5.0 Mustang & Super FordsHow To Chassis Suspension
Installing Maximum Motorsports' New K-Member
K-Max: For out-of-this-world handling on our open-track project machine
Having installed everything Maximum Motorsports makes for late-model Mustangs on the rear of our '96 open-track project car, we're now doing the same to the front end. The big news here is the company's all-new, first-ever, tube-frame K-member. Shown out of captivity for the first time in this article, the K-member clearly plays a huge role in balancing Maximum's already prodigious rear bite with front-carving ability.
Along with the K-member, we're presenting the rest of the full frontal Monty, including coilover spring/shocks, control arms, a bumpsteer kit, a sway bar, rack bushings, a lower steering-column replacemen--everything save the spindles (they do get modified), brakes (we already have big Baers in our wheelwell woods), and the wheel/tire combination (that comes in a later story). All the rest is new from Maximum Motorsports.
We'll let the sidebar on p. 160 tell the K-member specifics. For now we need to advise that while a senior enthusiast could manage this front install in a well-equipped garage, this really is pro work. Our install involved a special underhood engine support, a welder, a drill press, a drill, a tape measure, a plumb bob, the usual hand tools in plus sizes, along with the guy who designed it working with two technicians. The welder is optional, so it's no stumbling block, and Maximum's chief engineer has helped put together exceptionally well-presented instruction booklets. But still, be prepared for some real work for you and a willing friend. And, as usual, we have room here to hit only the highlights, as there are always numerous details to address we can't cover on these pages.
All that said, the Maximum parts are well engineered and fit. Yes, there are a few spots where opening up a drilled hole helps somewhat, and the vagueness associated with Ford's build quality leads to massaging things with a 2-pound sledge or 4-foot prybar, but those are just the facts of heavy undercar work. Good build quality from Maximum means the company has done what it can for fit. Whatever takes manipulation is typically the result of Ford screwing the basic Mustang together a bit sideways in the first place.
Install basics are simple in the extreme. The car is raised in the front, then the entire suspension is removed and replaced with Maximum gear. Everything has to go--struts, control arms, sway bar, K-member. The only stock parts retained are the spindles, and drilling modifies them. Because the K-member holds the engine mounts, some method of supporting the engine is needed. This can be done by any conventional overhead method, be that chain hoist or cherry picker, but these are cumbersome at best. Of the two, the chain hoist is preferred, as it leaves the undercar area clear, but this means removing the hood and positioning the car where a strong overhead support is present. A cherry picker makes the already crawl-around job under the car terribly constrained due to the hoist's legs, so forget that.
Best is a special cross-car bridge that hangs over the engine compartment and uses the inner fenders and strut towers for support. These are commonly used on front-wheel-drive vehicles during clutch or transmission work, so maybe you could borrow or rent one. Alternately, Maximum is looking at renting out these hoists with K-member sales, but that plan was just in the talking stage at press time.
Also be aware that there is a fair bit of alignment work in getting the K-member squarely positioned. This is done with tape measure and plumb bob, so the work is hardly brain straining, but measuring and adjusting the K-member for an hour can be tedious. A straight-driving car is important, however, so plan on investing the time.
Another heavy fiddle is the rear brace associated with the K-member. Often called a g-load brace, Maximum's version is a heavy, twin-tube, four-bolt mounting affair that doesn't like to bend but inevitably has to during installation. More leverage is the typical answer.
Because we have not driven our project car after the install and before press time due to time constraints, we won't give a driving-dynamics report--but you can bet your last lug nut this is one corner-cutting Mustang. You can also see the amazing extra space opened up under the engine. Header and starter work is hugely improved by the tubular K-member, so there's a plus right there.
In the photos, we skip across the installation highlights so you can judge what's involved. In following months, we'll continue coverage as we tune up the chassis in a logical progression toward our goal of unquestioned open-track competence while retaining street capability, so stand by.
Horse Sense: Working at the magazine means lots of great perks, but it has its own special tortures too. Not being able to sample our newly pumped-up project car until next month is one of them!
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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.