72 Bronco still has steering issues

[Blue71]

Still wanders and over steers at 45+ mph...

72 Bronco new 3.5" suspension
Brand new 35x12.50x15 Mickey Thompsons
15x10 Eagle 589 wheels
New F100 2wd steering box
New 7 degree c-bushings ( installed correctly)
New radius arm bushings
New adj. track bar and bushings
Adj.drag link from WH for 2wd box
Centered steering box
Centered front axle to frame
New tie rod ends R&L
Newer ball joints
Had alignment shop do their thing......pics below

Still wanders above 45 mph...I'm guessing I need more caster...I figured I'd be in the ball park on caster with 7degree

 

[71Broncitis]

 

[DirtDonk]

...I figured I'd be in the ball park on caster with 7degree

No such thing as a guarantee with these things. But yours is even less than most it seems. And so is your toe-in frankly. And I would even want to see more camber on the left. I think they handle better and get better tire wear with less camber than called for, but you're near zero on that one side (at zero according to one of the printouts) and some have found that not to be a good combination.

Are you sure you have 3.5" suspension lift? Looks like a little more, based on the caster numbers and the steering angles.
When you measure between the top of the axle tube and the bottom of the frame rail in the front, what do you have?

What pitman arm is on the box? Any drop bracket on the trackbar?
With this much lift you MUST use a dropped trackbar bracket (or riser if it seems called for) and then you have to try your best to get the angles of the trackbar and draglink as close to parallel as possible. It's ok to have the shorter draglink a little steeper than the trackbar, but they look a little more than is optimal in that picture. Which doesn't really show enough though, so it would be nice to see more.
Ultimately you want your angles as shallow as possible, and as close to parallel as possible.

Can you post a pic showing both ends of the trackbar and draglink? In other words, just a couple more inches in both directions from the pic above.

What are your air pressures?
Remember that with 10" wheels, although they can work fine on a Bronco, every little thing that's out of whack is magnified from the added leverage that the wheels and tires have on things.
How are the wheel bearings? Been re-packed and adjusted by the book?

Have you checked for excess flex in things by doing the test where a helper racks the steering wheel back and forth continually while you watch all the stuff underneath?
It's practically a must with these rigs.
You can even see if something is loosey goosey in the rear end.

Good luck.

Paul

 

[Broncobowsher]

Unless you actually get the caster checked you are only guessing. My guess, until proven wrong, is not enough caster.

 

[75junebug]

With that steering box, you may have some excessive frame flex if you dont have the support bracket that goes acroos to the pass side frame...Dont be surprised if the front end shop that checked your alignment has things pretty much wrong.....Once you get the Castor angle thing figured out, Toe in is easy to set. I have 2 pcs of 2" angle iron cut at 40" each and a hole at 20". With the wheels off, the angle bolts to the bottom most lug(pointed down) and the at the front there is another hole on each pc(vertical hole) for a pc of allthread with double nuts and washers. the allthread is vertical and lets you set the level of the angle iron. Measure at the back across the 2 pcs of angle (end behind the tire) and again at the front edge(front of vehicle) set the front about 1/16" less than the rear measurement by adjusting the tie rod ends, then check if the steering is centered. This is assuming you have a 3way adjustable tie rod system.Sorry if this seems vague, weve been up the last three nights watching for rising flood waters and tornadoes with Harvey... I'm a bit loopy...

 

[Timmy390]

I don't like the 1/64th of an inch toe. Should be 1/8th to 1/4

Tim

 

[bronconut73]

More toe will make a noticeable difference.

 

[DirtDonk]

Are you still on (reasonably) high ground junebug? Hope so anyway.
After all, row row row yer boat isn't any easier on no sleep either!

Good luck to you and yours.

Paul

 

[75junebug]

Paul, we are very fortunate to be on high ground....All around us within 5 mile radius there is massive flooding, tornadoes and power outages.....we only went 4 hrs without power, and I only had to push water off the patio 1 night.....Cant go anywhere, but we have plenty of food, water and adult beverages.....I even managed to modifye my soft top to get in and out of the garage without taking the top down, painted my hood, and put the door seals in I got from yall 3 years ago......Kids + stuck indoors 3+ days= garage time for dad.....
Not making lite of the situation, its bad from Corpus all the way up the coast beyond Houston.....Beamont is getting it today...

 

[WILDHORSES]

Just to reinforce the main issue. The problem is you basically have no caster to speak of. Fix that and you will have a night and day difference. Kudos on posting the numbers, makes the job easy.

Jim

 

[Broncobowsher]

Since you are already maxed out with the 7° bushings there are only a couple of fixes left. The front U-joint angle is probably maxing out as well, so I will skip any idea of radius arm drop brackets or long arms. They can fix caster but the U-joint angle will be too severe. So that leaves a few options. Less lift will add caster, but few want to go that way. Probably your best fix is a cut and turn. Flip one bushing on each side (cancels out the correction and gives 0° of rotation). This fixes the U-joint angle but will wreck the caster into nearly -7°. You then cut the outer "C" on the axle and rotate that back about 12°. Now you have a great U-joint angle and a great caster number.

