RPG's "Stage 3 Kit": National Spring Leaf Springs

This is a followup to my Stage 2 Kit install thread found here: http://www.fordraptorforum.com/f5/rpgs-stage-2-kit-rear-frame-support-fox-air-bumps-10553/ I wanted to break this install up into two different threads because the issues addressed by each stage are quite different. Where Stage 2 fixes and solves frame, axle hop and duckwalk issues, Stage 3 (http://www.rpgparts.com/rear-suspension/stage-3-kit/) is all about improving off road performance and handling by introducing RPG’s custom National Spring leaf springs.





If you were to call up National Spring and ask for their Raptor springs, they’d thank you for the call and politely ask you to contact RPG to complete your order. These springs were co developed by both companies, and are exclusively available via RPG. They went through half a dozen or more iterations before everyone was happy, and production was started. They were installed on Raptors, tested by Raptor owners in various off road situations, removed and inspected by the experts, tweaked to refine desirable ride characteristics and dialed in to remove undesirables. Several sets were thrown away or redone from scratch, reinstalled and then the process was started all over again. The end result are the two types of springs you and I can buy from RPG today; the standard and HD versions.

I went with the HDs. I carry a heavy load in my truck when I off road it; extra fuel, extra water, camping gear, food, cooking equipment, fire wood and on and on. Also, I’m much more the explorer type of off roader; I do not tend to blast thru the dirt at high speed or thru the air at significant heights. If you do, and if you don’t tend to carry heavy loads, the standard springs might be the better choice you. For my money, and for my purposes, the heavier duty HD springs were a no brainer. If you're unsure, talk to Corey or Jarrett (http://www.fordraptorforum.com/members/rpg/) and they'll definitely help you chose.

As I mentioned in my Stage 2 install thread, this install took place at RaptorAddict’s shop. bstoner59 came with Corey of RPG and together with RaptorAddict, these guys busted their butts to get things done, allowing me to take a ton of pics and notes so I could bring these posts to you guys. I can’t thank them enough.

Also as I mentioned, the following is not meant to be comprehensive installation instructions. RPG's website has downloadable written instructions, and videos you can watch that cover all the required steps and specs in great detail. This is only meant to show some of the stuff I found particularly interesting or noteworthy.

The install started off by unboxing the new hardware, getting my truck on the lift and inspecting the current state of everything underneath. She came up clean in the rear and so the guys set to work uninstalling the stock parts

National Spring only uses steel from North American sources, and they make everything in the USA.


















On the driver side, the bolt that holds the stock spring is mounted with the bolt side facing the gas tank. The RPG spring install requires this nut to be cut down and flipped around, so that the nut is facing the tank.



You can safely cut the bolt down to size while its still installed, since there’s a good sized airgap and lots of hardware between you and the tank.







But there’s not enough room to remove it and flip it around with the gas tank installed. You could cut it off and use a new bolt, but keep in mind that sparks and fuel vapors often like eachother a bit too well. RPG recommends dropping the tank to remove the bolt. It adds about ½ hr to the install, but that’s time well spent to stay safe.

The filler neck needs to drop with the tank. As its dropping, it needs to be rotated 90 degees to clear the fenderwell and other parts.


The passenger side has similar clearance issues with the exhaust, so dropping it makes things much easier






The kit comes with new U bolts (top). The new bolts are slightly smaller, but also its good practice to never reuse U bolts. They’re what’s called “torque to yield” bolts, meaning that when you torque them down, they deform and stretch by design. When you remove the nuts, they don’t spring back to the shape they were pre-torquring; they stay stretched. So if you were to reuse them and torque down back to spec, you’re stressing/stretching them beyond design, and you run the risk of them snapping under stress out on the trail.




Here’s a good look at the stock bump pad and lift block. You won’t be reusing these.

See why?






Here’s one of the unique features RPG demanded; a double wrap eyelet for serious strength and longevity (shown left) vs just a single wrap like the stockers have (right). The upshot? This is a far stronger design that helps prevent stretching or sagging. Its also a great way to minimize axle wrap.


And in they go


Here are the stock U bolt groves. This is how Ford stopped the U bolts from walking up or down the spring. This works, but under serious stress its not as solid as it could be


RPG’s hardware actually captures the U bolt above the axle, and reuses the factory hardware below. This virtually eliminates any walk, making for a much more solid coupling of the spring to the axle.








And done!


