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1949 Chevy Custom Air Suspension - Suspending BeliefOur Project '49 Chevy Gets Custom Air Suspension From the March, 2010 issue of Rod & Custom By Kev Elliot
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I haven't yet mentioned which... I haven't yet mentioned which management system I'll be using, as we'll cover that next month (it's the latest RidePro e3), but here's the complete package I received from RideTech, extremely comprehensive right down to PTFE tape already installed on all the air fittings. Around a decade ago now, when the Purple Pig first came into my possession, one of the first jobs after replacing the entire lower 8 inches of bodywork and chopping the roof, was to cut the front coil springs and add dropped spindles, and fit crazy 6-inch lowering blocks to the rear. Just before the '49 was loaded on a British ship bound for California, I C-notched the rear of the chassis, still with the leaf springs and blocks. The car has always ridden low-probably too low as it had a mere 1/4-inch of suspension travel until I notched the frame, so when its long-overdue revamp was planned, rear airbags were part of the equation. Indeed, they'd been the intended reason for the C-notch. However, with the inclusion of the Classic Performance Products trailing arm rear suspension, the notion of 'bags was quickly ousted in favor of ShockWaves (from Air Ride Technologies, now known as RideTech), and followers of the project will remember the rear of the car sitting very low with aluminum ShockWaves when the rearend install was complete. Unfortunately for me, those were merely on loan from CPP! I figured I'd only run ShockWaves in back, as the coil-sprung Chassis Engineering IFS that came next would work just fine, thank you. But it just wasn't low enough for my liking, despite setting the neat adjustable upper spring mounts to their highest (and hence lowest ride height) setting. I'll admit I like my cars lower than most, though still with a safe scrubline, and the Chassis Engineering suspension is ideal for many people. When I heard that RideTech was introducing budget versions of the ShockWave in steel, known as the Black Series, not only did they appeal to my lowly journalistic pocketbook, but I could see a way to get the front of the Chevy as low as the rear. Though the C-notch was already... Though the C-notch was already done, and the lower A-arms took some figuring out, one of the most time consuming fabrication jobs was the sunken trunk floor. Obviously not necessary in every case, I have a family that requires trunk space (for the luggage, not the kids!) and wanted to hide the air suspension components and Aeromotive gas tank under the floor, so I made this "box" to take up the space where the stock tank resided, as well as to leave space on either side for the exhausts to run alongside the chassis. Which in my usual drawn-out fashion, brings me to this latest installment of the Project '49. Until now all the parts used on the Chevy have been of a bolt-in design, a conscious move on my part to show how a project car can be built with minimal fabrication. OK, there's been a little welding, such as the bearing mount in the steering linkage, but in the main everything was bolted in. Until now. While the CPP rear suspension is designed for the ShockWaves to bolt to brackets on the trailing arms, upper mounts had to be fabricated owing to my C-notch. Up front, however, I had some planning and fabrication to undertake; likewise in the trunk, where the air pump, tank, and solenoid block were to be mounted. While there's no reason to go as fab-crazy as I did back there, as you'll see, this all needs mounting somewhere. So the air suspension installation will be split into two parts, with the heavy fabrication work covered this month, and the plumbing, electrical hookups, electronic suspension management system, and level sensors in the next issue. So with the welder fired up, grinders and air tools at the ready, and the Emergency Room on standby, let's begin. Steel Yourself
Introduced in 1999, the original aluminum-bodied ShockWave, now called the Master Series, was a significant development in air suspension, allowing the air spring and shock absorber to become a single component, rather than having to mount shocks off the side of suspension arms and the like. RideTech invented the ShockWave, and holds two U.S. patents for the design and function. Over the past decade, the Master Series has been refined, now offering single or double adjustable shock valving, optional internal ride height sensors, multiple air spring configurations, and a wide range of stroke lengths, load capacities, and mounting styles, the most common being eye or stud mounts. RideTech has recently added two new versions of the ShockWave: the Titanium Series, which features 24 position compression and rebound valving, remote reservoirs and a monotube gas pressure design, which I guess will appeal to the road racers and track day stars out there who want optimum handling and the ability to fine-tune their ride quality in a high-tech package; and the Black Series, a twin-tube steel body shock that retains all the mounting and installation advantages of the Master Series, but is comparable in price to a separate airbag and shock system. However, the Black Series isn't available with internal ride height sensors. After using up yet another... After using up yet another favor and taking over Circle City Hot Rods' bender and bead roller for a couple of hours, I clamped the three sections to the only suitable large flat metal object available at our tech center-the rolling road-and welded it into a single component. Not My Bag
