Bending a Pitman Arm

What is the best way (if any) to change the angle of a pitman arm? Is it safe to heat and bend then slow cool a pitman arm? Anyone with experiences?

Edit: I did a search and saw some info but the car that I need to modify has power steering. I assume that there could be more load applied quicker to a p/s pitman arm. Would bending affect the arm?

mike

 

This was discussed on another board:

http://www.hotrodders.com/forum/bending-vega-pitman-arm-142631.html?highlight=pitman+arm

 

Once you bend it, heat the whole thing and put it in the middle of a bucket packed tight with sand.... then you're good to go.

 

Heat to cherry red,bend as required,cool slowly.

 

Pretty obvious, but be careful you don't elongate the splined holes.

Not sure how the other guys did it, but:

Clamp one end in a vise.

Heat one end of the arm, on the arm, between the cast boss/splined hole and vise where the bend will be.
Do not heat the splined hole or boss.

Use a 10" - 12" Crescent (Adjustable Spanner to the UK and down under gang) with the jaw over the splined hole and bend to half the angle you need.
Be careful you don't go too far, easy to do if you don't watch it.

Let the arm cool to ambient temp.

Swap ends in the vise and repeat.

Keep the splined ends/bosses parallel for a nice look as well as good alignment with the (draglinks) tie rod end.

I did this on a blanchard ground aftermarket pitman arm from SoCal and it worked well.

 

Those guys don't seem like they know what they're talking about.

 

i assume that the pitman arm is made from forged steel and not cast , but you should make sure before you do any heating/bending

 

Mike- great question... I bent mine (F-1) using the same method as C9 and it worked well

not to hijack, but let's just say I needed to bend my arm a little bit more... is it safe to use this method again?

is it better heat and bend, or v-cut and weld?

Do you think the Indians will ever get their land back?

-Jake

 

Yes

Heat and bend

Yes

 

Thanks for the replies,

36-3 window, I believe it is forged steel but my understanding is there are different types of forged steel with different carbon content. They would all be candidates for heating and bending, but the cooling process would change.

The arm is a stock 48 buick arm. I am going to remove it from the car later today and inspect it better to make absolutely sure what it is.

Jaker, I didn't know the cleveland indians owned land?

I am now a Jets fan.

mike

 

Fwiw - Super Bell bolt-on lower steering arms as well as the Super Bell fore & aft draglink drivers side upper steering arms are forged.

I had at one time an extra Vega steering arm and it looked to be a ductile forging leading me to believe that heating and bending it would be ok.
Do some research on your own though, this is just my opinion.


Just a somewhat educated guess here, but I doubt that any major manufacturer is going to take a shortcut and use castings for any pitman or steering arm.

Major manufacturer meaning FoMoCo, GM, ChryCo and the like.

Probably true in the hot rod aftermarket as well.

 

I would have thought the same,until Don in Fla posted pics of his broken pitman arm.

Speedway pulled them off the market.

 

#4 on the jersey, but #1 in my heart.

 

I'd like to draw a metalurgist into the conversation as I resurrect this old discussion.

The OE vega steering box I am installing this weekend has a dropped pitman arm on it. I might be able to mount the box high enough that this isn't an issue, but will bend this arm if needed. I'm not concerned at all about bending it and understand the slow cooling process etc. What I wonder, any thoughts on using blacksmith methods to straighten it? I have a hammer and anvil, but the vice part could be a little tricky. In my mind, heating the area both sides of the bend enough and driving it out shouldn't have adverse effects. Forging is forging, even with a hammer. Anybody?

 

How far are you trying to bend it? Or does that even matter once it is heated and bent even a little?
Mine could use a bit of tweak, just to raise everything an inch or two.

