Tutorial on rear arch tubbing

Thread in 'Technical Questions' started by smoody, Apr 8, 2016.

  1. smoody

    smoody Member

    Mar 29, 2010
    Likes Received:
    Right, this may not be how everyone tubs arches, may not be the "correct" way in some peoples eyes, but its how I done mine.
    one of my friends was asking how to do it and thought I could post it on here so he can access it or anyone else can search and find it.

    This way of tubbing the rear arches will give clearance for wheels when fitting wider overfenders, it is up to you if you want to extend the tub to sit flush against the new overfender but I did not, I will highlight this point further down.

    I don't this over a year ago and sadly don't have too many photos of the process but its the best I have.

    if you do this and it goes wrong I hold no accountability :smokin: but if youre struggling give me a shout and I may have some advice.

    • Remove wheels and axel stand car (for safety and stuff…)

    • Estimate how high you need to take the arch tub using the original arch tub’s highest point as a gauge.

    • Draw in an arc to where the new arch tub will be and remember to keep the angle steep from the sides and curved at the top for maximum wheel clearance

    • With a slitting disc cut from the outside through both outer and inner skin as close to the arch lip as possible and remove that section, this will separate the outer and inner skin.

    • Cut only the outer skin around the line drawn earlier to make the shape of the arch tub

    • Grind back all paint and underseal on outer and inner skin where welding will take place

    • Slit the inner skin into sections making the sections shallow around the sides and deep at the top so it can fan out correctly.

    • Bend these slits up to meet the outer skin

    • Push the outer skin in about 10-20mm and tac weld each slit in place, this will allow the new arch to sit in a natural position and not pushed out by the welds or plates.
    • Around the side the outer skin doesn’t need to be pushed in as much as long as more care is taken when welding
    • Once all are tac welded in place the excess can be cut off before or after fully welding each piece in place depending on preference
    • Make a template out of paper from 10mm past the slit into the inner skin to the edge of the outer skin (will look like some form of half moon shape)
    *** if you wish the tub to extend out to the arch tape the arch into place and make the template meet the overfender skin***

    • Use this template to then cut out a 1.2mm steel plate
    • seam weld the plate in to seal the arch tub
    • Paint with black paint
    • Stone chip and underseal the tub and some of the original arch

    • Paint the tub from the inside if you can access it through the inside of the car
    • Line up and rivet on new overfender

    please don't attempt this if you have never welded before or you may end up wit a large hole and only hopes and dreams to fill it

    if anyone has any input as to why this is a bad technique im all ears.. but it works fine for me :nod:

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