RPG's "Stage 2 Kit": Rear frame support and Fox Air Bumps

BigJ

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Since I picked up my Raptor two years and 40k miles ago, I’ve driven the heck out of it and enjoyed every minute. This truck has served as my daily driver, my professional workhorse and my weekend play toy.

And while I’ve been very happy and satisfied with its performance, the modder in me has always kinda wondered what the ‘next step’ might mean for a Raptor and its suspension. That, combined with the lingering frame bending question and the new evidence showing spacer kits like my Truxxx might not be the best idea, set me on a research and investigative path that eventually lead me to Raptor Performance Group (RPG).

Among other things, RPG offers three kits, broken down in stages. “Stage 1” is their frame support kit (Stage 1 kit), “Stage 2” adds Fox 2.5” Air Bumps to the mix (Stage 2 kit) and “Stage 3” introduces RPG specific National Springs leaf springs (Stage 3 kit).

When I first talked to Jarrett (FORD RAPTOR FORUM - Ford SVT Raptor Forum - Ford Raptor - View Profile: RPG) I explained how I used my Raptor, my concerns about the Truxxx and asked his thoughts. That conversation resulted in what ended up happening yesterday: Corey Kaush, owner and lead designer/engineer behind RPG, agreed to meet me at RaptorAddict’s shop with a truck full of parts, give my suspension and frame a through inspection and we’d go from there. bstoner59 caught wind of all this and joined us too. All the sudden we had a cool little M&G / Tech Session on our hands!

What we found during the inspection straight up shocked me. I discuss that in great detail in another thread, (http://www.fordraptorforum.com/f5/4...ding-blown-shock-bent-frame-10550/#post146422) and I’d ask if you have specific questions about the Truxxx kit, frame bending issues or the blown shock, please ask them in that thread. I’d like to leave this thread about RPG’s kits and install specifically.

The bottom line was we in fact found my frame was about ⅜” bent, and I gave the go ahead to install RPG’s Stage 3 kit in part to 1) fix what’s currently bent, to 2) prevent it from ever happening again and 3) to improve the responsiveness and compliance of the rear. This thread is about those first two goals... this thread is all about RPG's "Stage 2" kit. Their "Stage 3" kit adds National Spring leaf springs, which I cover in a separate thread, found here: http://www.fordraptorforum.com/f5/rpgs-stage-3-kit-national-spring-leaf-springs-10591/

On with the Stage 2 build!

Corey brought me everything just as it ships from their facility.
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I’m a sucker for pretty welds
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Here’s the cross brace. Check out those laser cuts. Cllleeean
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Grade 8 hardware! Anyone who’s read any of my install threads will know this, but just in case... I’m a stickler for grade 8 stuff. RPG is the first company of any that I’ve modded my Raptor with to provide grade 8 hardware. Kudos to them.
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Just a quick point. You can order the Stage 1 kit from RPG without it being bump stop ready, and save a few pennies. If you do, you don’t get the pad, or the welded in tube. Corey said they haven’t sold a single set like that though; it just makes sense to buy the stuff with the parts ready to go. If you ever decide to add the stops, you’ll be all set and install will take you a few minutes, rather than needing to uninstall and basically start over.

Here’s the bump stop stuffs; the pads and Fox 2.5” Air Bumps.
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Here’s how the pads install. Please note these are not meant to be comprehensive install instructions. RPG has downloadable written instructions (complete with pics, torque specs hints tips and tricks!) and vids on their website that walk you thru step by step how to do this. So rather that redo all that, I’m just trying to show you the highlights that I found interesting.

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The pad is captured by the locating pins, between the axle and springs (the springs shown are the National Springs, but this is exactly the same and true for the stock springs)

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Then the U bolts go thru the pads, locking everything down as one incredibly solid piece
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BigJ

BigJ

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By the way, notice how the pad has been moved to the outside of the leaf. The stock location is inside the leaf. Effectively, that’s about 8-9” of outboard movement on each side. What’s the point? By moving further out (as far as it can go, by the way) you’re minimizing “duckwalk” of the axle; a situation where the axle literally looks like its waddling like a duck if viewed from behind. Some have experienced this so badly that they’ve broken axle housings.

