Last month, we showed you how to get into the sophisticated, high-performance Heidts Pro-G front suspension with help from our friends at Stang-Aholics. This month, we're going to show you how to install the Heidts Pro-G Independent Rear Suspension (IRS) for '65-'70 Mustangs. When you build in Pro-G suspension technology, you've effectively changed your classic Mustang forever. There's really no turning back, because once you experience the difference, you probably won't want to go back to a conventional Mustang suspension again.
This isn't a sales pitch, but a fact, because this is radically different suspension technology for these dusty old classics. Old Mustangs come alive with Pro-G. Installing Pro-G fore and aft changes everything and here's why. The Heidts engineering team has taken independent rear suspension and raised the benchmark with a system capable of withstanding up to 600 horsepower. There has never been another suspension system like it for Mustangs because it features a fully welded and boxed frame designed to fit your classic Mustang platform. It can be bolted or welded in, though we suggest both. Here's what you get for your money:
- Bulletproof 9-inch aluminum housing
Iron third member in a variety of gear ratios including 3.00:1, 3.25:1, 3.50:1, 3.90:1, and 4.11:1 Heavy-duty CV joints and halfshafts Strong tubular upper and lower control arms Fully welded and boxed upper crossmember Heavy-duty frame mounting brackets Forward struts (used with subframe connectors) Billet single-adjustable coilover shocks with chrome springs Optional parking brake kit Optional parking brake cable kit
What's This Going to Cost Me?
This kind of technology doesn't come cheap. Expect to spend a minimum of $8,000 plus any taxes and shipping for the Pro-G Independent Rear Suspension system. Parking brake calipers and cables will cost more. If you want high-performance slotted disc brakes, the price goes upwards of $8,300. The nice part about Pro-G is the convenience. You can bolt this system on first, then weld it in place later once you're confident it's a keeper. After a testdrive with a good four-wheel alignment, we're confident you're going to like the new Pro-G system.
What's In It For Me?
Heidts technology lowers the ride height for vastly improved center of gravity--a real road hugger you're going to want to drive daily. That old-school Falcon-esque “clunk” from road irregularities like chuck holes and dips vanishes, is replaced by a buttery smooth event void of road shock. The ride becomes smoother and the handling crisp. You'll hop into your buddy's concours-restored original Mustang and want to file for federal disaster relief because this upgrade is that good.
The Heidts Pro-G Independent Rear Suspension isn't a simple system you can install in a weekend with basic handtools and jackstands. You must have some fabrication skills or know a good fab shop with a known good reputation, because there's a lot of cutting and welding going on here. If you don't have access to a welder or know how to weld, you can bolt this system in. Good advice is to have it welded once it's bolted in and properly aligned for best results.
There's never been another suspension system like it for Mustangs because it features a fully welded and boxed frame designed to fit your classic Mustang platform. It can be bolted or welded in, though we suggest both.
1 The Heidts Pro-G independent...
1 The Heidts Pro-G independent rear suspension is an involved package consisting of a lot of parts. These are all driven components able to withstand 600 horsepower--CV joints and shafts, halfshafts, 9-inch aluminum housing and iron differential, and hubs. Steel parts can be painted or powdercoated. Keep in mind powdercoating involves heat--around 300 degrees F. Too hot for grease and seals. Powdercoat only bare steel and aluminum parts with bearings, seals, and hubs removed.
2 Tubular control arms with...
2 Tubular control arms with adjustable Heim joints make this system durable, tunable, and smooth. No clunk, just smooth racetrack articulation.
3 Adjustable coilover shocks...
3 Adjustable coilover shocks and Wilwood 10.5-inch brakes bring real understanding where the rubber meets the road. Adjust these shocks for ride quality or handling. Because Wilwood is primarily a racing brake, count on extraordinary performance because these binders provide real stopping power. Optional parking brake calipers and cables are available.
4 These frame boxes bolt...
4 These frame boxes bolt or weld to your Mustang's rear framerails. Ron Peter of Stang-Aholics suggests both bolting and welding. Bolting for proper alignment and positioning. Then, welding for solid security.
5 DRIVER'S SIDE - You're going...
5 DRIVER'S SIDE- You're going to need to bore these holes at the leading edge of the trunk pan above the rear axle for upper control arm hardware access.
6 A 3-inch hole saw gets...
6 A 3-inch hole saw gets the job done once you have dimensions figured out.
7 The IRS saddles dovetail...
7 The IRS saddles dovetail onto the rear framerails. But first, measure 24-inches from the rear leaf spring shackle mount (shackle bushing bore in framerail) forward to this point on the framerail. Make sure both sides measure up the same, keeping in mind there may be some past accident damage. If your framerails are not true on both sides, don't proceed with this installation. You must have spot-on framerail dimensions. This is where your Heidts saddle should be positioned. Before drilling or welding, double- and triple-check your measurements.
