Cracks in front frame rails under K frame mounting points

[andrewwoz]

Found some cracks in the front frame rails when I pulled the k frame off, they are both around the rear mount holes for the K frame. I saw another thread with some cracks in the same location but they looked quite a bit worse than mine, everyone in that thread was saying replace the rail(s).

I'm really not looking to replace the frame rails and I think with how minor these are repairing in place would be ok but would like some more opinions.

My plan would be to drill a small hole at the ends of the cracks, use a die grinder to V the cracks a bit and weld it up and then grind it smooth. After that, make some plates from 12ga steel to spot weld on as extra insurance. Would "spacing" the k frame .100" cause any issues?

 

[funknut]

I went through this exact issue and had a guy come out and weld them up. I've done some basic welding on floor pans and such, but wanted someone with more experience on this job. When he left they looked good as new.

 

[Cranky]

I went through this exact issue and had a guy come out and weld them up. I've done some basic welding on floor pans and such, but wanted someone with more experience on this job. When he left they looked good as new.

What type of weld did he lay down? TIG, MIG or Stick?

 

[gtx6970]

I think you have a good plan.
Definitely drill the ends though.

 

[funknut]

What type of weld did he lay down? TIG, MIG or Stick?

It was MIG. Drilled the ends, ground them out and then a couple passes with MIG, I think it was 0.30 wire.

 

[andrewwoz]

What type of weld did he lay down? TIG, MIG or Stick?

I was thinking about this too, I may try TIG welding it first but I have a feeling not being able to clean the back side is going to produce poor results. Have a MIG machine as well if that doesn't work.

 

[Don Frelier]

I don't know how you would spot weld there?
See if you can get a repair cap or make a piece of channel to wrap around.
I would drill a few holes in it and weld them shut.
I don't think 0.100" would make any difference.

 

[eldubb440]

just burn it in there with a mig..... it'll be fine, unless the area is packed with rust; which doesn't appear to be an issue

you can also drill those spot welds a bit and burn right into them

 

[ckessel]

Had that on my 65 too. Drilled at the ends of the cracks, V'd them out a bit, burned it in with the MIG. Ground the areas down, good to go.

 

[Runcharger]

Yup: After 50 years that won't be a big deal. Be nice if it's on a rotisserrie rather than overhead welding it.

 

[Donakey]

GMAW solid wire is good just make sure it’s clean . GMAW hates any contaminants. If a guy bevels a runoff tab the transition from the frame to the tab won’t be a step up. I would go an 1” past the crac if you drill a hole. That stuff is thin if you open it up use 1/16 disc. The run off tabs ensure there is no start stop. Start stops aren’t welds. There incomplete and extremely brittle. It’s in the overhead. I would practice first in that position with the same guage of steel first and put in hot. 150-160 wire speed with 17-19 volts might be a starting point or it might not

 

[3sloppydogs]

I had that problem on my 66 coronet and after a few checks by rapping it with a ball pen hammer it was worse than it looked. I had to cut the whole section out and weld a new one in. I spot welded the nut in position and mocked up the k member. Took a slew of measurements then spot welded it to the frame and checked again. Then did the final welds and it worked out great. There was really nothing holding it before that.
But we do live in the rust belt

 

[sam dupont]

I would open it 1/8 and use 1/8th 7018 with the machine set a little hot to weld overhead.

 

[autoxcuda]

I did that with my 68 Barracuda on 3 of the bolts... in 1997.

Been about 50k miles since then. All with .99" torsion bars and 1.14 T-bars. Those spring rates are double and triple respectively. And also with 245/50/15 low profile tires. Needless to say, it's driven hard.

 

[j-c-c-62]

GMAW solid wire is good just make sure it’s clean . GMAW hates any contaminants. If a guy bevels a runoff tab the transition from the frame to the tab won’t be a step up. I would go an 1” past the crac if you drill a hole. That stuff is thin if you open it up use 1/16 disc. The run off tabs ensure there is no start stop. Start stops aren’t welds. There incomplete and extremely brittle. It’s in the overhead. I would practice first in that position with the same guage of steel first and put in hot. 150-160 wire speed with 17-19 volts might be a starting point or it might not

View attachment 1741258

I don't see any advantage here of drilling when doing a properly prepped weld, other than to create another future stress riser.
Additionally, fixing the crack by simply welding does little to correct the apparent weakness of the design.
Good catch by the OP.

 

[eldubb440]

thread a bolt in the hole before welding anything, a little piece of weld spatter in the threads can ruin your day

you can also add a plug weld or 2 on each side; you're already drilling the end of the crack, so your half way there. I'd probably move them a slightly tighter to the hole, to ensure there is something backing them up

it's a 10 minute fix at this point

 

[not so famous bob]

Found some cracks in the front frame rails when I pulled the k frame off, they are both around the rear mount holes for the K frame. I saw another thread with some cracks in the same location but they looked quite a bit worse than mine, everyone in that thread was saying replace the rail(s).

I'm really not looking to replace the frame rails and I think with how minor these are repairing in place would be ok but would like some more opinions.

My plan would be to drill a small hole at the ends of the cracks, use a die grinder to V the cracks a bit and weld it up and then grind it smooth. After that, make some plates from 12ga steel to spot weld on as extra insurance. Would "spacing" the k frame .100" cause any issues?

View attachment 1741218

View attachment 1741219

no , the original 68 hemi barracudas had 1/2'' plates on them for engine clearance issues ,
mine had cracks around one hole if I remember right , welded up and ground smooth , no problems since...

 

[Krooser]

Weld it and forget it...

 

[autoxcuda]

I don't see any advantage here of drilling when doing a properly prepped weld, other than to create another future stress riser.
Additionally, fixing the crack by simply welding does little to correct the apparent weakness of the design.
Good catch by the OP.

If you look at my pictures I added plates on the sides.

No plate on bottom since that's where K-member bolts to.

 

[dvw]

My racecar was cracked on both rear k frame areas. One side was thin due to a mouse nest causing internal rust. Migged it all up with a small patch on the bad side. 12 years worth of wheel stands later it’s still good.
Doug