Roof chopped BMW mini cooper S

rkde · May 25, 2010

Hello everyone,

Through this website I have learned lots and earlier this year I started on my project a CAT D mini which I planned to turn in to a chopped ride. I have spent many hours on it so far and I am learning loads as I go on.

I am already a few months into the build and have not posted anything on here as of yet.

To catch up I have a link to my blog but plan to update the site here too for your viewing pleasure

www.rkde.blogspot.com

I think I am now up to a stage where its all sheet metal and welding so thought it a good time to put it on here. Loads of work left to do here and I am especially looking forward to getting the weld in roll cage and giving that a go.

I will get some photos on the forum ASAP too and summarise it to save trawling through the blog

fran9r · May 25, 2010

Great project, love to see it done. Any other mods planned?

gavuk · May 25, 2010

Interesting project,have you had the glass priced up yet? are you cutting the original or bespoke glass?

rkde · May 25, 2010

Along with the roof I am also going to fit some bravia lights to the back. I will also be building the engine to race spec, fitting it with a roll cage and also doing a whole new interior

I am going to use plexi glass for the sides and rear as that was toughened glass and would cost loads and the front will be stock screen which I am going to cut down... Maybe I will need a couple.

This is what I plan so far, Knowing me it could end anywhere

This was planned about a year ago and I have decided on many changes since doing that picture

the snooper · May 25, 2010

rkde said:
I am going to use plexi glass for the sides and rear as that was toughened glass and would cost loads and the front will be stock screen which I am going to cut down... Maybe I will need a couple.

will it pass an mot with plexi glass ? all windows have to have the british standard safety mark on the windows the glass in a car has to shatter into tiny pieces to avoid causing large cuts.
plexi glass will break into large pieces.

i cant see the windscreen being easy to cut either as they are laminated

rkde · May 25, 2010

The side windows are aloud in the MOT to be plastic but the front by law needs to be glass. If you have glass on the side then it needs to be BS marked, or this is how I understand it to be. All rally cars have plastic windows and they have to have an MOT but I have read up on it a while back and as long as they are solid fixed and or have an opening then they are OK for MOT though its not just a normal plexi its a special flexi polymer which doesn't shard

The way to cut it is with sand, basically mark out the line with alloy tape and use a sand blaster to remove the glass then cut the laminate away, worst case I will take it to a local 5 axis water getting company.

I am lucky that I used to work with glass and have some very good contacts

the snooper · May 25, 2010

if you have contacts in the glass industry i think id get them to cut the front screen it might be cheaper in the long run.

ive had some safety glass cut about 80 quid for a 2 foot square so you plastic sould be quite a bit cheaper and it will bend to shape most safety glass is flat.

good luck with your screen

rkde · May 25, 2010

Cheers, I have one spare to try and then plan, funny that the screen is the least of my worries. I worry about chopping the roof skin and having to put it back together like it was never cut.

I am excited about finishing the bodywork as I think its going to look very special

BMH · May 26, 2010

Not wanting to be a wet blanket mate, but before you weld everything up you could do with the windscreen to try for fit, as with the original mini you had the screen cut and did the chop to that.
A bit of a different site but http://www.rodsnsods.co.uk/forum/ might be helpfull, especially the threads regarding the biva (new sva test) .
Also check out http://www.the-ace.org.uk/ this gives you the ins a outs of modifications.

Bryan

rkde · May 26, 2010

I agree with you, dimensionally I am in within 1mm which has been a task, I have laid on a spare screen to ensure that all the lines are correct. The mini shell allows the full size screen to sit in place so I was able to ensure that when cut it would still contact.
The car has been fairly easy to chop but its putting it all back together which I know will be hard. I have kept all the angles and lines the same as original and dropped it all 100mm +/-1mm at the front and +/-2mm at the rear.

Good tip though. Glad I have already done it or I may be feeling a little down

The whole IVA stuff I am unsure about as its looks to be a bit of a mess at the moment. I have been told lots of different things including vosa telling me that there is no need to tell the BIVA... Some work will need to be here, I will have to ask more questions.

