The Stovebolt Site Forums The Shop Area Driveline Heating steering parts, how far can you go?

My King Pin is frozen in place and so are all the bolts that hold the brake backing plate to the yoke and I cannot even get the steering linkage connecting arm off the bolts that connect it to the yoke/spindle. How much heat can be applied to the parts to help ease removal? I have a rosebud oxy acetylene tip so I can get it red hot. I ask because of the advisory not to heat steering linkage parts excessively. Truck is a 49 chevy 3100
The steering connector and and spindle/yoke will all need to be heated to get the bolts out of them. Then there is the kingpin.

Warm it up enough that water sizzles when sprayed on it, or possibly until a lead wheel weight melts when touched to the parts. The lead weight test would be 400-something degrees. I'd be very reluctant to go much hotter than that. Spraying the parts with KROIL while warm will help it penetrate. Heat- - - -soak- - - -tap with a BFH- - - -repeat as necessary. The main thing is to be very patient and let the penetrating oil do its job.

www.kanolabs.com

Jerry

Heating then soaking with a product such as KROIL allows the penetrant to be pulled into the tiniest of spaces. An example would be like soldering copper plumbing connections. 🛠

The 1950 manual provides a warning about heating steel drop forged parts such as axles. the manual says that under no circumstances should heat be applied. Heat will weaken the material. It mentions this for straightening bent axles. “Always straighten forgings cold.” Heating to help penetrate Kroil into the pins doesn’t seem as extreme as heating to bend and straighten.

If the metal gets hot enough to change color, that's too hot. The crystalline structure of the metal starts changing somewhere around 600 degrees on the steel alloys I use in some of my knife making and/or gunsmithing projects. Steering and suspension parts need to be tough, not brittle, and heating to the point of changing color can seriously change those characteristics. Other important factors are how the metal is cooled- - - -oil or water quenching, air-cooling, or slow cooling buried in sand, etc.

One really fun project is making a V-shaped leaf spring for a flintlock muzzleloader hammer. A piece of annealed high-carbon steel is hacksawed and filed into the exact shape it needs to be, then it's heated cherry red and quenched in water. Then it's polished and placed in a shallow pan of non-detergent motor oil. Heat the oil with a torch until it all burns away, then cover the part with lime and let it cool for several hours. If the V can be compressed fully in a vise without breaking, you've got a spring. If it breaks, start all over!
Jerry

"The steering connector and and spindle/yoke will all need to be heated to get the bolts out of them. Then there is the kingpin."

Joe,

Decades ago when I had a motorcycle crankshaft that couldn't be pressed apart even with a 50 ton press an old engine shop owner taught me a very useful trick to solve the problem. This has to be done skillfully to avoid damage to adjacent parts but piercing a hole along the axis of the stuck bolts and kingpins with a flame cutting torch somehow loosens them and allows them to be easily removed.

I was skeptical when that was first was suggested to me but I'm a believer now because it works amazingly well.

The motorcycle was a 1974 Bultaco and the problem was very common only in that one year of Bultaco production. Here's a photo of me in a Southern California AMA District 37 desert race on that Bultaco "back in the day".

Thanks to all for the excellent information and also the spring heat treating and the motorcycle experience! It has helped to stifled any "go for broke" hastiness, literally and figuratively.

The answers given above are only partially correct. Disclaimer, I'm not trying to argue just provide info about something I know a lot about.

First- pure lead melts at ~600 and lead alloys can be anywhere from 350-800 degrees. So unless you know exactly what you have you need to be very careful with this technique for temp. Wheel weights can even vary quite a bit.

Second- the real answer to the OP's question requires information about the condition of the material you heating up. For example alloy steel that has been quenched and tempered to 500F can be heated up to 500F for a short duration with no real problems. 1008 steel can be heated and cooled countless times with no significant changes in material properties. Austenitic stainless steels can be heated to bright red and quenched and nothing happens, but if you heat them to say 5-600F and hold for duration they get slightly harder and stronger but become highly prone to inter granular corrosion (there is a lot of science here that I can explain if anyone actually cares). And we can keep going for a myriad of conditions and materials. The long and the short is that if anyone knows the alloy and condition or an approximation thereof I can tell you how hot is OK, otherwise its guesswork - which sometimes works and sometimes....

Pro garage shop Tip on ASUTENITIC Stainless Steel. We all know that it work hardens ( again I can explain this if anyone actually cares) and sometimes can be difficult to cut or drill. Well what you can do to soften it back up is heat it above about 1400F and quench it in water and it will go dead soft again. If you have a difficult hole in a thick piece you can do this a couple times.

