Lightening your K frame

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rmchrgr

Skate And Destroy
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So I have this '73-up spool mount K frame sitting around. I keep looking at it thinking I might try to lighten it up by trimming the pinched lip that runs around the whole thing. I would keep the mounting holes and what not.

Someone has already tried to 'modify' it for what looks like oil pan clearance. The inner lip was indeed cut and they did something that resembles welding but it looks like either they had no shielding gas or were drunk when they did it. My hope is to get a much cleaner result.

I thought about it and it looks like a good way to go about it might be to cut the bottom part of the pinch, trim the top half a little and bend/hammer it down to meet where the bottom was cut and weld the seam there.

I had the idea though that this may create a stress point which is perhaps why Chrysler used the pinch. More likely though it would also have been a huge amount of work to trim off all the excess and weld the two stampings together. The factory welds also look like they were done by drunks but I guess they were adequate.

I have cut off tools and a grinder. We have a lovely Miller 140 at work.

Anyone done this? Got any suggestions for this endeavor? I'm basically doing this to see how much weight I can save without going too crazy. Plus, I can do it for free.

Any input is appreciated.
 
I'm with you on reworking the stock K frame and those thinking they're going to shave a bunch of weight by replacing the stock K frame with a fabricated piece made out of tube probably haven't picked up one bare, much less actually weighed it.
The factory piece is a pretty tough act to follow with the basic structure made up of two light weight sheetmetal stampings spot welded together at a pinch flange. The weight of the steel making up the pinch flange can't amount to much, not much more than a few ounces at best, and probably contributes slightly to the overall rigidity of the piece.
While trimming the factory pinch flange to just a vestige large enough to weld solid wouldn't save enough weight to compensate for the steel you added beefing the K frame up, with the added gussets and everything welded solid it probably wouldn't hurt anything either, and would be beneficial to component access. Doing so might even allow you to lengthen the engine's oil sump slightly.
My buddies around here and I have been thinking along those lines also. I won't get into things like universal motor mount pads to change easily between engine families or moving the steering box mount ahead to accommodate my C body steering column, but you can imagine we're giving some thought to stock K frame mods.
Dick Ross (Firm Feel) has been beefing up the stock piece by welding all the seams solid, gusseting, and adding a skid plate for years. He will sell you the coupon kit if you want to do it yourself. I'll ask him what he thinks about eliminating or minimizing the pinch flange next time I get over there.
 
I took some pics to illustrate what I would like to do. Might be a little tough to make out but I made some marks where I planned to cut and weld. The marks may be a little too far up right now. This is just the initial planning stage, I will probably alter the point where I make the cut.

We have a sandblasting cabinet at work but it does not really do the job for larger parts like this frame, hence the half-finished appearance. It is difficult to wrestle around in there and the hard-to-reach spots are tough to get cleaned up. I also remembered that I have access to a plasma cutter which would take care of that flange in seconds. But I digress.

The third pic down shows where the previous owner had started/tried/failed/butchered the flange.
 

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Whats going to hold it all together once you trim all that off? I bet you will only save three pounds cutting all of that of. There really isn't that much weight to a factory K-frame
 
Whats going to hold it all together once you trim all that off? I bet you will only save three pounds cutting all of that of. There really isn't that much weight to a factory K-frame

I agree, the weight savings is not tremendous but I bet it would be more than 3 pounds. Everything adds up...

In regards to holding it together after trimming; what I was saying before is that I might want to try and cut the bottom part of the flange and only trim the top half to where I could bend/hammer it down to meet where the bottom is cut, then weld the seam there.
 
The entire k-member weighs right about 35lbs. You aren't going to save enough weight to make any difference.
 
I think your doing a good job. Ive done stuff like this before and was able to shave off 5 lbs, done larger cuts and shaved over 10 lbs. I did have to weld more metal back it for support. But if you take your time and think about how it is gonna all work out, you'll be just fine
 
not to mention how much strength are you going to take out of that simple stamped kframe!!! What do you think holds the front end of the car together? Read around a little bit and you will see everyone reinforces and strengthens thier kframes! Sure every little bit adds up, but at what expense. After you destroy that one let me know I will sell you my extra....hopefully you will still have a car to use it in!
 
I wouldn't bother trying to save weight on the k member. What are you going to lose? My guess is 4 pounds max. Not even worth it in my opinion.
Actually, you would be better off welding all of the seams solid and fixing the crappy factory welds that they all have, and then putting on extra gussets to strengthen it.
This is actually my next project as well!
That's what i am going to do to mine.
 
Wow, lot of opposing views here. Did you all actually read what I said?

Essentially, the K frame holds everything in place: steering components, motor mounts etc. True, the torsion bars apply a good deal of force to it. Is it a stressed member? Not sure, I am not a chassis engineer.

Cutting and boxing the thing for oil pan clearance is standard issue stuff that's been happening since forever. I'm not even going that far.
 
My 2 cents:

That flange you want to shave off, and replace with melted welding rod adds significant stiffness to the part. I would not trim any of it. The K member resists all the torsional forces exerted from front suspension, and engine.

If you want to make a stronger front end, reinforce the lower cross member running under the radiator, and find something that is nonstructural to put on diet, such as a back seat, a spare tire etc…

You may want to compare the weight of melted rod vs. metal trimmed. I bet it is almost a trade-off.
 
i wouldn't bother trying to save weight on the k member. What are you going to lose? My guess is 4 pounds max. Not even worth it in my opinion.
Actually, you would be better off welding all of the seams solid and fixing the crappy factory welds that they all have, and then putting on extra gussets to strengthen it.
This is actually my next project as well!
That's what i am going to do to mine.
x2
 
What you doing with the car?


Will only be out your time for the most part so I don't see why not. As long a it will hold up to the intended use of the car.


Was going to cut mine down too for lighter weight and oil pan clearance. But mine will be drag only car.

Do a search. There are a few good threads here with pics of cut down K's.
 
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