Pro Comp's Poorly Designed Bracket for 1990-1995
Toyota 4Runner Rear Coil Suspension Lifts
While Installing a new 4" suspension lift made by Explorer Pro Comp on my 1990 Toyota 4Runner, I noticed one of the brackets is far from fitting correctly. The part number for the rear suspension kit is 10-57489, and it includes all hardware except the coil springs which are purchased separately. The rear suspension of a 1990-1995 Toyota 4Runner is a 4 link coil type. There are two upper link rods and two lower link rods that attach to the rear axle. To achieve the lift, the mounting points for the link rods are essentially dropped 4 inches at the frame side of the lower link rods and at the axle side for the upper link rods.
While trying to install the lower link rod relocating brackets (LLRB), I noticed it does not fit correctly on my 1990 4Runner. Looking at the diagram below, you can see how the bracket sits as-is. The proper fitment is that the upper hole for the LLRB should align with the factory frame rail hole for the link rod's original mounting point, and the front face of the LLRB should lay flush with the factory frame rail. As you can see by the picture, if I align the LLRB's upper hole correctly, the forward face is off by 1 1/4" where two bolts are supposed to run through the bracket to the frame for secure attachment. If I install the bracket so that the forward face of the LLRB sits flush with the factory frame rail, then the LLRB's lower bolt hole is off by 1 1/4" of the frame rail bolt hole.
Also notice that new mounting point for the lower link rod moves with each position of the LLRB. Which position is right, if either of them? I don't know. A Pro Comp technician told me to just install the bracket as the picture shows below--I don't think so! He said to just try and tighten up the bracket as much as possible and install two longer bolts (than given in the kit) on the forward face through the bracket to the frame.
What are the possibilities? Well for starters, a safety issue. The LLRB has the potential to pivot around the upper mounting hole. Should "slop" develope over time from the bracket and/or frame rail deforming from stress, the bracket will flop around and possibly snap off the bolts. Why not just install a spacer between the LLRB and frame? Well, I would if I knew I had proper rear axle alignment with the bracket aligned as shown.
Second, with different possible positions for the lower link rod mounting point, the rear axle's pinion can be rotated too far up or too far down. I have no idea which it will be either since the bracket doesn't fit! If the axle housing is rotated too much one way or the other, a multitude of problems can arise such as poor driveline angle, vibration, and lack of lubrication of the differential pinion gear.
Third, if the lower link mount isn't in the correct position, the 4 link suspension can bind. With 8 mounting positions that must all work together to swing the axle up and down, it doesn't take much to cause a bind. Binding can cause limited suspension travel as well as stress on all mounting points to the frame and axle. Oops, the LLRB bracket just ripped off the frame!
All this might be doable for a street driven truck or show truck, but what about the stresses created off-road or Heaven forbid in an accident.
It will be interesting to see if Pro Comp decides to do anything about this. Feel free to E-mail me if you have any comments on this issue or anything else on my page.
please excuse the fuzziness of this drawing. It happened when I converted the picture from BMP format to JPG.