Another advantage? This approach basically eliminates wheel hop.
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Here is showing the cross brace going above the frame and below the bed. It slides right in, and then it captured by and bolted to the supports once in place, creating a solid unit from side to side.
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Now the frame support slides on the frame. This is a CNC cut, precision welded part made of 3/16” plate steel. By design, it extends slightly higher than the frame, on the outboard facing side. Why? In theory, this design maintains the integrity of the frame’s crush zone. If you are hit from behind, the frame will still fold as designed, protecting you. The extra length of this mount just makes sure it folds up or inward. And that cross brace? It ties the two supports together independent of the frame, so when that stop is under load the braces don’t torque the frame. So in other words, it strengthens the part of the frame that needs it, and yet still allows the frame to crush for safety if ever needed.
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Its locked to the frame via that grade 8 hardware. The nut goes inside the frame and the bolt bolts down to it, clamping the support to the frame from the outside. Once torqued down, this design actually ends up pulling the frame into the support, and locking it there in place.
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Here’s where the strength of this part, and how its designed become very apparent. See that daylight there? This was with the support bolted down but not torqued yet. What you’re seeing there is evidence of my bent frame.
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And this is after torquing it down. All gone the bend!
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Here you can see the top of the bump stop mount
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And installed
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Job done!
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A couple other notes:
The Fox 2.5” Air Stops come preloaded with 200psi of nitrogen. That’s a lot of pressure to run with on the road, but just about right for off road use. On road, a good starting point is probably 100psi or so, maybe moving up to 120psi. That O ring is used to show you where the stop’s max compression was, and you can play with pressures from there. I don’t have a way (yet) of adjusting the pressure, so I left them at 200psi for now. I’ll see how I like it for on road use, and will probably get a gauge and recharge canister soon so I can play if needed.

The install of the bumps is literally a 2 minute job per side. Obviously do what your budget dictates, but give serious thought to buying the supports that are ready for them first, rather than the option without. You might never plan on adding stops, but if you ever change your mind, you’ll be a very happy camper that you got the stuff that are ready for ‘em. Other than initial cost, tere’s no disadvantage otherwise.

Officially speaking, RPG recommends professional installation for these. But, I don’t see any reason you and a buddy couldn’t knock these out in a few hours in your driveway. Other than a torque wrench and big ass sockets and wrench, you don’t need any special tools to make this happen.

I can’t thank Corey of RPG enough. His expertise is obvious within minutes of talking to him, and his professionalism is first class. He stopped working many times to llet me take dozens of pics, ask a bunch of questions and to make sure I understood not only the how, but the why. He also pointed out several things to me, totally unrelated to his products offering helpful advise and tips. He loves this stuff, and it clearly shows. I can’t speak more highly of the experience I’ve had with both Corey and Jarrett.

And finally, I gotta give major props to my very good friend bstoner59, and my new bud RaptorAddict. These guys took a rainy Saturday out of their busy lives to come down, get wet muddy oily and greasy while working on my truck. They kept me clean, letting me take pics and notes so I could properly document all this for you guys. If you ever get the chance, please give ‘em an ‘atta boy’ thanks for making yesterday, and this post, really happen. (and it was very cool to meet MicTouch and Mrs. MicTouch who joined us for lunch!)

Questions? Fire away!
 
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RPG

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I read the original lift blocks are bevelled to set an angle for the pinion gear. Are the new landing pads bevelled, or isn't that a concern?

First off, great write up BigJ. Cant wait to hear about your first off-road excursion with everything on, your gonna love it....


Debate,

The Leafs were designed to retain the correct pinion angle. This was a major factor for us in the design phase becuase I was one of those numb nuts who removed their rear blocks to see how she felt and put the block back in because of that very reason.

The Leafs are Military Double Wrap, hand formed and built exactly for our application.

We couldn't be happier with the Results.

Thanks for the question.
 
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BigJ

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Thanks Jarrett! I can't wait to get 'er off road either :)

Just a followup on your comments: does that mean you (RPG) does not recommend your stage 2 with the stock springs? Or am I misunderstanding? Is there something about the stand alone stage 2 kit that accounts for this angle issue, when used with the stock leafs?

Thanks again!
 

debate

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Debate,

The Leafs were designed to retain the correct pinion angle. This was a major factor for us in the design phase becuase I was one of those numb nuts who removed their rear blocks to see how she felt and put the block back in because of that very reason.

The Leafs are Military Double Wrap, hand formed and built exactly for our application.

We couldn't be happier with the Results.

Thanks for the question.

You're welcome, thanks for the insight. I'd like to keep the stock springs and switch the liftblocks side-to-side, putting the landing pads outboard. Would RPG consider designing a version of the brace with the bumps mounted higher for that mod?
 

f16YODA

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BigJ, great write-up. Can't wait to install my RPG kit this spring.

Curious though. You mention installing the Stage 2 kit, but then your pictures show National Springs. Did you already have the springs or did you actually get the complete Stage 3 kit?
 

Hockster

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I read the original lift blocks are bevelled to set an angle for the pinion gear. Are the new landing pads bevelled, or isn't that a concern?

If I remember this right its tapered like 1/4 or 5/16 in... And you should make sure that it keeps the factory angle or the pinion bearing will prematurely wear out and start singing... I seen them take 40 or 50k miles before it starts ... If the springs are not tapered that a is easy to piece to make...
 

RPG

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You're welcome, thanks for the insight. I'd like to keep the stock springs and switch the liftblocks side-to-side, putting the landing pads outboard. Would RPG consider designing a version of the brace with the bumps mounted higher for that mod?

Already ahead of you.

Fox built us a custom pad extensions for the Bump so you can run the OE Leafs with the Stage 2 kit. No nead to switch the block. But I strongly recommend getting a set of leafs. The Nationals make the everyday drive so much better, let alone the improvements in the dirt.
 
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