Welding Steering knuckle on my truck?

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The last time I did any welding was YEARS ago in high school. While trying to change my brakes, I stripped out the brake caliper pin threads on my truck. It costs over 600 bucks to replace the steering knuckle. Since I always wanted a welder, I figured it's as good a time as any to start. I ordered my Hobart handler 125 which is on it's way.What I want to do is weld the hole where the threads were, then tap it for a new caliper pin.  My question is, should I drill out the hold to make it smooth, or is it better to leave the threads (that are shot) in there?  Any other advice would be very helpful! As I said I'm new to this, and there's a good chance I'll screw it up (no pun intended). Thanks.
Reply:Are you sure we're not talking about cast here? Especially if it's just a couple of small lobes sticking out. Some carefull thought and finesse may be involved here.I'm sure there are a lot of folks more qualified than me to touch on the subject of automotive steering parts, cast and welding, but I sure wouldn't just jump in there with a mig quite yet.
Reply:Originally Posted by mjshortThe last time I did any welding was YEARS ago in high school. While trying to change my brakes, I stripped out the brake caliper pin threads on my truck. It costs over 600 bucks to replace the steering knuckle. Since I always wanted a welder, I figured it's as good a time as any to start. I ordered my Hobart handler 125 which is on it's way.What I want to do is weld the hole where the threads were, then tap it for a new caliper pin.  My question is, should I drill out the hold to make it smooth, or is it better to leave the threads (that are shot) in there?  Any other advice would be very helpful! As I said I'm new to this, and there's a good chance I'll screw it up (no pun intended). Thanks.
Reply:Theres no problem if tapping 70k steel. I did it for my barstool steering support...nothing a little bit of grease won´t handleMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:Why not use an insert like a Helicoil?
Reply:I would have to vote for the insert simply because you may be dealing with cast and if so you could make it worse than it is.  Since it's a caliper bolt there shouldn't be a lot of force pulling it longitudinally its mainly there to hold the floating calipers in place.  An insert would be more than adequate on strength and probably take less time and effort to install.
Reply:/ Originally Posted by elvergonTheres no problem if tapping 70k steel. I did it for my barstool steering support...nothing a little bit of grease won´t handle
Reply:Originally Posted by 383bigblockI would have to vote for the insert simply because you may be dealing with cast and if so you could make it worse than it is.  Since it's a caliper bolt there shouldn't be a lot of force pulling it longitudinally its mainly there to hold the floating calipers in place.  An insert would be more than adequate on strength and probably take less time and effort to install.
Reply:It never even occurred to me to use a helicoil!  So much for my welding aspirations!  At least I'll have a welder now. Where can I buy a helicoil (I never had to get one before). Thanks for the suggestions!  I was worried about it being cast.
Reply:Originally Posted by mjshortIt never even occurred to me to use a helicoil!  So much for my welding aspirations!  At least I'll have a welder now. Where can I buy a helicoil (I never had to get one before). Thanks for the suggestions!  I was worried about it being cast.
Reply:Try a good auto parts store, or the local machine shop. They usually have them in stock and will walk you through the procedure.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Originally Posted by SandyAre you sure we're not talking about cast here? Especially if it's just a couple of small lobes sticking out. Some carefull thought and finesse may be involved here.
Reply:pics would be a big help..solutions to those problems are no problem if i know what i'm getting into.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by zapsterpics would be a big help..solutions to those problems are no problem if i know what i'm getting into.....zap!
Reply:I have welded cast steel before with 80-18 stick rod. But, i would first pre-heat it (the casting ) to about 200 F. and maybe some post heat. if that don't work, i'd weld it with a bi-metalic rod , like a high nickle content , BUT - i think the way to go is with the heli-coil process .[SIZE="5"Yardbird"
Reply:Originally Posted by Roy HodgesI have welded cast steel before with 80-18 stick rod. But, i would first pre-heat it (the casting ) to about 200 F. and maybe some post heat. if that don't work, i'd weld it with a bi-metalic rod , like a high nickle content , BUT - i think the way to go is with the heli-coil process .
Reply:ok.. i see what you mean..the part is probably 4140-4150 alloy cast..thats why it gets so hard after welding..you need to seal up the holes...then send the parts out to a heat treat place that will draw down the hardness or "anneal" the parts so you can re-drill and tap to what you need..have a good machine shop do this for you..then i really would not worry about the hardness factor very much..you'll never break the piece in the first place.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by zapsterok.. i see what you mean..the part is probably 4140-4150 alloy cast..thats why it gets so hard after welding.....zap!
Reply:Originally Posted by 96XJIt is the weld that gets hard the sarrounding casting is OK.Is there a rod alloy that will stay soft after the welding?
Reply:Originally Posted by zapsteryeah its because of the carbon content in the base material..as far as a rod that will stay "stable"..no..its in the heating of the base materal that makes it hard..no matter what you use for filler...once you mix the two metals its hard and thats that......zap!
Reply:what you could do is drill out the holes about 1"..have some "plugs" as you suggested made that are pre drilled and tapped..but they have to be drilled and tapped "off center" like a cam eccentric so you can position the threads where they need to be...once you position them where they need to be...weld in place and be done with it..just another idea......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by zapsterwhat you could do is drill out the holes about 1"..have some "plugs" as you suggested made that are pre drilled and tapped..but they have to be drilled and tapped "off center" like a cam eccentric so you can position the threads where they need to be...once you position them where they need to be...weld in place and be done with it..just another idea......zap!
Reply:anytime... let us know how you make out.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Hope this doesn’t move us backwards. Are you retrofitting disc brakes to something? Can I ask what type of axle you’re working on?  Does the bore pilot correctly but the bolt circle is off?
Reply:Originally Posted by denrepHope this doesn’t move us backwards. Are you retrofitting disc brakes to something? Can I ask what type of axle you’re working on?  Does the bore pilot correctly but the bolt circle is off?I think zapster is on to it. Maybe a plate behind the bracket, index the bracket to minimize hole overlap. Maybe socket head or 12 point bolts accessed through clearance holes or counter sunk screws.
Reply:Originally Posted by denrepI think zapster is on to it. Maybe a plate behind the bracket, index the bracket to minimize hole overlap. Maybe socket head or 12 point bolts accessed through clearance holes or counter sunk screws.
Reply:Ya… And all you have to do 96*j is to build it!
Reply:Originally Posted by denrepHope this doesn’t move us backwards. Are you retrofitting disc brakes to something? Can I ask what type of axle you’re working on?  Does the bore pilot correctly but the bolt circle is off?