The IVA Test

[lizbillings]

Re: The IVA Test

I still think you need to get a move on with these builds as the goal posts keep moving and will continue to do so.

[Terry_Scott]

Re: The IVA Test

who is cbs?
terry

[Terry_Scott]

Re: The IVA Test

now thats an interesting thought, how resourceful, but there are not to many vehicles with flat screens, apart from old land rovers i guess.#
interesting it had been extended three times, learn something every day, thanks

[Robert in Cumbria]

Re: The IVA Test

http://www.cbsonline.co.uk

who is cbs?
terry

[danny_nelson]

Re: The IVA Test

Car Builders Solutions
Danny

[danny_nelson]

Re: The IVA Test

Also worth a mention here. A roadster which is reg correctly and has been on the road since 1986 has been refused a MOT this year, and one of the notes refers to the extended steering column. Marlin and some other kit car manufacturers have been supplying new made to length colums for some time now.
Danny.

[Robert in Cumbria]

Re: The IVA Test

Perhaps the individual tester is the issue here.

I asked the MOT tester I normally use about a number of issues which concerned me before I started this and their attitude was, "if it's a kit car, almost anything goes because it's old and amateur built". We will of course see if that translates into a pass...

[b_caswell]

Re: The IVA Test

Also worth a mention here. A roadster which is reg correctly and has been on the road since 1986 has been refused a MOT this year, and one of the notes refers to the extended steering column. Marlin and some other kit car manufacturers have been supplying new made to length colums for some time now.
Danny.

Its quite a good point as recently a member had the welded extension on a hybrid chassis let go luckily he was turning round in his drive at the time. Now rewelded and staked for peace of mind if not for the MOT.

[Robert in Cumbria]

Re: The IVA Test

Ben, in my experience welded joints tend to fail in the solid bar in the heat affected zone next to the weld. Staking the tube to the bar wouldn't fix that.

This is based on experience fabricating machinery for the construction industry, excavators and the like, mild steel shaft is the best bet, anything better than that and it can be dodgy. If it stands a good wellying with a hammer then it should be OK.

[b_caswell]

Re: The IVA Test

But surely a stake which goes through the tube and shaft further down would prevent the loss of steering should the welded joint area fail? Who knows what Triumph used when they made the original shaft?

[Robert in Cumbria]

Re: The IVA Test

Hi Ben, think weakest link...

Back of envelope sketch and an extract from AC Davies 'The Science and Practice of Welding' Cambridge University Press ISBN 0-521-27840-6, 8th edition.

The changes of grain structure at the boundaries of the HAZ are the weakest point in any weld, especially good welds with optimal penetration. In the early days JCB's suffered badly in this respect with cracks at the edges of stressed welds. It was fixed by a combination of changes to the methods of welding and the order in which welds took place. Some critical welds were heat treated to modify (correct) the grain structure.

The correct way to join the steering column components would be to machine new splines on a bar of known quality and use commercially available 14mm clamp type splined sockets as the manufactures do (did?).

Many years ago I was asked to re-create an Allard J2? chassis using an original Ford pilot chassis and axles, I moved the cruciform back and shortened the torque tube, but instead of cutting and welding the propellor shaft to shorten it as Allard's did, I made a new, shorter one from an EN16 steel bar by milling the splines at each end to replicate the original. It worked perfectly I understand.

All that said I have welded but not staked my column at two points using 3mm wall tube which was a press fit onto the solid bar ends of the original cut steering column on the basis that it has been done many times before and works.

The advent of DIY MIG welders has made it too easy for anybody to weld without having sufficient background knowledge of what they are doing, or understand their limitations. For this reason all the welds I have done on the Marlin chassis have been stick welded, despite me owning a perfectly good MIG set.

Steering column sketch.jpg

Extract from AC Davies Book.jpg

[b_caswell]

Re: The IVA Test

My mind was working on what happened with the roadster columne mentioned, the weld had not taken and the inner shaft spun in the extension tube. But this only became apparent quite some time after the car being put back on the road and after reasonable mileage.

[Robert in Cumbria]

Re: The IVA Test

Good pont Ben. Do you know if it was MIG?

In the early days when I first started using MIG after years of stick welding I found things falling apart, the weld only 'sticking' to one half of the joint. With MIG it is essential to clean all oxide skin and mill scale from the weld area and to weave the torch slightly sideways to ensure the arc is heating/melting both halves of the joint. I was welding a lot of railings at the time and the bars were dropping out occasionally because I wasn't cleaning the mill scale off the rails. It didn't happen with stick welding because the flux floats the junk out of the weld to a large extent.

There is also a phenomena known as arc blow, where the ark is 'pulled' to one or the other sides of the weld by magnetic force caused by the layout of the structure being welded, complex lattice structures like roof trusses and crane jibs can be bad for this. Re-locating the earth point and welding the other way may fix the problem but it's a real nuisance at times.

[CABRIOBOB]

Re: The IVA Test

Robert

Last year I converted an Artic 4 axle low loader step framed 40ft to 6 axle 60ft to carry 140ton and had to heat the joining steel sections up to 250* before welding using hardox and weldox mig wire for max penetration. It cost over £1500 just for the wire. It costs about 350 - 400 for hardox wire plus metal just to re-fab and brace a 40ton digger bucket compared to normal mig wire would be about £60 for the same job.

[Robert in Cumbria]

Re: The IVA Test

Sounds interesting and HOT! Was that 1.6 flux cored wire? I have used that with special sprocket rollers in the wire feed for hard facing and coreofill for a work hardening steel we got from Track Weld in Durham? I forget now, it was 20 years ago.