Building the Tom Henry RS

Part 5, Page2

Brake Maintenance and Upgrade

In a testament to the durability of stock GM brake pads–or maybe it's that we're easy on brakes–we went 10 years and 100,000 miles on the car's original binders. Though the pads had adequate thickness and there were no apparent problems elsewhere, as a preemptive move; it was time for brake service. We also wanted to repaint the calipers using an Eastwood Brake Caliper Paint Kit (PN 11838 Z). We did this before but decided, after six years, to do it again because, in spots, the paint was chipped or flaking.

With the car on stands and the wheels off, we started at the front by cleaning the suspension and brakes with our Karcher Pressure Blaster and Simple Green "Heavy-Duty Cleaner and Degreaser", a product designed specifically for warm water pressure blasters. Next, following instructions in the 2001 Camaro Service Manual, we removed the brake calipers and pads, rotors and front hubs.

When you tear the calipers down, safely remove the pistons by putting a short section of 2x4 between the caliper piston bores and the outside brake pad mounting surface then use air pressure to push the pistons out. You can use two pieces of wood in a stepped arrangement to make it easier get both pistons out. Keep your fingers out of the way and apply air pressure slowly from a blow gun you can control easily. When they pop loose, the wood keeps them from shooting across the shop.

We washed the calipers with Simple Green Motorsports Cleaner and Degreaser and scrubbed the really dirty spots with Norton Bear-Tex, a woven abrasive, general purpose hand pad. We inspected the bores and found them to be like new, a testament to our periodic flushes of the brake system since '01. With modern brake calipers, since they have piston seals stationary in the caliper bores, honing is unnecessary. If there's light corrosion or scale in the bores, it can be removed with some fine sandpaper or a Bear-Tex pad. 

When we blew the calipers dry, more of the original paint flaked away. The first time we painted the calipers, we did it on the car. As a result, our preparation insufficient. Since the first painting didn't adhere well, washing, then blowing dry made the problem worse by lifting more of the paint.

Now, we had to get all the paint off and, for that, we used Eastwood Company's "Powder Coat and Paint Dissolver". We filled a two gallon pot with it, dropped the caliper in and, with occasional agitation and a little scrubbing with a parts cleaning brush, let the Dissolver work for about four hours per caliper. The Dissolver is water-soluble and washes off. Next, we scrubbed the calipers in Simple Green Degreaser, again, rinsed them, then blew them dry.

Next we sprayed the calipers with Eastwood's "Pre", a surface preparation product, then gave each one final wipe down with one of the Kimberly-Clarke Wypalls we like to use. We mixed the caliper paint and hardener per its instructions. Once the hardener is added, the paint has a relatively short "cup life" so some planning is necessary. Do the calipers two at a time. Have them ready to go before you mix the paint. Give them one coat, then put the paint in the refrigerator and wait 45-60-minutes then give each a second coat. The faster you can paint, the better but, keep in mind that if you go too fast, you'll make a bit of a mess so put some newspaper down. You may find it easer to mix the paint in a smaller quantity but that makes measuring the hardener difficult with the large cup Eastwood puts in their kit. We suggest one of those tiny plastic measuring cups which come with some cough medicines and a smaller four or six ounce mixing cup.

The best way to apply this coating is with a small paint brush. A conventional brush with bristles rather than sponge works better. We gave each caliper two coats of Eastwood's Red Caliper Paint. We hastened the hardening process by baking them in the oven for 45 minutes at 250°F then let them cool overnight.

The caliper guide pins and the guide pin bores in the caliper mounting brackets must be cleaned of all grease residue. Gun cleaning brushes work well for that. We cleaned the exterior of the mounting brackets with some more Simple Green Motorsports Degreaser, dried them, then painted them with a couple of coats of Eastwood’s Silver High-Temp Coating (PN10396 Z)

Finally, the pistons must be cleaned and ours required little more than a wipe down with some brake cleaner and a wipe dry using a Wypall. If your pistons are dirty, under no circumstances should you use abrasives to clean them. If you can't clean the pistons with non-abrasive methods, replace them.