 

I have a stock vega arm with 2" of drop in it. I would like to take 1" of drop out of it, but could really use a flat pitman. $50 being what it is, I'd take some bend out of it if I could do so with the tools I have at hand.
Once you get the metal to a certain temp, it doesn't care how far you go, so long as you don't ask it to stretch farther than it's mass can fill. (think of a dropped axle that gets that funny thin spot when it's stretched too much in one spot)

 

i have heated and bent flat a lot of vega pitman arms , i do one end at a time and use my press for slow steady pressure. i'm sure it would work to beat on it with a hammer . i just would be concerned with leaving big hammer marks or distorting it....that would probably be OK on the tie rod end because you will retaper it for an early ford tie rod end anyway , but on the other end you still need to re-install it on the vega box output shaft

 

What I wonder, any thoughts on using blacksmith methods to straighten it? I have a hammer and anvil, but the vice part could be a little tricky. In my mind, heating the area both sides of the bend enough and driving it out shouldn't have adverse effects. Forging is forging, even with a hammer. Anybody?[/QUOTE]


You're OK with that but forging is the act of compressing the molecules
of the metal by heating it to a perscribed temperature and pressing it
between two surfaces. Makes it stronger like the difference between
soft rubber and hard rubber.
Bill.

 

You mean like a blacksmith's forge? You know, hammer, anvil, red hot?

 

Yes and no.
what I mean is heating and bending it is OK. Cool it slow.
Using a forge to heat it doesn't mean you are forging it.
Or heating it with a torch or carbon arc doesn't mean you could not
forge it.
Forging is the compressing that takes place when you push, hammer or press the metal together in a controled (confined & at the correct temp)
manner to strengthen and shape it.
Take a scrap piece of steel or a forged pirce if you like and heat it up and bend it. Bend it too tight or with the wrong heat and you will see the stress marks.
Visit a local Blacksmiths group and they will be happy to give you pointers.
Repeat the last sentence!
Bill.

 

Good info. I am getting ready to drop my vega arm this is perfect info.

 

I have an aftermarket vega made from a huge chunk of plate. It's not in front of me now...but I'm guessing it's 3/4 or 7/8...it's pretty hefty.

Lotsa heat?

Another question...with the Vega pitman...would you have to put a double bend in it to correct the offset? or can you just bend it down at an angle and let the tierod end handle the rest?

 

you want the output shaft of the steering box and the tapered pin of the tie rod end parallel

 

In other words...no bind in the tierod end...

Double bend is necessary

 

Depending on how you are bending the arm it may get physicaly shorter or longer and could effect steering geometry.

 

Metallurgically, (forged steel) heat red, bend any way you want (don't beat on either end..!), just don't stretch/thin it.

BUT....does anyone really know what the original hardness is ?

Cooling slow (dry sand) = soft end product
Cooling inbetween (air) = medium soft end product
Cooling inbetween (warm oil) = medium hard end product
Cooling quickly (water, ambient temp. oil) = hard end product (possibly brittle)

Me...before I went and trashed the original heat treatment on any OEM suspension part, I'd really like to know what it was originally so I could at least "try" to get it back to something "close" to its, as designed state.

And to those geniuses touting the heated and bent I-beam axles.... Have you actually watched them go down the freeway at speed...? Not pretty !
Most people don't drive their hot rods that much, that far, so beating these parts up are probably a 40%/60% deal with failure (40% being the failure). And the more the car is driven the percentage goes up.

Me, for a small bend, I'd do my best to bend it cold...it just takes five or six times the force to do it this way....which is a good thing..!
For a big bend...don't know what I'd do, haven't come across that problem yet.

Mike

 

When you say cold bend are talking basically using a press to bend it?

 

Cold bend is just that...jam er in there and jam the press down...

I really have an i-Q of zero in the metalurgy dept...but I can tell you I've bent stuff cold and hot...I always feel more comfortable bending things hot??? Don't know why?

Maybe it's because I've cracked stuff trying to cold-bend 90 degree turns in plate ...

 

I heated mine cherry red, still attached to the steering box, on the end going to the drag link. Used a large cresent wrench to bend to desired position. Had to bend up about 5/8" and side to side about 1/2". This was on a STOCK 55 Chevy pitman arm. I will tell you that even though 1/2 the entire arm was cherry red, it wasnt easy to bend that little bit! Heated 3 times to get desired results, but very happy with results. This was done on my 55 project Im working on. Putting a straight axle front end under it, useing the stock steering box and pitman arm. Let air cool, that sucker was still hot to the touch for a good 15 minutes!