Chopped Pitman Arm

Suspension, Brakes, Tires, Wheels steeringetc..
Post Reply
User avatar
Rawbert
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 180
Joined: Mon Apr 15, 2013 10:06 pm
City: Yorba Linda
State: CA

Chopped Pitman Arm

Post by Rawbert »

After installing my dropped beam I had to deal with my bump steer problem. Choppin' the pitman are was the way to go. I have a 71' with power assist, so my arm has the bend. To keep the geometry aprox. the same minus the amount of throw, I built a jig to keep everything strait. I put a deep chamfer around everything and T.I.G. weld the crap outa it. Six passes around the whole thing, while letting completely cooling between passes. Strong as hell!. In the end I ended up moving the lower mounting hole up 1.750". Mounted up is just right. Drag link is now parallel to the ground. No more bump steer! Let the pictures do the talkin'.
Image
Image
Image
Image
Image
Image
Image

StinkFinger
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 174
Joined: Sat Oct 20, 2012 8:11 pm
City: mission
State: Foreign

Re: Chopped Pitman Arm

Post by StinkFinger »

thats about how i did mine too. did you pre/ post heat ?

User avatar
Rawbert
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 180
Joined: Mon Apr 15, 2013 10:06 pm
City: Yorba Linda
State: CA

Re: Chopped Pitman Arm

Post by Rawbert »

Just pre-heat. Let it cool for about 2 hours in between passes

User avatar
dodgeboykim
Sweptline.ORG Pioneer
Sweptline.ORG Pioneer
Posts: 3004
Joined: Wed Dec 31, 1969 6:00 pm
City: Chilliwack. B.C. Canada
State: Foreign
Location: chilliwack.

Re: Chopped Pitman Arm

Post by dodgeboykim »

Some nice looking Tig passes. :Thumbsup :Thumbsup

User avatar
jwing68
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 173
Joined: Tue Jan 29, 2008 4:49 pm
City: Lethbridge,Alberta
State: Foreign
Location: lethbridge Alberta. Canada

Re: Chopped Pitman Arm

Post by jwing68 »

Very nice welds, unfortunately it is highly illegal to chop and weld steering components in this neck of the woods.
66 Fargo W100 Sweptline SWB Poly 318
67 Fargo W100 Sweptline SWB Poly 318
68 Fargo W300 dually LA 318
66 Dodge W200 Poly
65 Dodge W300 dually Poly 318
68 Pontiac Firebird 350
2005 HD FXST Custom

User avatar
Rawbert
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 180
Joined: Mon Apr 15, 2013 10:06 pm
City: Yorba Linda
State: CA

Re: Chopped Pitman Arm

Post by Rawbert »

Bummer... And I thought California was strict.

nytemuvr
Sweptline.ORG Pioneer
Sweptline.ORG Pioneer
Posts: 915
Joined: Tue Apr 10, 2012 9:49 pm
City: Rio Linda
State: CA

Re: Chopped Pitman Arm

Post by nytemuvr »

Rawbert wrote:Bummer... And I thought California was strict.
Actually it's on the books here, but they don't inspect cars like they do up in the Great White North.

User avatar
rmansberger
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 101
Joined: Wed Oct 02, 2013 2:44 pm
City: East Lansing
State: MI
Location: East Lansing, MI
Contact:

Re: Chopped Pitman Arm

Post by rmansberger »

What is bump steer?

Rick
Rick Mansberger
1967 Mustang "Duke"
1970 Dodge D100 "The Dude"
1978 GMC Suburban "Big Cub"
2006 C300
2014 RAM Limited "Master Sergeant"
517.599.7667

User avatar
slick
Sweptline.ORG Pioneer
Sweptline.ORG Pioneer
Posts: 3095
Joined: Wed Dec 31, 1969 6:00 pm
City: Tucson/AZ
State: AZ
Location: Tucson, AZ
Contact:

Re: Chopped Pitman Arm

Post by slick »

Damn those are some nice welds..
1963 Crewcab
1965 Crewcab
1968 D-100 Longbed
1948 Dodge Panel Truck
1964 Dodge Polara
1957 Shasta

User avatar
Rawbert
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 180
Joined: Mon Apr 15, 2013 10:06 pm
City: Yorba Linda
State: CA

Re: Chopped Pitman Arm

Post by Rawbert »

I don't know the technical definition of "bump steer" but it is like driving with little control. the front wheels pull when brakes are applied or when ever the wheels are not strait. When you counter steer to keep it strait it pulls that way. Kinda fun but extremely dangerous.

User avatar
Hardcase
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 81
Joined: Thu Jul 15, 2010 9:09 am
City: Meridian
State: ID

Re: Chopped Pitman Arm

Post by Hardcase »

rmansberger wrote:What is bump steer?
Rick, the steering components tend to operate in arcs, while the suspension moves linearly. The steering geometry is set up so that when the components move, as much of the motion as possible is close to linear so that when you hit a bump, the wheels don't turn in a different direction due to the differences in motion. When you lower or raise the front suspension, you change the angles of components like the Pitman arm and the drag link so that their motion is in a slightly different direction when the suspension moves. It doesn't take much of a change - if the drag link isn't close to parallel to the ground or the Pitman arm isn't close to vertical, when you hit a bump, instead of the drag link just moving up and down, it will also move fore and aft a little, pulling the steering one way or another...or, if the tires stay straight, the wheel will jerk in your hands.

User avatar
66patrick
Sweptline.ORG Pioneer
Sweptline.ORG Pioneer
Posts: 5038
Joined: Wed Dec 31, 1969 6:00 pm
City: Central
State: OK
Location: OK

Re: Chopped Pitman Arm

Post by 66patrick »

http://en.wikipedia.org/wiki/Bump_steer

The link has a couple of good illustrations to bolster the definition.
[b]Patrick - 1969 D300 cab & chassis[/b]

brucer
Sweptline.ORG Member
Sweptline.ORG Member
Posts: 4
Joined: Mon Oct 08, 2018 11:06 pm
City: 59443
State: MT

Re: Chopped Pitman Arm

Post by brucer »

I lowered my 66, used original springs and had them re-arced at spring shop. White knuckle driving!! From bump steer. I moved my steering box to in front of axle, using original draglink. Also made a bracket and raised it so drag link was running horizontal. Then took to alignment shop and had toe set. Installed 22" tires. drives straight, no bump steer fun to drive now.

Brucer

Post Reply