The next step was to assemble the brake calipers using GM Caliper Repair Kits (PN 18026160, front, four required, and PN12530687, rear, two required) sourced from Tom Henry Racing. First, apply brake assembly lube to the caliper bores, the pistons and the seals. Put the piston seals in the bores. Install the piston boots on the pistons and push the pistons into the calipers. Assemble the calipers and mounting brackets by smearing silicone grease on the guide pins and installing new pin boots and guide pin bolts out of the repair kits. The last step was to install the two pad abutment shims and an anti-rattle spring then load each caliper with Baer "Decelapads" (PN D0749, front and D0750, rear). We selected Decelapads because they're a good choice for the high-performance street duty cycle.

In the front, we installed two, new, AC Delco wheel bearing/front hub assemblies (PN 2086) from RockAuto.com followed by a fresh pair of Baer Eradispeed-Plus brake rotors (PN 2301006). These are a racing-style, two-piece combination of an aluminum "hat" and a bolt-on, grooved and drilled cast iron brake disc. Eradispeed-Plus rotors have an enhanced vane design for improved brake cooling and are made with premium materials. The final step was caliper installation with Valco Cincinnati Medium Strength Thread Locker applied to the caliper bracket bolts and the bolts torqued to 74 ft/lbs.

At the rear, the caliper rebuild and painting process is similar to what's covered above in the discussion on front brakes. Once the calipers and rotors are removed, inspect the parking brake hardware. If the shoe assembly is worn, replace it. Disassemble and clean the brake springs and adjuster.

We installed two Baer Eradispeed (PN 55050-020) one-piece grooved and drilled rotors. Our repainted rear calipers, loaded with the Baer pads, went on next. The caliper bracket bolts were cleaned, the threads given a couple of drops of Valco Cincinnati Medium Strength Thread Locker then torqued to 74 ft/lbs.

With the calipers and rotors in place, we moved on to the master brake cylinder. At this writing, mid-September, 2011, the master cylinder repair kit for '98-'02 Camaros (PN 18029859 or ACDelco PN 175431) has been discontinued by General Motors and is no longer available from Chevy dealers, however, the ACDelco version of this part (PN 175-431) is still sold by RockAuto.com. Our research showed that in spite of listing the part as "discontinued" GM still had stock of this part in its Lansing, Michigan warehouse. We suspect RockAuto will continue to sell this until the stock is exhausted. Once the repair kits are gone, if you have a faulty master cylinder; your only choices will be a new cylinder from GM or a new or remanufactured cylinder from the aftermarket.

If you're one of the lucky ones who can get a repair kit–to service the cylinder, chuck its mounting flange in a vise and release the reservoir by knocking out the roll-pin retainers. Depress the piston assembly with a round-ended tool, remove the retainer, then pull out the primary piston assembly. Cover the inlets and the rear outlet then apply low pressure air to the front outlet to push out the secondary piston assembly and the return spring.

Clean the interior and exterior of the cylinder with denatured alcohol then inspect the cylinder bore with a bright light. If you see cracks, scoring, corrosion or pitting, scrap the cylinder and get a new one. The bores in aluminum master cylinders cannot be honed. If the secondary piston hardware is damaged or corroded you, also, must replace the cylinder.

Our master cylinder's bore and secondary piston were in good condition. Knowing we were going to do a brake job on a car with 104,000 miles, luckily, we had ordered a GM repair kit earlier in the year from our GM parts source Tom Henry Racing. We used its contents to replace the secondary piston seals and seal retainer then reinstalled the secondary piston. We followed that with the new primary piston assembly included in the repair kit. Finally, we reinstalled the piston retainer and the reservoir.

Additional, more specific information on '98-'02 Camaro brake service, consult the Camaro Service Manual.

New Suspension Mods

One goal we had for Part 5 of the THRS project was taking our Camaro's suspension to the next level. After consultation with Doug Norrdin, owner of one of our suspension sponsors, Global West Suspension, we decided to try a new spring/shock package consisting of: 600-lb/in. Eibach front springs, Global West 190-lb/in., constant-rate, rear springs and QA1 double-adjustable shocks. In the front, Global West groups the Eibach spring and QA1 "DA" shocks along with some additional parts of its own design, into a coil-over-shock assembly (PN CO32-SR). The rear shocks are a stand-alone, QA1 pieces (PN  TD704).

There are a number of advantages to the QA1s, the first being, by virtue of the QA1s' aluminum shock bodies, a slight decrease in unsprung weight over the Bilsteins we ran before. Shocks which are separately-adjustable for both compression and rebound simply by turning dials on their exteriors have great appeal on a car like ours which is, at various times, street-driven, driven hard on twisty roads or run on a drag strip. The QA1 Double Adjustable front shock for 4th Gen F-cars is a coil-over-shock design so it, also, offers easily-adjustable, front ride height.

