6 replies to this topic

[Zak]

Im about to seam weld both subbie's but i also want to lighten them as well by drilling out holes, anyone thats done this could they post some photos please, Cheers Zak

[bmcecosse]

Why are you doing this ? Seam welding on it's own will do very little for the subby - and hole drilling will save very very little weight! We used to weld AND plate subbies for rallying - which added considerably to the weight. If you want to save weight eliminate the rear subby completely!

[Zak]

Why are you doing this ? Seam welding on it's own will do very little for the subby - and hole drilling will save very very little weight! We used to weld AND plate subbies for rallying - which added considerably to the weight. If you want to save weight eliminate the rear subby completely!

I would love to fit a rear beam & coilovers, but my budget simply is nil so while the shell is stripped of unwanted tin I hope to achieve a little weight loss on the welded & gusseted subbies even if it's only for look's

Anyone got any photo's?

[icklemini]

dont bother.. its simply not worth it...

A super strong subby is great in theory... though it reality what happens in the event of an 'incident' is that the body shell will get more damage... Its usually cheaper and easier to replace a bent subframe than it is to try and re-jig a bent shell...


(unless you are installing a multipoint full weld in cage that is picking up on the subframe mounts..)

Edited by icklemini, 13 July 2009 - 06:39 PM.

[rick.spi]

there was a section on it not long ago im sure i read up on it...

Edited by rick.spi, 13 July 2009 - 06:54 PM.

[Cooperman]

I have often thought about lightening the front sub-frame. I reckon it's well over-engineered. Then I thought about the advantages on a rally car, which seem to work out at about zero. The rear frame is about right in terms of strength, but as bmcecosse says, we always plated them for forest rallying so that the stones and gravel wouldn't wear away the underneath flat part.
The sub-frames are low down on the car, so there is less incentive to make them lighter. It's far better to lighten the higher parts like fitting perspex or polycarbonate windows, lightening the doors, removing the sound-deadening from under the headlining, etc. Incidentally, the black sound-deadening which was sprayed onto the floors on all later Minis weighs over 15 KG. That's well worth getting out. I used an air chisel with a bolstering chisel fitting, 2" wide, to do this.
So, on my rally Minis I have left the sub-frames standard, except for some seam welding on both of them and a bit of plating on the back one. The only holes drilled in my front sub-frame are to gain access to the clutch cover bolts to make clutch changes easier, plus, of course, the welding in place of nuts for the sump guard bolts to go into.
I hope this helps.

[Zak]

I have often thought about lightening the front sub-frame. I reckon it's well over-engineered. Then I thought about the advantages on a rally car, which seem to work out at about zero. The rear frame is about right in terms of strength, but as bmcecosse says, we always plated them for forest rallying so that the stones and gravel wouldn't wear away the underneath flat part.
The sub-frames are low down on the car, so there is less incentive to make them lighter. It's far better to lighten the higher parts like fitting perspex or polycarbonate windows, lightening the doors, removing the sound-deadening from under the headlining, etc. Incidentally, the black sound-deadening which was sprayed onto the floors on all later Minis weighs over 15 KG. That's well worth getting out. I used an air chisel with a bolstering chisel fitting, 2" wide, to do this.
So, on my rally Minis I have left the sub-frames standard, except for some seam welding on both of them and a bit of plating on the back one. The only holes drilled in my front sub-frame are to gain access to the clutch cover bolts to make clutch changes easier, plus, of course, the welding in place of nuts for the sump guard bolts to go into.
I hope this helps.

Thank's 'Cooperman' all views welcome, My shell is stripped of all unwanted material from tiny tag's to boot floor, plus will have alloy skin doors + poly windows ,and fiberglass bonnet+ boot etc ,also my six point cage will grow to multipoint and pick up on subframe points, I dont get on the computer much so thats why i would like to see if anyone has lightend their subframes what they have done and if it's worth me doing. Cheers Zak