Ford 4.5″ Coilover 2.5 Bypass System, 2008-2010
Providing height adjustability, dual front shocks and ultimate bottom-out resistance, the Coilover Bypass kit is the best option for the avid off-roader. 2.5″ Coilover and 2-Tube, 2.5″ bypasses adorn the front wheel well, while 3-Tube Rear Bypasses and Full Progressive Leaf Springs round off the rear. This system maintains great on-road manners and is the most off-road capable of our 4.5″ lift lineup.
Base Kit Includes:
CS-FCO25SPKG-BYP-45-05 Carli Custom Tuned KING 2.5″ Remote Reservoir Coilovers, 2-Tube Front and 4 Tube Rear Bypass Shocks, with Stainless Shafts & Reservoir Mounts
CS-FCOMKIT-08 Coilover Mounts
CS-FORDBBL-08 Brake Lines
CS-FRAD-05 Radius Arm Drops
CS-FBDF-05-4.5 Bump Stop Drops
CS-FCASTERSHIM-4.5 1° Caster Shims
CS-FPRB-05 Track Bar
This is one of our most capable off-road systems. Similar in street ride to the Coilover and Pintop kit with seemingly no bottom, we spec’d this system with King 2.5” Front Coilovers, 10” Stroke 2-Tube Front Bypasses, 12” Stroke Rear 3-Tube Bypass with an oversized rebound tube. This system is also height adjustable approximately 1” to compensate for large bumpers/winches.
For those unfamiliar, a bypass shock has external tubes with one-way check valves that are fully adjustable to allow users to tailor the amount of fluid that bypasses the piston/valving on either the compression or rebound stroke within the effective range of the bypass tube. Typically, there will be a tube surrounding the compression zone at ride height that will allow fluid to freely move around the piston giving a supple ride. Once a large hit is encountered, the piston will move upward closing off the port, thereby forcing all fluid through the valving which substantially increases the shock’s resistance in this secondary zone. This acts as an internal bump-stop of sorts and gives tunable progression to the shock making it the perfect dual purpose setup.
Conversely, on the rebound side, we normally spec tubes that are oversized and deep in the travel stroke to allow a high volume of oil to bypass ensuring the shock shaft comes out quick enough to maintain contact with the ground (doesn’t get hung-up in the bump-zone after a large hit). As the shock extends and closes off the rebound tube, all the valving on the rebound side engages to slow the shaft as it reaches maximum extension, top-out. Simply put, the larger the shock diameter, the more capable the setup; the more tubes and “zones”, the more adjustability; the larger the tubes, the more fluid can flow around the piston and the more valving you can run to increase the stopping power in the “bump-stop” or “top-out” zone.
The Coilover/Bypass system boasts Carli specific, blueprinted, King 2.5” shocks on all four corners. In an effort to provide customers with the best product, we designed a custom piston to determine proper base flow rates to ensure the shock works well in the heavy duty truck platform; we then tuned the shocks around the custom pistons based on the only thing that matters to us, seat-of-the-pants feel. We round off ALL our King shocks with shafts machined and polished from a solid piece of 17-4 Stainless. Unlike King’s standard shafts, there is no coating to wear off, weather can’t hurt them and if there is a small chip, you can round the edges with emery cloth to ensure the seal housing isn’t damaged as they’re not brittle like the stock, hardened shafts. The shocks are finished with King oil good to -55° F. Note that all King shocks are built with a plated steel body. If subjected to inclement weather for extended periods, we recommend wrapping your shocks in 3M to provide a moisture barrier that’s replaceable.
The truck will sit 4.5” higher in the front and have more wheel travel thanks to the coilover that mounts in the Carli Coilover Conversion Bracket. Radius Arm Drop Brackets reset the pivot point and keep the travel linear for the best ride while Sway Bar Links or Drop Brackets reset the sway bar engagement point. While Bump Stop Drops protect the shocks from over-compressing, the Adjustable Track Bar centers the front axle and Stainless Brake Lines firm up braking and ensure there is enough line for the newfound travel. To round off the front end, we include Caster Shims to tighten the steering.
The rear is outfitted with a Full Progressive Spring Pack requiring no block to achieve proper ride height; thus, travel is extended and wheel hop/axle wrap minimized at the cost of 15% less load capacity than a stock F250. The Coilover-Bypass is an Off-Road oriented system; thus, we recommend the purchase of a Differential Guard for axle protection, High Mount Steering Stabilizer for steering control and Fabricated Radius Arms for strength and Limit Strap mounting. At this level of suspension, a roll cage is also recommended if the system will be used to its full potential.
Being bypass equipped, customers can expect to hear clicking from the opening and closing of the check valves in the external tubes of the shocks. On the bright side, the suspension is tuned by Carli but fully adjustable to the customer’s preference. Customers can turn tubes for more float and ride comfort or engage more valving for better control and off-road performance. From Carli, these shocks are setup with a wide open rebound and neutral compression (our recommended, all around specification).
Wheel and Tire:
Factory Wheels SHOULD NOT be run with oversized tires. They’re known to rub the radius arm, sway bar and most concerning – Brake Lines. Factory tires and factory wheels will work without issue but we DO NOT recommend running oversized tires on factory wheels. On our 4.5” Bypass equipped Ford Systems, we recommend 17”-18” wheels, no more than 9” wide with 4.5”-5” of backspacing with a 37”, E-Rated Tire. The more rubber, the better the small bump compliance will be at proper inflation pressures. The ride will firm up as you go larger in wheel diameter. For more details, see our article on wheel and tire selection and tire pressures: