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Filbee

Welding chassis?

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My 501 Elite has a rusty rear crossmember (surprise surprise!).

My preferred solution is to replace the chassis with a good one, but they are getting more difficult/expensive to get hold of.

I will persevere with my hunt for one, but I was thinking about the possibility of repairing my existing chassis. However, there seems to be a consensus that you shouldn't weld the chassis. I just wondered if there is a valid reason for not welding it? After all, Lotus welded it together when they made it! The only thing I could think of was that the chassis might have been heat treated, but imagine that's unlikely.

I've also had a look through the workshop manual. Whilst it mentions chassis replacement following an impact, but it doesn't mention welding.

 

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There is absolutely nothing wrong with repairing existing chassis by carrying out welding.. As you say its how they were manufactured in the first place..   However you will need to do it correctly and to a standard that meets approval..   If it is a galvanized chassis then some extra preparatory work will be needed and care not to inhale fumes from any zinc not fully removed..  I tend to use my air fed mask when doing this sort of work , just to be safe.. 

The old school may tut and frown , saying its unsafe and should be replaced..  That's twaddle , there is no reason why it can not be done in a professional manor to meet all standard and requirements..  

The reason they say replace after accident is because the structural integrity could have been comprised , However with a proper Jig and replacement sections , once again there is no reason why a repair can not be carried out.  This is not a job for the armature mechanic and not cost effective at present .  However as the chassis become more and more scarce then the balance on costing will meet the needs..  The only worry is,  will there be any engineers left to do this sort of work in the future..  

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Access is the issue. You can get to the bottom of the box section and weld it from below, but getting access to the top of that box crossmember is a body off job. Once you have taken the body off, your as well replacing it with a galvanised one as a cure all.

I've looked at cars that had a welded plate on the bottom of the crossmember, but if the bottom of the section has rotted out, the chances are that the top is also rotten, and the only way to find out is to lift the body for inspection (I suppose if it is your car, you could drill a hole for an illuminated borescope?)

A box section with one strong side and one rotten one isn't going to be strong. A proper repair is an involved job, and anyone seeing your repair section will immediately question what is above it.

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As the above said, you could also look at spydercars they can repair the chassis, I had them carry out extra strengthens to my chassis for racing. They no longer list anything Elite Éclat but you could try speaking to Andy Widnall

regards Dan

Edited by eclat22
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Thanks folks.

Don't worry, I'll be taking the body off because whether it needs a replacement chassis or just some patching, I wouldn't want to do half a job (plus the idea of welding a car with a highly flammable GRP body doesn't give me a warm, cosy feeling!)

I would swap the chassis for a galvanised one in a heartbeat, but try finding one!! My plan is to try and get a good solid non-galvanised one if i can't get a galvanised one and sandblast it before giving it a couple of coats of Rust buster 121 epoxy mastic paint.

 

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5 hours ago, CHANGES said:

There is absolutely nothing wrong with repairing existing chassis by carrying out welding.. As you say its how they were manufactured in the first place..   However you will need to do it correctly and to a standard that meets approval..  

If I do the welding it will be done to the best of my ability, but I'm not a certified welder!

How can someone check it's done to a standard that meets approval, and apart from the MOT, under what circumstances is someone likely to check?

Just asking out of curiosity more than anything :thumbup:

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My personal view is that the tester will fail it when the rear suspension turret starts trying to punch its way through the bodywork. Until then it will pass :-)

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3 hours ago, Filbee said:

I would swap the chassis for a galvanised one in a heartbeat, but try finding one!! My plan is to try and get a good solid non-galvanised one if i can't get a galvanised one and sandblast it before giving it a couple of coats of Rust buster 121 epoxy mastic paint.

Why not get what ever you end up with galvanised, ?

2 hours ago, Filbee said:

How can someone check it's done to a standard that meets approval, and apart from the MOT, under what circumstances is someone likely to check?

Its really a bit of common sense . By using the correct steel , forming the sections being replaced correctly, then welding up making sure you have  full penetration of the weld.. Not snotting on patches to cover the problems..   You would be surprised what will pass an MOT. but does not mean its that great...  A lot of DIY welders tend to blow holes or pigeon shit weld,  both cause weak structure and will crack if flexed.  Most competent DIY welders can get the required finish needed , its all about experience.  So if you are quite good then you should have no problem ,, But if in doubt get a professional to do it for you..  Usually if it looks correct it generally is..   Then as i said above finish off by getting it hot dip galvenised ..     

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12 hours ago, CHANGES said:

Why not get what ever you end up with galvanised, ?

Any idea roughly how much that would cost for an Elite chassis?

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10 minutes ago, Filbee said:

Any idea roughly how much that would cost for an Elite chassis?

The cost vary with the price of zinc and the pre prep.. The paint that remains will need shot blasting first before the de grease and acid dips.   I have a customers S3 chassis going through the full shot blast and galve process early next year,  I will be able to get a fairly accurate costing from that for you..    You must also take into account that all the threaded sections and holes will need  re- threading and reaming out before you re build part onto it..  Also an alignment check before and after is well advised..    

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