I'm doing a few modifications to my Clubman and I need some info before I get started.
1. I'm wanting to construct my own full boot floor panel out of aluminum or stainless steel, anyone know if there would be a decrease in strength using ally over the steel stamped panel? Or any things I need to consider before doing this? It's a custom application for a new tank design and also for smoothing out the boot area for trim and the stereo.
2. I've read a few times that quite of bit wind/drag gets caught up in the front guards and removing the inner panels is the best way to solve this. Have any of you done this on a road car and if so, what are the things to consider when doing this? Strengthening etc?
3. I know this will create a bit of a stir but....what is the best way to de-seam a mini, in particular, a Clubman. (I'll be keeping the roof seam). I'm more interested in the modifying techniques used by Miglia / Hillclimb / Autocross etc, teams as their cars are usually done to the strictest engineering guidelines.
Fabrication Advice
Started by
Clubbed_76
, Sep 29 2012 10:23 AM
14 replies to this topic
#2
tiger99
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Posted 29 September 2012 - 10:50 AM
Your boot floor is primary structure, part of the monocoque, and not only will it dangerously reduce the torsional stiffness of the shell, but you cannot pass the MOT without it being properly welded in place, and being equivalent to the original. Aluminium, which would have to be rivetted or bonded, is a guaranteed fail. Also, such a modification makes you require an IVA test, which Minis have absolutely zero chance of passing without major modifications. You can of course fit a false floor over the original, and I think that is your only real option.
If you know what you are doing, you can weld stainless to mild steel (use 306L MIG wire, not cheap), and so, with a vast amount of effort, a stainless floor could be achieved legally. But be aware, forming stainless is very difficult, and it really does need the stiffening ribs, and there will tend to be rapid corrosion at the weld between dissimilar metals.
For the same reasons you cannot remove the inner wings, and I think that what you have heard about them causing drag is nonsense. Subframe bracing bars, properly, designed, would be vital, and again, expect to fail the MOT and have to put it back as it was or face an IVA.
Cars driven only on the track do not, as you seem to think, comply with "strict engineering guidelines", and if used on the road, most of them would suffer some sort of fatigue failure within a few thousand miles. Track mileage is generally quite small, so what you can cut out for track use is generally a complete no-no on the road.
Deseaming is dangerous if not done correctly. In some places, most noticeably the rear corners, but also the A pillars, the seam is providing vital stiffness, and the equivalent stiffness must be added on the inside.
If you had to ask these questions, you do not have the knowledge or experience to do the job safely, so please do not ruin another Mini.
If you know what you are doing, you can weld stainless to mild steel (use 306L MIG wire, not cheap), and so, with a vast amount of effort, a stainless floor could be achieved legally. But be aware, forming stainless is very difficult, and it really does need the stiffening ribs, and there will tend to be rapid corrosion at the weld between dissimilar metals.
For the same reasons you cannot remove the inner wings, and I think that what you have heard about them causing drag is nonsense. Subframe bracing bars, properly, designed, would be vital, and again, expect to fail the MOT and have to put it back as it was or face an IVA.
Cars driven only on the track do not, as you seem to think, comply with "strict engineering guidelines", and if used on the road, most of them would suffer some sort of fatigue failure within a few thousand miles. Track mileage is generally quite small, so what you can cut out for track use is generally a complete no-no on the road.
Deseaming is dangerous if not done correctly. In some places, most noticeably the rear corners, but also the A pillars, the seam is providing vital stiffness, and the equivalent stiffness must be added on the inside.
If you had to ask these questions, you do not have the knowledge or experience to do the job safely, so please do not ruin another Mini.
#3
Ethel
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Posted 29 September 2012 - 10:52 AM
Someone will have to mention the IVA test if this is for UK roads.
1. See Paul Wiginton's Car
2. If it was a problem it would be better to stop the air going in, in the first place. Consider how air is directed through the radiator too.
