1985 GMC K3500 Suspension Parts

The Air Command Standard Duty Dual Electric Air Compressor System Kit Allows You To Adjust Your Air Springs With The Touch Of A Button. It Offers A Built in Air Source For Your Suspension System, Making It Easy To Alter Your Springs To Align With The Load Type And Environment. When Shopping For Air Accessories, You will Find That Firestone Air Command Standard Duty Dual Electric Air Compressor System Kit Is Designed To Have A Couple Of Special Benefits. First, The Air Command Standard Duty Dual Electric Air Compressor System Kit Comes Ready To Install, So You Can Set It Up And Get Back To The Road where You Want To Be. Just Connect A Few Wires To The Compressor And A Few To Your Vehicle. The Air Lines And Wiring Harness Can Be Plugged Into The Same Side Of The Unit For Smoother Routing Of Lines And Power Supply. After The Air Command Standard Duty Dual Electric Air Compressor System Kit Is Properly Installed, You Can Make Pressure Adjustments By Pressing A Single Button. This Air Command Standard Duty Dual Electric Air Compressor System Kit Component Allows For Side To Side Or Front to rear Leveling, Real time Pressure Readout, And Dual Left And Right PSI And Pressure Control Readouts. The Air Command Standard Duty Dual Electric Air Compressor System Kit Easy to read Needle Gauge Can Be Viewed Day Or Night, Without Straining Or Squinting Your Eyes. Prior To Installing The Air Command Standard Duty Dual Electric Air Compressor System Kit, Review The Instructions And Identify All Of The Components To Help Make Sure You Get Maximum Performance From Both Your Air Springs And Air Command Standard Duty Dual Electric Air Compressor System Kit. The Installation Steps Are Different Depending On Whether You are Enhancing An Existing Air Helper Spring System With The Air Command Standard Duty Dual Electric Air Compressor System Kit Or Installing It With A New Air Spring System.

Product Features:

• Individual Air Accessory Components Are Also Available, Including Compressors, Air Tanks, And Mounting Solutions, Providing A Wide Variety Of Air Control Assist Solutions
• Adjust The Ride For Various Load And Road Conditions With A Switch, Remote Or Mobile App
• Provides An Instant Air Source For The Air Helper Springs Or Accessories
• Dual Point Fill (Both Air Springs Fill Independently Of Each Other)
• Light Duty Compressor Specs (120 PSI Max Air Pressure, 9 Percent Duty Cycle, 0.32 CFM)

By constantly introducing design enhancements that extend product life and simplify installation and replacement, MOOG has earned its reputation as the chassis industry’s Problem Solver.

Product Features:

• Easy to install
• Restores like-new steering and handling
• Engineered to provide long life and dependability
• Construction and design validated by MOOG engineers
• Incorporates proven design and engineering features

By constantly introducing design enhancements that extend product life and simplify installation and replacement, MOOG has earned its reputation as the chassis industry’s Problem Solver.

Product Features:

• Easy to install
• Restores like-new steering and handling
• Engineered to provide long life and dependability
• Construction and design validated by MOOG engineers
• Incorporates proven design and engineering features

This high quality chassis part will improve overall vehicle handling, reduce tire wear and increase the life of other steering and suspension components. These chassis parts are manufactured to meet or exceed OEM.

Product Features:

• Rubber or Heat Treated bushings
• No Squeak
• Reduces vibration

Monroe® Shock-Mate® Shock Absorber Boot Kits are universal replacement shock boots use to protect the shock’s piston rod from dirt, mud and other contaminants – protecting the life of your shocks.

Product Features:

• Protects the shock’s piston rod from damage
• Universal design for easy installation
• Tie-strap included for a secure fit
• Constructed from high quality urethane for maximum durability
• Multiple color choices available

Monroe® Shock-Mate® Shock Absorber Boot Kits are universal replacement shock boots use to protect the shock’s piston rod from dirt, mud and other contaminants – protecting the life of your shocks.

Product Features:

• Protects the shock’s piston rod from damage
• Universal design for easy installation
• Tie-strap included for a secure fit
• Constructed from high quality urethane for maximum durability
• Multiple color choices available

Product Features:

• Incredible Improvement in Control
• Maintains Proper Caster and Camber Alignment
• Increase in Handling and Control
• Greatly Reduce Wheel Hop on Quick Acceleration
• Even Braking Control is Improved
• Better Suspension Stability

Product Features:

• Incredible Improvement in Control
• Maintains Proper Caster and Camber Alignment
• Increase in Handling and Control
• Greatly Reduce Wheel Hop on Quick Acceleration
• Even Braking Control is Improved
• Better Suspension Stability

The shock that started it all! Rancho® RS5000 series has been the shock of choice for light trucks and sport utility vehicles since 1985. Available for stock and lifted applications, RS5000 is ideal for on and off-road use, at an affordable price.

Product Features:

• Ten-stage velocity sensitive valving – Provides tuning specific for each vehicle
• 5/8-in. (16mm) diameter piston rod (select applications) – Adds strength and durability. Size varies by application.
• 1 3/8-in. (35mm) diameter piston (select applications) – Ensures performance in any environment
• Protective boot included – Protects the shock rod and oil seal

HYDRO H7000 series shocks are recommended for multiple shock applications and mild to moderate off-road use. Skyjacker(R) hydro shocks, Skyjacker(R) suspensions offers you a high quality shock absorber with true velocity sensitive valving. Shock absorbers, or spring dampers as it is called everywhere else except in the U.S, control the rate at which suspension springs compress and rebound. As the shock is pushed together, this is called bump or compression. As the shock expands, this is called rebound or extension. Absorbing the shock of bumps and suspension loading is actually performed by the springs in the suspension. The shock real job is controlling the energy stored in the springs. The performance specific internal components of Skyjacker shocks respond to the on- and off-road conditions instantly. Whether you are going over rough or smooth terrain at slow or fast speeds, the true velocity sensitive valving produces a stable, controlled level of resistance for better handling, improved stability, and maximum comfort. The technological innovations of these durable, long lasting shocks from Skyjacker(R) deliver a noticeable advantage over the original equipment and other shock dampeners. Skyjacker shock absorbers deliver a safe, comfortable ride with improved handling and stability. They keep the tires in contact with the terrain and put you in control of the road ahead

Product Features:

• Hydraulic Action. Leak Proof Seal Prevents Hydraulic Fluid From Passing Around Piston Head For A Consistent And Reliable Ride
• Multi Stage Velocity Sensitive Valving
• Twin Tube Construction. DOM Tubing Reduces Internal Wear For Longer Product Life
• Bonded Iron Piston For Durability And Longer Shock Life
• Chromed Piston Rod Features Micro Polished Shaft For Improved Product Life And Performance
• Orifice Disk For Axle Control In Any Condition
• Red Polyurethane Bushings

HYDRO H7000 series shocks are recommended for multiple shock applications and mild to moderate off-road use. Skyjacker(R) hydro shocks, Skyjacker(R) suspensions offers you a high quality shock absorber with true velocity sensitive valving. Shock absorbers, or spring dampers as it is called everywhere else except in the U.S, control the rate at which suspension springs compress and rebound. As the shock is pushed together, this is called bump or compression. As the shock expands, this is called rebound or extension. Absorbing the shock of bumps and suspension loading is actually performed by the springs in the suspension. The shock real job is controlling the energy stored in the springs. The performance specific internal components of Skyjacker shocks respond to the on- and off-road conditions instantly. Whether you are going over rough or smooth terrain at slow or fast speeds, the true velocity sensitive valving produces a stable, controlled level of resistance for better handling, improved stability, and maximum comfort. The technological innovations of these durable, long lasting shocks from Skyjacker(R) deliver a noticeable advantage over the original equipment and other shock dampeners. Skyjacker shock absorbers deliver a safe, comfortable ride with improved handling and stability. They keep the tires in contact with the terrain and put you in control of the road ahead

Product Features:

• Hydraulic Action. Leak Proof Seal Prevents Hydraulic Fluid From Passing Around Piston Head For A Consistent And Reliable Ride
• Multi Stage Velocity Sensitive Valving
• Twin Tube Construction. DOM Tubing Reduces Internal Wear For Longer Product Life
• Bonded Iron Piston For Durability And Longer Shock Life
• Chromed Piston Rod Features Micro Polished Shaft For Improved Product Life And Performance
• Orifice Disk For Axle Control In Any Condition
• Red Polyurethane Bushings

