welding thick metal to thin metal

  1. luke_sibley New Member

    Posts: 3
    beckenham
    hi just after a bit of advice, im welding new engine mounts into my project car, its its high power iv used a thick steel for the mounts 5mm. but obviously the car is only max 2mm in some places the rest normal bodywork thickness... so basicaly what is the best way to weld these into the car ? because if i go to hot il burn threw the car.. but its got to be hot enough to penatrate the thick steel.. maybe heat with a blow lamp 1st ? thanks guys.
  2. rtbcomp

    rtbcomp Moderator Staff Member

    Would it feasible to bolt them in place using spreader plates instead of welding?
  3. luke_sibley New Member

    Posts: 3
    beckenham
    hi no they cant be bolted as there is nowere to bolt them. also welding would be better as its going to be like 500bhp, just basicaly need to no the best way to weld thick metal to thin metal. thanks.
  4. madkayaker

    madkayaker Pro sparkey Pro Welder

    Posts: 13,726
    Cumbria
    Can you get behind the thin metal and use a heat sink
  5. brightspark

    brightspark Member

    Posts: 9,942
    yarm teeside
    on a simlar note make up some larger 2.0mm plate lay it on a piece of thick steel . place the 6mm mounts on it then weld at the higher current . it wont burn through the thinner plate because of the heat sink behind :laughing:then weld the 2mm mounting plates onto the 2mm bodywork ;)if u gas welded it you wouldnt have a problem :laughing:easy to weld disimlar thickness metals without burn through . the oldies are the best :D
  6. mike os

    mike os just a little insane.....

    Posts: 3,346
    North Wales
    I'm not convinced just welding them straight in will be sufficient with the bodywork being so thin... mount points are usually fairly heavily reinforced

    I would go with brightsparks method... thin plate to the mount (maybe 3mm to reduce the thickness differences in both welds) then thin plate to thin plate in the body... couple of spot/plug welds as well as edge.

    using an "in between" thickness will probably mean you can mig the lot
  7. luke_sibley New Member

    Posts: 3
    beckenham
    ah ok thats a pretty good idea! il take some photos and get opinions again anyway. there welded in now but just to mock everything up iv got my proper welder being delivered soon so i will cut them back out clean everything up and do it the best way suggested.
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