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Outside tire wear

Posted: Fri Mar 07, 2014 5:20 am
by BroncoJim
Hello everyone, I am looking at replacing the front tires on my '76 again. They are wearing on the outside edge. I've had this problem ever since I gave it it's first 2 1/2" lift 25 yrs ago. Is there anyway to keep this from happeneing? Right now it has a newer BC Broncos 2 1/2" lift. The trac bar is stock and so is the steering linkage.

Posted: Fri Mar 07, 2014 8:05 am
by Stan
That's not uncommon - a lot of them did it even when they were new.
You might try a little less "tow in" and rotating the tires more. This does help the wear pattern - especially on " traction type tread".
I believe there is /was a fix involving Ball joint shims and/or steering knuckle shims to decrease the amount of camber. Waay back when they were heating and bending the axle tubes to get better caster but not sure if that was a fix for camber issues.

Posted: Fri Mar 07, 2014 8:11 am
by oldwinghunter
make sure the tow in is about 1/8 inch ....not any more, or it will buzz the outsides right off ...

Posted: Fri Mar 07, 2014 8:31 am
by Stan
oldwinghunter wrote:make sure the tow in is about 1/8 inch ....not any more, or it will buzz the outsides right off ...
Boy that's the truth :) I was sperimenting a few years ago before i redid my entire front suspension and steering - put too much "Tow " and felt and sounded like i was plowing the highway - I changed back pretty quickly.
One of these guys might know - but would a change of caster help with the outside tire wear? With the suspension and steering geometry of these things being sorta interdependent and related and tied together ??
Have you taken your Bronco to an alignment shop for some " readings" to let you know what you've got .
I took mine to a shop that had an oldtimer who knew about D44s and tie rod overs and etc, - he said the basic problem is that the Dana specs called for too much camber and not enouigh caster and that not every D44 on a Bronco came from the factory/forge with the same measurements. 8O What - no two Broncos built the same ? :lol: :laughcry:

Posted: Fri Mar 07, 2014 10:49 pm
by DirtDonk
Ford (or Dana?) called out for too much positive camber, and back when it was just manual steering, wanted too little positive caster. You can get away with more toe-in if you have better settings on the other two, but it's still a crap-shoot.

The spec for camber was something like +1° to +2° with +1.5° being optimum. That might have been true back when, but I think they work just as well, if not better, and don't wear the tires near as much with from zero to +1/2 degree. Never tried negative camber, like you do on sports cars, but never felt the need either. Get it to a 1/2 degree or less and you should at least get some more mileage out of the tires.

Caster's a toss-up. If you're running manual steering still, any more than 3° positive and your really learning the meaning of "armstrong" steering!
If you have power assist though, the sky is almost the limit. Try to get 4 or 5 degrees positive caster and you'll be much happier. Usually...


Posted: Sat Mar 08, 2014 1:57 pm
by Tom Dummer
Toe, TOE, it's TOE - in.
Tow usually means there is a rope involved.

Posted: Sat Mar 08, 2014 2:15 pm
by Stan
:) -always the stickler for details. :)

Posted: Sat Mar 08, 2014 5:52 pm
by BroncoJim
Honestly I had no idea toe-in could effect tire wear. I thought it was camber and the Broncos were un-adjustable due to the straight front axle.
Shows how much I know.
I don't think I have ever had it aligned but I did set the toe myself when I re-did the suspension. It looks like I need to have it done when I get the new front sneaks.
Thanks everyone,

Posted: Sat Mar 08, 2014 7:57 pm
by DirtDonk
Toe will be at least part of the equation of tire wear, but it's having more effect when the camber is out at the same time. Because then not only is the tire "riding" on it's outer edge (camber) but it's also "pushing" on it's outer edge (toe-in).
So yeah, it's going to have at least some effect.

I don't know about yours, but most EB's I've ever been involved with wore out the right front noticeably quicker than the driver's side.

The ball-joint eccentric collars are available in multiple ratings, but since it's adjustable, it makes sense to just go big and get the 1.5° max version.
The camber shims that fit between the spindle and the knuckle are commonly in either plastic/nylon or aluminum. Ford used two styles of spindle, so if you've got a '75 or earlier front end with drum or aftermarket disc brakes, you would want the 6-bolt compatible shims. If you've got a '76 and later, or have converted to disc brakes using all Ford components (Dana 44 only) then you would find the slightly harder-to-find 5-bolt spindle shim.
I think they too have a max. rating of about 1.5°


Posted: Sun Mar 09, 2014 6:39 am
by BroncoJim
Great information Paul thanks.

Where can I find these components? Do I need the collars and the shims or is it a choice?

Posted: Sun Mar 09, 2014 11:51 pm
by DirtDonk
All personal choice, or both if your numbers are out more than the 1.5 degrees of correction available from just one. But they're not exclusive of one another at least.
Some of the better parts stores can get them both. Some of the big players still make the stuff too, like Dana, TRW, Moog, etc. As well as companies like Napa having their own private label stuff.

There's also a company called Ingall's Alignment Products that should have it all as well. Maybe even fleabay? I've been trying with no luck yet (too many irons in the fire maybe?) to get us to carry them all. Would help us become a little more towards the one-stop-shopping source I'd like us to be. But honestly we don't really get that many calls for the stuff either, so that's probably why it's not on the decision-makers' radar. Yet.

Like mentioned, the eccentric ball joint collars are available in multiple ratings, but just go for the max 1.5 versions. If you only need 1 degree of camber correction, you can always orient it such that the other .5 degree is towards the rear for a half-degree more positive caster. A win-win for the collar.
And for the disc brake "Ford" brand brakes, the correct spindle shim has five bolts with an offset pattern. Conversions using the stock spindles ('66 to '75) just use the more common 6-bolt shim.