K-Member / Rack & Pinion Steering Suggestions
IMHO,.... snout / J bars that attach to the 18 ga OEM vent sheet metal above the firewall is like wearing a condom with pinholes punched in it....just a matter of time until problems. There is very little structural support with that thin sheet metal. Of course, thru the firewall and attached to a cage would be excellent.
Matter of time? How about 30k street miles? Look the same as the day I installed them, crappy MIG welds and all.
J-bars are no different than ANY cage installed in a unibody car. What do you weld to? Sheet metal. What are the frame rails? Sheet metal. You use a landing plate on the tube to capture enough surface area to spread the load that you want to carry. On the J bars on my car the lower edge of the landing plate is welded to the seam between the firewall and the cowl, and is tied into the corner that makes up the base of the A-pillar. I could have done it a little better and gone around the corner and captured the seam where the inner fender attaches too, but it's already tied into one of the strongest corners on the chassis. So, no, I'm calling BS on that.
And really, they're just there to stop the flex between the frame rail and the firewall/cowl. It shouldn't be a large force they're carrying, especially on a torsion bar suspended car. They eliminate cowl shake, and since mine are also tied together at the front (tubular lower radiator support), they resist twisting in the front of the car as well.
Likewise, I do not put much value in the US CAR & Tool weld in support when it comes to a coil over conversion....it may help (?) in the unibody flex department, but I do not believe it was designed or intended to take the load of the coil over requirement.
Well, when US Cartool designed them they were for improving chassis flex on the unibody, not for backing up coil overs. But structurally they box the frame, firewall, cowl, and upper shock mount. They also form a decent sized structural member if you consider the inner fender as the opposite side. Not all that different than the US Cartool subframes using the floor pan and the top of the box. It basically makes a frame stub that ties in the top of the shock mount, adding additional resistance to vertical flex between the cantilever frame rail and the cowl, which normally is just supported by the inner fender. They capture that whole corner between the firewall, cowl and inner fender, so they're pretty strong.
But what is time-tested and proven..... the HDK upper shock mount (now available in (optional) .250 thick aluminum to trim another 4 lbs off) and chromoly support hoops. 100% bolt on, no welding or cutting. HDK re-enforces the stamped OEM upper shock mount while transferring the vertical load back to the OEM frame rails thru the HDK chromoly support hoops / hardware. It all remains hidden too... incognito to keep the OEM look. 25 years on the job....zero defects. Lets see the OEMs match that.
Right, no argument on the hoops supporting the shock tower, they do. Personally I think the "bolt in" feature is attractive for home installs, but like bolt in subframe connectors they would work a lot better welded int. But in either case they do
NOTHING to reinforce the largely cantilevered frame rail. The shock tower and hoop become a structural tower to support the coil-over, but, the frame rail that wasn't attached in a way to support a vertical load like that is left untouched as far as support to the rest of the chassis. Same issue with the RMS, the tower for the coil over mount is strong, but the up and down flex between the frame rail and firewall/cowl is not addressed at all. That's the weak spot, because normally he suspension loads were translated into radial forces in the K member. Much less duty for the frame rails in the torsion bar suspension.
Clearly both the HDK and the RMS AlterK have both been on the road for quite some time. But a lot of those applications are getting additional chassis stiffening, and I'm sure quite a lot of them aren't being subjected to autoX beatings and road courses. I'm sure some are, but, what's the overlap to other chassis reinforcements?
There's no way I'd run a coil-over conversion without more chassis reinforcement on the front of the car, rails to firewall/cowl.
