When it comes to lowering a classic truck, it seems that the job is divided into two camps: the simple and the difficult. Trucks equipped with an independent suspension setup from the factory, such as the 1967-72 Chevy C10s, are of the simple variety. That is, the components needed to modestly lower a truck are all bolt-on. Drop spindles, springs, and shocks are all items that are readily available and replace their stock counterpart with no fabrication required. Other trucks, such as those equipped with either a straight axle or the long-running Ford twin I-beam design, are a different story. To really achieve a proper drop with contemporary suspension accoutrements, it's necessary to get rid of the original suspension design. That usually means that anything that bolts to the chassis forward of the firewall needs to be binned, including the crossmember. This results in a lowering job that is much more difficult, with a bit of talent required (i.e., fabrication and welding skills).
There is a silver lining however in that once the job is done not only will you have a lower riding, and arguably better looking, truck on your hands, but if you use a kit from a company like Fatman Fabrications, you'll have a truck that rides, stops, and steers better than anything that left the factory that same decade.
We've made a few upgrades in the past on our buddy Danny Valenzuela's 1969 Ford F-100 and one thing he always bugged us about was lowering his stock, longbed hauler. Knowing that bolting on a pair of lowered I-beam axles wouldn't result in the contemporary suspension geometry that he desired, we opted to contact Brent VanDervort at the aforementioned Fatman Fabrications. What Brent recommended was their Mustang II-based IFS kit that would not only get rid of those heavy, swingin' I-beams, but it would also upgrade the stock drums brakes to disc (though in our case we had already installed a set on the original I-beams). The stock steering box would also get set aside in favor of a power rack-and-pinion setup, a must on these trucks. For our project, we'll be using the tried-and-true coil spring option, though Fatman offers coilover and air ride setups as optional upgrades for those who desire truly trick suspension components. All of this trick stuff will also give us a 6-inch lower ride, not a bad package if I do say so myself!
Though it does take some fabrication skills to install a Fatman Mustang II kit in a 1965-79 Ford truck, the majority of the modifications can be done in a day with a simple MIG welder and a four-inch grinder. We'll be using a Millermatic 211 for all the welding requirements on this install, coupled with their Spectrum 625 X-Treme plasma cutter. If you've never used a plasma cutter before, it makes tasks such as this truly a breeze.
This month, we'll cover the fabrication portion of the suspension job, followed by the bolt-on components next month. We'll wrap up with a flip-kit install out back to get both ends of the truck sitting nice and low atop a rebuilt, stock 9-inch Ford rearend. Be sure to follow along to see what it takes to drop a twin I-beam Ford!
1. Here are the Fatman components that we'll be installing this month. The new crossmember replaces the stock unit and locates the lower control arms and rack-and-pinion while the shock towers will locate the upper shock and coil spring mounts as well as the upper control arms. Four gusset plates will be used to strengthen the shock towers.
2. Arguably the most important part of the entire install is the proper setup of the chassis before we even get started. Since we'll be removing the stock suspension components, if we don't set up some baseline measurements before we get going, things will go downhill fast. First, the truck is lifted and set on jackstands, installed at all four corners. Next, the chassis is checked for level, side to side, with the corresponding jackstand shimmed if needed. It's a good idea to check for level at more than one location as well to make sure the frame isn't twisted.
3. A 2-3 degree forward rake is more or less industry standard spec, so we set up the chassis to reflect this measurement as well before we get started.
4. The next step is to mark the axle centerlines. I like to do this using two methods, consider it a combination of old and new. First, I use a string and plumb bob to mark the location on the shop floor.
5. I also use a laser level lined up with the string and plumb bob as it will project a line through to the other side of the chassis. This isn't so important at this point, but once the opposite side's axle centerline is determined, I can use the laser level to compare the two to ensure the axle centerline is square to the chassis.
6. I also like to take the time to mark the rear axle centerline as well. This allows me to measure the wheelbase to be sure our plumb bob specs are within factory parameters (131 inches for a longbed). Once the axle centerlines are marked and everything looks good, the front suspension components can be removed.
7. The last bit of preparation necessary before we get started is to tack weld a few pieces of stiff steel tubing or angle iron across the framerails. This will ensure that the 'rails don't twist, rise, or dip out of level when the crossmember is cut free and the new crossmember is welded in place.
8. Now it's time for the fun bit! Using our trusty Miller 625 Spectrum X-Treme plasma cutter, I set off trimming the fat away from our Ford chassis. If your truck is as greasy as ours, do yourself and anyone within a country mile a favor and grab a couple fans to blow the offending smoke out the door. I also like to keep an air hose with a blower attached nearby to help extinguish any small fires that might erupt (they will!).
9. The obligatory safety shot. Usually when I use the plasma, I can get away with using my tinted safety glasses, but I recently upgraded to a Miller Digital Elite helmet and found that its added protection along with its capability to auto-darken in “cut” mode makes it pretty handy for these big plasma jobs.