8a The Heidts IRS saddle,...
8aThe Heidts IRS saddle, after having been test fitted several times, is driven into place.
8b It took several times...
8b It took several times for Ron Peter of Stang-Aholics to feel confident about fit and positioning because no two Mustang bodies are perfect. Check and recheck.
9 Again, Ron checks the measurement...
9 Again, Ron checks the measurement from the rear leaf spring shackle mount to the trailing edge of the saddle before drilling or welding. It should be exactly 24 inches.
10 Once you're confident...
10 Once you're confident about measurements, mark the holes, center punch each hole, and start drilling a 1/4-inch pilot hole. Then, drill to capacity with a 1/2-inch bit.
11 The IRS saddles are now...
11 The IRS saddles are now positioned and drilled, which makes them ready for bolting and welding.
12 Next, the crossmember...
12 Next, the crossmember is readied for installation, first with the differential housing. This is a mock-up installation, which is why the crossmember has not been painted. Four 1/2-x 2-1/2-inch bolts are installed here and torqued to 70-75 ft-lbs.
13 The crossmember/housing...
13 The crossmember/housing combo is raised into position and bolted in at each end.
13
14 The installed diff/crossmember...
14 The installed diff/crossmember package is bolted in place and ready for continued assembly.
15 A word of caution: Be...
15 A word of caution: Be very careful about differential halfshaft seals. The spring lip is secured around each halfshaft with a spring like this one. If you disturb the spring and it pops off, you will have a leak.
16a Ron uses The Right Stuff...
16a Ron uses The Right Stuff sparingly between gasket and housing and gasket and differential. He also uses it on studs and locknuts.
16b Examine contact surfaces...
16bExamine contact surfaces for irregularities. Warpage and scoring is why differentials leak
17a The axle halfshafts are...
17a The axle halfshafts are installed next with Ron being very careful not to disturb axle seal tension springs.
17b The disc brake brackets...
17bThe disc brake brackets are installed at the same time.
18 Wilwood 10.5-inch brake...
18 Wilwood 10.5-inch brake rotors and hubs are married next with bolts being torqued to 180 in-lb (that's inch-pounds) in a crisscross fashion with a thread locker.
19 The pinion plate is next...
19 The pinion plate is next to be installed with Grade 8 bolts provided in the Heidts kit.
20 Next, the pinion plate...
20 Next, the pinion plate crossmember is tied to both the different and framerails
21 The lower control arms...
21 The lower control arms and these dog bones are next. Shims go on both sides of each bushing. Install, but do not tighten, as you will need to make adjustments.
22 The hub assemblies are...
22 The hub assemblies are secured to the lower control arms next. Again, this is just a mock-up phase for Stang-Aholics. It's all going to be painted once proper fit is ascertained.
23 CV joints and shafts are...
23 CV joints and shafts are next.
24 CV joints and shaft assemblies...
24 CV joints and shaft assemblies are installed along with Wilwood rotors and hubs. Heidts calls these hubs
25 Upper control arms are...
25 Upper control arms are next, leaving everything loose for alignment purposes.
26 CV shaft hub nuts are...
26 CV shaft hub nuts are torqued to 100 ft-lbs.
27 CV-joint-to-halfshaft...
27 CV-joint-to-halfshaft bolts are torqued to 57 ft-lbs using a thread locker.
28 Coilover shocks arrive...
28 Coilover shocks arrive unassembled. Though assembly is fairly easy, you must set these guys up properly or face potential suspension damage. First thing you want to do is adjust ride height, which is done with no load on the suspension. Then, place your Mustang on the ground and check ride height. Never adjust ride height on the ground.
29 The Wilwood calipers are...
29 The Wilwood calipers are up next. Use a thread locker like Loctite 271 and torque these bolts to 40 ft-lbs. The pads just drop right in.
30 Last in line are these...
30 Last in line are these strut rods Heidts has engineered in for stability. They connect to our Heidts subframe connectors, which are already there.
31 Eager to impress your...
31 Eager to impress your buddies? You will with the Heidts Pro-G Independent Rear Suspension. Not only is this IRS system fully adjustable, but you'll leave your buddies in the dust when it's time for canyon chasing. Stang-Aholics knocked all this apart and dressed it in satin black.
32a For a couple hundred...
32a For a couple hundred dollars more, you get this bolt-on parking brake caliper and cable system. It's easy to install and cheap to get into. Would you trust your Mustang to an automatic transmission parking pawl or engine compression? Think about it.
32b Would you trust your Mustang...
32bWould you trust your Mustang to an automatic transmission parking pawl or engine compression? Think about it.