RMS AlterKtion on Steroids::

It's my opinion the RMS IFS after over ten years on the market is a well designed, well built, well executed, proven much copied IFS Mopar system that serves its intended purpose well, and that purpose is to offer a lighter weight IFS, improve or equal OEM bump steer, allow increased oil pan clearance /size/configuration, remove TB from being a header clearance issues, improve steering response by using a rack steering design, and allow use of coil springs ( which may or may not be helpful, on a case by case basis). Many arguments have been made over the years with this designs perceived shortcomings, mostly opinions, with little, if any concrete proof for support.

Regardless, any design can be improved, that will always be the case, including my upgrade.
My application for use will be on the heavy side, big block, early b body. It is likely to be street driven hard, and will see limited non competitive open track time. I'm using a 13" /6 piston brake package, starting with 550lb coils, 1 1/18" Solid Swaybar, and min 295/35/18 front tire. Ability to remove a decent amount of the right side upper inner fender, to allow use of the 2x4 long ram intakes ( which were never offered in the 62 B body) and good handling, are the primary objectives with this RMS system. I have other cars to chase other solutions. This one uses RMS.

I also believe that with my intended upgrades of the RMS, one glaring weak point will remain, and that is use of the Wilwood Alum Hub, what I consider to be, an Alum undersized bearing package/hub for my intended use. i will as best as i can minimize front end weight, optimize wheel centering over center max load carrying point of the two hub bearings, inspect often. cryo the alum hubs ( which on Alum achieves little), and cool the area with brake ducts. Later, if an easy spindle upgrade becomes available, i likely will chose that route. I have since upgraded to DR Diff more robust alum hubs with same bearings. Regardless these pinto II spindles do see some circle track use with other racers, and have been used on thousands of similar vehicles for over a decade of all makes..

My upgrades will center on increasing the proportional robustness of the other components of the RMS system and to handle the expected weight, and higher cornering/braking loads.

The K frame was upon receiving, completely deburred and sharp edges rounded, and then powder coated. I then developed this plan to beef up this design.

The original K member weight after powder coated and deburred was 39 lbs. For reference a typical dirty OEM k member weighed on the same scale surprisingly, approx 39 lbs

First task was for simple reference sake, to get at least one measurement baseline of approx deflection of the RMS member. There are going to many loads from a multitude of directions applied to this K member, and measuring all of those loads is beyond the capability or my willingness to measure or even understand, in the scope of this project. However having one "typical" base measurement of a predictable likely load, would give me some reference, as to what improvement i can gain , compared mainly to weight gain of adding all the various stiffeners. Granted for simplicity, this measurement will not a have the added stiffness of the cars unibody gained once bolted in, but I still feel it is worthwhile task. Besides few of us argue the facts, it's the interpretation of the facts, where most of us differ. This case will likely hold that to be quite true.

So my thinking is, we know the approx weigh of the front of the car ( figuring 3900lbs wet/driver) approx 2300lbs front, and under hard braking that will be closer to say 3300lbs weight transfer ( 4" in coilover travel total, 550 lbs/in, say 3" under hard braking, 1650lbs wheel). Other dynamic loads of course likely higher. We know the approx angle (15Deg) of the coilovers, motion ratio, and can calculate the resultant horizontal force inwards at the top of the RMS coil over mounting points. Therefore, I will induce this force, up to this maximum calculated force (426lbs), equally, in tension, between the two upper coil over mounts, and then measure the deflection, before modifications, and then after. If I was real ambitious, I would do this after each stiffener was added. Feel free to knock yourself out on yours. LOL

First K member mod was to lighten the 3/8" x 1.5" vertical steel fixed end sway bar mounting points. They are welded on all 4 sides, welds loaded in shear. Not sure why they are so robust. I could cut, remove and replace, but warpage could be an issue since they are right on the two biggest bends of the k. I hogged out/bull nose the center of the mounting flat bar between the 2 threaded mounting holes . These grooves will not be visible when the sway bar is in place, nor do I see any way this weakens the assembly.

