Veering problem after James Duff 3.5" Ultimate Kit

[bubobronco]

Ok, here's the situation....I installed a JD ultimate 3.5" suspension lift on my '74. Initially it was almost undriveable as caster came in at -1.5. Installed JD drop brackets and that brought it to +1.5. Still drove like crap. Uninstalled the drop brackets and went with the JD long travel radius arms which now brings the caster to +4.0. Truck handles much better and will track straight down the road at constant highway speeds. However, it will quickly pull to the right when I take my foot off the gas and pull to the left when accelerating. Also will veer toward the right when hitting road bumps, very unnerving....and it did not do this before the lift.

I did not expect new tires to fix the problem but FYI..the problem existed with the old crappy 31" tires and still does it with brand new 33" MT Baja ATZ's mounted on MT Classic Lock chrome beadlocks (sweet rims bought from a member here). I also brought air pressure down to 28 from 34psi. as suggested from another bronco guru and no help there...

Sorry about the novel here but I need some HELP!!

Ps. All steering components are original stock parts..

 

[garberz]

Sounds like you have a locker in the rear and now the suspension has uncovered it's road behavior, because it's working. Old suspension components hide a lot because of the lack of movement.

Mark

 

[broncnaz]

Need to look at your track bar and drag link angles you are experiancing bumpsteer. Also a softer suspension will load when on the gas and unload when you let off the gas which would cause pulling. If you can fix the bumpsteer issue it should minimize the accel/decell issue. Although you might not totally get rid of that issue.

 

[DirtDonk]

Popping in to listen to the discussion too.
But like broncnaz was saying, did you install the dropped pitman arm and trackbar brackets? I think the kit automatically comes with the drop bracket, but you always have to install a pitman arm to match the bracket with a '74's stock steering linkage.
If the angles of the draglink and trackbar are no longer parallel, you will get some funky motions.

And regarding the negative caster reading, that's kind of strange. Not that we don't get low readings of course, but with supposedly 7° degree bushings included with the kit, you should have had at least 1.5 to 2 degrees positive I would have thought.
Almost like you have one half of the bushing pair installed correctly, and the other half incorrectly.
You didn't happen to verify visually that you received the full 6.5 or 7 degree bushings by any chance, did you?

Good luck.
By the way, got any pics of your rig from the front, showing the steering setup?
If you don't have an online image hosting site you use (to link us to pictures) you can e-mail me (or anyone with a yellow "contributor" below their user name) the images and I can post them directly for you.
Or you can pay the 13 bucks and become a contributor yourself. That lets you upload directly from your computer to the site.

Paul

 

[bubobronco]

Sounds like you have a locker in the rear and now the suspension has uncovered it's road behavior, because it's working. Old suspension components hide a lot because of the lack of movement.

Mark

What's a "locker in the rear?" Sounds a little kinky..

 

[norm02]

Popping in to listen to the discussion too.
But like broncnaz was saying, did you install the dropped pitman arm and trackbar brackets? I think the kit automatically comes with the drop bracket, but you always have to install a pitman arm to match the bracket with a '74's stock steering linkage.
If the angles of the draglink and trackbar are no longer parallel, you will get some funky motions.

And regarding the negative caster reading, that's kind of strange. Not that we don't get low readings of course, but with supposedly 7° degree bushings included with the kit, you should have had at least 1.5 to 2 degrees positive I would have thought.
Almost like you have one half of the bushing pair installed correctly, and the other half incorrectly.
You didn't happen to verify visually that you received the full 6.5 or 7 degree bushings by any chance, did you?

Good luck.
By the way, got any pics of your rig from the front, showing the steering setup?
If you don't have an online image hosting site you use (to link us to pictures) you can e-mail me (or anyone with a yellow "contributor" below their user name) the images and I can post them directly for you.
Or you can pay the 13 bucks and become a contributor yourself. That lets you upload directly from your computer to the site.

Paul

Pictures would be very helpful and the $13 is worth it

 

[broncnaz]

What's a "locker in the rear?" Sounds a little kinky..

He's refering to a traction device in the rear axle. Such as a limited slip, or full locker like a detroit they tend to have some handling charateristics similar to what your experiancing but I think its more due to your lift.

 

[diiulio]

Ditto above about pitman and drag link, but also check your engine and transmission mounts. My FJ40 would pull left on hard accelerator and come back right when I left off. Replaced all the bushings in the suspension and still had the pull. Checked motor mounts and one is completely shot.
Good luck.

 

[bubobronco]

Popping in to listen to the discussion too.
But like broncnaz was saying, did you install the dropped pitman arm and trackbar brackets? I think the kit automatically comes with the drop bracket, but you always have to install a pitman arm to match the bracket with a '74's stock steering linkage.
If the angles of the draglink and trackbar are no longer parallel, you will get some funky motions.

And regarding the negative caster reading, that's kind of strange. Not that we don't get low readings of course, but with supposedly 7° degree bushings included with the kit, you should have had at least 1.5 to 2 degrees positive I would have thought.
Almost like you have one half of the bushing pair installed correctly, and the other half incorrectly.
You didn't happen to verify visually that you received the full 6.5 or 7 degree bushings by any chance, did you?

Good luck.
By the way, got any pics of your rig from the front, showing the steering setup?
If you don't have an online image hosting site you use (to link us to pictures) you can e-mail me (or anyone with a yellow "contributor" below their user name) the images and I can post them directly for you.
Or you can pay the 13 bucks and become a contributor yourself. That lets you upload directly from your computer to the site.