Spartan

What I think is missing from all of this talk of "how hot do we need to go" for these bolts is what is going on with a nut and a bolt as we heat them in an attempt to let them turn loose from one another.
All that we are trying to do is take advantage of how different metals, or differently shaped metals of the same alloy, respond differently from just a little heat. This little bit of heat will cause slight expansion of one type of metal faster than the other, resulting in separation of the mating surfaces. This also takes place with a nut and a bolt made of the same alloy, due to the difference in shape and mass of the two parts.
Having said all of that, with these particular nuts and bolt, I make sure that there are no cotter pins in the end of the bolts, I heat the nuts until the grease/oil/dirt catches on fire, put out the fire, and put an air impact wrench on the nut and a box end wrench on the bolt head and buzz them off. If they break, then I know that it was time to replace them anyway. I have never broke one this way and they always came off.
Carl

How much austenic stainless steel is there in a 1950's stovebolt front axle?
Jerry

Jerry- that info and examples were on how heat effects the micro-structure of different metals, it just goes to show that there are no absolutes. Long and short is that more info is needed to have a definitive and correct answer about "too much heat" that's all I am saying.

Spartan

I've heated many a steering component until it glowed cherry red and was maleable as butter. None has failed yet, but I guess that makes me a test driver, right?

And that's how they drop axles too:

It's always a pleasant surprise to see the depth of knowledge on this site. That said, to determine the temperature of heated parts a melt stick like this works. Or a digital laser infrared thermometer here is another option. One plus for the IR thermometer is it's a lot more fun and useful around the shop. Works for finding cylinders not firing, cold/hot spots involving the cooling system and of course answering the frequent question "just how hot or cold is it in this dadgum shop".

For our purposes I would not worry about getting a NIST (National Institute of Standards and Technology) certified device.

RonR

Thanks for more great answers! The problem I was having was freeing the parts from the bolts that had rusted to the steering pieces. The nuts came off with no problem. Following all the advice above, I heated the parts gingerly, used the penetrating oil as suggested and after banging away on them I was relieved when they actually came apart! Now onto getting the kingpins out. I am reading the past threads about that subject.

One almost “sure fire way”.........Removing the axle and using a press with helper and well thought out fixture.

I have used a home-brewed "press" consisting of two pieces of 3/4" all-thread rod, heavy wall square tubing, and a bottle jack to move stubborn kingpins without removing the axle from the truck. The top piece of tubing has a hole drilled in it to allow the pin to come through it.
Jerry

We have heated our delivery truck straight axles at work bright red and beat the king pins out with a sledge hammer with full over the head swings, sometimes it just takes as much force as you can apply! Try heating them up till the grease and oil burn off, let cool, give it another heat/ cool cycle, then on the third try, beat the crap out of it. The trick is to not mushroom out the top so you drive them through the hole, be it a bolt or pin. I have had decent luck welding on the heads of stuck bolts, nothing fancy, just a big old glob of weld, the heat migrates up the shaft releasing them from the rust. Keeps from heating the surrounding metal.

Joe

"We have heated our delivery truck straight axles at work bright red and beat the king pins out with a sledge hammer with full over the head swings, sometimes it just takes as much force as you can apply!"

Joe S and Joe H,

Here is what a single cylinder Bultaco crankshaft looks like. As you can see the pin that the 2 crank halves are pressed on to is similar to a vehicle kingpin. The crankshaft that I couldn't press apart was similar to this. After piercing a hole through the pin it pressed out easily. Piercing that hole with a flame cutting torch left the crank halves so cool they could be picked up with bare hands because they are massive and the piercing only took a few seconds. No brutality was required nor would I have used any because these are precision parts.

Regardless of microstructure of metal, heat up the thing you want to expand and don't heat up the other thing. Don't need red hot to get a .001. The penetrating oil, as said, will do it's work. Use an air chisel with a very blunt tip to vibrate the parts. Vibration is a good tool. It is the baby brother to BFH. This will greatly increase penetration of the oil. Do it a lot around the whole area and do it on the pin. You can bang bang in between sessions if you have aggression problems. Make sure you can notice the slightest movement so you will know it's working. That will give you renewed vigor.
You can also buy a Snap-On king pin remover for about $8000.

You heat things red hot and bang hard on them, they may bend. Try to support things around there with a jack and piece of wood...or chain them to the frame.

Thanks again for an interesting thread that provides important information that may not have ben covered as thoroughly as before.
I got the steering linkages removed from the back plate using you helpful info. some heat and penetrating oil with it. Now on to a new thread about my odd problem removing my kingpins and fitment of new.

Jerry's home-built press should work. Once you apply pressure with the press, take a BFH and hold it against one side of the axle where the kingpin goes thru, and smack the opposite side with another BFH. That makes the rust molecules quit holding hands to cover their ears.

The shock and momentary deflection of the axle helps loosen things up. A little heat will also make the parts loosen up as has been said.

To klhansen.
I an inclined to go in that direction, pounding on it increases risk of irreversible damage. After the snowstorm tonight I am going to hit Home Depot, Lowes and tractor supply and see what they have for steel.
Picking up real structural steel around here has gotten harder and harder.

Best regards,

Joe

The 2" heavy wall square tubing that's used to plug into trailer hitch receivers works well, and most places that build and/or install hitches just might have a piece of that stuff around for custom fabrications. A welding shop should be able to cut you a couple of short sections, also.
Jerry