RideTech offers two types of airsprings; double convoluted and rolling sleeve. The former has more load capacity, a shorter stroke and a more progressive spring rate, making it appropriate for front end applications, where the weight of the engine and trans require the increased load capacity. The rolling sleeve design has a longer stroke, more linear spring rate and usually a smaller diameter. The short stroke of the double convoluted design isn't a problem, as most front ends mount the spring inboard of the load point, meaning the stroke length is almost doubled at the actual wheel. While RideTech can supply bespoke kits for a number of vehicles-mainly muscle cars, pickups, and Tri-Five Chevys-they can supply components for a custom install, which is what I was looking at with the project Chevy. A number of aftermarket Mustang II-based IFS systems are also covered, though Chassis Engineering's crossmember isn't one of them, so I had to do a little math, a lot of thinking, and some fabrication to make it all work correctly, ensuring the recommended ride height of the ShockWave was adhered to, and that the suspension geometry was where it should be at ride height too. Add in the fact that the airspring must not touch any part of the chassis or body throughout its travel, no components should hang below the scrubline at ride height, or touch the ground on full drop, plus I wanted the finished deal to look neat, and there was a lot to consider.  The reason for grinding the...  The reason for grinding the bolts flush was because the plate was welded to the floor, eliminating any bolt heads, threads or nuts visible from underneath. Similarly, the air tank was mounted to the side of the recessed section of floor using bolts welded to 6 x 1 1/2 x 1/8-inch plate, which in turn were welded to the outside of the "box" to spread the load. I then installed Dynamat to reduce noise and heat transfer, as the exhausts will run behind this area.  With nuts welded to the underside,...  With nuts welded to the underside, the solenoid block will mount to this bracket. This shot more clearly shows how the tank is mounted (and yes, I'll use larger diameter washers at the final install).  Here's why one corner of the...  Here's why one corner of the "box" is angled; it provides clearance for the CPP Panhard rod.  In the center is a pair of...  In the center is a pair of Black 7000 Series ShockWaves, which feature 4-inch-diameter rolling air springs (as opposed to the double convoluted design of the front ShockWaves) with a 5-inch stroke. They are equipped with covers, or AirCANs, to reduce the risk of damage from the sleeve chaffing on other components , the chassis or body, while allowing them to be mounted closer to other components than would normally be acceptable. These feature a compressed height of 11.56 inches, an extended height of 16.56 inches, and an intended ride height of 14.5 inches. The front ShockWaves, owing to being mounted inboard of the wheel, don't require as long a stroke as the rears, these having just less than 3 inches, which equates to about 5 inches of travel at the wheel. Note the stud top mount rather than an eye, to fit the Mustang II-based suspension.  The compressor, Model 327...  The compressor, Model 327 and rated at 0.5 cfm at 150 psi, mounts at three points using rubber insulating pads with sleeves to prevent crushing. Rather than mount it directly to the sheetmetal floor and risk vibration or droning noises, I drilled and tapped an 1/8-inch plate, mounted the compressor, then ground the exposed threads of the mounting bolts flush with the base of the plate.  Here's what careful planning...  Here's what careful planning and not-inconsiderable fabrication and welding produced: a recessed trunk floor in which the gas tank, air tank, compressor, and eventually, the air solenoid block will reside. Once the gas tank is plumbed I'll fabricate a cover and all this will be hidden, eliminating the possibility of accidental damage and reducing noise. I drilled air vent holes in the rear wall of the "box" to allow an air supply to the compressor.  Electing to mount the rear...  Electing to mount the rear ShockWaves first, 3/16-inch steel was used to make all bracketry. I installed two 3/16-wall thickness 2x1-inch box section crossmembers fore and aft of the C-notch when I modified the chassis, then CPP added the upper ShockWave mounts and the sturdy gusset when they installed the rear suspension.  With everything painted, here's...  With everything painted, here's the aluminum ShockWave installed at CPP when they fitted the axle and trailing arms. CPP made the lower mount bracket to suit. Note this ShockWave uses poly bushings top and bottom.  Here's the new Black Series...  Here's the new Black Series ShockWave, which employs rod end-type eyes. The swivel elbow fitting is installed through a hole in the AirCAN.  While the poly bushing eyes...  While the poly bushing eyes measure 1 1/4 inches wide, the rod end style are 1-inch wide. I keep a bunch of steel spacers on hand, and digging through the drawer produced four 1/4-inch-wide, 1-inch OD spacers. Most decent hardware supply houses stock spacers of varying sizes.  Installed with Grade 8 hardware,...  Installed with Grade 8 hardware, and a spacer top and bottom, the rear ShockWaves bolted easily into place.  Unlike most aftermarket Mustang...  Unlike most aftermarket Mustang II-based suspensions, the Chassis Engineering crossmember doesn't use conical upper shock mounts, as it features this neat threaded combined shock and coil upper mount. The top of the coil sits under the gray "disc" while the shock bolts through the hole in the center of the threaded portion. As can be seen in the background, the thread can be raised or lowered to adjust ride height. Very cool, but it posed me problems with mounting the ShockWave.  With the ShockWave temporarily...  