New metal, thickness?

[Pnoddy]

Ok, quick technical question.

I'm going to weld in new metal into the A-post to hold the door hinges as the old stuff had rotted away completely! What thickness of steel should I use? I know I should match metal thicknesses when welding and I measured the existing stuff and it came in at about 2.5mm. Does that sound right? Is that a genuine thickness of steel, am I going to get laughed at by the man behind the counter (and possibly be sent around the yard to look for a "long stand")

What thickness have people used in the past and how successful was it?

Pat

[mat_fenwick]

Way too thick to easily work with - it'll be a bugger to shape and to get decent penetration on the new stuff, you'll blow holes in the existing metal, assuming you're butt welding them together. My guess is you're measuring either a double layer of steel, or where rust has expanded the metal to give a falsely high reading. I use 1 mm galvanised steel mainly, but be careful of the (toxic) fumes when welding it.

[Pnoddy]

Coolios!! And structurally speaking 1mm is ok is it? I'm going to be using it around the front door hinges where the drain from the sunroof (well its more of a rain roof because THERE'S NO SUN HERE EVER!!!!!) has rusted away all the metal around the top hinges on both sides.

[Dollywobbler]

Most cars are built out of even thinner metal, so 1mm should be fine. I think 0.8mm tends to be the standard.

[Vanny]

The metal in the boot of the BX which I've been repairing over the last week is 0.72mm including the paint on both sides (measured with micrometer).

I've been welding back in with plate which is nominal 0.95 +/-0.05mm before paint. I couldn't actually find anyone who kept stock of 0.7mm, it was all to order below 0.9mm.

I've not found anything as thick as 2mm in the BX apart from the chassis rails (not to say its not there) and where I need that little extra thickness I've been putting in 1.5mm galv plate (because that's what i have lying around).

I can't help but wonder if this 2.5mm that you've measured is actually two or more pieces over lapping?

[Tinkley]

Not forgetting that BX are made of metric steel guages not imperial. 0.9mm corresponds to the old 20 SWG, 1.2 is 18 SWG, 1.5 is 16 SWG and 2mm is 14 SWG. The old 20 guage is supposed to have been replaced by 1.0mm material.
I believe that BX and PUG 205s' were built from 0.7 or 0.8mm to keep the weight down. They suceeded!. One of my biggest gripes with modern cars is the extra 250Kg of weight. Boy, a few side impact bars and an MP3 socket are heavy. Then along will come a politician and tell me all about how light modern cars are....
So Mr Politician, why is my car a full car load of people lighter than yours? I fully accept that the newer ones are safer after you have had an impact but lighter ones are better able to avoid the impact in the first place. There's a suppressed TRRL report that came to this conclusion but has not been put in the public domain - can't think why!.

[Pnoddy]

I MUST have measured wrong. I'm going to pass the blame off on a cheap vernier calipers!! Not my fault, twas this Vernier chap! 1mm or there abouts it is.

On a side note, I think I'd feel safer in a heavier car to be honest. I see your point about lighter cars being able to avoid collision better, however, as we all know a lot of the time you're unaware of an impact until after it happens. In which case a lighter more agile car wouldn't be of much use.

[Way2go]

On a side note, I think I'd feel safer in a heavier car to be honest.

If it's safety you want as a priority then you should be looking at a new/modern car with airbags, side airbags, side impact bars and high prison windows.

The BX was designed with safety in mind with its crumple zones and to keep the passenger compartment as intact as possible in severe collisions. However it is a car which is in excess of 21 years at its youngest so now really only for those that appreciate "something different".

[citronut]

you will find most cars even newer euro box's are only built with very thin metal, the strength is in the forming of the tin work, not the thickness of the steel,



regards malcolm

[Vanny]

newer euro box's are only built with very thin metal,

Well, except for the sub crash structure such as cross car beam hidden under the dash, side impact protection beams hidden in the doors etc they can be quite thick metal.

On the topic of safety,

There is no getting away from it, new cars are getting fatter and fatter.

Also, heavy does not equal safer. Aluminium bodied cars are much lighter than there steel counter parts, and can fit in a lot more energy absorption because of the weight saving.

And yes i know it's a semantics issue, but there is no evidence that an airbag has saved any humans life on the road (see how carefully i worded that).

You can say that there is a good probability that someone survived because of an airbag, but without putting the same person through exactly the same real world situation, without the air bag, and killing them, it's only a probability you have.

Conversely the statistics for the number of people killed as a direct result of an airbag, is quite scary IMHO

I don't like airbags, and so far i've never had to use one, and long may it continue!