In the past, the shocks we've used have been "monotube" gas shocks, however, QA1's are twin-tube gas shocks. Both monotube and twin-tube designs use gas pressure to inhibit the shock oil's tendency to foam during severe duty. Monotube shocks use an inert gas at relatively high pressure on the opposite side of a floating piston to keep a constant volume of oil in the shock body as the piston adds and subtracts volume when it moves. To achieve the same end, twin tube shocks use inert gas at a lower pressure inside a flexible containment envelope or "bag" located between the inner and outer shock tubes.

One drawback of high-pressure monotube shocks is the gas pressure. Let's say the shock is pressurized to 80 psi and has a piston area of 3.1 sqin. That adds 250-lbs to the spring rate on compression. As Roger Wilson, QA1 Motorsports' Sales Manager told us, "This causes the nose of the car to push upward going over a rise or bump at road speed rather than the vehicle following the contour of the road as much as possible. The QA1 gas bagging method exerts no rod or piston pressure as the shock begins its rebound stroke so the vehicle nose more closely follows the road, which enlarges the tire contact patch and enhances control characteristics."

 "The shock adjustments control the amount of fluid which passes through the base of the shock." Wilson continued. "Damping authority increases as the adjustment valve is closed. A single adjustable model increases or decreases rebound and compression simultaneously as the knob is turned clockwise or counterclockwise. A double adjustable model separates the rebound and compression adjustment and allows adjusting the shock from, say, a 90/10 to virtually just the opposite.

"The advantage of a double adjustable is the enormous versatility–from a competition-ready drag shock to a shock with a level of control appropriate for road racing or autocrossing and to even a smooth, controlled ride for daily driving–available from the same shock."

Some believe aluminum-bodied shocks are not as durable in a street application as are more common, steel-bodied shocks, however, QA1 Motorsports uses 6061 aluminum heat-treated to the T6 specification and shock pistons having bronze-impregnated Teflon sealing bands. Both features make a QA1 shock quite long-lasting. Additionally, the twin-tube design is less vulnerable to external damage which would render a steel monotube shock unusable.

For the chassis mods in this part of our series, Global West volunteered its installation work at its facility in San Bernardino, California. First Global's guys removed the rear springs, shocks and track bar. Eighteen months ago, for Part Four of this series, we installed GW's Track Bar Kit and noted an improvement in the car's handing, especially on corner exits.

Since then, Global West developed an Upgrade to its Track Bar which makes it even stronger and more adjustable. Global West upgraded us to the new design (PN PHC-32K) which further stiffens the track bar mountings and adds three height adjustments which enable the user to tune corner exit traction. Whereas the basic Global West Track Bar is a bolt on, this Upgrade is not. Extensions have to be welded to the track bar brackets on the underbody structure and on the rear axle. Global's Eric Norrdin did that work for us.

An intermediate level of arc welding experience is required to install the Track Bar upgrade's brackets. A wire-fed welder makes the process easier. Image: CHpg Staff

The upgrade includes this brace which reinforces rear axle track bar mount. Image: CHpg Staff.

 

One of the weaknesses of the 4th Gen Camaro front suspension is the rear bushing in the front lower control arms. They have a short service life on cars capable of high lateral grip and which are driven hard. In our case this was our second set which went five years and a little less than 50,000 miles. GM no longer services the high-performance 1LE bushings, but Moog sells the same part in its bushing kit (PN K6490). We ordered two kits from RockAuto.com and replaced the rear bushings in both arms. Image: CHpg Staff.

To assemble the front coil-overs, Eric Norrdin began by installing a QA1 Torrington bearing on each front shock's adjuster ring followed by an Eibach 600-lb/in spring, a spacer and a low-rate Eibach "helper" spring which keeps the main spring on its seat when the suspension is at or near full rebound. Next, to go on was a QA1 compression stop (PN BC01) which may be needed in some street application because QA1s for coil-over applications do not have stops. The BC01, must be cut to fit. The top three sections are removed and what's left is installed in the shock.

Assembling a true coilover is much easier than doing the stock shock/spring combos because neither specific "clocking" of the parts, discussed in the Factory Service Manual, nor spring compressors are required. Image: CHpg Staff.