Coo · May 26, 2010

excellent work....luvving this info

rkde · May 26, 2010

Any tips from anyone is really welcome and suggestions and advice is always appreciated.

Going to make the boot hatch fit the rear before I weld that up, once thats correct then off I go.

stormin · May 26, 2010

Glad to hear you're putting a roll cage in afterwards.
I believe the roof pillars will be high strength steel for crash purposes, hence why you're having a bit of difficulty welding them and they'll be nothing like as strong as before.

rkde · May 27, 2010

The problem with the roof pillars is more the fact that they are 0.80mm thick and thin out in the middle. I have spoken with BMW designers and they say the whole car is CR4 throughout - body wise. As well as welding them back together I have also been welding a 1.4mm sheet inside the pillars too. For that I rightly or wrongly sliding the material inside the pillar and drilling 8mm holes in the pillar to weld the plate in so its the full length of the pillar. Anything to add more support. Bit like filling a spot weld and I am making sure that there are at least 4 points of contact, 2 below and 2 above.

I personally thought the same as you but was told that the main strength of the car is in the floor pan as it was designed to be a convertible, though it does miss a few support bars.

Have to say when I had the car half chopped and half stock, the pillars I had welded a plate into has less movement than the stock side but I have increased the material from 0.80mm through to 2.2mm. Even with all that I decided that I wanted a roll cage for track days and thought I may as well use that to help support the car even more. "You can't put a price on safety"

Tin Can · May 27, 2010

Just a bit of info - I worked at an MG Rover dealership for 27 years which in the early days emcompassed Triumph and as a result purchased a fixed head TR7 which i still have. When Triumph brought out the TR7 drop head i took quite an interest in how they accomplished removing the roof but still kept the strength. It turned out from what i remember that there was a terrific amount of body flex which was corrected by not just strengthing the sides but the bottom too - in other words a 'strengthing horse shoe type' of support effect. The Rover 200 cabriolet was the same and although this too incorporated this strengthing loop it suffered from what was called 'panel scuttle' whereby the dashboard seemed to 'wander around' quite badly. In fact Rover at the time ran a scheme called Rover Commitment which was a guarantee that if you werent happy with your NEW Rover you could return it for a refund within 30 days - quite a few 200 cabriolet owners did return them as the 'floating' dashboard was quite disorientating

Hope this info gives you a bit of lateral thinking

Mark

rkde · May 27, 2010

Cheers Mark, not sure what to make of that but I think your saying try and keep the feel about the same?

As I build it I am trying to keep almost the way it was but this will change something, it has too. I think its wise for me to add more structure to the pillars anyway but time will tell. I discussed the chop with people who do that sort of thing day in day out and at the moment I am following the advice, I just hope that at the end when the cage is in its nice. I will probably drop and engine in when done and take it for a drive once the body work is done and see how it feels.

pedrobedro · May 28, 2010

The idea with the old mini was to cut the screen pillar bottoms and lean them back then take part of the roof out to shorten it and still use the original screen just with a steeper slope on it. This means the door tops will have to be modified as well but it was easier than cutting a screen in those days.

langy · May 28, 2010

Is this a track day car, If its road going you will have problems if you chop the roof as its a monocoque and DVLA/VOSA will have something to say about it.

rkde · May 29, 2010

Just as a point of reference for a question regarding the use of plastic windows for the sides and rear

Section 45 Safety Glass of the BIVA

All other windows (including sunroofs and removable glass panels) and side-screens must be “Safety Glazing” (which may be made from glass, or from plastic) and display the relevant markings. (see notes 2,3 and table 1)

Langy, I have sent a pm asking for some help, I hope you do reply. I am sure I need to go for a BIVA and have planned that from the start. Any help is greatly appreciated

oz. · May 29, 2010

langy said:
Is this a track day car, If its road going you will have problems if you chop the roof as its a monocoque and DVLA/VOSA will have something to say about it.

But how do Locosts/kit cars pass... They're pretty much a spaceframe with a few sheets of ally bolted on.

If the roll cage is designed properly - going to the all the suspension points - then there should be no problems as with VOSA. So basically you're making a spaceframe inside the original bodywork

Roof chopped BMW mini cooper S

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