Jim Smart July 12, 2017

If you have owned a 1967-1970 Ford Mustang or Mercury Cougar, you are undoubtedly familiar with cracked shock towers. There are a lot of theories about why cracked shock towers plague these cars, but one holds true time and time again. Upper control arm bushings on these popular ponycars seized up from neglect, causing the shock towers to bend and twist with front suspension movement. The repeated cycling of the tower causes metal fatigue and failure at the control arm attachment points.

We have seen many shock tower repair jobs that have not held up, because no matter how well they are welded they will surely crack again. There have also been catastrophic shock tower failures where control of the vehicle was lost with horrible results. The greatest favor you can do your Mustang or Cougar in the interest of safety is replace cracked shock towers with heavy-gauge steel components from Mustangs Plus.

Manufactured by Dynacorn out of thicker-gauge steel than original equipment, these high-quality reproductions are strong. If you take proper care of your upper control arm bushings with routine lubrication, these shock towers will serve you well for the rest of your Mustang or Cougar's service life.

Shock tower replacement is a task best left to a trained body professional with good fabrication skills. However, we thought we'd walk you through it to show you how it is done. Shock tower replacement is best performed with the engine removed for ease of access. If you are going to replace one shock tower, you might as well replace both because if one is cracked, the other will likely crack in time.

When you replace shock towers, it is strongly suggested you bolster new towers with a shock tower reinforcement package to make each tower stronger. Mustangs Plus offers a chassis stiffening kit to eliminate body flex in classic Mustangs. This kit should also be installed by a body professional or at least someone with good welding skills.

1 Classic 1967-1970 Mustang and Cougar shock towers are notorious for cracking and buckling due to binding upper control arm shafts and bushings. These bushings were never factory fitted with grease zerks for routine lubrication. Few factories had the presence of mind to install grease fittings either. As a result, they've grown dry and seized, causing the upper control arm to bend and twist the shock tower.

2 This is how bad it can get when the shock tower breaks from cyclic fatigue. In the interest of safety, replace cracked shock towers. Never try to repair them.

3 A coil spring compressor designed for coil-on-upper-control-arm installations is used to compress the spring for upper and lower control arm removal. Keep your legs away from the spring's path. Uncontained coil springs can maim and kill.

4 Upper and lower control arms are removed along with the brake assembly for tower removal. This is the upper control arm attachment point.

5 Each and every spot weld (and there are many) is center-punched for spot weld cutter guidance.

6 A spot weld cutter bores out each spot weld as shown. Drill slowly and carefully. It's a good idea to use a lubricant to keep the cutter cool. Thick, sandwiched joints can be very difficult to bore through, which is why drill speeds are kept low. High-speed drilling will break the cutter.

7 It takes a lot of time to cut the spot welds. Each cut must be executed slowly and methodically.

8 Drilled-out spot welds generally look like this. You want to drill through that first layer of steel without penetrating the second. As you can see here, that's not easy to accomplish.

9 Once all of the spot welds are drilled out, an air chisel is used to separate the shock tower from inner fender aprons and chassis.

10 The shock tower is removed as shown, and discarded. Obvious to us, these towers were never strong enough to handle the stresses a chassis encounters. In 1968, Ford went to a reinforced shock tower for only the big-block Mustang and Cougar models when they all needed reinforcement.

11 Inner fender aprons are hammered and dollied into shape for shock tower installation.

12 Contact surfaces are sanded smooth to give shock towers and aprons a solid bond.

13 Shock tower repair kits from Dynacorn/Mustangs Plus give you the kind of strength your Mustang or Cougar deserves. It is suggested you install new upper control arms and spring perches when you replace shock towers. Install grease fittings along with liberal doses of chassis lube.

14 The new shock tower is test fit before being welded to the body. Contact surfaces must be flush and void of any gaps.

15 To achieve a solid bond, the new shock tower is bolted to the inner fender aprons as shown. Spot weld holes will be rosette welded (plug and fill) for an even better bond than your Mustang or Cougar had from the factory. This is part of the fitment process. Note the jig pins for optimum fit.

16 Once we had the shock towers bolted to the aprons we realized we hadn't applied weld-through primer. Towers were removed and weld-through primer was applied at the joints.

17 Shock towers are rosette welded on both sides of the apron inside and out. This gives the tower a solid bond.

18 Shock tower welding is complete inside and out, with rosette welds on both sides for a solid bond. Welds will be ground smooth and be virtually invisible. Some restorers use a center punch to simulate spot welds.

19 Shock towers are welded at the framerail as well like this. This area should be flushed out periodically to remove road grime, which can cause rust.

20 This is the frame bracket for the lower control arm and engine mount brackets, which is center-punched for drilling and rosette welding. The frame bracket is secured with clamps at the framerail and checked for proper fit before welding. Everything must line up, which easily checked with jig pins or bolts.

21 The frame bracket is fitted with a jig pin and bolts where the upper control arms are secured. The frame bracket has been drilled for rosette welding.

22 With fit checked, the frame bracket is welded to the shock tower and framerail.

23 The frame bracket is secure and ready for suspension installation once rosette welds are ground smooth and dressed with an epoxy primer/sealer.

24 Shock towers should be bead welded here for added security. It is suggested you opt for a shock tower reinforcement kit from Mustangs Plus. The chassis stiffening kit is a bonus.

25 Any time you replace shock towers, toss the old control arms and get new ones, like this set from Mustangs Plus. Open Tracker also offers premium blueprinted upper and lower control arms and perches for classic Mustang and Cougar if your budget permits.