With the ShockWave temporarily bolted to the shock absorber mount on the lower A-arm and the threaded top mount removed, this is what I was faced with. The ShockWave is at full extension, but would only compress approximately 1 to 1 1/4 inches for optimum ride height. The lower arm should be level at ride height but was already sloping down toward the outer end, and the ShockWave was so far up in the "top hat" section of the crossmember that it would be physically impossible to access the air fitting. Hmm, time for some head scratching.  Here's the shock mount on...  Here's the shock mount on the lower A-arm that I temporarily mounted the ShockWave to, despite it using a 7/16-inch bolt while the ShockWave uses a 1/2-inch.  This little Allen-headed set...  This little Allen-headed set screw locates in a groove in the thread to lock it in place.  Poring over the RideTech literature...  Poring over the RideTech literature I surmised that a general rule of thumb when it came to ride height was to have the airspring compressed by roughly a third. This makes sense when you think about it as you want more suspension when you hit a bump than a dip. With this in mind I needed to deduce where one third compression was exactly. While the following may not be the by-the-book method, it proved the easiest to photograph, and while the suspension travel is greater at the ball joints than the eyes of the ShockWave itself, the 1/3:2/3 ratio is still the same. With that said, picture 20 shows 14 1/2 inches from the jack to the bottom edge of the upper A-arm (which remains stationary throughout the following as there's no spindle connected!) with the ShockWave fully extended.  Picture 22, with full compression,...  Picture 22, with full compression, gives a measurement of 10 1/2 inches. Using the 1/3:2/3 ratio, ride height should be just a tad below a measurement of 12 inches. Picture 21 shows the suspension at this ride height. All well and good, except the lower A-arm should also be level at ride height for optimum handling and suspension geometry, which you can see it is currently at full compression. The solution? Drop the lower ShockWave mount below where it is now, so the lower arm is level at ride height.  Not wanting to cut the crossmember...  Not wanting to cut the crossmember apart, I figured out how far the ShockWave could go up into the "top hat" and still access the air fitting, which put the top mount just about level with the top of the "top hat". By cutting the coil mount off the threaded section, it meant I would still be able to use this for the top mount, though whether I'll need its adjustability with air suspension may prove irrelevant! Also, if the ShockWave were to be moved any higher into the "top hat" I'd have to trim it for clearance around the airbag and to access the fitting. At this height there's 1/4 inch of clearance between rubber and steel.  However, with the lower arm...  However, with the lower arm level, currently the ride height is still too high for my liking, so I'll fit 2-inch dropped spindles to bring it down a little. As you can see, this will put the zerk fitting on the lower ball joint 1 inch above the scrubline (an imaginary line drawn between the bottom of each wheel, minus tires, ensuring no part of the car can touch the ground even with four flat tires) I elected to lower the bottom ShockWave mount by 1 3/4 inches, keeping it a scant 1/4 inch above the scrubline.  The gap between the two brackets,...  The gap between the two brackets, which I planned to weld to the inside of the stamped steel A-arms, was exactly 3 inches, and with the ShockWave eye measuring 1 inch, I turned up a couple of 1-inch spacers from 1/8-inch wall seamless steel tube. With everything tack-welded in place, I installed the ShockWave for a trial fit.  Viewed from the side, you...  Viewed from the side, you can see how the lower mount is fitted, Grade 8 hardware used once again. The spacers will be welded to the brackets, though I'll weld nothing until I'm certain everything will work as it should.  I fabricated new lower mounts...  I fabricated new lower mounts from 3/16-inch steel plate, the mounting hole 1 3/4 inches below the shock mounting hole on the A-arm. Here I'm using a transfer punch to accurately transfer the center of the hole to be drilled in the second bracket.  I like to use Roto-broach...  I like to use Roto-broach hole cutters when tackling jobs like this, as they produce a perfectly round hole, unlike a drill bit, especially when drilling by hand, rather than using a drill press.  The ShockWave now passes neatly...  The ShockWave now passes neatly through the hole in the lower A-arm originally intended for the shock absorber, while the arm looks neater without the coil spring mount attached. Off the rack and sitting on its wheels with the ShockWaves fully deflated, it's obvious the car sits slightly nose-high, though the dropped spindles will rectify this. Apart from a psychological boost, there's a reason for this step. I wanted to ensure nothing could touch the ground at full drop, and also check that none of the suspension parts hit the body either. In the event of catastrophic failure I want to be able to steer the car to the side of the road, not be sliding along the blacktop with sparks flying. The rearend differential yoke does hit the driveshaft tunnel, so that will need rectifying despite me having raised the tunnel once already. However, this was a closed driveline car previously, and I wasn't too concerned if the torque tube kissed the tunnel every once in a while. In all seriousness, low cars look cool, but safety has to be considered foremost. Ask me sometime of my personal experiences of a modified car I bought whose builder ignored scrublines and why I like to fit front driveshaft loops!
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