Galvanising

[Roel J]

Hello,

Bought this summer from Richards a brand new chassis for the 90, without rear Xmember.

Welded my own rear bumper in it, got it shotblasted and had it galvanised last week.

On return to the workshop, I noticed the chassis was a little distorted on the long panels at the sides.

They are not straight anymore and show a little up and down....

Chassis seems straight, but is it normal that there's a little distortion ( 3mm) to be seen on the panels?

This distortion will not be seen when tanks and gearbox are in place , but it is an odd sight

Happy Christmas to all!

Roel

[Troddenmasses]

Hot dip galvanising is well known for distorting the parent material - especially when it is made of thin sheet.

[Roel J]

Troddenmasses,

So when I come over the various shows next year celebrating the 60th aniv., I will see at the trade stands all distorted chassis?

Seems very strange that no-one ever mentioned this....

Roel

[clbarclay]

If you heat any structure up enough then it will likely distort when it cools.

The temperatures required to hot dip galvanise are obivously enough to cause this.

Design of the structure will inflence just how much it distorts, the long thin sheets used to make flexible 4x4 chassis will be more likely to suffer more than say a stiff tubular frame. The rapid ness of heating and cooling can also affect how much distortion you get.

There is a vast amount of engineering knowledge out there, its little wounder that people don't here the half of it as some of it just gets assumed and the rest is not worth going into the details for the odd job. To be honest though I've seen distortion due to galvanising mentioned on forums a number of times and in the land rover comics as well so you may just have been unfortunate and missed it.

[iomlt]

I've had my chassi and bulkhead dipped with out any trouble what so ever....... i have had alsorts make and dipped and never had any problems...

i'd question the company doing the work for you....

[need4speed]

Hi Roel. I think that all this talk about chassis distorting when heating up / cooling down is nonsense. I'll be ordering a galv chassis from richards soon but when i go to collect i'll be having a good look over it - if theres any distortion/warping they wont be getting a penny piece! Yes, panels large in surface area will be prone to warping ie bulkheads, but no way should the chassis be warping.

If i were you id be having a good talk to richards...wish you luck fella cause at the end of the day when you pay good money, you want good engineering..

woopsie! Just re-read your post and realized its nothing to do with richards. am i understanding this right - you regalvanised an already galvanised chassis once you had fitted your x-member?

[portal pete]

I have a couple of tonne of galvanising done each week, mostly 3mm. The only distortion ive ever had is when the idiot on the forklift runs it over. Are there any signs of damage possibly before being galvanised?

[bishbosh]

Distortion during the galvanising process is normally due to the release of stresses locked in by the fabrication and welding processes.

A heavily welded item is more prone to distortion than a less welded item but that isn't the whole story. How itwas welded, if it was preheated or cooled slowly or even reheated to redistribute stresses during the fabrication process, the actual geometry - long, thin, braced, thick etc will all affect it.

Additionally, how the item is dipped can also play a part. I used to work for a company that fabricated modern day versions of the Bailey Bridge which were dipped. If a panel was dipped in the wrong fashion it came out as scrap. Of course, we also tailored the design and fabrication to minimise the risk of distortion.

[Roel J]

Well chaps, Thanks already for your answers!

I don't blame Richards: I read here and on other forums that they sell good chassis and are the most accurate.

And this was true, 'cause I already built the 90 casco up, prior to fitting the rear bumper and to get my roll cage mounts spot on.

I didn't spot any problems whatsoever and the chassis was straight on the inside/outside panelling.

On my old chassis though, an OEM LR, there was some very minor distortion, almost invisible, unless you put a long square bar next to it.

We're talking here about 2 mm inside wobbling.

Then I got the bare chassis shotblasted and got it hotdipped.

I think that the galvanisers were too fast in putting it in the bath, causing the distortion. No way they could fix that one out.

Distortion here is about 3-4 mm.

I aready did some measurements with a pliable meter (do you understand, that thing a builder uses for his measurements) and the difference between the two outriggers on the inside at the front x-member and the 2 riggers rear crossmember is only 2 mm.

I don't think that this, if correct measured, is of any problem, given the fact that there is always some room to play with on a Landy.

During the WE, a engineer from Bayer Materials will come, do some cross measurements, will take pictures and will discuss this with his colleagues to see if there is any problem to adress.

I don' t quit yet, for every problem there's a solution.

Will keep you posted!

Roel

[Roel J]

Well,

All is well in the end: chassis is perfectly straight!

Happy New Year then to all.....

Roel