WeldTec radius arm modification?

[This old va]

Curious as to the Weld Tech 2 wheel drive E350 radius arms.
I know they have extended radius arms that are 8 in longer that appear to mount further behind the stock mounting location, I'm assuming that they are longer that they push the radius arms forward?.

The second question is their (modified stock radius arms) that mount in the stock location.
I can't envision in my head how that is working if they are stock length how do they push the radius arms forward ?

Or am I not seeing the picture clearly. Someone school me.

Someone told me I could put spacers in my radius arms to gain a little clearance at the fender.? well however I looked at them I don't believe I have any room to put a spacer in there as the threads appear to only allow maybe half an inch.

I was told Weld Tec used to offer a modified radius arm ( kit) however I called them about 9 months ago and said not in production , but might make some..then was told to leave my number and don't call us we'll call you ...lol I never heard back, so assuming they don't sell them anymore maybe some kind of alignment problem or something?

I really like their kit but it's almost as much as I paid for my E350 diesel cargo van... Since my wife passed from cancer finances are darned tight .... I know frugal and projects don't mix well but I'm trying...lol

[MountainBikeRoamer]

Hey there this_old_va,

The WeldTec radius arms are indeed significantly longer (around 8”?) than the stock arms.

However —
To make sure the front wheels don’t “go any farther forward,” they **weld a new radius-arm mount** to the frame of the van, and locate it about 8” rearward of the stock radius arm mount (which then gets unbolted from the frame and discarded.)

The custom transverse “twin I-beams” are the WeldTec component that still mounts to the factory frame mounts. These are however precision re-formed (bent) to correct the camber of the front wheels once the van is lifted higher.

[This old va]

Forgive my ignorance but aren't the longer radius arms intended to push the suspension forward?

I am not following what longer radius arms would do if they are (just longer ) and just mounted further back?

I've looked for explanations online of this since so many Fords use them but I have yet to come across anyting ... other than "yeah it fixes geometry and lifts it". But no explanation of exactly why and how it goes about doing this.


Thanks again for any further light on this subject...

[MountainBikeRoamer]

No, you don’t want to push the front axle forward, as that would make the tire hit the fender openings when the suspension cycled up/down through its travel.

The longer radius arm gives you less “caster angle change” as the suspension cycles up/down (better for holding ideal steering geometry) and also just gives you a smoother and more controllable long-stroke suspension. That’s what’s so great about the WeldTec lifts, they actually give you more (usable!) total suspension travel (top-to-bottom stroke) as opposed to just raising the van up higher.

That said -
Some lift kits DO push the axle farther forward, but I think the only really notable mainstream one is the 4WD / lift setup that is engineered and installed by Ujoint Offroad.

[This old va]

Okay thanks.
Sounds like the two shops that told me I should put 1/2 spacers behind my radius arm bushings on the rear were they bolt on pretty much ......don't know what they're talking about...
one of them used to be a well-known offroad shop in southern California but the kid that told me that was like 20 years old and did not instill a lot of confidence......

[MountainBikeRoamer]

Not sure, I am imagining that you could “space” your factory radius arms forward a slight amount to gain a bit more tire clearance at the rear of the fender opening....but then you’d want to watch to make sure you weren’t banging your tire forward into your bumper.

[JWA]

Another major consideration of modifying radius arms is how that will affect caster. If keeping the 2wd configuration and using stock parts (I-Beams, etc) I'm sure Weld-Tech has the spacing and geometry figured out.

I would be curious how longer radius arms along with moving the frame mounting location is a benefit? I mean is this something ELSE I need to consider adding?

[This old va]

Originally Posted by JWA

Another major consideration of modifying radius arms is how that will affect caster. If keeping the 2wd configuration and using stock parts (I-Beams, etc) I'm sure Weld-Tech has the spacing and geometry figured out.

I would be curious how longer radius arms along with moving the frame mounting location is a benefit? I mean is this something ELSE I need to consider adding?

Exactly.....I cannot figure it out.. technical either. Generality Yes...but just longer ..makes no sense to me?
Without doing and seeing it....I'm at a loss.

[MountainBikeRoamer]

To simplify:

If you’re going taller (putting in a lift), you ideally want to take as much advantage of that extra height as you can by having **longer suspension travel.**

With a stock-length radius arm, if you increase the suspension travel you also dramatically increase the change in steering caster angle as the suspension cycles through its full travel.

With a longer radius arm, you get far less caster angle change as the arm swings through the same amount of suspension travel up/down.

So unless you are lifting the van a good 4-6”, there’s **no need to have longer radius arms** (as the stock arms keep the caster angles within a reasonable range as they cycle up/down through their full suspension travel.)

Take a look at highly-modified off-road race vehicles....the ones with long-travel suspension have long suspension arms. But then look at a road racing vehicle, they usually have comparatively short suspension arms. (As the travel is much shorter and there’s no advantage to adding lengthy arms and weight.)

[This old va]

M.B. Roamer...Thanks. For your explanations. It helps me envision the procedure����