Front end alignment

[FOMOCO_1546]

Hi everyone, my bronco has been to easy to steer as long as I've owned it. Couldn't find anyone to check the alignment because they said they would probably damage the wheels. Finally checked my local ford dealership and they had adapters. The caster is way to low and he wasn't sure what ball joint sleeves it needed to correct this problem. Thought maybe someone could help.
1973 bronco
Stock suspension
Power steering
Disc brakes
New bushings
West Texas steering box rebuild

 

[Timmy390]

What size lift and what degree C bushings are you running?

Tim

 

[FOMOCO_1546]

It has a 1" body lift and no suspension lift. The urethane c bushings were installed by previous owner. One thing that has bothered me is, there was a used 2-1/2 or 3-1/2 suspension lift in the bed of the Bronco when I bought it. Don't know if it came off my bronco or was meant to put on this bronco. Thanks

 

[DirtDonk]

That's crazy caster for a stock suspension. But it's not unheard of either, and probably a good part of why yours is so easy to steer.
It's possible that the old C-bushings are in backwards, or at least half-backwards to get that low of a reading. Or it's just the nature of your particular beast as we've become well aware that the Dana axles were not delivered to Ford with the expected readings on every one. You may be one of the unlucky ones with an axle at the extreme low end of the caster scale.
Only way to find out is to try different bushings.

No way you should need 7 degree bushings, but you know that your existing poly bushings are at least 2 degree types (that's the minimum) so going to 7's would net you an additional 5 degrees. Not bad, but probably more than is needed as well. At right around 1 degree already, an additional two degrees from a set of 4 degree C-bushings would be the sweet spot for stock height and small tires in my opinion.
And you could also use the shims to lower your camber out of the correct-for-the-era spec of 1 degree, to something slightly less. Something between the half-degree and three-quarters degree positive is a desirable setting for modern radial tires and modern roads.
But yours is certainly not bad enough to worry about if it handles good now. Just keep an eye on how quickly you wear the outside of the tires and see if you want to lower your camber down the road some.

While we're on the subject of C-bushings, can you post up a pic of your front pinion/u-joint angle so we can see if you have more leeway for more C-bushing offset? Most Broncos are fine with up to 7 degrees, but not all of them. Just like your camber is nowhere near what was expected from Ford, your pinion angle could be too steep already as well.

pays to have as much info as possible, but the only way you'll know what bushings will work is to try them.
If you can get a really good side shot of the C-bushings you have in there now, we "might" be able to tell if they're in correctly or not. We're looking for the built-up areas inside and how the axle is tilted, but with 2 degree bushings it's often hard to see.

Paul

 

[DirtDonk]

Just for information in case others are reading this thread in the future, it wasn't until '76 that we started to see at least slightly more consistent caster numbers in the expected 3 to 4 degree range. Before that it was hit-or-miss as to what your front end would have been delivered with from the factory.
Our friend bought a brand new Stroppe Baja Bronco from the dealer back in '74 and returned it as a lemon (before the lemon laws were in effect I think?) because he could never get it aligned properly and it continuously wore out tires.
Seems like they should have just replaced the entire front end under warranty, but maybe because it was a specialty rig that they did not do that for a Baja.
But then again, he was a crotchety old bugger too, so maybe they just wanted to get rid of him by giving him his money back!

Paul

 

[FOMOCO_1546]

I'll get some pictures up shortly. I am trying to figure out if my frame is level. Where should I check the frame with an angle degree guage. It always looked like my bronco is higher in the back than the front. Wouldn't that throw off the caster reading?

 

[DirtDonk]

Most Broncos are higher in the back, due to their load rating. The heavier duty rear springs held it up some, so that when you loaded it up with gear your headlights were not pointing at the sky.
There is also the possibility of sagging front springs, which is very common also.
So being level is normal for some, and being up in the rear is normal for others.

Rear tire carriers, full hard tops vs half cabs or soft tops, winch bumpers vs stock bumpers, back seats or not, dual tanks or not, all these things would have effected the ride height slightly from the factory. Just slightly, but enough that not all Broncos are precisely the same.

I don't know where you would find a consistent spot on the frame to measure this, but you can measure your suspension height between the top of the axle tubes and the bottom of the frame rails.
A stock Bronco is "approximately" 7 inches in the front and 6 inches in the rear.
If you are above this you have a lift, and if you are below this you have some spring sag.
However, even this is not an exact science, so I tell people to give themselves about a half-inch leeway in either direction. If yours is a half inch or less in either direction of 7" in the front and 6" in the rear, then it's close enough.

