Safety Checks on Motor Vehicles

In my E-mails tiday, I got a rather nice one from
Doug from PA.
Perhaps I was going on about standards of vehicle repair and conrasting the US with what I knew in much of Europe.
I was delighted to have such a detailed account and I fear that I appear to have refered to "duct tape" and " bailing wire". I can sort of guess but I haven't a clue about duct tape or baiiling wire and doubt if I could have used the expressions. If I have, well I sincerely apolgise. Doug does go on- and on about the standards in his County and contrasts them with other less stringent Counties.His appears to have little to criticise and I would admire the detail and care of his preparation. It does worry me about elsewere- and he supplied very worrying instances.

In Doug's very detailed expose, he does mention the use of arc welding and he rightly sounds due warnings and misgivings. I believe that this is the nub of my criticism and I certainly would go on about the use of plastic fillers. The two go together.

In modern vehicle repair, steel as we knew it was
mild steel. Provided there was enough metal left, it could be joined with arc, oxy, mig-mag or Tig. It could joined satisfactorily.
Today, steels are thinner, lighter and stronger than then. These benefits are only achieved with the addition of alloys such as small quantities of niobium. Here comes the crunch, bodies are constructed by spot welding and without going into a long dissertation, are designed to tear in a collision. The impact is lessened and occupants are no longer the shock absorbers.
Today, if detailed inspection is done, an auto body has the precise number of spot welds- and no more or less. An alteration in the seam constitutes a risk. An older vehicle which needs a repair may not have complete repair panel to replace the bad one. Even if one was available, the joining would or should be by spot welding or stitching with a Mig to approximate the manufacturers specification.A continuous seam is totally wrong whether by any of the joining methods mentioned. Here comes the question of Why. High strength low alloy steels become brittle during the joining process. they cannot be "let down" to their original temper as they came out of the factory.

The risk- and this is where I came in, is the joint made by arc or oxy will fail by cracking along the side of the weld. The only relatively safe joins are by spot welding- or by Mig-mag or Tig emulating spot welds as before.

I am sure that Doug and other readers will appreciate that the construction techniques of vehicles bodies are world wide. My knowledge is almost a decade out of date but movement will be towards more and more sophisticated techniques rather moving back to what was Ok for me- then.

I hope that this will be a change from my more usual view of things!

Norman

[ 02-12-2006, 11:13 AM: Message edited by: D. Thomas ]

>"High strength low alloy steels become brittle during the joining process. they cannot be "let down" to their original temper as they came out of the factory."<

While they *MAY* become brittle in the heat-affected-zones-HAZs, the brittleness can easily be removed by gas-reheating the weld area to a very dull red.

I suppose that you may well be right in laboratory conditions, I would be loathe to accept any one of my vehicles which had been repaired other than as laid down in "Thatcham" which is the Bible in the UK.

The question in the United Kingdom is whether an insurance company will honour the damage caused by repairs by techniques other than that which they themselves set- and by repairers which are not approved by them.

Once these matters have been cleared, I feel that my comments become even more relevent.

Norm

Norm, I thought one accepted practice was to change panels by drilling holes and filling this with a plug weld from a MiG, rather than continuous butt welding.

That should preserve most of the nice properties of the body panels.

Not to say that there's a wide variation in craftsmanship possible from that practice, though.

-Matt

Matt,
Of course, you are quite correct in adding the plug welding technique. Doug had set me a fantastically detailed account of his practices and understandingly, his concerns. It was difficult to telescope or precis my reply into a small space. I haven't commented on a fraction of his reply!

Returning to Mig Welding using the Mig- Mag process, I was assuming that filling a pre-drilled hole was normal practice in the jobbing repair shop. I would thank you for drawing our attention.

As you will appreciate, plug welding is the norm for the cheaper range of Migs and in the more professional repair shops, the time allowed for repairs demands a faster and safer stitching by literally using the Mig to melt a repair point so that the second pulse will push the wire into the pieces to be joined.

Looking at the replies so far, I am delighted and appreciate how much writers are concerned with road safety.

Norman

I survived a crash in a 54 Ford. I was the passenger. It knocked over a telephone pole, no air bags or seatbelts. I cracked the windshield with my head and put a dent in the steel dash with my chin. I ended up with two stitches inside my lip after I woke up. I was driving my 56 the next day. I drove down to look at the 54, it was a total.

As a sort of explanation, might I add the reason for some of my comments?

In the easrly 60's I was driving my firm's car with no seat belts and utility seats. A learner driver in a bus stuffed me in the rear and I was catapulted into the oncoming traffic. I was wearing one of those ancient Gannex macintoshes favoured by Prime Minister Harold Wilson and took the steering column chest on. I broke the front windshield and after coliding with an oncoming car, bent the lamp post which had grown
on the other side of the road. I walked out with nothing more than a damaged leg and pockets full of never ending broken glass.

Four years ago, my wife and I hit black ice at 6500feet on a mountain road within sight of where the Italian Job was filmed.
We fell 50 feet vertically and went 500 feet down into a frozen river after 5 somersaults.
I got all of the 18 bottles of wine and the two crates of beer on my head. My wife had her feet trapped under the pedals. The drivers door which was upside down was also jammed and I pulled her through the window. I lead her back to the road with her four broken ribs and a stay in a little French hospital and a half bottle of plonk each meal! Little notice was taken of my broken finger and I missed out on everything.

I drifted around -using her specs until she was released. The ambulance had dropped us at the hospital, turned up the other valley to repeat the collection of a BMW couple who had also gone off the road but had fallen only half the distance. They were both dead!

Each year, we have a little celebration but refuse encores!

Norm

Good greif, what a story!

There is an industry of salvaging wrecked late model autos which have either front or rear end damage. The car is basically cut in half and the good end is welded to the end of another car which has had a collision to the opposite end. So a car with a rear end collision would have its front half welded to the rear end of a car that had a head on. These repairs have been going on for years and I haven't heard of any problems with vehicles splitting in half going down the road.

Rick, The Brits call it Cut and Shut.

Thank you for your kind comments.
We survived. Three months later, I went back.
There was the remains of another two vehicles with ours. On the road above was a little cairn and cross with fresh flowers.

You will now appreciate why I say that I am a devout Christian!

Norm