Bronco Pulls to Side when Accelerating/Decelerating

[Revelation]

eyeball mine

The geometry of yours is maintained correct due to the drag link being mounted to the knuckle, not in the stock location, therefor keeping the drag link and track bar in relation to each other as intended by the team of engineers that designed it.

 

[NYLES]

The geometry of yours is maintained correct due to the drag link being mounted to the knuckle, not in the stock location, therefor keeping the drag link and track bar in relation to each other as intended by the team of engineers that designed it.

Thank you I done good! Did that drag link to tie rod mount not long ago but had to keep the tie rod under the knuckles becaue of conntact after installing the trac bar riser. With the TRO set up had too many bolt heads and nuts right there at the lower end of the trac bar...I like it so far and feel the tie rod is plenty high.

 

[NYLES]

After looking real hard at your pic. I think I would get rid of the trac bar drop bracket and the drop pittman arm.

 

[rjrobin2002]

Cut that track bar drop bracket off and adjust you track bar longer and you will feel like you have a new Bronco. Leave the drop pitman arm.

 

[bad 68]

You didn't say what stearing box your using, or did you.
I have 3.5 inch suspension lift with drop pitman arm and drop bracket for track bar. Both of them are very paralell.

I don't understand why it looks like you need to remove the drop bracket, but it does.

I have bad torque steer NO bump steer.

Goes to the driverside on acceleration, toward the passenger side ditch when I let off to shift gears. I don't mind it any more. Once I learned it now seems natural.

 

[Jeff76]

Here's a picture of my current setup.

As you can see, the trac bar and drag link are not parallel. They're off by 4.9 degrees, which is a pretty significant difference. I did the math and I would have to drop the pitman arm by ~2.5 inches to get the drag link parallel with the trak bar. I can't see that happening without going to a different steering box.

I've recently replaced the entire front and rear suspensions, steering setup, ball joints, brakes, you name it. No lockers and axles are stock. Shocks are pretty old and are pretty much shot. When I had the rear axles out, I did notice the splines had started to yield and are slightly rotated. I also noticed that the factory Trak-Lok rear differential is basically completely shot as I can hold one tire with my pink finger from spinning when the truck is up on jack stands and in gear. There is also a fair amount of slop in the rear end when rotating a tire back and forth, so maybe the differential is shot.

I'm running a 3.5" suspension lift with a 1" body lift, wildhorses rock crawler springs, adjustable track bar, wildhorses 3-way adjustable steering linkage, trac bar drop bracket, drop pitman arm, factory bronco power steering box rebuilt by yours truly, 7 degree C-bushings (I think), stock radius arms, and customized original solid steering shaft. I did have a wheel alignment done on this and the caster was within ford spec, but was a little low.

Also, my Bronco does indeed have bump steer. When I hit bumps, the wheel does jerk one way or the other, in addition to jerking one way or another when accelerating or decelerating. It also rides like a wagon on a dirt road, not sure if that is because the springs are too stiff or because my shocks are completely toast. All in all, it makes for a pretty exciting ride.

Funny, but I've recently done almost the same as you . I started a bumpsteer thread over in Tech also.

For some reason, I keep looking at your drag link. Mine is from TBP, so its different. I know this is not likely, but is it possible that the orientation of that drag link is backward? Just seems strange to me that the adjustment is so close to the Tie rod end, rather than the the pitman arm side. Is it possible that it could bind on the tie rod under compression? Probably I am off base, but like I said, something seems off there, and I cant put my finger on it.

 

[rjrobin2002]

I learned the hard way like you are that it is best to do your steering first, then order what you need to get the track bar parallel. Not order everything at once.

 

[maverickconner]

OK, Im just going to throw it out there, did you check your tire pressure, geometry is great as long as you are equal. I have seen this multiple time, simple things first.

 

[mavman427]

I agree, the track bar drop bracket need to go.

That's going to be a real pain in the ass, it's welded to the frame. I'm toying with the idea of using a mag drill to drill another hole 2.5" further up the trac bar drop bracket and then hacking off the excess with a cutoff wheel.

I am considering going with the WH exteme steering gear as I'm not super happy with the OEM one, not sure if the output is any lower than what I have now. That might partially solve the problem if it is.