 

[Bajabrewer]

Don't know if this will get you what you need in the way of caster but it may help. I'll admit I know nothing about correct angles so I'll let the experts chime in.

http://shop.broncograveyard.com/Spindle-Shim-66-75-80-96/productinfo/12214/

 

[Broncobowsher]

Don't know if this will get you what you need in the way of caster but it may help. I'll admit I know nothing about correct angles so I'll let the experts chime in.

http://shop.broncograveyard.com/Spindle-Shim-66-75-80-96/productinfo/12214/

That won't do it. It will only change camber (the caster in the description is wrong). It mounts between the spindle and the knuckle, doesn't alter the alignment of the ball joints (which is caster, the imaginary line through both ball joints).

I did forget about the eccentric ball joint option. But that is still rather limited in what it can correct.

 

[Blue71]

Paul, yes new 3.5" front coils from Toms and frame to axle tube measurement is about 10 3/4"

It has a welded-on...drop track bar bracket.

stock pitman arm to get my drag and track bars close to parallel.

Tire pressure is 35 psi...(would less or more air possibly help)

Steering wheel has no play side to side when sitting still. With a helper I've checked all the front stuff and nothing really seems to flex much.

Wheel bearings replaced and packed when new disc brake kit was installed

 

[Blue71]

I didn't see a brace so I might add one..good suggestion...thanks and hope you all are safe down there.

Andy
Blue71

With that steering box, you may have some excessive frame flex if you dont have the support bracket that goes acroos to the pass side frame...Dont be surprised if the front end shop that checked your alignment has things pretty much wrong.....Once you get the Castor angle thing figured out, Toe in is easy to set. I have 2 pcs of 2" angle iron cut at 40" each and a hole at 20". With the wheels off, the angle bolts to the bottom most lug(pointed down) and the at the front there is another hole on each pc(vertical hole) for a pc of allthread with double nuts and washers. the allthread is vertical and lets you set the level of the angle iron. Measure at the back across the 2 pcs of angle (end behind the tire) and again at the front edge(front of vehicle) set the front about 1/16" less than the rear measurement by adjusting the tie rod ends, then check if the steering is centered. This is assuming you have a 3way adjustable tie rod system.Sorry if this seems vague, weve been up the last three nights watching for rising flood waters and tornadoes with Harvey... I'm a bit loopy...

 

[DirtDonk]

Well, one solution for the angles would be to make or buy a trackbar drop bracket with slightly more drop. Can't really see well enough to know which one you have now, but dropping the mount a bit more would help in two ways. One it would get the two bars even more parallel, and two, in doing so would also serve to lower the overall angle of the trackbar.
Less angle and more parallel are both good things with Bronco geometry.

But you're right. Yours is not that far off, and not as steep as some. But both could still be improved.
This may not get rid of your troubles, because you do still need more caster no matter what. But it still helps.

Paul

 

[NC-Fordguy]

Not sure if this would help but I'm running on my 74, 17x9 on 37 in tires and and they like 27 PSI for good handling on road and even tread wear.

My 77 that just got wrecked with 35in tires with 15x8 wheels liked about the same

 

[Blue71]

What about these? Says for 66-79 Broncos and has 4.25 dog caster built in like the long tube arms, but are direct replacements? With 7 dog bushings surely that would get me in the 3-4 deg or more range?

Blue71

 

[DirtDonk]

...Tire pressure is 35 psi...(would less or more air possibly help)

Yes. Very likely less air would help. But what are the pound ratings on the side of the tire? Load Range too?
Most members here end up liking 28 to 32 in the front. Almost always less in the rear by a couple of pounds, but that's not universal. I've had tires that liked equal pressures, but most preferred less in the back.

Your 35 is not way out of line, but it's worth the experiment. Many tires can actually react quite a bit to just a few pounds. While with some it hardly makes any difference.
Give it a shot at 30 front, 28 rear, and see what you get.
Or do what I do and just lose 2psi per test until you find the sweet spot.
Takes longer, but worth knowing the range.

Steering wheel has no play side to side when sitting still. With a helper I've checked all the front stuff and nothing really seems to flex much.

Excellent news. Actually these boxes are known for being pretty tight and reliable. But it's always good to know for sure.

Wheel bearings replaced and packed when new disc brake kit was installed

Did you follow the official Dana adjusting procedure?
It's pretty strange, so worth asking.

Good luck.

Paul

 

[DirtDonk]

What about these? Says for 66-79 Broncos and has 4.25 dog caster built in like the long tube arms, but are direct replacements? With 7 dog bushings surely that would get me in the 3-4 deg or more range?

Blue71

Sure, it gets caster back. But like someone was saying before, you can only do so much for caster before your front u-joint won't take it anymore.
Can you post up a pic of your diff yoke and driveshaft from the side?

Paul