1. This is a "Rule of Thumb"...
2. Anything over 2" and you'll need to change to a drop Pitman arm.

 

Thanks Leve,

Does the rule of thumb continue onto saying that the amount of drop in the pitman arm should be equal to the amount of suspension lift?

 

Leve?... your input, please.
thanks..

 

Trivia question of the day: Does anywone know where the saying "Rule of thumb" came from?

 

I have a total of 4 inches of lift on my YJ, and when I tried to put in a dropped pitman arm I couldn't get the old one off, I figured I would put the whole thing back together, and maybe try and pull the arm at some other time. Well I am still driving around every day with the stock arm, and no front sway bar. It doesn't really bother me that much, and the Jeep is still very streetable. I am also running 33X12.5's.
I am not saying that I recomend that you don't change arms. If I could get my old one off, I would swap to a dropped arm in a second... I am simply trying to say that it IS possible to drive a Jeep with 4" of lift without one.

 

I believe it had something to do with the size of stick you could beat your wife with. Anything up to the size of your thumb. Hence, "The rule of thumb". Am I right?

 

1. Leaf springs move the axle up and down.
2. The drag link swings in an arc,
3. When it swings, it's lateral position changes.
4. End result is when you hit a bump, the suspension compresses and creates steering input.
5. Or, simply Bump Steer...
6. The CJ has a Front Track bar.
7. As the suspension cycles,
8. The trak bar also cycyles,
9. Minimizing the Bump Steer.
10. A lift will change the geometery.
11. The Drag link and the Track bar movement no longer match.
12. To elimanet this a Drop Pitman Arm is used.
13. However, it doesn't always minimize because it can't match both
14. Track bar and Drag Link movement.
15. So, in reality, correction is a misnomer...
16. Minimization is a better term.
17. So how big does the Pitman Arm drop need to be?
18. It's a good question...
19. It depends on the geometery needed to be corrected,
20. The operative movement is the Vertical movement of the springs..
21. If the drop is going to accodimate the vertical movement...
a. which is the size of the lift!
b. However IMHO... go a little longer!
22. That's about the best you can do with a new Pitman Arm.
23. Otherwise.. its modification of the other suspension pieces.

 

Olin,
I busted a pitman arm puller or two before I got mine off my 78. I kept soaking it in PB Blast and learned a new trick. With the last puller, I keep slowly adding pressure on the puller till it was close to busting. Then I tapped/hit the outside of the pitman arm by the splines with a small sledge and eventually it will let go. Good thing the part store has a loan a tool program and you don't have to pay for broken tools.

 

In reply to:

I kept soaking it in PB Blast and learned a new trick. With the last puller, I keep slowly adding pressure on the puller till it was close to busting. Then I tapped/hit the outside of the pitman arm by the splines with a small sledge and eventually it will let go.

[/ QUOTE ]

That's not a "trick", that's how you do it. The end of the puller screw is made to be hit. When you hit it, the shock transfers to the shaft having the exact same effect you did by hitting the side of the arm. If you were only tightening it down until it snapped, you were doing it wrong.

 

It didn't come with directions so I guess that makes me pretty smart for figuring it out on my own.

 

In reply to:

It didn't come with directions so I guess that makes me pretty smart for figuring it out on my own.

[/ QUOTE ]1. I'm sure you said this "tounge in cheek", but
2. As I've been saying for years:
3. "You're your own best mechanic."
4. Your as smart as most mechanics,
5. If not more so,
6. So pat yourself on the back,
7. Multiply the knowledge by
8. Helping out others when needed.
9. You have done well, but you can do better...

 

"1. Leaf springs move the axle up and down.
2. The drag link swings in an arc,
3. When it swings, it's lateral position changes."


How does that apply when the suspension has been modified to coilover shocks (front & rear) which is my specific case?
Resulting in an approx lift of 3" (work not final yet).

 

1. With Coil overs... it gets worse...
2. You've got a lot more movement...

 

Oh gosh!...

Tell me now what should I do to pre-empt trouble....

 

1. I wish I could..
2. But, my understanding of Coil Over movement is limited, at best.
3. The only thing I'd be worring about is any horizontal movement of the axle built into the system.
4. If the control arms do a good job, now, of limiting movement then,
5. If so, you should be OK with a drop pitman arm for the height of the lift...
6. If the control arm bushings are worn... there will be some:
a. Possible binding.
b. Possible tracking problems.
7. You now know what I know...

 

1. I wish I could..
2. But, my understanding of Coil Over movement is limited, at best.
3. The only thing I'd be worring about is any horizontal movement of the axle built into the system.
4. If the control arms do a good job, now, of limiting movement then,
5. If so, you should be OK with a drop pitman arm for the height of the lift...
6. If the control arm bushings are worn... there will be some:
a. Possible binding.
b. Possible tracking problems.
7. You now know what I know...

 

Thanks Leve,

I am using the same set up in the front and rear:
Land Rover Defender front control arms. They were also used on '86 Range Rovers. Same style control arms are still used on Monteros and Toyota Land Cruisers... I hope you know which ones I'm talking about... (They brace the diff from underneath it...in two points)

Since they were salvaged, I have purchased new original bushings for them.

 

1. Cool... those are darn fine parts.
2. You should have no problems with them.
3. I hope you are coing to share your project with the Forum.
4. This is one project I'd like to follow...

 

Thanks Leve,

Currently finishing welding work on the frame...

The originator (the one thatput the bug in my ear !!!) is AB@shortwheelbase.com ... someone I think you know well...