NITRO N8000 series shocks are recommended for full size vehicles and moderate to extreme off-road applications. Skyjacker(R) nitro shocks, Skyjacker(R) suspensions offers you a high quality shock absorber with true velocity sensitive valving. Shock absorbers, or spring dampers as it is called everywhere else except in the U.S, control the rate at which suspension springs compress and rebound. As the shock is pushed together, this is called bump or compression. As the shock expands, this is called rebound or extension. Absorbing the shock of bumps and suspension loading is actually performed by the springs in the suspension. The shock real job is controlling the energy stored in the springs. The performance specific internal components of Skyjacker shocks respond to the on- and off-road conditions instantly. Whether you are going over rough or smooth terrain at slow or fast speeds, the true velocity sensitive valving produces a stable, controlled level of resistance for better handling, improved stability, and maximum comfort. The technological innovations of these durable, long lasting shocks from Skyjacker(R) deliver a noticeable advantage over the original equipment and other shock dampeners. Skyjacker shock absorbers deliver a safe, comfortable ride with improved handling and stability. They keep the tires in contact with the terrain and put you in control of the road ahead

Product Features:

• 150 PSI Pressurized Nitrogen Gas
• Multi Stage Velocity Sensitive Valving
• Twin Tube Construction. DOM Tubing Reduces Internal Wear For Longer Product Life
• Bonded Iron Piston For Durability And Longer Shock Life
• Chromed Piston Rod Features Micro Polished Shaft For Improved Product Life And Performance
• Orifice Disk For Axle Control In Any Condition
• Red Polyurethane Bushings

Gas-charged shock absorber that provides improved vehicle control for today’s light trucks, vans, full-size picks-ups and 4×4’s at an economical price.

Product Features:

• Available for import and domestic trucks, vans, full-size pick-ups and 4×4’s
• Gas-charged unit
• Improved handling and control
• Economical OE replacement
• Meets OE product specifications

Valvoline DEXRON®-VI ATF is a full-synthetic transmission fluid formulated with advanced additive technology to meet and exceed the requirements of the General Motors’ DEXRON®-VI specification. It is officially licensed and approved by GM and is fully back-serviceable and can be used wherever DEXRON®-II and/or DEXRON®-III are recommended. Recommended for use in the following applications: DEXRON®-VI, DEXRON®-III, DEXRON®-II, and Allison C-4.

Product Features:

• Formulated with full-synthetic base stocks and advanced additive technology to meet the challenging demands of automatic transmissions.
• Enhanced anti-shudder protection for smooth shifting and maximum power transfer
• Developed with anti-wear technology to help improve transmission durability
• Engineered with a proprietary blend of base oils and advanced additives to provide better oil flow at low temperatures and greater film protection at higher temperatures

Valvoline DEX/MERC ATF is a high-quality transmission fluid formulated to meet the challenging demands many automatic transmissions. Its responsive low-temperature fluidity is beneficial in both electronic and hydraulic controlled transmissions and transaxles. Recommended for use in the following applications: MERCON®, DEXRON®-III, Ford M2C138-CJ and M2C166-H, Allison C-4 and TES-389, and Caterpillar TO-2.

Product Features:

• Formulated with premium base stocks and advanced additive technology to meet the challenging demands of automatic transmissions.
• Enhanced anti-shudder protection for smooth shifting and maximum power transfer
• Developed with anti-wear technology to help improve transmission durability
• Engineered with a proprietary blend of base oils and advanced additives to provide better oil flow at low temperatures and greater film protection at higher temperatures

By engineering bracketry or replacement components Belltech Shackles and Hangers to reposition the front and/or rear leaf Spring Mounting points Spring eyes you can simply and effectively lower your leaf Spring equipped sport truck or SUV without changing the factory Leaf Spring. This allows you to retain OEM Ride Quality and possibly more importantly factory load capacity. At Belltech, we offer both Belltech Shackles and Hangers as individual components as well as complete kits depending on your Lowering requirements. Belltech Shackles and Hanger kits are designed to lower the rear of your Leaf Spring equipped sport truck or SUV by up to 5 Inch depending on the application.