[citronut]

i have an air bag in my TZD , well at least when i have her indoors in the car

regards malcolm

[Tinkley]

It was the 1994 EU crash regs that scuppered the BX, which was designed to a much older standard rooted I believe in 1972 as a basis. Hence the Xantia as a 'replacement'. That did meet the new standard - it is no coincidence that the last BX were diesels from 1994....

If weight was a good thing for manoevrability F1 cars would be 3-4 tonnes. It is correct that a heavier vehicle will carry on and tend to be safer for those inside - unless you hit the proverbial vertical cliff. A certain consumer magazine (which once selected the BX as a best buy!) would probably support us driving round in tanks with half a metre of rubber and Nerf foam protection.
My point was merely that the extra braking and steering available in a lighter vehicle can allow it to escape or minimise the force of an accident in many cases. I've had a few (m/cycle and car) none my fault and fortunately all minor (only a broken wrist) but all my bikes were good handling light Italian jobbies and the last BX was written off twice... shunt from behind, pulled out in front.

The first BX write off was 100% on the woman behind and the second was because the young woman froze when she saw me and braked instead of accelerating. Least it took an Astra with it...
Been in some other minor car ones but all at slow speed. Had a few close ones in the BX's over the years but it's always allowed me to find an exit so to speak. Most of it is anticipation, 360° awareness, and having a decent handling and stopping vehicle.

If you search hard enough you will find that research has shown a 30% drop in vehicle weight would result in at least 10% fewer accidents. Still we would'nt want to hurt our financial servce sctor now would we.......

Stangely I thought light weight improved fuel consumption but having read about the tricks used to obtain some modern figures maybe I should just have nitrogen filled 125 X 100 x 14s' tyres etc etc.
So 'safety' comes at the price of weight which equals more resources and more fuel used in a vehicles life. That's the trade off the politicians have made on our behalf. Rant over...

[Pnoddy]

On the airbags issue:

I have no strong opinions either way and I def have heard of incidences where airbags have caused injury and death BUT . . . I was watching some show on Sky1 years back. One of those Pig Cops Maximum Chase EXTREME jobs. Lad in an Impreza come around a corner running from the law. Ploughs straight into the oncoming vehicle of a member of the constabulary. The camera on the front of the car shows the guy in the Impreza had no seatbelt on and the airbag went off. He hit the airbag bounced back into the seat and was gone out of the car running in a flash. Now obviously he should have been wearing a seatbelt, much more important than an airbag, but I was amazed at how effective it was at stopping him going through the window.

Been in some other minor car ones but all at slow speed. Had a few close ones in the BX's over the years but it's always allowed me to find an exit so to speak. Most of it is anticipation, 360° awareness, and having a decent handling and stopping vehicle.

The lack of visibility is a real gripe I have with new cars. I have a Saab 93 as my daily car. Great car to drive!! But the A-pillars are soooo thick. Its to prevent the roof from collapsing in in the event of rolling the car. Which is great! But it makes visibility in certain circumstances (pulling out of junctions) quite bad. I'd say the A-pillar on the BX is about half the thickness. But then again it doesn't have to hide airbags.

Its a comparison that I've never seen being done. Real world scenario, heavy less agile car vs. lighter more agile car. I suppose it'd be very hard to test.

[Mothman]

i have an air bag in my TZD , well at least when i have her indoors in the car

regards malcolm

OOOH, ile tell her when i see her next. Be prepared to loose certain bodily parts Malcolm when i do.

Andy

[michaelr]

The lack of visibility is a real gripe I have with new cars. I have a Saab 93 as my daily car. Great car to drive!! But the A-pillars are soooo thick. Its to prevent the roof from collapsing in in the event of rolling the car. Which is great! But it makes visibility in certain circumstances (pulling out of junctions) quite bad. I'd say the A-pillar on the BX is about half the thickness. But then again it doesn't have to hide airbags.

Have a look at the A pillars of a Citroen DS They are deliberately narrower than the distance between the driver's eyes. There is NO blind spot. My Ds is a delight to drive in modern traffic with huge glass areas and the BX is not far behind in terms of visibility.

But heaven help you in a DS in a roll-over. Flimsy pillars and a bolted on fibreglass roof offer little protection and I always wear a seatbelt as I would not trust the single spoke wheel to "deflect the driver's body" and save my life.

Modern cars are considerably safer in an accident and seat belts and airbags without a doubt do more good than harm. The problem is that they are also usually very boring to drive. A BX or DS pilot is much more engaged in the driving experience.

The thread was supposed to be about steel thicknesses however! Just bear in mind that not all steels are equal. Many areas of a new car will be built of "high strength steel" in critical areas and assembled with far greater precision than I can achieve with my handyman MIG welder. The crash performance of thin light materials carefully designed and assembled can easily exceed that of old school body building.