Since caster is read in reference to the ground, then yes a rear-high stance will change the caster reading. But since the caster is adjusted in reference to the axle-to-frame relationship, and is built in to a solid axle like ours, you can still run afoul of too much pinion angle if you try to over-compensate for lack of caster by installing c-bushings, offset ball joint sleeves, radius arm drop brackets, or even radius arms with built in caster correction.
The only method that is an actual "solution" to changing the caster numbers is the "cut-n-turn" method. That's where the steering yokes (where the ball joints are) are turned in relation to the axle tube they're pressed and welded on to. With this method you can achieve the perfect pinion angle AND the perfect caster angle for your particular setup. Since most are not wanting to get that deep into it at first, the c-bushings and all the other parts were developed.

Let us know what you find out and we'll keep digging into the issues.

Paul

 

[Rustytruck]

the caster is low but before power steering it was only 2 degrees or so with a 1/2 degree less on the passengers side. the 1/2 degree less was put in there so you will run in a ditch instead of head on if you fell as sleep at the wheel. apparently falling asleep at the wheel was a pretty common thing back in the day. now the roads are crowned to deal with the problem and alignment is properly balanced. the little camber problem is maybe from the worn kingpin or ball joints depending on what your axle is sporting.

 

[reamer]

Just had mine done too, 0.7 degrees on both ends, and it wanders all over. The only TRUE way to get correct caster is to grind off the weld that holds the steering knuckle to the axle tube are rotate the knuckle back 1/8 of an inch and reweld.
Using C-bushings for caster throws off the front driveshaft angle, so you gain correct caster, but ruin driveshaft angle.
Rotating the knuckles on the tube gives you BOTH correct caster and correct driveshaft angle....

 

[FOMOCO_1546]

After getting under the bronco, I realized I'm full of crap! 20 years ago when I bought this bronco I remember it had new Trac bar and other blue urethane bushings. When I painted frame and suspension parts everything got painted black. I swore it had new radius arm and c bushings. They definitely look like stock rubber bushings.
I measured the frame up front to the axle tube and got very close to 7" both sides. The rear measures approximately 9" both sides. I did replace the rear springs with stock springs.

 

[DirtDonk]

Definitely rubber bushings. But by the look of them they were replaced at some point, so it might have been natural for you to assume they'd been replaced with poly if the PO said so.

That 7" measurement is right on the money for the front being stock and not suffering from sagged springs.
So you said the rear sits high? I can see why!
That rear measurement indicates that your replacement springs are still holding you up higher than expected. A fairly common occurrence and especially true if the Bronco is not driven often, or very far, and does not get loaded down with weight or taken out off-roading. What's not so common is that they look to be holding it up near 3" over stock.
You can play around with loading it up and driving it around, or you can go straight to removing a few leaves to let it settle down.
This lowers the rear, softens the ride, should improve the caster and handling, and should get you a look that it sounds would be more to your liking.

Good angle on the driveshaft (basically stock) so you have much leeway for C-bushing choices. However I would get the stance the way you want first, by lowering the rear (unless you've been contemplating raising the front maybe?) and then re-checking caster.
But based on just the look of the pinion angle I'd say you can easily get away with 4° bushings if you decide that's what you need. Still a few things to factor in however.
For example, do you have power steering, or manual? If manual, are you ever going to change to power? Manual steering favors low caster numbers, power steering favors higher caster numbers.

But no matter what, I'd still mess with lowering the rear before choosing your bushing. That way we can see directly if, and if so, just how much caster in the front is gained by lowering the rear.

What type of springs are in the rear? No blocks or coil-over shocks, correct? Got some pics of the setup?

Thanks

paul

 

[FOMOCO_1546]

Thanks very much for the input. I have power steering off of a 1974 donor truck and disc brakes from a 1976 bronco axle I bought.
The new stock leaf packs I installed I bought from Jeff's Bronco.
I have only been driving this bronco a few hundred miles a year without a top or any weight in the bed. I'm concerned about lowering the rear very much because of tire rub.
With the frame to axle measurements 3" to much in the rear does that just cause the alignment machine to give a false reading or does that actually throw the caster off? Thanks

 

[DirtDonk]

I believe (but more experts on alignments can correct me if I'm wrong) that they work together. A caster reading is the same as the real world setting, so if the height in the rear does indeed effect the reading, then it's effecting actual caster and road manners.

If your tires are going to rub if you bring it back down to stock height, that could be an issue for you as well and you should perhaps consider raising the front instead. Assuming you'd prefer a more level stance that is?
What size tires are on there now? And more importantly, what size wheels, and what offset (or backspacing) are they? If the truck comes down a bit in the rear, are they sticking out past the wheel well opening enough to rub?

