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13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 SERVICE INFORMATION GENERAL INSTRUCTIONS • During servicing, keep oil or grease off the brake drum and brake linings. • During servicing, keep oil or grease off the brake disk and brake pads. • Drain the brake fluid from the hydraulic brake system before disassembly. • Contaminated brake disk or brake pads reduce stopping power. Clean the contaminated brake disk with high-performance brake degreaser and replace the brake pads.
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13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 REAR WHEEL REAR WHEEL REMOVAL Place the machine on a level place. Remove four nuts attaching the wheel. °ØElevate the rear wheels by placing a suitable stand under the rear of frame. Support the machine securely so there is no danger of it falling over. Remove wheel. Nuts INSPECTION Measure the wheel runout. Service Limit: Vertical: 2.0 mm Lateral: 2.0mm Replace wheel if out of specification.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 Nut Washer REAR WHEEL HUB REMOVAL Remove rear wheel nuts. (See page 13-4) Remove the wheel hub nut cover and cotter pin. Loosen nut attaching the wheel hub. Nut Cover Cotter Pin Remove rear wheel. (See page 13-4) Remove wheel hub nut, washer and wheel hub. °ØElevate the rear wheels by placing a suitable stand under the rear of frame. Support the machine securely so there is no danger of it falling over.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 REAR AXLE REMOVAL Remove the rear wheel hub of the both rear wheels. (See page 13-5). Remove the collars on the rear axle right and left side. Collars Drive Chain Relax the drive chain. (Refer to the “DRIVE CHAIN SLACK ADJUSTMENT” section in chapter 3.) Remove driven sprocket. Driven Sprocket Remove the rear axle from right side. Bolts Rear Axle Bolts Remove the two bolts and caliper and then remove brake disk.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 Remove the four bolts and rear axle hub. Bolts INSPECTION Replace it if the rear axle is scratched (excessively) or damage. Replace if splines and threads of the rear axle is wear or damage. Measure the rear axle run out. Service limit: less than 1.5mm Replace if it is out of specification. °Ø Do not attempt to straighten a bent axle. Replace it if the driven sprocket is cracks or damage.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Inspect the driven sprocket. Replace sprocket if more than 1/4 teeth wear or bent teeth. Mongoose/KXR 90/50 Brake Drum Cover Replace it if the brake disk is cracks or damage. Replace it if splines of the brake disk is wear or damage. Splines Inspect rear axle hub. Replace it if bearing allow play in the axle hub or the bearing turns roughly. Replace it if oil seal is wear or damage. Replace it if rear axle hub is cracks, bend or damage.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE INSTALLATION Reverse the “REMOVAL” procedures. Install the rear axle hub. °Ø Apply grease onto the oil seal lips, bearings and bushes. °Ø At this time, the rear axle hub should not be tightened completely. Final tightening is done after the chain slack adjustment. Install the rear axle. Install brake disk, driven sprocket and collars. Install wheel hub (see page 13-5) and rear wheel (see page 13-4). Adjust drive chain slack.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 REAR SWING ARM REMOVAL Place the machine on a level place. Elevate the rear wheels by placing a suitable stand under the rear of frame. °ØSupport the machine securely so there is no danger of it falling over. Remove the rear wheels, rear hubs, rear axle and axle hub. (Refer to the “REAR WHEEL” section in chapter 13.) Remove the lower bolt attaching the rear shock absorber.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Check the swing arm side play by moving it from side to side. If side play noticeable, check the inner collar, bushing and thrust cover. Check the swing arm vertical movement by moving it up and down. If vertical movement is tight, binding or rough, to check the inner collar, bushing and thrust cover. INSPECTION Inspect the shock absorber rod. Replace the shock absorber assembly if bends or damage. Inspect the shock absorber.
. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 Swing Arm REAR SWING ARM REMOVAL Remove the nut and pivot shaft, then remove swing arm. Nut Drive Chain Remove the three bolts and chain guard. Remove the drive chain. Chain Guard Bolts Remove thrust covers and collar.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 INSPECTION Roll the axle on a flat surface to inspect the pivot shaft. Replace it if bends. °ØDo not attempt to straighten a bent axle. Inspect the swing arm. Replace it if crack, bend or damage. Inspect the thrust cover, chain guide, collar and bush. Replace them if wear or damage. Collar Chain Guide Thrust Covers Inspect the drive chain stiffness. Clean and lubricate or replace it if stiff.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 °Ø This machine has a drive chain with small rubber O-rings between the chain plates. Steam cleaning, high-pressure washes, and certain solvent can damage these Orings. Use only kerosene to clean the drive chain. O-ring INSTALLATION Reverse the “REMOVAL” procedure. Apply grease onto the collar, bush, pivot shaft and thrust cover. Install the swing arm and tightening the nut. Torque: 6.0_ 8.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 HYDRAULIC BRAKE BRAKE FLUID CHANGE Place the machine on a level place and set the handlebar upright. Remove the two screws attaching the brake fluid reservoir cap. * Use shop towels to cover plastic parts and coated surfaces to avoid damage caused by splash of brake fluid. Screw Connect a transparent hose to the brake caliper bleed valve and then loosen the bleed valve nut. Use a syringe to draw the brake fluid out through the hose.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 BRAKE SYSTEM BLEEDING Connect a transparent hose to the bleed valve and fully apply the brake lever after continuously pull it several times. Then, loosen the bleed valve nut to bleed air from the brake system. Repeat these steps until the brake system is free of air. * When bleeding air from the brake system, the brake fluid level should be kept over 1/2 of the brake reservoir height.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 BRAKE DISK Measure the brake disk thickness. Service Limit: 3.0mm Measure the brake disk run out. Service Limit: 0.3mm Fluid Tube Bolt BRAKE MASTER CYLINDER REMOVAL Drain the brake fluid from the hydraulic brake system. * Do not splash brake fluid onto any rubber, plastic and coated parts. When working with brake fluid, use shop towels to cover these parts. Remove the two master cylinder holder bolts and remove the master cylinder.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 DISASSEMBLY Remove the piston rubber cover and snap ring from the brake master cylinder. Snap Ring Pliers Master Cylinder Remove the washer, main piston and spring from the brake master cylinder. Clean the inside of the master cylinder and brake reservoir with brake fluid. Spring Main Piston Snap Ring I INSPECTION Check the cylinder inside wall, and spring for scratch, corrosion or other abnormal condition.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 ASSEMBLY Before assembly, apply brake fluid to all removed parts. °Ø• During assembly, the main piston and spring must be installed as a unit without exchange. • When assembling the piston, soak the cups in brake fluid for a while. • Install the cups with the cup lips facing the correct direction. Install the main piston and snap ring. Install the rubber cover. Install the brake lever.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE Mongoose/KXR 90/50 BRAKE CALIPER DISASSEMBLY Remove the brake caliper, brake pads and pad spring. (See page 13-16) Place a clean container under the brake caliper and disconnect the brake fluid tube from the brake caliper. * Be careful not to splash brake fluid on any coated surfaces. DISASSEMBLY Remove the brake caliper holder from the brake caliper. Brake Caliper Holder Remove the pistons from the brake caliper.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE INSPECTION Inspect the caliper cylinder wall and piston surface for scratch, corrosion or other damages. If any abnormal condition is noted, replace the caliper. ASSEMBLY Clean all removed parts. Apply silicon grease to the pistons and oil seals. Lubricate the brake caliper cylinder inside wall with brake fluid. Install the oil seals and then install the brake caliper pistons with the grooved side facing out.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE INSTALLATION Connect the brake fluid tube to the brake caliper, aligning the fluid tube with groove in the caliper and tighten the fluid tube bolt. Torque: 3.0_ 4.0kg-m Add the recommended brake fluid into the brake reservoir and bleed air from the brake system. (Refer to 13-15.) Mongoose/KXR 90/50 Aligning The Fluid Tube With Groove Fluid Tube Bolt Washers Install the brake caliper onto rear axle hub and tighten the bolts. Torque: 2.9_ 3.
13. REAR WHEEL/SWING ARM/ HYDRAULIC BRAKE INSPECTION Inspect the inner surface of the brake drum is scratches, polish brake drum lightly and evenly with emery cloth. Measure the inside diameter of the brake drum. Service limit: 131mm Replace it if it is out of specification. Measure the front brake lining thickness (A). Service limit: 2.0mm replace it if below INSTALLATION Reverse the “REMOVE” procedures.