Dropped Pitman Arms

[Ranger44]

I'm looking into buying dropped pitman arms. I've heard that with the 6in lifts they usually give you a new arm that is too short. Is this the case for the skyjacker 4in lift or will the 4-6in drpped arm do well at properly aligning my steering linkage?
Thanks

 

[Ranger44]

bump

 

[du510]

I had no problems properly aligning with my 4" kit - with the drop arm that came with it.

If that helps you at all....

 

[rickcdewitt]

the only reason i diden't run one in my truck is because i noticed the driver side frame rail twisting visibly with the steering box when i turned the wheel.open your hood and start the truckthen reach in the cab where you can see the steering box still.when you move the wheel the box should rotate a little against the direction of the pitman arm.a drop pitman arm gives it that much more leverage on the frame.i built a brace that goes from the pass. side of the engine crossmember to a clamp around the bottom of the steering box(like the jeep braces you see in mags) which helped a lot.my trucks a long bed so the bump steer isen't too bad but i want to run a superrunner set up when i can afford it.

 

[Ranger44]

Thankyou!

 

[4x4junkie]

The arm that comes with a lift will work acceptably at 3-4" lift, but not any higher (you'll need the Skyjacker pt# FA600 arm (or a custom K-link setup) to get the linkage aligned well at 5-6" lift).

 

[Evan]

The longer pitman arms increase the force on the gear box quite a bit. I think Todd recently had his gearbox bolts tear right through the framerail, and had to weld on a beefy backing plate.

 

[88mudder]

most 4" arms dont work good witha 6" lift. Too short. 4" arms work with any lift 2-4". STX highrider pitman arm is the same exact dimensions as a 4" arm FYI. Jeep CJ 4" arm is the same as a ranger/b2 arm.

 

[MAKG]

The longer pitman arms increase the force on the gear box quite a bit. I think Todd recently had his gearbox bolts tear right through the framerail, and had to weld on a beefy backing plate.

How might that be?

I could see large tires or uncorrected alignment increasing the force on the gearbox, but the drop should be parallel to the sector shaft, and therefore shouldn't change the force on its own.

A correct drop will also not change the steering linkage angles from stock; that's the point of dropping it.

 

[rickcdewitt]

How might that be?

I could see large tires or uncorrected alignment increasing the force on the gearbox, but the drop should be parallel to the sector shaft, and therefore shouldn't change the force on its own.

A correct drop will also not change the steering linkage angles from stock; that's the point of dropping it.

put it this way,the frame rail is the pivot point and the distance from its center to the point where the end of the drop arm would be perpendicular to the sector shaft is the distance that steering forces have as leverage against the frame.if you move the distance down the sector shaft centerline you make more leverage against the frame so it twists more and fails sooner.bigger tires will increase the amount of force to turn them but the drop arm will increase the leverage.not a good combo when put together.i figured you'd understand that MAKG

 

[MAKG]

That's not leverage on the gearbox. It's leverage on the mounting bolts.

So use bigger mounting bolts and reinforce the frame.... IF it's really a problem. I have a very hard time believing that it's anywhere near as bad as you say -- most drops less than double the distance, so those bolts would have to be marginal in stock form. Or your buddy spun his truck out and whanged a curb.

 

[Evan]

How might that be?

I could see large tires or uncorrected alignment increasing the force on the gearbox, but the drop should be parallel to the sector shaft, and therefore shouldn't change the force on its own.

A correct drop will also not change the steering linkage angles from stock; that's the point of dropping it.

You have a good point. I actually can't think of why the force on the frame rail would be increased from a Physics standpoint.

It does seem however, from practical experience, that it is increased. I know someone above said they noticed the rail twisting much more after the install and built a brace. Todd had his longer arm in for no more than a month before the bolts tore right through the rail. After I installed mine, my gearbox sprung a leak in the lower sector shaft seal.

Now, you could reasonably say that this is caused by running large tires, locked axles, and abuse on the trail, but the timing is suspicious.

Maybe the longer shaft causes the box to want to rotate more on a perpendicular plane around the frame rail rather than on a parallel plane which is more the norm, and what the bolt pattern is designed for.

A vector diagram would be hepful here, as I have a lot of trouble visualizing all the forces on a TTB.

 

[Evan]

...I have a very hard time believing that it's anywhere near as bad as you say -- most drops less than double the distance

Even a 50% increase of a lever's length translates into a lot of force. Some of the arms I've seen on 6" lifts are really long! It takes a big drop to get down to that level.

 

[MAKG]

A 50% increase of a lever's length leads to a 50% increase in force. That's it.

An impact can raise the force by a factor of several (easily), possibly much more.

 

[Evan]

A 50% increase of a lever's length leads to a 50% increase in force. That's it.

Yup. I don't think you'll find anyone passed the 4th grade who would argue with that. Good old simple machines.

I'm saying that a 50% increase in force is quite a bit.