Cracked frame under front spring hanger kwt800

Metal will stress with time. Before you weld it, drill a 1/8"-1/4" hole at the end of the crack. That will prevent it from spreading further.
I would clean it up and grind you a channel like you said and run atleast 3 passes. I wouldn't grind it flush. Just clean it up and paint it.
A plate would make it stronger, but it's a rust trap. Put it on the back side if you can. Protect your tires from the schlag if you leave it on.

 

disconnect the batteries before welding if it's electronic

 

It is stupid. Disconnected batteries increase risk of damage of electronic components with welding. Yep, you save batteries, but they are cheapper any electronic part

 

Many C-channel frames cannot be welded. There is often a tag on the frame, or sometimes it is stamped right into the frame web.

They are heat treated, and any welding further weakens the steel.

 

Any manufacter publish manuals about frame repare and modifing. Welded frames are rare, they are usually on European trailers ore on some military vehicles (like Russian UAZ), and made with welding frames much heavier but more tought, especially on torsion. But they use different steel for welded frames, steel like used for car substructure ore European cab susbstructure, but thick, 6/8/10/12/15 mm!!! Semitrucktor frames are made of C-channels with riviets ore frame bolts and will be weaken in points of welding so the only way is to use pices of steel secured with riviets. But it is not easy job if you wanna get really good frame, look for sertified frame workshop. If frame is bent never use "fire wrench" to heat it. Inductive heaters may be used only, else you will burn carbon out and steel will be like soft iron.

 

The frame can be welded, you need to pre-heat to 150 degrees C and post-heat to about 400degrees C. then wrap area with insulation and let it cool down overnight. best practise is to also install a second section of chassis rail that is about 18 inch to 24 inch long. (like double chassis) . Bolt the extra section in and bolt on verticle section not on horizontials/flange, dont weld it in.

 

Not an uncommon problem on KW. I had to fix my 96 and my brothers 01,these were 900L's V it out weld it up and put an insert on the inside.

I didn't do any pre or post heating and I did mine over a year ago.

If mine cracks again i'm going to see if the hangers from a later model will work they are bigger and spread the load better.

 

i might be able to help here. i was an x-ray welder for 14 years in between my 2 tours of duty as a truck driver. groove it out and make sure it`s clean. weld both sides, put the ground as close to your work as you can. you do need to pre heat it as far as stress relieving it. ( slow cool down) without the proper equipment you`re s.o.l. wrapping it in insulation is a waste of time. weld it, grind it and bolt a piece of plate over it and you`ll never have to worry about that spot again.

 

never heard that someone manage to crack frame on front axle

i can see it sometimes near rear end on construction trucks with T ride leaf springs so very hard suspension while rear end is overloaded for more than 40-50% than it is rated and used on hard terrain


i would consider to make reinforcements (twin frame) at place where it was cracked ....