As for ride height, here’s the ‘before’


Here’s the immediately after


And here’s after about 500 on road miles


PS: Here’s where I’m sitting up front with the Truxxx spacer (that is coming out soon, in favor of the middle perch mod. See here as to why: http://www.fordraptorforum.com/f5/40k-mile-suspension-checkup-binding-blown-shock-bent-frame-10550/ )


Looks like I’m up about 1 1/8" in the rear thanks to this install (after accounting for the new slightly taller tires)

So how does it feel? Of all the descriptions of mods I’ve ever done, describing the change these springs have made to the ride is turning out to be the toughest. Added to the difficulty is that I haven’t had a chance to get the truck off road yet with the springs, so all I can really do is try to articulate how its different on the road. And even so, everyone I’ve talked to about this mod has said the same thing; the only way to ‘get it’ is to drive it. No amount of typed words can sum it up. Bah... that’s never stopped me from trying before

If I was forced to boil it down, I’d have to say the truck just feel more planted, or stuck to the ground. On a way tiny scale, the difference kinda feel to me like holding a magnet by your fingertips and passing it over a block of wood. Casually move that magnet up and down over the wood and your fingers freely lift and lower the magnet. Now hover over a block of metal, move down and just as causally try to move up; your fingertips are held down ever so slightly... you can feel the resistance as the magnet fights to hold you close to the metal. Now blow that up and try to translate it to driving a truck over rough roads, and you can kinda get a sense of the difference these springs are making.

Or let me try another analogy. Have you ever drag raced? The difference feels like drag racing on an unprep’d track vs a well prep’d track. Or cold tires vs warmed up tires. Or street tires vs slicks... its not so much in the application of the power to the ground that I’m trying to descibe, but rather the lack of hop, or rear end lift when you might otherwise consciously (or unconsciously) have expected it to be there.

As I was driving home, I was tired from the long day and not really paying attention as I was rockin out to some Heart. Just as I was about to scream out Ooooh Baracuda! I hit a strip of pavement I’ve been over in the Raptor easily 200 times. Before I knew it, my perfect harmony with Ann was interrupted. I found myself automatically lifting just a touch out of my seat in anticipation of a particularly nasty bump, but there was no seat that came up and met me. The seat stayed down, aka the truck stayed down and hugged the bump the whole way, leaving me hanging mid air and gaping open mouthed.

All kidding aside, I’m a beliver now that in order to really ‘get’ what these leafs can do for you, you just need to feel it. But if my ramblings above make sense to ya, you’ll have a good idea of what you’re in for if you go this route. That rear of ours goes from sometimes feeling like a bucking bronco, to a fine speedboat riding the rolling waves. I can’t wait to get ‘er off road and back out to those world famous Death Valley washboards, or Mojave whoops, or Anza Borrego sandy washes... And when I do, I’ll definitely keep this updated with my thoughts as they evolve.

Another great writeup! Thanks BigJ.

Nice. I am looking to replace my leaf springs sometime.

Spring comparison

I have 4WD ¾-ton pickups for hauling heavy loads. I have two questions about the Stage 3 conversion:

1) Is there only one spring choice? You mentioned an "HD spring". Is that the National Spring that is "Stage 3", or is it one of two National springs?

2) So, if my goal is running quickly down washboard dirt roads, I should go with Stage 2 and stick with the stock springs? I know I prefer softer springs/long travel on that kind of surface. That's why the Raptor is so appealing to me.

I'll take a shot at these, but also ask RPG to pipe up since they're the experts.

chartguy said:

I have 4WD ¾-ton pickups for hauling heavy loads. I have two questions about the Stage 3 conversion:

1) Is there only one spring choice? You mentioned an "HD spring". Is that the National Spring that is "Stage 3", or is it one of two National springs?

Click to expand...

One of two. RPG developed two springs with National. You may chose between the two. RPG has some published specs (that I can't find off the top of my head) that help describe the differences between the two.

2) So, if my goal is running quickly down washboard dirt roads, I should go with Stage 2 and stick with the stock springs? I know I prefer softer springs/long travel on that kind of surface. That's why the Raptor is so appealing to me.

Click to expand...

I do not think so. I think if that's your goal and if you don't carry heavy loads when traveling those roads, I'm betting Jarrett will recommend the standard springs for your application.

But like I said, lets get the experts in here and answer your questions for sure.

When do we leave?!!?!!??

bstoner59 said:

When do we leave?!!?!!??

Click to expand...

As soon as I fix that shock! I can't stand the clunkin goin on

How much more payload can the hd springs carry?

BigJ said:

As soon as I fix that shock! I can't stand the clunkin goin on

Click to expand...

Just turn the music up!!! You have the frame kit so you don't have to worry about doing any damage