Paul

I will try to get some pics on here one way or another. Hopefully over the weekend when I get back home... Thanks.

 

[DirtDonk]

Here are some pics of bubo's front linkage. There is no dropped pitman arm, but there is a slightly dropped trackbar bracket. So there is a slight misalignment of the links, along with a fairly steep angle on them both.
Looks like a better combination of drops to bring things back to parallel and to drop the overall angles would be in order.

Not sure if Duff also sells a bracket with more drop (haven't looked yet, but maybe Mike will see this and chime in), but that would seem to be appropriate for the taller 3.5" lift in use here.
Along with a pitman arm of course.

 

[bubobronco]

Ditto above about pitman and drag link, but also check your engine and transmission mounts. My FJ40 would pull left on hard accelerator and come back right when I left off. Replaced all the bushings in the suspension and still had the pull. Checked motor mounts and one is completely shot.
Good luck.

I don't notice it as much on acceleration as I do when slowing down. Let's just say, if I loaned the truck to someone I would be sure to warn them about it first. If your driving and just take your foot totally off the gas it will quite suddenly point you toward the ditch. Of course if you know its coming and slowly let up on the gas and get ready to counter steer to the left....no bigee.

The motor mounts were just replaced when I rebuilt the engine...

 

[KBUCK1]

U bolts. How Tight Are They. Bet thats your problem

 

[tad3790]

I had a 2" lift with a lowered track bar but NOT a lowered pitman arm and I had the **exact** behavior you are describing. Lowered pitman arm installed.....problem solved.
At this very momment I am installing this exact kit also. (moving from the "add a leaf" lift to the Duff part# 5000G kit. It will be a few weeks before I can get it installed, but when I do I will let you know if I have any issues.

For what it's worth, I believe all the ideas I just read here are possible .... but I think your lowered pitman arm is the answer based on how mine was acting prior to changing the pitman. It was a white knuckle experience to lift out of full throttle.

 

[Broncobowsher]

I've seen worse steering. I suspect there is some bumpsteer. Easy to check. Take the front shocks off. Take something and a couple of clamps and lock the tie rod to the axle tube. You can do this with a 2x4 and a couple C-clamps. Now bounce the front of the truck. Watch the steering wheel. Does it saw side to side matched with the bouncing? That is the bumpsteer. That is bad geometry of the drag link and track bar. Something else you may notice, the body shifting side to side during that bounce. That is the track bar angle causing that. At steeper angles it causes more side shift.

But that isn't all folks! The rear end can do it as well. What shape are the spring bushings in? If one has gone bad it will allow that side to shift forward and rearward. That causes the rear axle to steer, something very obvious in a short wheelbase vehicle. But since you feel it on bumps and dips I think it is more of a front end problem and not the rear axle.

 

[KBUCK1]

Sounds like rear steer to me too. Ubolts to about 80 ft pounds. That's super tight. Mine was doing the exact same thing. Had to retorque them. Problem solved

 

[bubobronco]

Here are some pics of bubo's front linkage. There is no dropped pitman arm, but there is a slightly dropped trackbar bracket. So there is a slight misalignment of the links, along with a fairly steep angle on them both.
Looks like a better combination of drops to bring things back to parallel and to drop the overall angles would be in order.

Not sure if Duff also sells a bracket with more drop (haven't looked yet, but maybe Mike will see this and chime in), but that would seem to be appropriate for the taller 3.5" lift in use here.
Along with a pitman arm of course.

View attachment 388316 View attachment 388317 View attachment 388318

Thanks to DirtDonk for posting the pics and the advice from all. I am talking with the guys at Duff to work on a solution...

 

[bubobronco]

Sounds like rear steer to me too. Ubolts to about 80 ft pounds. That's super tight. Mine was doing the exact same thing. Had to retorque them. Problem solved

Checked the ubolts and the right side were slightly loose. Cranked them back down as hard I could with with a 3/4" box end wrench. Test drove with the same results. It tracks straight as an arrow at a constant speed. I can keep the truck where I want it on the road (totally hands off) just steering with the gas pedal. Add power=truck goes left.....Let off on gas=truck goes right (big time right).

 

[ohpoo2]

Like dirtdonk said them bars need to be together so it all moves together. He helped me with my bronco that was just plain scary on the road. Thanks again Paul!

 

[needabronco]

I'm going to jump in here and ask if your front C bushings are correct AND installed the right direction? It's really easy to install them upside down and even backwards. That would easily explain your castor problem, having one side wrong could easily explain it darting off the road. If you look at your front end your axle isn't centered under your truck either, that can cause some of your 'twitchy' feeling. Your track bar/drag link are slightly off which will give you some bump steer as well.

The rear suspension is also something you need to address. As stated a loose rear end can cause the same symptoms.

Go over every nut and bolt in your suspension and steering system also.

 

[KBUCK1]

Checked the ubolts and the right side were slightly loose. Cranked them back down as hard I could with with a 3/4" box end wrench. Test drove with the same results. It tracks straight as an arrow at a constant speed. I can keep the truck where I want it on the road (totally hands off) just steering with the gas pedal. Add power=truck goes left.....Let off on gas=truck goes right (big time right).

you arent getting them anywhere near 80 ft pounds with a box end wrench. not even close