Product Features:

• To Reposition The Front And/Or Rear Leaf Spring Mounting Points Spring Eyes You Can Simply And Effectively Lower Your Leaf Spring Equipped Sport Truck Or SUV Without Changing The Factory Leaf Spring
• Direct Bolt-In, No Additional Modifications
• Belltech Shackles And Hanger Kits Are Designed To Lower The Rear Of Your Leaf Spring Equipped Sport Truck Or SUV By Up To 5 Inch Depending On The Application
• Easy To Install

Get ahead of fatigued or rusted leaf spring shackles before they become dangerous. Made of sturdy steel with a power coated finish to resist corrosion, this leaf spring shackle is a direct replacement for your vehicle’s stock shackle.

Product Features:

• Direct replacement – This leaf spring shackle fits and performs like original equipment shackle
• Quality construction – manufactured from durable steel and powder coated for corrosion resistance and a long service life
• Excellent value – original equipment quality at a lower price
• Ready to install – all essential hardware is included for an easy installation

By constantly introducing design enhancements that extend product life and simplify installation and replacement, MOOG has earned its reputation as the chassis industry’s Problem Solver.

Product Features:

• Easy to install
• Restores like-new steering and handling
• Engineered to provide long life and dependability
• Construction and design validated by MOOG engineers
• Incorporates proven design and engineering features
• Greaseable socket reduces corrosion and wear by allowing new lubricant to flush contaminants

By engineering bracketry or replacement components Belltech Shackles and Hangers to reposition the front and or rear leaf Spring Mounting points Spring eyes you can simply and effectively lower your leaf Spring equipped sport truck or SUV without changing the factory Leaf Spring. This allows you to retain OEM Ride Quality and possibly more importantly factory load capacity. At Belltech, we offer both Belltech Shackles and Hangers as individual components as well as complete kits depending on your Lowering requirements. Belltech Shackles and Hanger kits are designed to lower the rear of your Leaf Spring equipped sport truck or SUV by up to 5 Inch depending on the application

Product Features:

• To Reposition The Front And/Or Rear Leaf Spring Mounting Points Spring Eyes You Can Simply And Effectively Lower Your Leaf Spring Equipped Sport Truck Or SUV Without Changing The Factory Leaf Spring
• This Allows You To Retain OEM Ride Quality And Possibly More Importantly Factory Load Capacity
• Belltech Shackles And Hanger Kits Are Designed To Lower The Rear Of Your Leaf Spring Equipped Sport Truck Or SUV By Up To 5 Inch Depending On The Application
• Direct Bolt-In, No Additional Modifications
• Comes With Installation Instructions

Get ahead of fatigued or rusted leaf spring shackles before they become dangerous. Made of sturdy steel with a power coated finish to resist corrosion, this leaf spring shackle is a direct replacement for your vehicle’s stock shackle.

Product Features:

• Direct replacement – This leaf spring shackle fits and performs like original equipment shackle
• Quality construction – manufactured from durable steel and powder coated for corrosion resistance and a long service life
• Excellent value – original equipment quality at a lower price
• Ready to install – all essential hardware is included for an easy installation

Gas-charged shock absorber that provides improved vehicle control for today’s light trucks, vans, full-size picks-ups and 4×4’s at an economical price.

Product Features:

• Available for import and domestic trucks, vans, full-size pick-ups and 4×4’s
• Gas-charged unit
• Improved handling and control
• Economical OE replacement
• Meets OE product specifications

Ride Comfort may be important, but restoring a vehicles Ride Control, stability, stopping, lane change responsiveness and handling is critical. KYB Excel-G Shocks and Struts are designed for the most important performance purpose: Restoring the vehicles original capabilities. KYB is a world leading supplier of shocks and struts to new vehicle manufacturers and the Excel-G is made on the very same KYB OE assembly lines, uses the same OE quality components and is calibrated to restore original, designed performance, not change it. That has earned Excel-G the classification: OEA (Original Equipment for the Aftermarket). The KYB Excel-G is a nitrogen gas-charged, twin-tube design that includes every quality component that our global OEM products include and it is the preferred choice by professional technicians.

