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Bent Inner C (knuckle)

TonyPDX

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Feb 3, 2004
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338
I think I bent the inner C (knuckle) when a lost a U-joint on Cadillac Hill this summer.

If it is bent, I think I could put a long 5/8" bolt through the ball joint holes to pull the top part of the "C" back down then add a gusset to keep it from bending again.

Questions:
1. Does anyone know the inner C dimensions and how to measure it?
2. Who makes good gussets for the Dana 44 inner C?
3. Should I use heat on the upper part of the C while straightening it?

I would prefer to not replace the C as it is also my track bar mount...

Thanks, Tony
 

bronconut73

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Aug 7, 2012
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The Jeep JK's have an issue with weakness in that same area. A few companies make a reinforce ment kit that you weld on. Its for the Jeep JK 44 but it may fit our 44's too.
 

Rustytruck

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Feb 24, 2002
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10,875
If it was mine I would strip the other side and cut a steel tube spacer to fit tight in the inner C. Then get a long bolt and heavy duty washers and nuts. Take the tube from the other side that was made and put it on the bent side with the bolt holding it in place. Now take the torch and heat the bent area red hot and take the bolt and tighten down the inner c until it clamps down the tube. Now let it all cool naturally. Don't force cool it. Now if welding in gussets then leave the tube in the inner c clamped up. in my case i would preheat the inner C when welding on it since the mass of metal is so different. Bending the inner C is pretty tough. I would have thought that the tube would bend first. If you do this make sure you have thought out what your doing you don't want a failure on the road. Cold bending steel puts allot of stress in parts.
 

ntsqd

heratic car camper
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Heating to red hot takes a lot of the strength out of it too. Danged if you do and danged if you don't.

I'd take it no more than straw colored and would more likely use the pure acetylene soot method of temperature indication. Take it no hotter than the heat needed to burn off the soot. Just a neutral burning flame won't do it, the metal has to be up to temperature too.
Make a tool that tightly fits the flats of the 'C' and has a really long and stout lever on it. Much easier to be precise with a lot of leverage and not much effort than with not much leverage and a lot of effort.
 
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TonyPDX

TonyPDX

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Well, I went ahead and did it tonight. I measured between the ball joints and set it to that dimension. It was just over a 1/4” out. I didn’t get it glowing hot but it was pretty hot and I quenched it by pouring water over a wet reg rapped around it.

Tomorrow I will remove the bolt and see how it fits.

Thanks for the replies.
 

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ntsqd

heratic car camper
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I wouldn't be surprised if it springs up a little bit. May need to repeat the process. May also need to pull it just a little past the ideal point. Interested to hear the results.
 

nvrstuk

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Tony, you should cool it as slow as possible after heating...I really think it would be worth checking into reheating it and cooling it sure slow. My small # of metallurgy classes and Gary led me to cool my steering parts covered in sand so i didnt change the grain structure.

I think, think you can reheat and cool all affected areas again and return the grain structure to normal...I think it's important enough to check into.. somebody here has a degree in metallurgy...

Glad to hear you have it straightened out .

I will forward you the contact info of the guy I got a slick D60 inner and outer C bracing kit from. Fit perfect and really strengthened them up. Hopefully he makes one for the D44
 
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ntsqd

heratic car camper
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Quench steel too fast and you freeze the metal in a brittle state. A super slow cooling from above the Critical Temperature will result in an annealed condition, dead soft. The trick is to not heat it up so far that you lose the cold work strength from the forging process, but hot enough to allow it to bend more easily.

Most of this is covered in "Engineer to Win" by Carroll Smith (the other Carroll @ Carroll Shelby Ent.) and said in plain English. I frequently referred to it to explain some concept that my Engineering textbooks failed miserably at explaining.
 
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TonyPDX

TonyPDX

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Thanks for the input guys! It did spring back more than I had hoped so I got a second MAPP gas torch and heated it for 30+ minutes and slowly tightened the bolt again until it was a touch past where I wanted it, about a ~7” spread. I then wacked the top of the bolt with a 3lb mini-sledge and cooled it with the wet rag technique and let it sit for a day before removing the bolt. This time it worked! So, to address the metallurgy question… I could not get it to 375C where the yield strength starts to really drop, nor could I quench it in an oil bath but hopefully this process left it in a similar state and somewhat annealed.
 

Apogee

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The axle C's are low-carbon steel, so they're not going to respond to heat treating the same way as a higher carbon content alloy, and should be fine with the process you used IMHO, especially if you reinforce it with some stiffening gussets/ribs.
 

ntsqd

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I was more concerned about the process eliminating the cold-work hardening induced by the forging process than any possible heat-treating.
 

Apogee

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I was more concerned about the process eliminating the cold-work hardening induced by the forging process than any possible heat-treating.

Valid concern, but my understanding is that the C's are hot forged by Dana above the recrystallization point, otherwise they'd have issues with them pulling when they welded them to the tubes.
 
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