New find for radius arm ram trucks

[Explorerinil]

Informative post!

So at what point does the OEM radius arm setup become a liability for an offroad-oriented Ram? I'd imagine that driving over rough, even unimproved and rutted roads and tracks should be fine...plenty of people drive their Ram's on bad surfaces and I don't hear about axle bind being a common issue.

You mentioned something about Cooper from Diesel Power Products encountering issues. Was that on a technical rock crawl?

Is this Lewis Radius arm the only setup that addresses the issue? I believe Carli offers aftermarket radius arms too, no?

Cooper from diesel power products had an issue with his ultimate adventure built ram, something 99% of us will never encounter. I would say you’ll be fine unless you are rock crawling or running through areas with lots of articulation on a regular basis. I blast down frozen rutted up farm fields getting to fall hunting spots, sometimes pulling a trailer or hauling a lot of stuff with my carli suspended ram running factory radius arms... no problems here

 

[Explorerinil]

Informative post!

So at what point does the OEM radius arm setup become a liability for an offroad-oriented Ram? I'd imagine that driving over rough, even unimproved and rutted roads and tracks should be fine...plenty of people drive their Ram's on bad surfaces and I don't hear about axle bind being a common issue.

You mentioned something about Cooper from Diesel Power Products encountering issues. Was that on a technical rock crawl?

Is this Lewis Radius arm the only setup that addresses the issue? I believe Carli offers aftermarket radius arms too, no?

I forgot, yes carli makes radius arms, they are good, however the Lewis arms are different, due to them being fully adjustable and will allow for lifts without using drop brackets.

 

[kmcoop7]

I wish they made some type of "articulink" for the ram 2500 like they make for the power wagon. Cooper at Diesel Power Products has broke the front housing in Howitzer twice now. I can only assume its from the twisting load put on the housing when you articulate the suspension beyond the max deflection point in the radius arm / axle housing mount bushings. I have actually seen this before in the early FORD radius arm design.

Those lewis built arms do exactly what the PW articulink arm does....add a busing/pivot point on the raduis arm it self, independent of the two axle locating bushings

 

[marshal]

The power wagon uses what they call an Articulink on the drivers side radius arm, it provides a link from the radius arm through a heavy rubber bushing to the upper axle mount on the axle housing. this in effect allows for some reduction in suspension binding as the axle moves during articulation... Certainly, FCA understood this and it is for sure why they limit the amount of axle articulation with a relatively short amount of suspension travel in the front of the ram trucks. Im sure there is some calculation concerning bushing deflection and axle articulation (look at the bushings on the axle housing, they are huge and allow a good amount of deflection)....

Anyways.... I hope this made sense...

It’s actually both radius arms have the extra link.

 

[Ravenmad]

Thats awesome. I've only ever seen pics of the driver side... Now I won't feel bad about having lewis built modify both arms.... Thank you kind sir. Question????? did you go outside and look? I myself am not a power wagon owner.

 

[marshal]

Thats awesome. I've only ever seen pics of the driver side... Now I won't feel bad about having lewis built modify both arms.... Thank you kind sir. Question????? did you go outside and look? I myself am not a power wagon owner.

Yep! It’s also worth pointing out that the Lewis built arms have FK rod ends on the control arm side of the upper. That coupled with the Johnny joint at the frame should mean they have less bind and are able to articulate further than the PW radius arms. Ideally, pressing out the rubber bushings on the axle and replacing them with Johnny joints would be the best setup for rebuild ability and articulation.

The trouble is, radius arms that are built with a separate “upper” like the Lewis ones - require some amount of bind (IE, a solid bushing at one end) in order to keep them upright. Otherwise they’ll flop over until they hit a binding point of the joint.

 

[Tex68w]

Well I guess the million dollar question is, would these be a worthwhile/beneficial upgrade for those of us with PW's?

 

[marshal]

Well I guess the million dollar question is, would these be a worthwhile/beneficial upgrade for those of us with PW's?

the questions you would have to ask yourself is, are you going to need to push your axle forward to clear tires off the fire wall/pinch weld because of the tire size or wheel offset? And, are you going to do full articulations on your front suspension often enough that the stress upon the housing a joints becomes a failure point? The rubber bushings are only rated for so many cycles before they give up the ghost and need to be replaced, where as the Johnny Joint and FK Rod end are spherical bearings and are designed for that purpose. Also, if you are trying to rebuild the front suspension to exceed the stock 10" of travel (say 12-14" of travel).