Product Features:

• KYB Recommended Orem Replacement Shock
• The KYB Excel-G Helps Restore The Designed Control And Handling Of Your Full-Size Gm Truck
• The KYB Excel-G Uses A Triple Lip Fluid Seal To Reduce The Chance Of Oil And Gas Leaking Out
• Vehicle Specific, Hand Assembled, In-House Damping Valves Correctly Manage Tire Contact, Steering Response And Body Movement
• Electronic Safety Systems Depend On The Suspension, Brakes And Tires Operating As The Vehicle Manufacturer Intended. The KYB Excel-G Helps Keep Electronic Safety Systems Performing As Designed.
• KYB Has The Strongest And Thickest Strut Bodies And Brackets In The Industry; Minimizing Flex To Maintain Correct Alignment In All Conditions

Get premium control and performance with Rancho RS9000®XL shocks. Recognized as the first nine-position manually adjustable ride control series in the off-road market, RS9000XL shocks are ideal for on- and off-road use, towing and more.

Product Features:

• NINE LEVELS OF PERFORMANCE — Nine-position easy-to-adjust knob allows customized damping control and firmness for on-road and off-road flexibility
• DESIGNED FOR HARDWORKING VEHICLES — Ideal for stock or lifted trucks, SUVs and Jeeps that tow, haul or go off road
• INDUSTRY FIRST — Recognized as the first nine-position manually adjustable shock series in the off-road market
• REDUCES FADE — Nitrogen gas pressurized to 120 PSI to minimize air-to-oil mixture and reduce damping performance fade and foaming
• STRONG AND DURABLE — Features an application-specific 18mm nitro-carburized piston rod to resist scuffs and corrosion, double-welded loops at stress areas and 1.25-in. sintered iron piston for enhanced structural integrity
• HANDLES EXTREME TEMPERATURE CHANGES — Up to 2.75-in. tri-tube body (application specific) filled with all-weather fluid allows for cooler operation, increased vehicle control and ability to withstand internal temperatures of -40 to 248°F
• SMOOTH PERFORMANCE — Polyurethane rebound bumper and bushings and graphite-filled fluon-banded piston help absorb ride harshness and enhance responsiveness to changing road conditions for an overall smoother ride
• BUILT TO LAST — Low-friction, self-lubricating seal retains gas and oil for quicker rebound and smoother compression while the long-lasting premium liquid metallic finish and polyvinyl protective boot ensures long life

Monroe® Gas-Matic truck shock absorber are gas charged and provide improved control at an economical price.

Product Features:

• Available for import and domestic light trucks and vans
• Gas-charged unit
• Improved handling and control
• Economical OE replacement
• Meets OE product specifications

HYDRO H7000 series shocks are recommended for multiple shock applications and mild to moderate off road use. Skyjacker(R) hydro shocks: Skyjacker(R) suspensions offers you a high quality shock absorber with true velocity sensitive valving. Shock absorbers, or spring dampers as it is called everywhere else except in the U.S, control the rate at which suspension springs compress and rebound. As the shock is pushed together, this is called bump or compression. As the shock expands, this is called rebound or extension. Absorbing the shock of bumps and suspension loading is actually performed by the springs in the suspension. The shock real job is controlling the energy stored in the springs. The performance specific internal components of Skyjacker shocks respond to the on and off road conditions instantly. Whether you are going over rough or smooth terrain at slow or fast speeds, the true velocity sensitive valving produces a stable, controlled level of resistance for better handling, improved stability, and maximum comfort. The technological innovations of these durable, long lasting shocks from Skyjacker(R) deliver a noticeable advantage over the original equipment and other shock dampeners. Skyjacker shock absorbers deliver a safe, comfortable ride with improved handling and stability. They keep the tires in contact with the terrain and put you in control of the road ahead

Product Features:

• Hydraulic Action. Leak Proof Seal Prevents Hydraulic Fluid From Passing Around Piston Head For A Consistent And Reliable Ride
• Multi Stage Velocity Sensitive Valving
• Twin Tube Construction. DOM Tubing Reduces Internal Wear For Longer Product Life
• Bonded Iron Piston For Durability And Longer Shock Life
• Chromed Piston Rod Features Micro Polished Shaft For Improved Product Life And Performance
• Orifice Disk For Axle Control In Any Condition
• Red Polyurethane Bushings

Ideal for vehicles with a higher center of gravity, Monroe® Reflex® light truck shock absorbers feature ASD valving technology that automatically adjusts the unit to absorb the impact, helping to reduce vehicle roll and dive.