 

[mavman427]

OK, Im just going to throw it out there, did you check your tire pressure, geometry is great as long as you are equal. I have seen this multiple time, simple things first.

Yeah, tire pressures are good.

 

[ssray]

While the bump steer is going to be there from non parallel linkage it seems the effect would be the opposite of what's happening. I'm assuming under acceleration the front lifts or in effect the front axle drops a bit. The track bar will move the axle a bit to the driver side. However the drag link being at a higher angle will move the tie rod further driver side then the axle in effect causing steer to the left rather than the right. And deceleration would be the opposite. Either My vector analysis is screwy or it's torque steer or other steering issues going on. Just trying to understand this as well.

 

[Jeff76]

While the bump steer is going to be there from non parallel linkage it seems the effect would be the opposite of what's happening. I'm assuming under acceleration the front lifts or in effect the front axle drops a bit. The track bar will move the axle a bit to the driver side. However the drag link being at a higher angle will move the tie rod further driver side then the axle in effect causing steer to the left rather than the right. And deceleration would be the opposite. Either My vector analysis is screwy or it's torque steer or other steering issues going on. Just trying to understand this as well.

I think your analysis of the action is correct, but the driver perception may be different. If the axle moves left under acceleration, then the body moves right relative to the axle, hence the feeling of 'moving right'.

 

[Jeff76]

That's going to be a real pain in the ass, it's welded to the frame. I'm toying with the idea of using a mag drill to drill another hole 2.5" further up the trac bar drop bracket and then hacking off the excess with a cutoff wheel.

I am considering going with the WH exteme steering gear as I'm not super happy with the OEM one, not sure if the output is any lower than what I have now. That might partially solve the problem if it is.

Someone suggested on my thread with a similar topic that I do what you are considering. (drill a hole higher hole in my track bar mount in order to be more parallel to the drag link) I have thought about this a lot, and I am not sure that is going to help you.

We've got two issues: Bump steer, and general 'wallowing/flighty feel' to consider on a bronco. You bronco needs to be predictable. If its predictable, and even a small bump/torque steer issue can be managed with driver input.

I think the bronco tie rod / track bar needs to be as parallel as possible to eliminate bump/torque steer, but I also think the track bar needs to be as horizontal as possible through as much of the standard street travel of the suspension as possible to give it that 'planted / straight tracking' feel that we rely on for confidence.

I am not an expert on this (and I wish one would chime in), but I believe a parallel draglink / track bar that is positioned too vertically with still result in a 'flighty' steering feel, and that will not give you the confidence that you need. I think our goal is to keep the track bar as horizontal as possible, and with that positioned in place first, then set out to make the drag link arc match as closely as possible through parallelism.

My two cents. As you can see, I'm searching as well...

 

[chuckinphx]

didnt look through all posts but torque down the u bolts on spring... a few times...(after a lil offroad play..) mine were loose.. every shift id be all over the road... good luck...

 

[bad 68]

I am still not convinced that torque steer and bump steer have to be related. Have you checked rear spring bushings and shackle bushings?

 

[NYLES]

Did you replace trac bar bushings?

 

[bmc69]

I am still not convinced that torque steer and bump steer have to be related. Have you checked rear spring bushings and shackle bushings?

Neither am I. I didn't see where the question about whether or not the rear dif had a Detroit in it was answered. ? The one EB I have that has a Detroit in back will practically change two lanes with one touch of the gas peddle....%)

 

[mavman427]

Did you replace trac bar bushings?

Yeah, truck has new bushings all around.

 

[mavman427]

Neither am I. I didn't see where the question about whether or not the rear dif had a Detroit in it was answered. ? The one EB I have that has a Detroit in back will practically change two lanes with one touch of the gas peddle....%)

No Detroit locker, but something funky may be going on with my rear end. There is substantial play it seems like.

 

[ssray]

No Detroit locker, but something funky may be going on with my rear end. There is substantial play it seems like.

I don't think I've ever heard of this but if something in the right axle broke and locked up the pinion as well you'd be running a left wheel drive which would be pretty squirrelly the way you describe. As a couple of the others have mentioned double check rear suspension hardware, especially the right rear. Something unexpected there could be letting the right rear tire move forward under acceleration and the reverse under decelleration causing rear steer. Hope you find the culprit, squirrelly Broncos are not fun!