'78 cj knuckle

[juggernaught]

Just "over reamed" the knuckle on my '78 cj7 while trying to install a high steer tie-rod. Can anyone tell me if the knuckle/arm is a mild steel material or a cast material so I can weld it properly and reream the hole. Please reply ASAP as I need to complete this quickly. Thanks.

[juggernaught]

Went ahead and welded the hole so I could reream...........as soon as I tried to ream the welded hole I could tell that the material had become "hardened". In fact it was so hard it could not be reamed and could only barely be shaped by a carbide deburring bit. To anyone else trying this, you DO NOT want to over ream a knuckle hole. It was a nightmare to finish the 7degree tapered hole so the tie-rod end would fit. The key is to SLOWLY sneak up on the desired hole size by trying the fit several times. Hope this saves someone else what I went through.

One another note.........everything seems to work well. No more pill when braking, steering seems tight, and I gained strength and clearance (3-4"). I wish Partsmike had been a little more informative about the procedure and parts they sent as I had to also cut down the rods as they were fabbed long.

[tufcj]

Glad you got it. My guess would have been cast steel. I'd think if you welded, the hardness would depend on the rod you used.

Bob
tufcj

[Old Rugged Crosser]

Juggernaught: as Bob says, it all depends upon the rod you used to weld up the hole. Coming from the stock car industry I have welded up many tie rod holes and re-tapered the holes. It is not a never do situation, it is how you carry out the procedure.

[juggernaught]

Just used a mild steel 7018 welding rod. The rub seems to be that I used an air nozzle to cool the knuckle ear down quickly (mostly so that the heat would not transfer to far). Evidently, by doing so I hardened the metal. This was confirmed by Mike at Partsmike. I wish I could find a way to go and reream the hole now as the best I could do was finish it with a high speed deburring bit. That bit BARELY removed any metel.

[Old Rugged Crosser]

If you still need to ream it try heating it up red hot with your torch and then let it cool slowly and then you can ream it.

[juggernaught]

Thanks that was my thought, just needed to talk to someone who had done it before.

[ironman_gq]

I wouldnt call 7018 mild steel. It is a low hydrogen rod used for welding high pressure pipe and structural steel and has a tensile strength of 70,000psi. A softer rod would have been a 6010/6011 and penetration would have been higher. Best would have been to use a gas setup as those welds usually come out softer and more ductile than any of the arc welds tig would be next but not usually doable for most people. Weld material will almost always be harder than the base material, its just the nature of welding and having the metal cools so quickly. I definately would keep the welded area hot for a while and let it cool slowly so the grain structure can normalize and reduce cracking problems (probably not a problem anyway)