rear bulkhead, can it go?

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tickle
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Mon May 29, 2006 6:20 pm

im looking at removing the metal panel behined the passenger seat and putting a strut brace on the back to regain strength.

is this legal? just that tourings dont have it so i wouldnt have thought it would remove that much strength.

im converting it into a 2 seater you see and am considering fitting a removable hardtop to make it more of a roadster setup winkeye

i dont want have to get it sva tested, the insurance would kill me
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Andy325i
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Mon May 29, 2006 6:31 pm

erm. . . Is this on a cab you have or you going to chop the roof off the one in your siggy pic? :lol:

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tickle
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Mon May 29, 2006 6:35 pm

it would be the one in the pic if i do go ahead with it, all i know about the differences between cab's and saloons is the lack of parcel shelf and stronger sills.

the roof would be miles down the line though + would include a full custom cage, my priority is the rear bulkead + parcel shelf. it's starting to rot around some of the seam + i would prefer to do away with it.
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Mon May 29, 2006 6:42 pm

Interesting Project, and total respect to you for attemping it (keep us posted, with lots of pics!)

What difference will there be between yours and a regular cab?


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Brianmoooore
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Mon May 29, 2006 6:46 pm

Strut brace wouldn't do a lot for tortional rigidity. You'd need to replace the bulkhead with a cross brace or heavy rectangular frame, which would weigh considerably more than the original panel.
As for removing the roof - there's a bit more to designing a cab than attacking a saloon with an angle grinder.
The cab cills impart a lot more rigidity than the saloon ones, and there's extra bracing under the floorpan as well.
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tickle
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Mon May 29, 2006 6:48 pm

the roof will be a hardtop, so it' on or off + i would'nt mind getting a fibreglass one to keep weight down.

dont want the cage to come above the doorcard level, this would allow me to fit a half roof skin over the rear seats to keep it all neat, it would have to be removable of course. two mx5 style roll bars situated behined the seats would also look great on it methinks
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tickle
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Mon May 29, 2006 6:49 pm

would the cage stiffen it up enough + keep it legal
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tickle
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Mon May 29, 2006 6:58 pm

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here is a rough idea of how ill do the cage, would this design be up to strengthening the rear, i aint got round to designing the front yet
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Brianmoooore
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Mon May 29, 2006 7:00 pm

tickle wrote:would the cage stiffen it up enough + keep it legal
If the cage is substantial enough, then it becomes a spaceframe chassis, and the monocoque can be chopped about as you like.
You're heading towards territory where you (officially, at least)h7, need SVA.
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tickle
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Mon May 29, 2006 7:08 pm

would a sva be needed without the roof chop, just the bulkhead? or rather would i get hell by the mot people, there is no spare so they have no reason to go in the boot.

there will be a facia panel on the inside also covering it from sight. how did they regain dtrength on the touring?
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Brianmoooore
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Mon May 29, 2006 7:12 pm

Triangulate!
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tickle
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Mon May 29, 2006 7:31 pm

mmm cheese :mad: ,

cheers geez, sounds good,

when you made reference to sva before did you mean i'd need 1 even if i just remove bulkhead or just roof?
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Mon May 29, 2006 7:57 pm

Removing the bulkhead would be an MOT fail, no doubt about it. Even when people cut larger holes in the parcel shelf for speakers it is an MOT failure because it is all structural.

If you modify any of this it will have to be SVA tested, only thing you can do is remove the ski hatch in the middle.
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tickle
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Mon May 29, 2006 9:46 pm

oh well, how would it work with replacing panels with carbon fibre? we used to use a bonding agent by 3m which is meant to be stronger than a weld. if i bonded carbon fibre sheeting in it's place would it maintain it's rigidity as i have a feeling that if it was painted no-one would be any wiser, and after all carbon fibre is far stronger + doesnt rust,

the ultimate goal is to keep the weight to a minimum + rid myself of as many rust points as possible, the roof removal was more of a side shoot idea. to me it's more about what i can getaway with without risking the lives of passengers, bearing in mind there is no such thing as a rear seat in my motor
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Mon May 29, 2006 10:04 pm

Think if it were me, I'd buy a cab rather than trying to make one!

