "billet" for machined parts.  All those 1990s streetrodders misappropriated it and the balance of The Universe will never be the same.

Jim,

I think stainless is too hard /brittle to use for a subframe. You could have a new one sandblasted and plated, galvanized, etc.

Stainless is not easy to work with either. hard to cut and drill.

Craig i'll buy you a beer! you spoke!! 

Craig, come on you know billet is the way to go. Just look at Jegs or Summit, billet is the key word.

Where are the billet pulleys and brackets for a Mini.. oh wait a minute Retrosport DSN Classics has them.

Terry

Sounds like a great use of vacuum hot-brazing!  It's the preferred method of fabricating electronic boxes for space vehicles.  You start with a block of the right aluminum (6061-T651 or some 7075-T Whatever) that is clad on one side or more with maybe .050 inches of an aluminum alloy that melts at a slightly lower temperature.  Machine out what doesn't look like a subframe side, front or rear section.  Clamp them all together in a close tolerance fixture and shove them into a vacuum dip braze furnace for an appropriate time and when it comes out... Viola! An almost finished frame that needs to be final machined to mount the other parts required for a Mini.

Should only cost a couple of million dollars to develop and might be profitable if there were enough people lusting for them.

Machining a complete subframe would be much more expensive and time consuming as it would walk all over the place while it's being machined even with multiple stress relieving steps.  The forged billet would most likely cost almost as much as developing the machining methods and take a long while to source.

A welded tubular subframe would be easier, but would still need considerable machining to get the mounting pads and all right.  It would be more economical than the other two, but how many would you be able to sell?  Someone in their garage will now most likely weld one up and tell me I'm wrong; anyone can do it over a weekend with no welding experience!

Sorry, nevermind me.  I'm retired and don't get to work on that kind of thing anymore.  That's what I miss about not working for a living, but the waking up every day and doing whatever I want to do is much better!

billet rear subframe would be sweet, but would probably take a long time to machine out and cost alot

I dare someone to machine one out of billet aluminum. 

I've had one subrame rot out in 22 years of daily driving a Mini, and it was already rotten when I bought the car.

Hot dipping twists the frame, I know a few people who've tried it.

Yep....lotsa Roo guts but no salt. 

Rear subframes rot out so fast in UK I'm surprised they were not hot dip galvanized.

OTOH, here in Oz they last forever as we don't salt our roads.

Mousy

http://www.force-racing.co.uk/home/

No but there's titanium ones, KAD I think.

Anyone make a  stainless rear subframe