I modified an old set of ALL4FUN radius arms using 2" quarter wall DOM and Balistic joints. Had the arms straight thinking the narrow frame rail and the wider axle would clear tires no problem. So I just put a relief cut 12" back and bent the arms in the press (took about 8k lbs to start moving) to make them similar shape to JD arms. My problem is I may have bent too far. With the caps snug using 7* poly C bushings the frame ends are probably 6" away from the frame mounts. If I leave the caps loose and attach the frame end I can start reaming the cap bolts down. Question is how much compliance do the poly bushings have? I'm probably asking 10-15 degrees more than they want from neutral. I am having to pull the frame ends in towards the frame rails to line up. The arms are the exact shape I was looking for, just the C's are not the ideal angle. Similar question for those who are running the 79 axle with JD arms: Do they just line up to the frame rails? Is there a specific arm for this application? Last question: Do the caps need to meet flush to be considered tight? The HD spring cups have an adjusting space on one of the bolts that would allow the caps to have a gap. Thanks all!
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79 F150 FW axle James Duff style arms/ Poly C bushing compliance?
- Thread starter 79INA69
- Start date
- Joined
- Nov 3, 2003
- Messages
- 48,236
I do not believe poly has that much stretch.
Yes if you bolt it up and then tighten them down you will probably squish the bushings instead, but with what result.
So in that respect it’s probably fine, but you’re almost literally destroying the bushes. But then again maybe not, since 15° isn’t a huge amount.
It’s just that they’re not gonna work as is if you tighten them down first. And then try to squeeze the tips of the radius arms in that far.
I think it’s just too much. Or is it 6 inches total and only three per side?
In that case I think you’ll be OK.
This is probably why some arms actually have a double bend rather than a simple single kink for tire clearance. I do not believI think this is why some arms actually have a double bend rather than a simple single kink for tire clearance.
Yes if you bolt it up and then tighten them down you will probably squish the bushings instead, but with what result.
So in that respect it’s probably fine, but you’re almost literally destroying the bushes. But then again maybe not, since 15° isn’t a huge amount.
It’s just that they’re not gonna work as is if you tighten them down first. And then try to squeeze the tips of the radius arms in that far.
I think it’s just too much. Or is it 6 inches total and only three per side?
In that case I think you’ll be OK.
This is probably why some arms actually have a double bend rather than a simple single kink for tire clearance. I do not believI think this is why some arms actually have a double bend rather than a simple single kink for tire clearance.
So those who have JD arms with the full width dana 44 from a 1979 F150: Do they just pull the arms in the extra 1.5" or are there different arms? I could see doing another pie cut and weld near the C to correct this if it is an issue. My only concern is if I am over stressing the bushings, affecting the caster, or not allowing the caps to fully seat? Do the caps need to be touching metal to metal?
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Yes, the caps should be metal to metal.
If for no other reason than to get the two top bolt holes to line up for the spring cups.
I don’t think you’d lose much, if any of your caster offset by over stretching the arms.
It’s mostly in and out force rather than a rotational movement.
But there are the unknown inconsistencies involved. There’s always a question mark.
If for no other reason than to get the two top bolt holes to line up for the spring cups.
I don’t think you’d lose much, if any of your caster offset by over stretching the arms.
It’s mostly in and out force rather than a rotational movement.
But there are the unknown inconsistencies involved. There’s always a question mark.
I see now the S bend. The wedges have what looks like a 10* kick in to them from the factory. I thought with the FW axle and frame rail mounting I would get lucky and line up with the one bend. I will look more closely this weekend and maybe put the S bend in. Radius arms bind enough as is, I don't want to make it worse. I feel like the angle it sits at now will be over torqueing the cap bolts to make them meet.
Here's a couple of pics of the bends, I hope it helps.
Attachments
Very helpful, thank you! I mean you just help create a lot more for me, but have the game plan now
I greased everything up, anti seize on the cap bolts and just ran them down. Looking at the pic the JD arms have a more severe bend than I put in. I would guess I'm 10-15* misalignment. The caps tightened all the way down before final torque and dont look that bad. I'm willing to sacrifice a set of bushings before attempting to cut and bent again at the C area. I cycled the axle with the springs out to get an idea of the range of movement and Its good, but its no 3 link.
