The Dana 50 TTB and getting it under my E350 van.

[Mwilliamshs]

Thanks for the videos. Fun and interesting to watch the susp work.

are we to accept that those videos are of the same "lower in the travel range" setup seen in MGM's pictures?

 

[4x4junkie]

Agile does box their radius arms where they meet the axle housing. Looks like an "L" if I remember right. They also have the lower tube kind of pinched over the bottom of the "L"
You can kind of see here where the lower tube sticks out below the axle housing in this screen grab...

I'm planning on gussets on my arms when I get to that point




Sent via flux capacitor

It's really hard to tell what I'm seeing in that pic...
I think I do see a section of tube used as a gusset on the side of the lower tube that the shock is mounted to, however it's the upper tube that concerns me... It looks unsupported from where it's welded onto the middle of the beam up to the top of the beam. Such a narrow design greatly increases the forces coming from the differential within the two tubes of the arm, causing flexing of the whole assembly, and over time this can lead to cracking and fatigue (I've broke much more robust setups on a little Ford Ranger pickup, forget about it under an upfitted Econoline van, especially if there also happens to be the weight of a Powerstroke diesel above it). Even high-volume suspension manufacturers such as Rancho and Superlift have had difficulty understanding how much torque a TTB differential puts on it's radius arm... You need to have it built as sturdy as possible in that area.

 

[Mwilliamshs]

You just need to remember that a TTB suspension is basically two levers that pivot at one end with the wheel at the other end. Both the bumpstop and shock are at mid-points on the lever... If the lever (axle beam) is able to move up say, 3" where it hits the bumpstop, the wheel (at the end of the beam) can move up maybe 5". So it's definitely possible there's 5" of uptravel, and 7" of down, for a total of 12" at the wheel...

agreed. limiting up-travel to allow lower ride height is a common move in the off--road world

 

[Mwilliamshs]

Based on the polish visible on the shock shaft I'd say you're pretty close to spot on with that 3" estimate, and maybe just a tad generous. Given that, 9"-10" of droop would be quite a drop.

Assuming the van has been driven recently in a manner sufficient to completely cycle the suspension...which is not likely IMHO opinion unless MGM met up with this guy following a speedy desert run or boulder-strewn climb. 12" (or 9") of suspension travel would take some doing to put to full use in everyday life

 

[tgreening]

Personally I think the picking at Agiles system, and inversely the picking at anybody else's system, is wearing a bit thin. And I've contributed. At the least move it to another thread and let this poor guy build his system without all the chaff. All in favor?


The thing I liked the best about the vids was the slow-mo. It was interesting to see how much non suspension related stuff was moving about under there across some of the rougher terrain. No wonder my coffee pot doesn't want to stay on the counter.


Edit: Given where this post fell in the line up I figured I should clarify the above. "Aimed at no one in particular".

 

[Mwilliamshs]

You just need to remember that a TTB suspension is basically two levers that pivot at one end with the wheel at the other end. Both the bumpstop and shock are at mid-points on the lever... If the lever (axle beam) is able to move up say, 3" where it hits the bumpstop, the wheel (at the end of the beam) can move up maybe 5". So it's definitely possible there's 5" of uptravel, and 7" of down, for a total of 12" at the wheel.


And I hope that it's just the angle of the pic and I'm not seeing a gusset up at the top, but that tubular radius arm with the upper tube that appears to be welded straight to the side of the axle beam right in the middle is a failure waiting to happen. The radius arm needs to span the entire width of the axle beam top-to-bottom (including the section of box tubing, if used) where it attaches to the beam.
The driver side radius arm alone bears the entire torque load being generated by the front differential, so it needs to be sturdy as possible (and gusset up top or not, the tubes should be gusseted or plated along sides for support also). For those here building their own arms, take a look at aftermarket arms such as Skyjacker or Camburg to get some ideas.

I'd also suggest try to design it so that it's similar to the OEM coil spring setup where the radius arm bolts to the axle beam rather than having the arm welded directly to it. To me it seems this way it would be even less likely to have a weld fail in this area over time.

this whole post is spot on. I think BajaSportsmobile has constructed his arms better than 4x4junkie can see in the pics but the principles are sound. I agree bracing the tubes of the radius arms is a very very good idea

 

[4x4junkie]

Thanks Mwilliamshs

Yes, my intention was not to bash Agile's setup, however I learned a very long time ago that the mere fact something comes from a professional shop or business is not an absolute guarantee that it is of sound engineering or design, so that's only reason why I brought it up. My intention was that IF the concerns I mentioned were present, I did not want to see philos or someone else copy it into their own design not realizing it (and at the same time suggesting to Agile where an improvement might be possible).

