Steering sensitivity issues

[Green_Bastard]

Hey guys
I'm hoping someone will have some ideas on how to tame my steering a bit. I recently got my 71 to a drivable state after a frame off build and I've found that the steering is extremely sensitive. If I hit a bump, it gets a bit squarely and as I pick up speed it starts wandering a bit. I wouldn't call this bump steer since the steering wheel doesn't jerk at all when I hit a bump. Its just so sensitive that its hard to keep it straight. I've been wondering if a stiffer steering stabilizer would help but if so, where would I find one? My setup is listed below and I've attached the alignment results from a few weeks ago. I'm looking for any suggestions to tame this a bit

3.5" lift
35" tires
Tom's steering stabilizer
Ruff Stuff 1 ton steering with "the cure"
Tie rod over
Trackbar riser
Explorer PS pump
4 turn 4x4x2 steering box

 

[billh1289]

Did you install a drop pitman along with the trac bar riser? Can you post a pic of the front end?

 

[Green_Bastard]

I don't have a drop pitman arm but I'm running tie rod over. The drag link and track bar are almost exactly inline with one another. After thinking about this, I think its probably the caster angle. Its currently negative. After reading a bit about it, it should be about 3.5 positive. Wonder if anyone can confirm this? I've worked on engines all my live but I've never done anything with alignments

 

[Broncobowsher]

You want positive caster. Lifting rolls the axle forward, going negative.

Stock specs are very low. Trying to get that manual steering to be easier to drive. With power steering you really want 5-7° positive caster. Most just settle for anything positive. You can only get so far with offset bushings. There is also front pinion U-joint angle issues that get in the way.

 

[DirtDonk]

Yes, I agree that caster is at least a huge problem. Even if it's not the only problem.
Do you remember what degree offset C bushings you installed for the suspension lift? Should have been 7° for most Broncos. Unfortunately a great many Broncos prior to 76 did not have very good caster numbers to begin with. Add a Lyft edit gets worse. Add bigger tires on water wheels and everything negative is magnified!

Definitely post up some pictures of your front end though. Just for the heck of it. Sounds like you have it pretty well dialed in, but it never hurts to check.

And if you have a chance to do the test anytime soon, make sure there's no cracking in the frame behind the steering box. It's very possible for even a big crack to be invisible to the eye even with the steering box removed, but as soon as you start torquing those big tires you can see the box flex on the frame.

 

[Rustytruck]

what tire pressure are you running? try closer to 30 psi.

 

[Broncobowsher]

Looks like you updated the post with an alignment sheet. Going from toe out to toe in is going to help. But you are still almost -2° on the caster. I can understand the wandering.

 

[73azbronco]

Do you have stock steering box or 4x4x2? My own poll. I'm reading your issue here more with folks with the 4x4x2 mod than stock. Mine included.

 

[englewoodcowboy]

I see the biggest issue being the caster. We try to get a minimum of 3° caster or more to have decent handling at speed. You have a 3.5" lift you should have used 7° C bushings but it may not be enough. Those numbers as others mentioned will get you into stock spec which was designed for manual steering. With power steering you need as much caster as you can get. You may need to look at radius arm drop brackets to get that thing tamed.

 

[Broncobowsher]

A radius arm drop can make front pinion U-joint angles severe.
Yet another option that fixes the U-joint angle issue and gets you caster is to cut and turn the outer C's on the axle tubes. Take out the offset bushing (or go very minor) to get a happy driveshaft angle and tip the knuckles back for happy caster.

 

[Apogee]

A radius arm drop can make front pinion U-joint angles severe.
Yet another option that fixes the U-joint angle issue and gets you caster is to cut and turn the outer C's on the axle tubes. Take out the offset bushing (or go very minor) to get a happy driveshaft angle and tip the knuckles back for happy caster.

X2...you could do what's stated above, or you can choose a c-busing to get the pinion alignment you want and then cut and turn the knuckles to get the 5-7 degrees of positive caster you want. In general, I would probably run a little more toe as well, noting that .26 degrees with 35 inch tires equates to roughly .08" of toe, whereas I would probably be double that. Once you get your caster in the ballpark, you can pick a toe-in number you like, as that's relatively easy to adjust.

Tobin

 

[Z Bronco]

One thing to check and is not always easy to spot is a broken frame at the powers steering box. That ended up being the problem with mine, though mine used to steer straight. It was all over the place till fixed. Now is back to one finger steering and I don't even have a steering stabilizer.

 

[Green_Bastard]

Hey guys,
Sorry for the slow response. I got one of my kids off to college recently and I'm still trying to get a few things taken care of for him. Answers to questions are below.

Yes, I agree that caster is at least a huge problem. Even if it's not the only problem.
Do you remember what degree offset C bushings you installed for the suspension lift? Should have been 7° for most Broncos. Unfortunately a great many Broncos prior to 76 did not have very good caster numbers to begin with. Add a Lyft edit gets worse. Add bigger tires on water wheels and everything negative is magnified!

Definitely post up some pictures of your front end though. Just for the heck of it. Sounds like you have it pretty well dialed in, but it never hurts to check.

And if you have a chance to do the test anytime soon, make sure there's no cracking in the frame behind the steering box. It's very possible for even a big crack to be invisible to the eye even with the steering box removed, but as soon as you start torquing those big tires you can see the box flex on the frame.

After the frame was blasted, it was thoroughly inspected for cracks around the steering mount and track bar mount. I've also welded in plates on both sides of the frame for the steering box as well as spacers inside the frame to prevent crushing so hopefully cracks will never be an issue. I've also attached a pic showing the geometry.

what tire pressure are you running? try closer to 30 psi.

I've got this dialed in at 31 psi with a good tread pattern.

Do you have stock steering box or 4x4x2? My own poll. I'm reading your issue here more with folks with the 4x4x2 mod than stock. Mine included.

I've got a 4 turn 4x4x2 box.

A little more info. I've got the BCB radius arms with caster adjustment built in. I feel like a newb for overlooking that adjustment. Since I had the ability to adjust the caster in the radius arms, I used 2 degree bushings thinking that would be plenty. I did adjust it out last night to its maximum and I'm now getting about 2 degrees positive. It feels MUCH better but when I hit a big bump I can tell I need a little more caster. I have a set of 7 degree bushings on the way and plan to install them this weekend and readjust and get it realigned as well. I'll let you guys know how it goes after that.

 

[DirtDonk]

Look forward to hearing the results. But also pay close attention to your front pinion angle. That's a lot of correction!
The potentially good news however is that you could have as much as 7° positive caster. Which is another thing that we are looking forward to hearing about your feelings on.

 

[Green_Bastard]

Look forward to hearing the results. But also pay close attention to your front pinion angle. That's a lot of correction!
The potentially good news however is that you could have as much as 7° positive caster. Which is another thing that we are looking forward to hearing about your feelings on.

I probably should have gotten 4 degree bushings but I figured I can always adjust caster out with the adjustment on the radius arms. Worst case I'll get the outer Cs adjusted but I'm trying to avoid that


Sent from my iPhone using Tapatalk

 

[73azbronco]

Within a week or so, stars willing, i will be throwing mine on the alignment table for first time. I'll add what I have when I know as I have the same OP symptoms.

 

[nvrstuk]

Been following but not adding comments till now. Caster for sure and then see where you're at. Just emphasizing what everybody else said.

6-8deg has been a magic number for many. ALL the guys I've talked with that have 8deg said they'd never go back to less than 8deg, me included. Seems to be a a magic # or something.

Let us know how it goes.

 

[DirtDonk]

10-4 on the adjustment. Nice to have when you need to fine tune things.

Paul