A key part of the front coilovers is Global West's spring seat adapters–the cast aluminum piece between the helper spring and the stock upper mount–which ensure the durability of the costly upper spring mounts. Image: CHpg Staff.

Installing the Eibach/QA1 coil overs is a little easier because they are slightly less in diameter and are lighter. Image: CHpg Staff.

Eric then added Global West Spring Seat Adapters, a key part of the front shock build-up as it vastly improves the durability of the front shock mounts. The design of 4th Gen F-car front upper spring mount has the majority of suspension load applied by the spring to the rubber upper mount through a spring seat molded into the mount. Only damping loads are applied to the upper shock mount which is concentric with the spring seat. Some aftermarket coil-over conversions for 4-gen Camaros apply all load through the upper shock mount. They do this because it simplifies the design and reduces cost, however, concentrating all the load on the smaller shock mount, causes the upper mount to wear rapidly–not good when you consider upper mounts are over $200 each. Global West's spring seat adapter is a cast aluminum piece which goes between the Eibach spring and the stock spring mount and insures suspension loads are applied to the upper mount in the way GM intended and that preserves the part’s durability.

Our road-ready, front suspension and brakes. Image: CHpg Staff.

After assembling the Global West front coil-overs, Eric set our baseline spring height adjustment at six-inches from the bottom of the threads on the shock body to the spring adjuster ring then put them on the car.

With the Track Bar upgraded and the new springs and shocks in place, Eric Norrdin began the final chassis modification for this part of the THRS series: installing a set of Global West Subframe Connectors (PN 905). The purpose of adding subframe connectors to a unit-body car is to increase the strength of its underbody structure which can flex in two ways. It can bend longitudinally or it can twist. When the aftermarket invented subframe connector (SFC) kits, it was drag racers who lead the way and many of the cars for which connectors were designed had the main subframe rails inboard from channel sections which underlie the car's rocker panels. Consequently, some subframe kits link the inboard rails. That makes an improvement to the car's stiffness in bending–which is great for drag racing–but not so much to stiffness in torsion because the greatest torsional deflection comes at the outer parts of the structure.

Global West's Subframe Connector kit for 4th Gen F-cars. Image: Global West Suspension.

Other makers of subframe connectors for 4th Gen Camaros, Global West included, tuck them into the cavity between the rocker panel and the pinch weld which runs the length of the car between the wheels. Such an installation stiffens the car both in bending and torsion and stiffness in torsion is important to a car's limit handing, especially when the car is modified for increased lateral grip and additional roll stiffness.

The Subframe Connectors are not a bolt-on part. They must be welded onto the car by an experienced fabricator. Image: CHpg Staff.

A proper subframe connector installation cannot be done with bolts. Global West's SFCs must be welded in place. One final aspect of subframe connector installations is an issue enthusiasts usually don’t consider. The connectors we installed are made from 0.125-in wall thickness, drawn-over-mandrel (DOM), 1020 mild steel tubing. That extra structure under the doors is a significant enhancement to the car's side-impact crashworthiness.

After all the work at Global West, it was time for the crowing touch, suspension alignment. Global uses a Hofmann, optical-sensing alignment system. "Targets" are attached to each wheel and light sensing devices measure alignment using the white dots on each target board. Seems a little "wizbang" at first, but the system is dead nuts accurate. Image: CHpg Staff.

Eric Norrdin at the controls of the Hofmann rig. The unit's computer displays caster, camber and toe information. Image: CHpg Staff.   The final task at Global West work was to 1) verify the ride height–Eric's initial adjustment was spot on–then, 2) do a front end alignment to our specs which are: -0.5° camber, 4.5° caster and 3/32-in toe in.

Another tool we used a lot since we got it last year is this Matco impact gun or, more properly the "1/2-in Quiet Air Impact Wrench" (PN MT1769QA). We like this tool because it's much quieter to use than the air impact we had before. The grip and the back half of the Matco are composite plastic and the hammer case and all reciprocating or rotating parts are metal. The Matco weighs 4.1-pounds, about six and half ounces less than impact we had in the shop before. Almost half pound makes quite a difference in the feel and handing of the tool. The MT1769QA is one of the most powerful 1/2-drive impacts Matco makes and are among the most powerful in the industry. Its nominal torque range is 50-650 ft/lbs and maximum rated torque is 780 ft/lbs. To go with our new impact, we ordered two sets of Matco's nearly indestructible impact sockets, metric and SAE. Image: CHpg Staff.

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