3. Clubbies have exactly the same external seams. The way to do it is to grind off and weld up a few inches of seam, leave a few inches, grind & weld a few more and so on.... That stops it springing apart .
Have you considered buying a fibreglass shell? http://www.absmotors...ody-shells.html
Tiger,
Wouldn't stainless steel alter the structure as much as aluminium and risk an IVA?
1. See Paul Wiginton's Car
2. If it was a problem it would be better to stop the air going in, in the first place. Consider how air is directed through the radiator too.
3. Clubbies have exactly the same external seams. The way to do it is to grind off and weld up a few inches of seam, leave a few inches, grind & weld a few more and so on.... That stops it springing apart .
Have you considered buying a fibreglass shell? http://www.absmotors...ody-shells.html
Tiger,
Wouldn't stainless steel alter the structure as much as aluminium and risk an IVA?
#4
Minidarren83
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Posted 29 September 2012 - 11:13 AM
As tiger has stated the boot floor for road use must be fully welded to pass an mot so you could make your own with mild steel if you are good at bending large sheets of it
Most mot testers are fine with inner wings being cut down as long as a correctly fitted set of brace bars are in place but bear in mind the front subby will need to be solid mounted to equal the stress levels at all mounting points
Also to add to Ethel it is also advised where possible to weld plate up the inside of the seam to add extra strength before grinding down the seams this will also put back some of the strength the flanges themselves create, think of a flat piece of steel all floppy like Rolf Harris wobble board then put a bent in it the panel would be rigid if that makes sense
All the things you have asked can be done with little or no experience but you will need to get pretty good at welding and practice making up little panels and welding them together mini bodywork is fairly thin so take some getting used to
If any of the above is incorrect please feel free to burn me at the stake
Darren
Most mot testers are fine with inner wings being cut down as long as a correctly fitted set of brace bars are in place but bear in mind the front subby will need to be solid mounted to equal the stress levels at all mounting points
Also to add to Ethel it is also advised where possible to weld plate up the inside of the seam to add extra strength before grinding down the seams this will also put back some of the strength the flanges themselves create, think of a flat piece of steel all floppy like Rolf Harris wobble board then put a bent in it the panel would be rigid if that makes sense
All the things you have asked can be done with little or no experience but you will need to get pretty good at welding and practice making up little panels and welding them together mini bodywork is fairly thin so take some getting used to
If any of the above is incorrect please feel free to burn me at the stake
Darren
#5
Clubbed_76
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Posted 29 September 2012 - 12:30 PM
This is a good time to mention that all of the fabrication work will be done at a very reputable car fabrication shop over here in Australia, and I mean very, they produce Top Engineered show cars every show. I'm asking because it's my car and I like to know as much of the process as possible so I can pass all this onto them if need be as Mini's isn't what they normally work on.
Well I'll keep the front wings, wasn't that fussed but was worth the question anyway, I'm still in 2 minds with the de-seam but seeing as everything else is getting the smoothed look, it would be a shame not to follow suit with the seams..I'll put that on the shelf for now. Thanks for feedback on the boot floor, I honestly didn't even think of a false floor.. I might just modify a new replacement boot floor so there isn't too many issues with strength and corrosion.
Well I'll keep the front wings, wasn't that fussed but was worth the question anyway, I'm still in 2 minds with the de-seam but seeing as everything else is getting the smoothed look, it would be a shame not to follow suit with the seams..I'll put that on the shelf for now. Thanks for feedback on the boot floor, I honestly didn't even think of a false floor.. I might just modify a new replacement boot floor so there isn't too many issues with strength and corrosion.
#6
tiger99
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Posted 29 September 2012 - 12:37 PM
Ethel, if you replicate the shape of the floor in stainless, I believe it would comply with the MOT regulations. The strength would not be very different. But fatigue in the area of the rear mounts may be, so the stiffeners would need to be in good condition. As you will know, they are often rusty.
I don't think that anyone is going to replicate a Mini boot floor in stainless at home (just try bashing it into shape!), so the problems will never arise.