I do hope it is just something I'm not seeing in the pic that was posted. A better pic of the area where the radius arm attaches to the axle should put this to rest if so.

 

[BajaSportsmobile]

Here is a van that we are just finishing up. It is the same setup as the one pictured above. This is our lower lift, ~3.25 inches above the stock 2wd height.

With the shorter spring, it gets ~11 3/8 inches of travel. Our taller lift can get over 12 inches... or more. We are building one with 17 inches, but it is extreme and not something we offer.

I measured from the wheel mounting surface, which would be the middle of the tire contact patch (a true measure of wheel travel) on a zero offset wheel.



This is at full droop:

This is at first contact with the bump stop:

This is at full bump:

There is ~1 inch of shaft at full bump.

 

[BajaSportsmobile]

We have built dozens of Prerunners and Race Trucks with the same basic design - as have many other builders. We have literally 10's of thousands of off road miles including Baja wins with the same basic design. We have proven it over and over. I would never build a bolt-on radius arm design like you mentioned above. I have seen way too many failures. I raced Stock Full F Series trucks for several years and those radius arms were the weak link - even with cheater 4130 "Stock Radius Arms" made specail for us by FORD - complete with stock part numbers on them. The bolt is a fulcrum point...

Thanks Mwilliamshs

Yes, my intention was not to bash Agile's setup, however I learned a very long time ago that the mere fact something comes from a professional shop or business is not an absolute guarantee that it is of sound engineering or design, so that's only reason why I brought it up. My intention was that IF the concerns I mentioned were present, I did not want to see philos or someone else copy it into their own design not realizing it (and at the same time suggesting to Agile where an improvement might be possible).

I do hope it is just something I'm not seeing in the pic that was posted. A better pic of the area where the radius arm attaches to the axle should put this to rest if so.

 

[philos]

How'd you make that coil spring disappear!?!?! Sorcery!
Thanks for taking it out to show us the full range of travel


Sent via flux capacitor

 

[ujoint]

So you guys measure travel with the coil removed?

 

[4x4junkie]

We have built dozens of Prerunners and Race Trucks with the same basic design - as have many other builders. We have literally 10's of thousands of off road miles including Baja wins with the same basic design. We have proven it over and over. I would never build a bolt-on radius arm design like you mentioned above. I have seen way too many failures. I raced Stock Full F Series trucks for several years and those radius arms were the weak link - even with cheater 4130 "Stock Radius Arms" made specail for us by FORD - complete with stock part numbers on them. The bolt is a fulcrum point...

I'm not sure that you understand how great the amount of torque put onto that arm by the front differential really is when the front tires are trying to claw their way up & over a rugged obstacle while in low range...
If you think about it, that one arm has to support thousands of foot-lbs, and it can even hit close to five figures when dynamics such as a bounce while on the throttle come into play. This is vastly different than what a radius arm is subjected to when blasting down a Baja race course (which I understand the majority is typically done in 2WD anyway).


Presented with what I see in those pics, I would box up the first ~24" of the arm coming from the axle with some 3/16" plate, and then add a gusset (3/8" or so thick) along the upper tube that reaches to the top of the axle beam where the section of box tubing is. This would increase the structural rigidity of where the arm is attached probably 20-fold.

So you guys measure travel with the coil removed?

That is how you objectively measure the (up) travel of any coil spring suspension.

 

[tgreening]

That is how you objectively measure the (up) travel of any coil spring suspension.

Why? Seriously.

 

[villageidiot327]

Why? Seriously.

When setting up a suspension, you want full bump before you bottom out the shock shaft. The reason for removing the spring, is so you can have the whole system and geometry done, but actually be able to put it thru the full range of motion. This measuring mostly applies to independent suspensions. Setting suspension to bump before shock bottoms out is pretty well the rule.

 

[tgreening]

I understand how shocks come into play, but I dont understand why you would want to remove the springs in order to measure wheel travel. A solid axle leaf sprung front (or rear) end is no different. You don't want to bottom out the shock at either end, but since I don't drive my vehicle sans springs.....

I assembled my suspension and picked it up in the air to see how much droop I would get. Then stuffed it up into the wheel well to see how much uptravel I could get before the spring started to get into negative arch. Add bump stops accordingly then took my stuff and droop measurements and went and bought shocks. My suspension runs out of movement at each end with the shock having about 1" left to go, at each end.

If I removed my springs so they didn't impede my "full range of motion", my uptravel wouldn't change a whole lot but my droop would be pretty much infinite.

If the coil is stopping your suspension from going through a full range of motion, and changes that range of motion when installed, then measuring wheel travel without the spring is giving false data on real world wheel travel. I don't imagine the owner of that van will be doing much driving without his coils installed, so the only measurement that matters to him is the one taken with his suspension fully assembled.