But speaking of springs... Those are not what I was initially thinking I don't believe. They look to be 6-leaf packs? That would more mimic the stock ride height and original design, but they look odd from here.
It looks like they have 5 main leaves and one thick overload leaf at the bottom. Is that correct? The odd thing is that with an overload design, the bottom leaf is not normally in contact with the rest out at it's ends. There is usually a substantial gap so that when the vehicle is unloaded the springs are riding on their "soft" sections, and when a heavier than normal load is applied they flex down to the point that the upper leaves contact the lowermost leaf to add capacity.
I'm guessing they ride very stiff at this point? If not then maybe I'm not looking at it correctly. Got some more pics of the rear springs perhaps?
The packs also look like they have more "S" shape to them than the normal standard arch. There are springs that are purpose made to be this shape, but I've not seen them produced for Broncos before. Or at least I've never noticed them.

Look forward to more pics when you get a chance.

Paul

 

[DirtDonk]

Back to the interesting S-shape again, it's also possible that a deformed spring perch on top of the axle could force the spring pack into an unatural shape once the u-bolts are torqued down tight enough.
Usually not a big issue with standard u-bolts and between 60 and 70 pounds of torque. But deformed spring perches used to be an often discussed problem. Haven't heard anyone mention it lately, but maybe now's the time!

Paul

 

[FOMOCO_1546]

The rear of the truck is as stiff as a log truck. I'm running 31x10.5x15". Wheels are 15x7 with 3.75 backspacing.
I'd be interested to seeing what would happen if I put a digital degree angle on a flat area of the frame and check the reading. Then jack up the front end and put 2 inch and a half boards under each tire. Set bronco back down on board and take that reading.

 

[DirtDonk]

Thanks for the great pics. And that's a great looking Bronco too! Very clean.
I know I can't tell 100% from here, but from the pic of the tire I'd say you will clear. Mine is closer with 31x10.50's with about the same lift currently (2.5 plus a block plus a shim) but removing the block to lower it back down (the front springs are now lower then previously) looks like mine will clear just fine.
But I suppose in your case there's one way to find out! Without modifying the springs, maybe a big load in the back to drop it down some would be the ticket.

But speaking of springs and loads, yikes! Yes, something is wrong with your spring packs. They are not supposed to be flat on top of those super thick bottom springs until there is a load. And considering there is no load, the springs are laying on the overloads AND you're still sporting approx. 3" of lift, something is amiss somewhere.
Were there part numbers stenciled on the springs that you could compare to the receipt to make sure you got the right ones? It's not a common occurrence, but it would not be the first time one of us vendors launched the wrong spring to a customer!

You can put the level on your body line (at the bed rail where the top would mount is probably the best spot) then just jack up the front until it's level. Measure the front before and after to see how far you lifted it up to match.
Another tack could be to just lift the front until you like the stance by eyeballing it. Then you still measure the before-and-after to see how high you went.
We used to talk about doing that all the time. Haven't seen it discussed in awhile, but anytime a Bronco has the stinkbug butt-high look, it comes up.

Good luck. Not sure what to tell you to do with the springs at this point, other than to perhaps remove just the lower overload leaf. No way to tell you how much it will drop over and above it's thickness until you actually do it.
The good news is that if you like it the ride will improve greatly. The bad news is that you would not be able to load it with as much camping gear or put quite as many high-school football players in the back seat. Could be worth the trade-off though.
As long as the tires don't rub that is...

Paul

 

[FOMOCO_1546]

Thanks again, I'm thinking I might try removing the over load springs and see what that does. After I take off the the u-bolts off and lower the axle, can removing the overload spring be a problem? Also what would my options be to lift the front end just a small amount? I have seen a few broncos with the front lifted excessively with 31's and it doesn't look good to me.

 

[DirtDonk]

Before starting verify that your u-bolts have sufficient threads to tighten after losing that 3/4” or so thickness of the leaf.
If good there, after dropping the axle you will need to clamp the pack together so that when you remove the center pin the other leaves don’t fan apart.

 

[DirtDonk]

As for lifting the front, it’s as simple as buying a pair of springs. They are available typically in 1 to 1 1/2 inch heights from the vendors, but you can probably retrofit a spring from a different model Ford to gain as little as 3/4 of an inch.

 

[DirtDonk]

No such thing as a coil springs spacer that I’m aware of for this type of coil.
There were devices designed to shore up old tired springs but those are not guaranteed for a specific amount of left especially in a non-stock application.