If you said yes to any of these questions, then they would be a good investment. Its worth noting as well, that while the Johnny Joints are the best in the business for a spherical bearing suspension joint, they still transmit quite a bit more NVH than rubber bushings and require regular maintenance. Now, the radius arms on these trucks are REALLY long, so NVH transmission should be minimal from that perspective, its still something to consider if that is a important factor to you.

For me, getting the arms is a no brainer, because I picked really really aggressive offset on my wheels and to stop any rubbing I need to push the axle forward. Right now in terms of performance I'm ok - I have very minimal rubbing at full stuff, but I would like to be at 0 rubbing if possible, and i would like to run a 12" travel shock in the front as well.

 

[Dalko43]

You are absolutely correct, normal use and even mild offload use should be fine. The problems begin to display themselves when you push the trucks suspension articulation wise. Cooper has something like 13 inch throw shocks on the front of Howitzer and is rock crawling it. He broke it on day 4 of Ultimate adventure last year if I remember correctly and then again in Moab for EJS. The lewis arms are a good start, but they were originally built for go fast dirt trucks. They will need the upper link ends to be replaced with a rubber end similar to the new terflex alpine joints in order to facilitate articulation, but even then they will have their limitations.

So does suspension travel have any part to play in this OEM radius arm issue? If you're dealing with at most a 3" lift, and the corresponding suspension travel, will the axle with the stock radius arms really be vulnerable for mild, even somewhat technical, rock crawling?

 

[marshal]

So does suspension travel have any part to play in this OEM radius arm issue? If you're dealing with at most a 3" lift, and the corresponding suspension travel, will the axle with the stock radius arms really be vulnerable for mild, even somewhat technical, rock crawling?

the issue you're running into is the control arms that the RAM's come with stock. heres what they look like (this explanation also carries over for the 2005+ Ford Super Duty's as they also use radius arms. Lewis also sells these same adjustable radius arms for the 2017+ Super Duty)



So - is a totally rigid piece made of medium wall box steel. As the suspension articulates - the upper and lower mounts of the axle side are moving in different arcs. The twisting available to the axle is allowed entirely within the deflection capability of the rubber bushings and the actual twisting of the radius arm itself. because there is extremely minimal twisting capacity from the radius arm itself, enormous stressors are being placed on the axle side and frame mounts and the rubber bushing is the primary energy absorber.

here is what happens to the bushings as you keep cycling them over and over and over again offroad



here is what the Power Wagon Articulink radius arm looks like by comparison




Chrysler shrank the size of the radius arm cross section, so it itself is more capable of twisting action, and then inserted an additional rubber bushing. This link setup allows the upper mount to move semi-independently of the lower mount and massively increases available articulation. The problem still exists in the fact that you're dealing with rubber bushings that are only good for so many cycles.

The Lewis arms are connecting to the stock upper and lower rubber bushings that are pressed into the axle, but use an FK Rod-end (heim joint) to on the upper link to allow fluid motion, and on the frame side, uses a Currie 2 1/2" Johnny Joint (spherical bearing). The Johnny Joint allows for 30° + and - (60° total) movement before bind, and the FK rod end is capable of 40° + and - (80° total). Because they're spherical and designed to roll around within a race, they minimize the amount of binding within the radius link itself, and therefore massively reducing the amount of stress being placed on the bracketry and the axle itself.

here are views of a Johnny Joint and a heim joint for reference

exploded:

FK Rod end (Heim) [big ones]

 

[blackdmax15]

Thanks to all for costing me 1400 more dollars for a truck that I haven’t even received yet as Ram has taken 8 weeks to get my custom built truck to me... Solid information in this thread as well.

 

[Bayou Boy]

Is it possible to swap that PW Articulink setup into a regular 2500/3500? I'd assume that would be an extremely cost effective upgrade for a diesel truck.

 

[marshal]

Is it possible to swap that PW Articulink setup into a regular 2500/3500? I'd assume that would be an extremely cost effective upgrade for a diesel truck.

I don’t see why not. The caster is setup slightly different on the PW links due to the factory 2” lift. My only concern would be the longevity of the smaller bushing with the extra 1000lbs of driveline

 

[Ravenmad]

No question, the lewis built radius arms are a better / longer lasting option ... When I spoke with them on Sat. He said they were all out of arms and waiting to get parts to build more. I believe He said they would be 9-10 days out. Plus, I have hunted around for a used set of factory PW radius arms, they are not easy to find...