I would argue that the battery box is not part of the monocoque, insofar as it does not stiffen the shell, although it does perform an important function, so the battery box could be replaced with stainless, or just closed with a welded in patch and the battery put elsewhere, but that is about as far as you can go without invoking the dreaded IVA. Deseaming is well into IVA territory.
By the way, the MIG wire for welding stainless to mild steel is 316L, not what I said.
Minidarren83, I agree about the seams. You need to approximate to turning the seams inside-out. Obviously you can't just hammer them over in the reverse direction, and spot weld on the inside, which would be structurally equivalent to the original, so if I were butchering a Mini that way (you never know, maybe I will, but I will be designing the mods to pass IVA if I do) I would get a piece of 1.8mm (i.e. the thickness of the two flanges), cut it to fit the shape of the body side, and weld it inside at right angles as a stiffener. That would be done just by positioning it behind the seam and welding through the gap left when the external seam is ground off, basically due to the bend radius of the flanges. The presence of that strip would make bridging the gap with weld easier anyway.
It occurs to me that the panel manufacturers such as M-Machine probably press the basic shape of the body side etc on one set of dies and put the flanges on as a seperate operation. If so, maybe it would be possible for them to supply a set with reversed flanges, or left unfinished with no flanges for us to do ourselves, to make deseaming during a rebuild simpler. The only problem then would be getting the spot welder to all of the necessary places, some would have to be MIGed.
The easy one would be the front wing to A panel, and as far as I can see, it should be feasible to do that seam off the car during a rebuild.
I don't think that anyone is going to replicate a Mini boot floor in stainless at home (just try bashing it into shape!), so the problems will never arise.
I would argue that the battery box is not part of the monocoque, insofar as it does not stiffen the shell, although it does perform an important function, so the battery box could be replaced with stainless, or just closed with a welded in patch and the battery put elsewhere, but that is about as far as you can go without invoking the dreaded IVA. Deseaming is well into IVA territory.
By the way, the MIG wire for welding stainless to mild steel is 316L, not what I said.
Minidarren83, I agree about the seams. You need to approximate to turning the seams inside-out. Obviously you can't just hammer them over in the reverse direction, and spot weld on the inside, which would be structurally equivalent to the original, so if I were butchering a Mini that way (you never know, maybe I will, but I will be designing the mods to pass IVA if I do) I would get a piece of 1.8mm (i.e. the thickness of the two flanges), cut it to fit the shape of the body side, and weld it inside at right angles as a stiffener. That would be done just by positioning it behind the seam and welding through the gap left when the external seam is ground off, basically due to the bend radius of the flanges. The presence of that strip would make bridging the gap with weld easier anyway.
It occurs to me that the panel manufacturers such as M-Machine probably press the basic shape of the body side etc on one set of dies and put the flanges on as a seperate operation. If so, maybe it would be possible for them to supply a set with reversed flanges, or left unfinished with no flanges for us to do ourselves, to make deseaming during a rebuild simpler. The only problem then would be getting the spot welder to all of the necessary places, some would have to be MIGed.
The easy one would be the front wing to A panel, and as far as I can see, it should be feasible to do that seam off the car during a rebuild.
#7
tiger99
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Posted 29 September 2012 - 12:46 PM
Clubbed_76, sorry I never noticed where you were! No IVA, as in the UK, but I understand that you do have to get an engineers report or something like that, which makes sense. So for you, a stainless floor is probably viable, if you can find a way of actually making it. Your fabricators may have a clue about that. It is difficult stuff to work into complex shapes.
You could perhaps put some of your effort into some kind of smooth undertray to reduce aerodynamic drag in the rear subframe area, maybe even a diffuser, if you are modifying in that region.
You could perhaps put some of your effort into some kind of smooth undertray to reduce aerodynamic drag in the rear subframe area, maybe even a diffuser, if you are modifying in that region.
