Caster & Radius arm help

[marcussly27]

I have a new build with stock radium arms with a 2.5 SL and 2 BL and my current caster is about 1.8. I'd like to get this up into the 3 or so range, which I'm told will help improve handling? So what's the easiest way to accomplish this? I believe I have 7 C bushings, but I'm not sure. My 265s also rub when I turn which drives me crazy. I'm thinking about spending the money on the DuffTuff stock Trex arms which will solve both problems I believe, but I don't really want to drop the dough so looking for advice.

Thanks!

 

[DirtDonk]

First, you have to make sure that you have 7° bushings.
If you do, that’s the maximum you can go with bushings. Yes, the arms will add another 4° just as radius arm drop brackets would.
The drop brackets are less expensive, but are not to everyone’s taste because they hang down visibly from the frame.
The other thing is, do you expect to use four-wheel-drive ever? When you keep adding twist to the axle with bushings and offset arms and brackets such, you run the risk of binding the front u-joint.
So double check that you have 7° bushings first as what I would say.

 

[marcussly27]

What’s the easiest way to check the bushings? Do I have to remove the arm cap? I tried and those bolts in there are tiiiiiiiiiiight. Guessing a torque gun would get the job done?

 

[Dne007]

Hi, on my '72 build, I had installed 2 degree bushings, not having known any better at that time. I discovered through my own alignment that I had basically zero degree caster resulting in poor driveability, drifting kind from left to right. The bushings have stamped on the inside of what they are and the orientation of which they are to be installed. If I hadn't known what degree they are, I'd have to pull them out and see what they are.
let's go from here

 

[Dne007]

After installation of the 7 degree bushings, helped tremendously, but I am running some fairly large tires, not as large as some

 

[Dne007]

on the inside of the coil spring at the base are two 5/8 bolts, I removed the front bolt which screws into the front c cap, but only loosened the back bolt to allow the base plate of the spring to lift a bit then could get a socket on the cap bolts. Then removal of the front large bolts, a cap may come off. If you were to go that far just to inspect the degree of bushing, you're kind of dedicating yourself to go all the way which is a loaded question/answer in performing the task at hand. I find it a fairly taxing job. I hate dealing with springs. I used some tie downs with the ratcheting feature to "collapse" the springs a tiny bit to get the job done. Probably best to remove the springs, but I cheated.

 

[jamesroney]

I have a new build with stock radium arms with a 2.5 SL and 2 BL and my current caster is about 1.8. I'd like to get this up into the 3 or so range, which I'm told will help improve handling? So what's the easiest way to accomplish this? I believe I have 7 C bushings, but I'm not sure. My 265s also rub when I turn which drives me crazy. I'm thinking about spending the money on the DuffTuff stock Trex arms which will solve both problems I believe, but I don't really want to drop the dough so looking for advice.

Thanks!

Measure the distance from the axle tube to the bottom of the frame. It should be 9.5 inches with a 2.5 lift.
If you are at 9.5 inches of static height, and you are at 1.8 degrees of caster, you do NOT have 7 degree bushings installed. (or you have 1/2 of them installed upside down)

7 degree bushings on a 3.5 lift will get you ~4 degrees of caster.

You want 6-7 degrees of positive caster running 265/75/17 tires.

Order a set of 7 degree c-wedges and install them. T-Rex arms will do nothing positive for you, but they will make your wallet lighter. If your tires rub, then go set your steering stops. You are under $75 from where you need to be.

 

[DirtDonk]

I was going to mention removing the springs too.
Makes it easier to remove the bolts.

If you just barely loosen the lower bolts a little bit, then remove the top clamp, you can then just “unscrew” the coil springs.
Easier to do it than to explain it.

And yes it’s a pain just to look at the bushings.
No receipt? Other records?
How about a nice closeup pic of the sides of th bushings for us to see?
If they are 7’s already you should easily see the offset "bumps" from the side.

James, I think this still falls into the "every Bronco is different" category. I don't think we can specify a caster angle based on bushings and lift because too many of the front axles in Broncos did not come with the same caster built in.
My '71 Dana 44 with 3.5" lift and 7° (installed correctly) has approx. 2.8 degrees on at least one side. Under 3 degrees on both though.

Paul

 

[reamer]

time to knock the knuckles back, you will get optimum caster AND straighten the front drive shaft!

 

[DirtDonk]

Yep.
Or as Corporal Hicks would say… “I say we bug out, go into to low orbit and nuke the bastards from above. It’s the only way“
Probably don’t have to go to those extremes, but cutting and turning the steering knuckles really is the only way to have your cake and eat it too.
But for now, if you can get a little more out of the bushings, that would still be a reasonable possibility.

 

[lars]

Measure the distance from the axle tube to the bottom of the frame. It should be 9.5 inches with a 2.5 lift.
If you are at 9.5 inches of static height, and you are at 1.8 degrees of caster, you do NOT have 7 degree bushings installed. (or you have 1/2 of them installed upside down)

7 degree bushings on a 3.5 lift will get you ~4 degrees of caster.

You want 6-7 degrees of positive caster running 265/75/17 tires.

Order a set of 7 degree c-wedges and install them. T-Rex arms will do nothing positive for you, but they will make your wallet lighter. If your tires rub, then go set your steering stops. You are under $75 from where you need to be.

^^^this. And, adding to what James wrote. There are endless threads on here about this, the search function is your friend. Reader's Digest version here: Install 2 degree C bushings or 0 degree rubber bushings, in order to keep pinion angle about where it needs to be. cut inner C's off axle tubes. Rotate (tops back) until you get 6-7 degrees of caster. Weld back on. Enjoy no wandering. Note that doing so won't necessarily prevent death wobble. Ball joints, tie rod ends, steering box, tires all need to be in good shape as well.

 

[jamesroney]

^^^this. And, adding to what James wrote. There are endless threads on here about this, the search function is your friend. Reader's Digest version here: Install 2 degree C bushings or 0 degree rubber bushings, in order to keep pinion angle about where it needs to be. cut inner C's off axle tubes. Rotate (tops back) until you get 6-7 degrees of caster. Weld back on. Enjoy no wandering. Note that doing so won't necessarily prevent death wobble. Ball joints, tie rod ends, steering box, tires all need to be in good shape as well.

I just buttoned up this 1971 (D1TA) D44 in my Bronco. Cut and turned 7 degrees. TRO with drum knuckles. WH riser. Factory caster to pinion angle was 12 degrees. (now 19) Ended up with 10 degrees of radius arm from horizontal. So I had to put in 4 degree wedges. (funny that is the same number that Duff puts in their arms...)

Current ride height is 11.5 axle to tube, (because I don't have any weight on it.) Caster is sitting at 6 degrees, pinion angle is sitting at 12, driveshaft is at 16. Should all come in correct at ride height. But we will see in a few weeks. @Ol'Blue might be interested.

and yeah, death wobble is a 2nd order compound failure mode. It has to want to wobble, and you have to enable it.