Now that the 12-bolt posi is put back together with my new 5 on 5” lug pattern as described in the previous article. I was ready to look at rear disc brakes. I was attracted to rear disc for the ease of maintenance, the additional stopping power and additional safety factor of the caliper being able to retain the wheel from falling off if an axle breaks. I found Doug with steel tech solutions inc. selling rear disc caliper brackets. They utilize the 82-88 Camaro front calipers, positioned so the bleeder screws are at the highest point, for easy bleeding while mounted on the rear. These brackets could also use ’85 Cadillac Seville rear calipers with the built in parking brake. I did not like the Cadillac’s caliper because of the dual cable complications, expensive calipers and the caliper parking brake requirements of needing to be used often or it gets out of adjustment. The ’82-’88 Camaro front calipers are cheep and simple.

    Next I searched for rotors that would work. I looked for something just like the recommended ’80 Camaro rear rotors but with a 5 on 5” lug pattern to fit the new axle lug pattern. I changed the lug pattern not just for the added strength, but to keep consistent with the lug pattern up front when using the b-body 12” disc conversion as is. I will describe that conversion in detail in another article. After a tip from a guy on Team Chevelle (www.chevelles.com) I found it with the ’79 Cadillac Fleetwood or Deville 11” rear rotors. A perfect match!

    There is an exposed “nub” in the casting of the Camaro calipers that have to be ground down to clear the mounting brackets in the rear. If you try to mount it, you will quickly see where the interference is. No big deal. The brackets would have worked great on a rear with stock axles, but because my new Moser axles had a thicker flange, I could not get the calipers positioned over the rotors properly. It is critical to have the proper travel for the caliper, so the caliper does not move over the caliper pins as pads wear down. I could put the brackets on either side of the rear housing flanges and it would not work. The bracket needed to be directly in line with the housing flanges, so back to the drawing board. I made a new adapter bracket and matched drilled the holes with the original bracket, then I cut the original brackets to clear the housing flanges. Bolt these up with grade 8 hardware. I painted the new rotors, axle flanges and calipers with the Por-15 method described in earlier articles.

I’ll be hooking up brake lines, hoses and cables in the next article. Now to get the rear in the frame we need to look at the bolts. The suspension bolts were rusted and I needed a good solution for the suspension hardware. I found hardware that I ordered in bulk and broke down into a kit. This hardware kit is specially designed for replacing all 12 mounting points of the control arms on a Chevelle. AVAILABLE HERE

    All components are Ultra-coated grade-8 high-strength medium-carbon alloy steel that has been quenched and tempered. It is an organic polymer coating, also known as armor coat, is applied to CADMIUM-PLATED steel to provide nearly twice the corrosion resistance of comparable hot dipped galvanized fasteners, and does not affect thread function. Salt spray resistance of 1000 hours per ASTM B117. Screws meet SAE J429. Rockwell hardness is C33-39 with a minimum tensile strength of 150,000 psi. Screws are manufacturer and grade marked on top of head (6 radial lines, indicating grade 8) has a clear silver finish. There is no doubt that these will last far longer then OEM hardware.

Due to the use of polyurethane bushings some have been unfortunate to discover that the increased vibration works the nut loose. Well the kit includes a flex top lock nut tightened down to the first nut to double insure the nut never backs off. Thread locker compound can even be applied. This lock nut is not Ultra-coated. It has a castle like top that spreads out as it is threaded on doing what typical ny-lock nuts do but it is reusable and provides more clamping force. It is not grade 8 but does not need to be. The first nut is taking care of that.

     Normally stainless is great! There are even grade 8 stainless bolts out there, but here is a unique situation. Suspension bolts are exposed to road salt, more so then say engine bolts or interior applications. Here is the problem with stainless steel when pressed together with anything causes an airtight surface on the stainless. Such as the space between the bolt and a washer or the space between threads. In this air-deprived region especially when chlorides are present, the stainless is not allowed to produce its protective layer of naturally occurring oxide. Then the chlorides attack the stainless steel causing pitting. This does not take the form of rust and this is not noticeable because you can not see it until the torque is reduces because of the loss of material then the bolts work loose. Stainless is not the way to go in an environment where it is common to use road salt period.