#8
skoughi
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Posted 29 September 2012 - 12:52 PM
My mini was deseamed before I bought her and it was a complete pig, once I dug out all the filler! I ended up cutting out a strip about 40-50mm wide and butt welding in a strip of new metal, took ages. Seems quite strong but no way to confirm this. I've seen someone spotwelding on a strip behind the seems then cutting the seam off and tack welding the edges down. Looked neat and didn't take long because of using a spotwelder. Some weld through zinc primer in the sandwich and good sealing should keep down on the corrosion problem. I would say that the battery box is important with regards to the strength of the boot floor, If you have a floor before a box is installed then it's very flexable.
#9
Clubbed_76
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Posted 29 September 2012 - 12:58 PM
On the contrary, the boot floor, both sides, will be completely flat so no need for complex shaping. If you can imagine "raising" all the low points of the boot floor level with the highest points to create a true flat boot floor. That's the concept. There is a need for this as we are prototyping new tank designs. I think thick mild steel is the way to go... As for any concerns with filler and dodgy welding techniques, don't bother, this is a strictly all metal job and the shop is renowned for their welding skills, they have to be with all the drag/show/race cars they build every season 
#10
skoughi
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Posted 29 September 2012 - 04:51 PM
If you're experenced welders/fabricators then i would say go with the butt welding where the seams are as that way any rippling can be planished out. Good luck with it and post up some pictures during and after. Its good to see things being done in a different way.
#11
donjarr
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Posted 29 September 2012 - 06:32 PM
When I de seamed my mini after speaking to a local mechanic who also races cars the best solution he suggested for the strongest join was to weld a 1mm thick strip two inches wide to the back of the seam on the inside, ( this was back seam only) and holding it in place with small bolts, seam weld it in place, (a small length at a time to avoid distorting it,) then when that was fixed, grind off the seam a section at a time and weld the bolt holes up as you go and two sides together and to the reinforcement plate at the back. It was a fiddle but there was almost no filling required as you could flatten the panels together prior to welding then just grind off the access weld.
As for the front he said drill out the spot welds then tap the seam a small section at a time to push it in, so you have a kind of 'W' shape, then doing a sort of sideways stitch pattern seam weld that together and grind down.
It's been done ten years now and no signs of anything moving or cracking so figure it was a good way to do it.
:)
As for the front he said drill out the spot welds then tap the seam a small section at a time to push it in, so you have a kind of 'W' shape, then doing a sort of sideways stitch pattern seam weld that together and grind down.
It's been done ten years now and no signs of anything moving or cracking so figure it was a good way to do it.
:)
#12
Shifty
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Posted 29 September 2012 - 06:41 PM
Theres quite an interesting method of de-seaming in this thread..
http://www.theminifo...-swiss-version/
http://www.theminifo...-swiss-version/
#13
skoughi
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Posted 29 September 2012 - 07:15 PM
Thats basically how my mate did the deseaming I mentioned. Spotwelded a plate on from behind then cut of the seam. But spaced the spotwelds a bit further apart than whats been done in that example.Theres quite an interesting method of de-seaming in this thread..
http://www.theminifo...-swiss-version/
#14
Shifty
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Posted 29 September 2012 - 07:17 PM
Did you see how he did the front pillars? He removed the inner panel and seam welded from the inside.
#15
skoughi
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Posted 29 September 2012 - 07:40 PM
Yep, that looks about the best way to do the pillars me thinks. I did my a-panels to front wings last week but I just cut off the seams then placed a straight edge (spirit level) from the front edge of the door to where the curve of the wing starts to bend and clamped the whole lot together then trimmed the edges of the a-panel and wing until I had a narrow gap then seam welded together. At least that way I can get most of the ripples hammered out. I have been looking at the door pillar and wondering about it though. It was done before I bought it so don't know really what it's like. This, and I hate to admit it, has got me thinking! I'm loathe to open up something else on her though as I'm nearly at the finish line with regards welding!
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