Sub-frame Lowering Kit # AV423
2005 - 2007 CRF450X
2 CNC Machined Sub-frame End Links
4 Stainless Allen Head Bolts
1 Mud Flap Extension Bracket
· Hacksaw or Bandsaw
· Masking Tape & Marking Pen
· Center Punch
· 3/8 Drill Bit (Included)
· 5mm Allen Key (Included)
· Phillips Screwdriver
· Thread locking compound
· Metal Epoxy (Optional)
This kit lowers the seat height by changing the position of the factory sub frame lower mount. Refer to these instructions and the accompanying photos to aid installation. This kit lowers the seat height by approximately 1.5 inches measured at the rear mounting bolt. Original seat height can be regained by installing commercially available tall seat foam.
Additional lowering of seat height can be obtained by removing the seat cover and trimming one inch out of the seat foam. This sub-frame lowering kit complements a trimmed seat by lowering the rear mounting points and reducing the banana effect normally experienced when trimming seat foam.
IMPORTANT: Read all of these instructions before proceeding. Installation of this kit requires a reasonable amount of technical skill to measure and cut the stock sub-frame. Please enlist the help of a professional or return this kit for a refund if you do not have the skills required for proper installation. Always double check your measurements before cutting!
NOTE: This kit was designed for the factory sub frame. Aftermarket sub-frames may not be constructed in the same manner and may not be compatible with this kit.
NOTE: The factory sub frame manufacturing process allows for variations in alignment of welded connections and mounting points. The CNC end links have been engineered to allow for this variation; however we have encountered some factory sub frames that are quite irregular. Contact SpeedMetal Designs for assistance if you have trouble aligning the mounting points.
NOTE: For racing or other high-stress applications, it is highly recommended to secure the end-link with an aluminum compatible metal epoxy in addition to the end link bolts. This epoxy is available at most automotive parts stores.
Installation Steps (05 07 CRF450X)
· Remove the seat, number plates, silencer, rear fender, mud-flap, and battery. Then detach all electrical components and remove the sub-frame / air-box assembly.
· Referring to Figure 1, Carefully measure 2 inches from the end of each lower mounting point and mark a line around the lower tube with a piece of masking tape. Measure both sides of each mounting point to ensure that the tape is square on the tube. Mark which side of the tape is the measured point with an arrow to ensure you cut the proper side of the tape.
· Referring again to Figure 1 for measurement locations, mark the locations of the mounting holes on the outside of each sub-frame tube above the marked tape line. Mark these locations with a center punch for easier drilling.
· Verify the measurements and hole locations before proceeding!
· Using a hacksaw or a bandsaw, carefully cut the sub-frame at the marked tape line. Be careful to make the cut square and even on both sides. A reciprocating saw cuts the thin metal too fast to correct a mistake using a manual saw ensures that you will cut squarely
· Using the center punch marks, drill two 3/8 holes through the outer wall of each sub-frame tube. To prevent cracking, do not drill through both sides of the tube!
NOTE: If you are planning to epoxy the end links to provide additional strength, DO NOT APPLY EPOXY UNTIL YOU HAVE TEST FIT THE SUBFRAME ON THE BIKE. There are variations in weld locations and fitment of factory sub frames. Always test-fit the modified sub frame before permanently securing it.
· Insert a sub-frame end link into each lower sub-frame tube. The 05 - 07 CRF450R end links are identical and will fit either side. NOTE: Ensure that the small arrow on the end link is pointing UP after the sub-frame is re-installed.
· Loosely install the 4 allen head mounting bolts in the holes (2 on each end link), securing the end links. Due to variations in factory sub frame construction and the accuracy of your drilling, you may have use the drill bit to enlarge the mounting holes to an oval shape in order to align the mounting holes.
· Re-install the sub-frame assembly using the original hardware, loosely inserting the bolts. Ensure that the air boot is completely attached to the carburetor flange. You can use a long flat screwdriver to help align the boot.
· Ensure that the sub-frame is straight and that the lower tubes are bearing on the end link flanges. Apply a thread locking compound and tighten the 4 allen head end link bolts if the sub-frame is properly positioned.
NOTE: The tubes and welds on factory sub frames may be slightly out of alignment due to variations in the manufacturing process. You can use a file or sander to even out the cut ends of the sub-frame tubes by removing a small amount of material (1/8 or less). To prevent tire rubbing, do not remove more than 1/8 of material. If the cut ends are severely out of square or they require more than 1/8 of material removal to align each side, you may enlarge the end link mounting holes, and use a high quality metal epoxy (available at most auto parts stores) to help secure the end links inside the tubes.
· Tighten the remaining sub-frame fasteners and ensure that there is no play in the sub-frame.
· Install the mud-flap, using the supplied spacer to increase the clearance between the mud-flap and the swingarm.
· Install the silencer NOTE: The stock 05-07 CRF450X silencer requires the following modification to reduce stress on the head pipe and prevent the silencer from contacting the rear brake. Aftermarket exhaust systems may require similar modifications.
o Mark and drill a 3/8 mounting hole on the rear mounting flange of the silencer as shown in the attached illustrations. (This hole is already present on some aftermarket silencers.)
o Cut a slot in the right rear number plate to allow clearance for the rear mounting flange as shown in the attached illustrations.
o If necessary, enlarge the hole for the mid-pipe mount to allow for more movement. A flat washer can be used if the mid pipe mount has become deformed. This step is normally not required for CRF450X applications.
NOTE: Loosen the head pipe if the silencer does not easily bolt into place. Many aftermarket exhaust systems have enough movement built-in such that these steps are not necessary. Some aftermarket silencers already have the required holes in the mounting flange. Contact SpeedMetal Designs if you have trouble mounting a specific exhaust system after lowering the sub frame.
· Re-install the electrical connections, battery, number panels, rear fender, and seat.
· Double check that end links are sitting flush on the ends of the lower sub-frame tubes and that there is no side-to-side movement of the sub-frame.
Illustrations to Assist Installation (05- 07 CRF450X)
Installed End Link Left Side Installed End Link Right Side
Number Plate Notch Example Stock Silencer Modification (Note New Hole)
Accurately Measuring the Sub-frame Aftermarket Silencer Modification (Typical)