Product Features:

• IMPROVES STABILITY — ASD (Acceleration Sensitive Damping) valving technology adjusts to impacts, reducing roll and dive for vehicles with a higher center of gravity
• EXCEPTIONAL HANDLING — Full displaced valving, tuned specifically to each vehicle, adjusts to road extremes while the larger bore provides more efficient damping control to provide consistency and a smooth ride
• CONSISTENT RIDE — OE all-weather fluid contains special additives to assist with extreme temperatures and help reduce oil breakdown while larger reserve tube holds more fluid to run cooler
• CONTROL AND DURABILITY — Fluon-banded piston provides consistent sealing between piston and pressure tube for better control and increased durability
• IMPROVES PERFORMANCE — Nitrogen gas charge maintains tire-to-road contact for improved ride and handling by reducing aeration
• 2-1/4 inch or 2 inch Diameter Reserve Tube: Allows more fluid carrying capacity for a cooler running unit.
• 1-3/8 inch Bore: Lower operating pressure than standard 1 inch bore units
• 5/8 inch Piston Rod: Heavy-duty nitrocarburized rod for long service life. On non-dust shield units only
• Special Seal: ‘Self-lubricating’ fluid seal designed to retain gas without excessive wear or friction.

NITRO N8000 series shocks are recommended for full size vehicles and moderate to extreme off-road applications. Skyjacker(R) nitro shocks, Skyjacker(R) suspensions offers you a high quality shock absorber with true velocity sensitive valving. Shock absorbers, or spring dampers as it is called everywhere else except in the U.S, control the rate at which suspension springs compress and rebound. As the shock is pushed together, this is called bump or compression. As the shock expands, this is called rebound or extension. Absorbing the shock of bumps and suspension loading is actually performed by the springs in the suspension. The shock real job is controlling the energy stored in the springs. The performance specific internal components of Skyjacker shocks respond to the on- and off-road conditions instantly. Whether you are going over rough or smooth terrain at slow or fast speeds, the true velocity sensitive valving produces a stable, controlled level of resistance for better handling, improved stability, and maximum comfort. The technological innovations of these durable, long lasting shocks from Skyjacker(R) deliver a noticeable advantage over the original equipment and other shock dampeners. Skyjacker shock absorbers deliver a safe, comfortable ride with improved handling and stability. They keep the tires in contact with the terrain and put you in control of the road ahead

Product Features:

• 150 PSI Pressurized Nitrogen Gas
• Multi Stage Velocity Sensitive Valving
• Twin Tube Construction. DOM Tubing Reduces Internal Wear For Longer Product Life
• Bonded Iron Piston For Durability And Longer Shock Life
• Chromed Piston Rod Features Micro Polished Shaft For Improved Product Life And Performance
• Orifice Disk For Axle Control In Any Condition
• Red Polyurethane Bushings

Featuring a unique, exclusive valving system and advanced compression functionality, Rancho® RS5000®X shocks deliver improved overall on- and off-road handling and performance.

Product Features:

• IMPROVED HANDLING AND PERFORMANCE — Cross Tuned technology featuring exclusive rebound valving system and advanced compression phase improves overall handling and performance on and off road
• MINIMIZES ROUGH RIDE — Exclusive Progressive Engagement Valving is custom-tuned for each vehicle to help reduce initial impacts at low speeds and minimizes a rough ride
• STRONG AND DURABLE — Features a 16mm nitro-carburized piston rod to resist scuffs & corrosion, double-welded loops at stress areas, 35mm sintered iron piston for enhanced structural integrity and polyvinyl protective boot
• HANDLES EXTREME TEMPERATURE CHANGES — Large twin-tube body filled with all-weather fluid allows for cooler operation, increased vehicle control and ability to withstand internal temperatures of -40 to 248°F
• SMOOTH PERFORMANCE — Polyurethane rebound bumper and rubber bushings help absorb ride harshness while the fluon-banded piston enhances responsiveness to changing road conditions for an overall smoother ride
• REDUCES FADE — Nitrogen gas pressurized to 150 PSI to minimize air-to-oil mixture to reduce damping performance fade and foaming
• MAINTAINS VEHICLE CONTROL — Compression Control Valve is custom-tuned for each vehicle to regulate fluid transfer to absorb impacts without disc flutter and help maintain shock motion control
• BUILT TO LAST — Low-friction, self-lubricating seal retains gas and oil for quicker rebound and smoother compression while the application-specific piston delivers heightened control of shock motion due to the expanded piston area
• Rebound Bumper