Next task is I closed any tube openings (6) with a filler stiffener plate with 14 gauge steel, custom fitted, and drilled/deburred for lightness, and to act as a vent for welding. I also drilled a water drain hole since the larger holes will allow standing water to gather inside . These filler plates are also bent to act as reinforcements/thickeners for the 4 main bolted k member attachment points. The two hole thickeners' towards the rear extend further outwards past the bolt and tie the bolted area directly to the coil over upper support.

The RMS 2 thru the frame 3/8" bolts in the upper coli over support, have welded in steel spacers added, these are long enough to extend beyond the outer box plate, added to this coil over support member, basically boxing it in. The 14 g outer box cover has 3 dimpled lightening holes. the lower hole is place to allow access to the LCA pivot shaft tightening screw.

Another single lightening dimpled gusset was added to the lower portion of Coil over support to help transfer any yaw /torsional loads from the LCA pivot points back to the rear mounting K member bolts.

The ends of the extending LCA pivot tube points were gusseted with cone shaped gussets on each end for 360 degrees, in 4 places, the reduce cantilever of the tubes

Each side main mounting bolt k member extension, was tied together with a 5 dimpled lightening hole 16g gusset, that are to help resist racking of k member and to assist in transferring loads side to side. This is the most difficult area to assess for needed reinforcement, with the main goal for an efficient, desiring a "high bang for buck" solution. But I am trying to not add any superfluous weight. I feel currently anything added so far will not cause any harm.

The lower K member crossover 2" square member is gusseted on the bottom by a 14g plate which ties the above 2 side 5 hole gussets together. This center gusset has a bent angle facing the front to help stiffen this gusset, and reduce chance of this member "catching' on road debris, etc.
The two open tube welded rack supports are braced.

I also gusseted where possible the motor mounts, as they by themselves locate the single largest mass on the vehicle

Pre reinforcement Test Pic #1
Tension between Upper CO mounts digital crane scale 426lbs
In Jig Free 40 10/32"
426lbs 40/ 5/32
5/32" movement

Out of jig free 40 10/32"
426lbs 39 24/32"
18/32" movement 9/16" .562"

With added JC reinforcement Pic #2
in Jig Free 40.187
426lbs 40.125
.062" Movement a .030" decrease
Out of Jig Free 40.240"
426lbs 39.875
.365" Movement a .197" decrease

I made measurements on the K both in the jig, and sitting free. I think it can be assumed the unibody adds some stiffness to the k. likely not much. However the amount of stiffness the jig provided was surprising. Real world results are obviously, somewhere between to two. And there is no easy way to retest, after installed in the car.


Pics #3, 4, and 5, Welding Jig #6
K member was then sandblasted, Vibratory Stress relieved, cryoed, shot peened, and powder coated a light color to help spot any cracking/overload.
LCA Pivot shafts were replaced with 3/4" 4130 HT shafts. The K member gained almost 10lbs with the above, again below cars COG, and with little increase in front of front axle, and just within what i hoped to be my upper weight gain goal.




The RMS LCA have many loads (bending, torsion, compression, tension) from the coli over, cornering loads which are mainly tension or compression , and braking loads which are mainly rearward, and all in any combination may arise. I am not concerned with large pot holes, concrete walls, hard contact with other cars, etc, and if they occurred, I prefer the LCA fail sacrificially, then other parts of the car. I do not feel the LCA has any significant shortcomings by being labeled a "single shear" pivot, almost every race/stock car has very similarly loaded single shear UCA, to little concern of most. And the often quoted "wideness" of the triangle offered by using a brake strut in an OEM mopar design, which main benefit is the compressibility of the strut bushing in case of hitting a large pothole, or something, which really seems counterintuitive to me in that its benefit is "give", and everywhere else on suspensions we chase "stiffness" without play. I'll take stiffness.


Looking at the attached picture #7 is the stock RM and JC modified LCA.

My modified LCA have been tigged shot peened, cyro, and powder coated., at 9:00 this holed added triangle gusset stiffens the LCA mainly for rearward braking forces.

Dead center, the 1/2" thru bolt mounting lower coil over bracket, has a 1/8" thick washers welded to ea outer side of the bracket. The center open coil over slot, which I am not completely certain of the reason this bracket was left as a open as a slot, most likely mainly for fabrication purposes, was filled/welded in.

