Hi and... Mk4 fiesta outer sill replacement - Do I need bracing?

[ben1777]

Firstly I'd just like to say hi and how impressed I am with this website. It's really helped me get into mig welding. I'm currently studying automotive engineering and I'm sure it will be invaluable to know how it's done. I've got all set up with a Clarke 90EN mig, think it was a bargain at £40!

Ok so I've been patching the sills on my 97 mk4 fiesta but have decided that really they should just be replaced if I want then to last any amount of time. I guess all the patching was good practice at least!

Basically I need to know wether or not I need to construct any bracing when removing the full outer sill? I think the answer is no as the car uses a semi-monocoque design so there is plenty of load paths. Just wanted to make sure before I take one off and fold the car in half!

A couple of other things. What's the best way to remove the old spot welds bearing in mind it is 3 sheets together and I'm wanting to just remove 1? And what size and spacing should the new plug welds be?

Thanks very much
Ben

 

[Chickenjohn]

Hello Ben,
provided the inner sill is OK and the floor pans are mostly solid then you will be OK to cut away the outer sill.

Lift the carpets and check! and keep the doors on to act as a guide and keep the door gaps OK.

" couple of other things. What's the best way to remove the old spot welds bearing in mind it is 3 sheets together and I'm wanting to just remove 1? And what size and spacing should the new plug welds be?"

Spot weld drill is the best, and when you offer up the new sill, if you can, plug weld through the holes in the other two layers onto the new sill.

 

[Spark plug]

No you won't need to brace anything just for a sill changel.

You can buy a specialised spot weld drill bit from most auto paint suppliers or off ebay.

The new plug welds should be about 8mm.

 

[steveo3002]

id just advise you keep the door shut and the car on its wheels , or stand the tyres on some wood to raise it a bit

make sure the door gap is nice before welding the new one on

 

[octo0072000]

check the rear of the inner sill near the rear axle they rot there thread on here with pic's not sure ware though

try this one


http://www.mig-welding.co.uk/forum/showthread.php?t=30675&highlight=fiesta+sill

 

[ben1777]

Thanks for all the quick replies! Sounds as though I should be fine then. Just out of interest if I was to take the old sill off tack the new one in place and find the door gap had changed how would you go about rectifying this? Sounds as though it should be fine but just curious as to how you would fix it.

I know exactly what you mean about the rear of the inner sills, I scrapped my previous identical fiesta because of this! If only I'd got into welding sooner. Luckily this one seems pretty solid back there but will have to see when it's in pieces.

Will hopefully make a start on this this evening so will let you know how I get on.

 

[steveo3002]

it shouldnt move if its sat square and not jacked up on one corner

if it did theres rams and stuff you can use to move things , but id not worry about that too much , just as always check stuff before welding

 

[Leedsutd]

Just done one Ben, jack up front and rear and tear away, measure door gaps just as a check (very doubtful that it will move but just check measure before you tack it up), depends on how long the seam welding is but with the three part sills it is nearly guaranteed that you won't notice any difference once completed, especially if it's only a small section.

 

[zardoz]

when I did this I drove onto a set of ramps then jacked the car on to another set of ramps for the rear wheels. This gives you a bit of height to work with (unless you are lucky enough to have access to a ramp/lift ?

 

[visor_down]

Realise this is an old thread but my Q is around the exact same issue.

Need to replace full outer sill and most likely inner parts, i also need to replace part of the floor pan where the rear beam mounts to the chassis. As such i can't follow the recommendation of leaving it on all four wheels either on the ground or on ramps as i nee to remove the rear beam/hanger.
What would be the best part to support on axle stands at the rear to allow sufficient access for the welding and to ensure the removal of the sill doesn't result in problems with alignment of doors etc?

Pretty much same problem as here, except i likely need to remove sill rather than patch it