The K-Member
Just to be sure we're all on the same page, the K-member is the large subframe bolted to the front of the Mustang unibody. It provides structural rigidity to the unibody, along with the attaching points for the front suspension, steering, and engine. As Ford builds it, the K-member is a massive, heavy amalgamation of welded-together sheet steel. It gets its name from its shape, which is K-like in plain view. Because it interfaces between the frame, suspension, and engine, modi-fying the K-member can affect the wheelbase, track, camber, caster, bumpsteer, engine height and setback, in addition to vehicle rigidity and weight. Also, there are large gains in working room when using an aftermarket K-member because Ford's sheetmetal version is bulky. However, the main reason to redesign the K-member is to reengineer the front suspension for increased grip and handling predictability. When Maximum Motorsports approached the K-member, it was definitely aiming at road racing and all-around street performance. So, while there are super-light drag-racing K-members available, Maximum's is not one of them. It's a combination of round and square tubing to best distribute loads, and at 38 pounds it is 13 pounds lighter than the 51-pound stocker. That's still a significant weight savings, of course.
Maximum also concluded its K-member customers would more than likely be diehard handling fans, and not every Maximum customer would necessarily buy a K-member. As we'll see, this led to some speciali-zation in the unit's design. Maximum's K-member has two sets of holes for the A-arm attachment points. The first set is 1 inch higher than stock (there is no stock-ride-height mounting hole); the second set is 2 inches higher. These holes allow lowering the front ride height 1 or 2 inches depending on how aggressive the overall suspension setup is. Our track-oriented car took the 2-inch drop, so pothole dodging and driveway-approach avoidance is in our future. Furthermore, these holes also give 3/4 inch more wheelbase (the A-arm is moved forward 3/4 inch), and are the stock distance in and out for no change in track (if track gain is desired, it is better to do it with the A-arm to avoid bumpsteer complications). When combined with the 3/4-inch wheelbase increase gained from Maximum's A-arms, this puts the wheels 11/2 inches forward--that's into the fender lips with big tires. So, you can run just the A-arms and be OK on the street with a 3/4-inch wheelbase gain, or add the K-member for more serious work on the track where fender-lip rolling is a given. There is no provision for stock spring styles--coilovers must be used. This is due to strength/bulk issues in the now-missing spring-mounting area. Maximum believes too much compromise would be required to use a stock-spring type, so after trying too hard to incorporate the stock springs and delaying the K-member's market entrance, the company said to heck with it and made its K-member coilover only. For the record, the stock spring-style K-member was 7 pounds heavier, bulkier, and more difficult to produce. Early prototypes had a fair amount of anti-dive built in (A-arm attaching points rotated with the rear attachment higher than the front, tilting the lower control arm). In testing, this proved to bind the suspension under braking, making brake modulation difficult.
Production K-members have stock anti-dive built in. This also gives a smoother ride, as the tire doesn't have to travel forward while compressing due to bumps. Ultimate stopping ability, if you can modulate the brakes properly with either case, is no different between high and low anti-dive characteristics, Maximum says. Engine height and setback with Maximum's K-member are stock or nearly so. Engine lowering can still be accomplished with shorter mounts, of course. Rigidity is substantially increased over stock, both due to a more rigid K-member and the stout rear (g-load) brace the stocker does not have.