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Up Topic Welding Industry / Technical Discussions / Welding on a Truck Frame
- - By newguy111 Date 05-09-2007 00:52
I need to weld on a truck frame.  I was told I could not weld accessories on truck frames but later found out that I would be able to as long as I adhered to the manufacturers guidelines (which I couldn't find).  Anyway my question is, can I weld on the frame as long as I stay away from the flanges? Also, I told welding on a truck frame causes a chain reaction which could damage the engine/computer, is there any truth behind this?  Thanks.
Parent - - By DaveBoyer (*****) Date 05-09-2007 03:20
Some heavy truck [BIG HEAVY TRUCK not pickup] frames are heat treated, and altho there are guys who weld them You really have to know what You are doing. Light and medium duty trucks use mild steel frames, pickup frames generally have some welded areas as manufactured. Welding on the web of the frame is the least risky place to weld, but there is ALWAYS a liability issue when You modify a vehicle. We always unhook the positive battery cable [s] before welding. This has worked for us so far, but I would suggest checking the manual, and with the dealer.
Parent - By jwright650 (*****) Date 05-09-2007 10:52
I have welded on vehicles before without damaging the computer, but I have always unhooked the battery and grounded very close to my work as a precaution. "So far" this has worked for me. I am speaking mainly about welding on exhausts and exhaust hangers that usually have O2 sensors that are directly in electrical contact with the welding taking place.
Parent - - By webbcity (***) Date 05-09-2007 16:13
newguy111 , look in automotive section page 2 "welding on a chassis " . good luck . willie
Parent - - By Tommyjoking (****) Date 05-10-2007 08:00 Edited 05-11-2007 06:17
Computers...... Make sure your Ground is close to your work area eliminates problem with blowing electronics...except with A/C..(I have welded on heavy equipment that costs in the millions with no damage  keep your ground close dude).   unhooking the battery will not hurt a thing (on a vehicle)...good idea really.

For stuff thats going down the road D.O.T.  

In general I have heard its illegal to weld anywhere in between the axels of a truck.  Reason being potential weakining of its road worthiness.  In practice when I built utility trucks we did no welding on the frame between the axels...probably because of liability i would imagine.

Your average American pickup is going to have a frame of mild steel that has been heat treated to make it somewhat stiffer.....if your welds continue along the length of the frame (within reason)  you wont affect it much.  If your weld path goes across the frame (against or across the length) you will weaken its integrety considerably.   Welding across the the frame is likely to produce cracks over time.    If I had to  do a considerable amount of welding between the axels I would aneal it with a rosebud ...it will take away the heat treat but it will help prevent undue tension around the weld area.

Your best bet for welding this is to stick weld it with a 120/18    a mild preheat before welding it would be a good idea.
Parent - - By DaveBoyer (*****) Date 05-11-2007 04:48
Light and medium duty truck frames are made of mild steel, they are not heat treated, as this material does not respond to heat treatment. I don't recall what filler material was used at the frame plant, but I am pretty sure it wasn't over 70 KSI. They were welded by MIG with CO2 shielding, no pre or post weld heat treat. I specifically remember the specified carbon content being 0.05% MAX on at least some of the frames. The heat treated frames found on heavy trucks were made from SAE 1027 modified. There are legal ways to lengthen these frames, hoops, hurdles, testing and certification, not something to be taken lightly, even if experienced in other areas of welding.
Parent - - By Tommyjoking (****) Date 05-11-2007 06:15
When I did the utility truck gig the frames did get extended for large hydraulic winches, bigger job boxes and such.  We always did this after the spring hangers....probably more because it was a commercial vehicle (liability) than a legality....your right I stand corrected. As far as mild steel heat treatment ...well I am just an idiot in my spare time LOL. 
Parent - - By dffay (*) Date 05-12-2007 01:17
The rule of thumb used to be less than 6000 GVW were NOT hardened frames.  From what I've seen and welded, the rule seems to still hold true.  But I can't offer a scientific citation for this. 
Parent - By DaveBoyer (*****) Date 05-12-2007 03:01
My information is a bit dated, but I doubt much has changed. I worked for Dana Corp. Parrish Pressed Steel from '84 into '91. That plant made auto and truck frames. The heat treated frames were for really big trucks, Mack, Freightliner, Peterbuilt, White, Navastar [International] etc. The heaviest [at that time] of the light frames was the F450 Ford, which was just a thicker version of the F350 mild steel frame.
Up Topic Welding Industry / Technical Discussions / Welding on a Truck Frame

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