Must admit I've never heard of or seen the parcel shelf or rear bulkhead checked in an MOT!

Think of the bulkhead, roof and floor panels like this though:

Take an empty margarine tub without it's lid on, hold it with both hands one at each end. Now twist the tub and notice how easy it is.

Now replace the lid and try to twist it again. Notice how that single sheet of very thin material has increased the stiffness massively.

Now imagine the tub of a car as being similar to the marge tub and think of the consequences of removing a panel.
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tickle
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Tue May 30, 2006 1:23 am

yea i figured that mate :roll: if i didn't know that after 5yrs of damn bodyshop labour id be kinda gutted :D

just trying to find a way to REPLACE lost strength! i may aswell explain exactly where im tryin to come from

1) i just dont get this, i know personally 1 person and have heard of many who have bought kits, i.e rienforcement + hood and thats all they have done, cars never bin a problem (not talkin e30's here, my mate did it to his mini and claimed it was far stiffer than before + never had it sva'd)

baur used to fit cab hoods to cars that never came with them, as did cooper cars and nobody seems to complain.

2) if you add strength then whats the problem, to nick your example:
get a tin box, with a carbon fibre lid, it'd be far stronger + lighter than welded tin

especially as thin tin is actually weaker when it's welded cos of the heat ,hence regulations stating that legally spot welds applied in this country should be a distance of 30mm apart, but mot man says seam weld rust??? WHY??? contradiction or what

besides im not just after making a cab, id just buy one if i wanted one so bad. it's about making something thats a break from the norm, something that is an acheivment to me, and something that no-one else will have!

and no, ive painted and fitted far too many crappy bodykits to be content with something like that,

maybe if i paint the bigger picture here:

lotus make cars with balsa wood+ cf, and generally are really nice cars, nippy as hell and faster than most bmw's

ferrari use hardwood in some of there chassis, and they make s#it hot cars.

now imagine if bmw made a car combining the strength of steel and hardness of carbon fibre( bearing in mind strength + hardness are opposites of the same coin),
everyone would be raving about it,
it would be stiffer,stronger, lighter and faster, simply by changing materials in the right place, this is my main objective.
open top is something that im considering, but won't decide on till i feel ive got all the info i need. but im strengthening the car now, so would prefer to take future options into account at the earliest stage poss

i know id never be able to acheive the kind of masterwork that bmw put into their paneling, but i know i can do better than ford!

i suppose what i should have said to start this thread was:

what did baur include in their cab conversions and how do people rate them who have them

+ what panels have people on the zone had replaced with cf and how has this changed the structure?

sorry bout the length of this but im rubbish at putting things into words :roll: + it' gonna be a little while b4 im back online so needed to include everything :D
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Tue May 30, 2006 8:13 am

besides im not just after making a cab, id just buy one if i wanted one so bad. it's about making something thats a break from the norm, something that is an acheivment to me, and something that no-one else will have!
Aah, now that I can relate to :D

Be interesting to see how you get on!
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Tue May 30, 2006 11:20 am

Are you thinking in terms of the M3 CSL? (for lightweight materials anyway)
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tickle
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Tue May 30, 2006 12:20 pm

is the m3 csl the e46 with the carbon fibre roof?

if it is this is where i got the idea from.

i was thinkin of replacing the boot floor, roof, rear quarters + the panels between inner arches + chassis legs with carbobn fibre as these are structural

the doors wings bonnet + boot i would like to relace with fibreglass

i have three options when it comes to composites.

carbon fibre, kevlar + fibreglass

(i have a friend who can use all of the to make moulds) how conveinient.

i think id be mad not to, he offered to line my car in kevlar for the price of the raw materials + help with his future projects winkeye
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Cars and girlfriends have alot in common.
They both make you angry+ make you cry, bleed your wallet + moan when they are old.
But at least the car makes sense!
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