At 6:00 I added an upper 3 weight saving hole bent gusset to stiffen the coil over bracket, and to stiffen the ball joint holder mount area. Just below that, I added 2 outer lower gussets to also stiffen the coil over bracket, and the ball joint mount. I believe these 3 gussets also stiffen the LCA from "racking" loads caused from mainly heavy braking loads.

At 3:00 I added a circular gusset to the top side of the sway bar mount tab. this is to stiffen the somewhat original cantilevered tab. I also added a small water drainage hole, just outside sway bar link bushing area. I also added a holed stiffener on edge bracket , that helps transfers some coil over loads closer to the pivot point, it helps transfer "racking" loads from heavy braking in tension only, and helps support the cantilevered sway bar tab.

I jigged the LCA with a 1" threaded rod was mainly for warpage stabilization during the above welding modifications.

The above additions added to the 5.9lbs original weight ,15.5oz./arm. A down side is that weight is mainly towards the unsprun/balljoint end. but all the weight is below cars COG and hardly in front of front axle.


I am not overly impressed, for my application, with the RMS UCA. However I don't currently have a favorable solution for an upgrade. I'm toying with a "SPC" fully adjustable arm, but am unsure if there is sufficient clearance to allow their use with the coilover. I am likely to use the RMS UCA until I resolve a better solution.

Pic #8
The spindles had a divot removed from the steering arm on bottom side, arms were polished, shot peened, cyro, and powder coated.

In Conclusion with this re-design, personal values play a role in determining what's important on this upgrade, few, if any, are going to agree on my value selection. Regardless I am satisfied with my choices.

My Objectives:
1. Increase Stiffness
2. Weight loss, but gaining stiffness vs some weight gain is acceptable
3. Any upgrade should be proportional to all other upgrades
4. Making the K failure proof is not a goal
5. Do no harm


The project turned out to be rather lengthy. I started trying to Mig it together, but soon changed over to Tig, and that process is slow. Preventing warpage was a big consideration. I did fabricate a robust 2.5"x.25" Sq tube jig with 3/4" grade 8 mounting bolts on a stand, and used an upper coilover locator during most of the build. I could have used much heavier gussets, and it would be stronger yet, but I am happy with the 12 lb total weight gain here, and not discounting , all of the gain is below the car's center of gravity.

Pic 2

Pic 3

Pic 4

Pic 5

Pic 6

Pic 7

Pic 8

interesting to say the least. how wide are the lower control arms between the pivot points ? you did say you were going to leave the rear mount in single shear ? it took me 3 1/2 years to study theory & design with fabrication of the front suspension on my 33 dodge "humpback" delivery. i studied the rms setup several times in person, and bill was always very gracious in knowing i was not going to buy his product, but needed knowledge in order to make something that would be safe in the end. as my project is mainly drag race oriented with some street time [a far cry from this forums purpose] , and because of the "look" i was after, the upper & lower arms were made of 1x1x1/8 wall square tube. i used 3/16 plate for the crossmember with massive 2" slugs internal and 1 1/5" slugs with 1/4" gussetts for the lower arm pivot area. the upper and lower arms were built in a jig i fabbed from 1" thick plate, and i can remake as many as needed, although i made 2 sets [just because] at the time. this work was done around 2005, and as my health issues have progressed, i still have not been able to try this out. ball joint braces need attached as well as a middle arm-to-arm brace on the lower arms. these will be attached with the arms back in the jig. these were left off on purpose, as i was a little uncertain of the coilover clearance at the time. i am also toying with the idea of running a bracing strap around the balljoint mounting rings from arm to arm to insure no failure in that area. after assembly i tested the travel and got 3/4" camber curve and only .158" bump travel in the total range of motion from full compression to full drop. also, the fab tolerance was kept to +/- .010 on all components. the spindles were also highly modified, but that is another story. i guess the point of this reply is my interest in learning by studying others solutions to similar endevours, and then applying those to fit my purposes. thank you in advance fo sharing your experiances.