Welding mx-5 front chassis rail problem

[J.o]

Ive made a mistake.
I constantly stitch welded and spot welded my mx-5s front chassis rail for repair until the welds attached together but then after all that I just found out from MOT regulations I need to seam weld the front chassis rails. I’m currently stressing out is their any way to fix this? Should I put under seal on it and hope they don’t see it or?

 

[tigdlo]

Post a photo, sounds like you have misunderstood the regs. If all the stitches join each other without any gaps then it would be considered a complete seam weld for MOT prurposes.

It's always best to coat it so the MOT tester can't see it.

 

[J.o]

 

[J.o]

Post a photo, sounds like you have misunderstood the regs. If all the stitches join each other without any gaps then it would be considered a complete seam weld for MOT prurposes.

It's always best to coat it so the MOT tester can't see it.

Tigdlo thank you for that. I will try and do that tomorrow I will weld up the holes and try and make it look like a full seam weld although it would need a lot more trimming and re-welding. I will also try to coat it with as much under seal as I can.

 

[tigdlo]

Did you grind the rust back to clean metal? I can't see much clean metal around the weld.

 

[minimutly]

I think that's pretty poor welding for a chassis rail. You need to practice more doing straight runs. I would grind those lumps off, get your settings and speed right, and wizz along it in one run. It's your life, but even if the mot man passes it, will you be happy with it?
Have you a decent helmet adjusted properly?

 

[J.o]

Did you grind the rust back to clean metal? I can't see much clean metal around the weld.

No not yet I was in the middle of doing that but I had to stop for the day. I will continue to grind off the remaining welds tomorrow.

 

[J.o]

I think that's pretty poor welding for a chassis rail. You need to practice more doing straight runs. I would grind those lumps off, get your settings and speed right, and wizz along it in one run. It's your life, but even if the mot man passes it, will you be happy with it?
Have you a decent helmet adjusted properly?

Thank you for the honest opinion. to be honest I thought that my welding was pretty bad too that’s one of the reasons why I’m on here. This is my first attempt welding so the bad welding was expected but I did not think it would be this bad I did do some practice on some metal panels I cut up it seems it was not enough.

In terms of my welder settings I will re tune it tomorrow also I will remove all the bad weld spots I did tomorrow then do some more practice on straight runs and then do a straight run on the chassis rail.

my helmet is from r-tech it has automatic darkening so it’s good I think the problem is that I did not tune the helmet properly so when I was welding the welds were too dark I couldn’t see where I was welding.

honestly I do doubt the MOT man will pass that it looks horrible. I will redo tomorrow.

Thanks for the help minimutly.

 

[RonMig]

Apparently "practice makes perfect"
but I've been practicing for 11 years and am not there yet.

Keep at it & remember - the grinder is your pal - (and why not)
Just try not to annoy the neighbors with it too much (like wot I did)

 

[J.o]

Apparently "practice makes perfect"
but I've been practicing for 11 years and am not there yet.

Keep at it & remember - the grinder is your pal - (and why not)
Just try not to annoy the neighbors with it too much (like wot I did)

RonMig thank you man.
This makes me feel better and less stressed about today just gotta keep at it.

I may have to take a day off or two I have been constantly working on my car for the past 4 days .

 

[Slowcoach]

No not yet I was in the middle of doing that but I had to stop for the day. I will continue to grind off the remaining welds tomorrow.

I think you’ve misunderstood tigdlo’s post. He meant you’re supposed to grind the original chassis where you are going to weld back to shiny metal and then weld your patch on

 

[bricol]

I wouldn't "wizz along it in one run" - you'll have distortion and more than likely a puddle on the floor and a big hole at this stage of your welding experience.

 

[Misterg]

honestly I do doubt the MOT man will pass that it looks horrible. I will redo tomorrow.

Leave it to the day after

Have a bit more practice first - whether the MOT man passes it or not, that rail is what's stopping the front of the car crushing you (and/or your passenger's) legs if you ever hit anything - it's not like a bit of bodywork, where the metal just needs to fill a hole, it's proper structural, so needs to be 100% IMHO.

 

[J.o]

I think you’ve misunderstood tigdlo’s post. He meant you’re supposed to grind the original chassis where you are going to weld back to shiny metal and then weld your patch on

Slowcoach thanks for reply
I understand now I will have to do that before I re-weld.
Thank you

 

[eddie49]

As tigdlo said, the original metal needs to be cut and then ground or sanded, so that it is: a) solid and b) clean.
This has to be carried over some distance away from the weld seam too, so that rust does not enter and contaminate the weld pool. For a butt weld, both sides of the parent metal need to be clean. A belt finger sander ( B&D Powerfile etc. ) is the best tool for doing this in a confined area.
E.G.

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[J.o]

I wouldn't "wizz along it in one run" - you'll have distortion and more than likely a puddle on the floor and a big hole at this stage of your welding experience.

Bricol thanks for that.
So I believe I would have to do small seam welds until they all attach together? or?

 

[J.o]

Leave it to the day after

Have a bit more practice first - whether the MOT man passes it or not, that rail is what's stopping the front of the car crushing you (and/or your passenger's) legs if you ever hit anything - it's not like a bit of bodywork, where the metal just needs to fill a hole, it's proper structural, so needs to be 100% IMHO.

Misterg thank you for this advice.

You’re correct quality comes first I need to practice more before re-welding the chassis rail as you said it is what will protect me from a head on collision perhaps I may need to use tomorrow or 2 days for welding practice. thank you

 

[J.o]

As tigdlo said, the original metal needs to be cut and then ground or sanded, so that it is: a) solid and b) clean.
This has to be carried over some distance away from the weld seam too, so that rust does not enter and contaminate the weld pool. For a butt weld, both sides of the parent metal need to be clean. A belt finger sander ( B&D Powerfile etc. ) is the best tool for doing this in a confined area.
E.G.
View attachment 452335

Products

Manufacturer of hand tools, power tools, fixings, hardware and more!

www.silverlinetools.com

Eddie 49 you are a life saver!
Thanks man
I will need to buy this because I only use an angle grinder to sand and cut but due towards my angle grinder being too big I can’t get those important spots to remove rust from.

 

[minimutly]

I wouldn't "wizz along it in one run" - you'll have distortion and more than likely a puddle on the floor and a big hole at this stage of your welding experience.

Fair point. but I would. Weld shrinks, nothing you can do about it, mostly just live with it - except where you're welding opposite sides. I will wizz along one side, let it shrink and cool, then weld the other side, this way you only have the shrinkage from one side to deal with - ie half.

 

[eddie49]

due to my angle grinder being too big I can’t get those important spots to remove rust from.

If you use the Search box at top right for words like Powerfile, belts, finger sander you will find lots of suggestions.
For a small angle grinder, Search for Parkside 12v angle, Katsu angle, and Roloc die grinder.
The tool list is endless...!