This is a very durable coating AKA armor coat. It is over cadmium-plated hardware. Cadmium is a very good rust preventative all by it self. It ranks very high on the list. However it has its problems too. It is easily sacrificed thru galvanic corrosion to the more noble metals around. The cad has to be sacrificed before the steel bolt is in jeopardy. Cad is far superior to black oxide bolts from rust. So assuming the coating is scratched off, there is still a superior protection remaining. Especially on the central body of the bolt. Which is where I have some almost entirely rusted thru.

With hardware selected, the upper control arms were galvanized then painted with por-15. You do not want to box these uppers especially when using polyurethane bushings because the rear suspension travel needs a flexing point and after the flex is taken up by the stiff suspension bushings the boxed lower arms, the only place left to flex is the upper control arms. If you box those, you are asking for trouble.      I also galvanized and painted the braces that SS, el Camino and wagons came with. They span from the upper and lower rear control arm frame mounts to stiffen the counter levered mounts.

 

    I purchased a 1-3/8” diameter rear sway bar. Normally that is too large but in this super wagon project it meets the requirements that the heavy station wagon demands. Normally the rear sway bar should be about 75% of the front sway bar’s diameter, but in this case the weight distribution warrants a 1:1 front to rear ratio. If the front and rear bars are not properly matched for the vehicles front to rear weight distribution, it can cause either the front or rear of the vehicle to slide out first on hard cornering especially if there is low tire to ground friction.

   

    I boxed the lower control arms and drilled drain holes for any water to escape. I also welded (4) steel ¾” OD x ½” ID x 2-3/4” long tubes to the control arms, 2 on each side. The first one is 13” back from the center of the front bushing; the second is 5 more inches back. The rolled lip must be ground away to allow the tube to lay flat against the control arm’s side. This was done to accommodate the ’73-’77 1-3/8” rear sway bar. ’73-’77 control arms mounted on the bottom and the ’68 – ’72 mounted on the inside face of the control arms. The bottom-mounted bars are better because they don’t require shims to eliminate sideward bushing preload. The sway bar has slots that provide all necessary adjustments.

   I added the polyurethane bushings and sand blasted the lower arms and painted with Por-15 process. To get inside the arms, I taped up all the holes but one and dumped Por-15 inside. Taped up the remaining hole and slosh the paint around. Take the tape off and let it drain out. Apply polyurethane bushing formula-5 grease between the inner sleeves ant the polyurethane bushing. This is the interface where the steel rubs the polyurethane and could squeak, so don’t forget this step.

     I bolted the rear upper and lower control arms in. With the coil springs out, flex the rear thru its full suspension travel. It turns out I had to replace the center rubber bumper with a steel bracket. The bracket had to be made in such a way to clear the parking brake caliper cable, but also make contact with the rear housing before the rotor or caliper would hit the frame in the event of the suspension being “Bottomed out”. The bracket ended up being 3” x 1” x 1” wide angle steel 5/16” thick with a 3/8” mounting hole in it. Then I installed the urethane spring pads between the springs and the frame, and then I installed new KBY shocks. The shocks not only dampen bounciness, but they limit the rear suspension travel, which holds the springs in place. I used grade 8, 7/16-14 x 4-1/2” long ultra-coated bolts and hardware to secure the sway bar to the bottom face of the control arms. And because I mounted my control arm 1.5” lower on the right side, I could use a 3/8” stack of washers on the rearward drivers side sway bar mount to achieve similar sway bar angle on each side so there is no preload on the rear bushings.

 Next I will describe the front suspension, 12” B-body disc brake conversion, front sway bar and steering components.

 

Next

 

-   Frame mods         -   Rear Differential mods         -   Rear Brakes & Suspension mods         -   Front Brakes & Suspension mods         -   Chassis Component Assembly         -   Body mods & resto         -   Motor & Transmission         -   Options & Modifications

 

back to home

www.einstyn.com