Smart Car Parts UK - Quality Used & Genuine Parts

How to Replace Smart Clutch Actuator

The clutch actuator is one of the most commonly replaced components on Smart fortwo models with automated manual transmissions. This electronic motor controls clutch engagement and is notorious for failure causing gear selection problems and the dreaded "three bars of death" dashboard warning. Replacement requires working underneath the vehicle but is manageable with proper tools and safety precautions.

Step-by-Step Instructions:

1. Safely raise and secure the vehicle. Use proper jack and jack stands to elevate the vehicle providing clear access to the transmission area underneath. Never work under vehicle supported only by jack as this is extremely dangerous. The clutch actuator is located on the transmission underneath the car accessible from below. Ensure vehicle is on level ground and securely supported before proceeding.
2. Locate the clutch actuator assembly. The clutch actuator is mounted on the side of the transmission bell housing and consists of an electric motor with pushrod that operates the clutch release mechanism. On 451 generation fortwo (2007-2014), the actuator is particularly prone to failure due to inadequate lubrication from factory. Identify the actuator by its cylindrical shape with electrical connector and three mounting bolts typically 10mm or 13mm.
3. Disconnect the electrical connector. Press the release tab on the electrical connector and carefully pull straight out to disconnect wiring from actuator. Inspect connector and wiring for damage, corrosion, or chafing as wiring problems can cause similar symptoms to actuator failure. Many Smart owners report chafed wiring causing intermittent gear selection problems that mimic actuator failure, so verify wiring condition before assuming actuator needs replacement.
4. Remove the three mounting bolts. Using appropriate socket, remove the three bolts securing actuator to transmission bell housing. These bolts typically require 10mm or 13mm socket depending on model year. Keep bolts organized as they may differ in length. Note the position of actuator alignment marks if visible as proper positioning is important for clutch engagement geometry. On some models, actuator uses slotted mounting holes allowing adjustment.
5. Carefully remove the old actuator. With mounting bolts removed, gently pull actuator straight away from transmission. The pushrod will disengage from clutch release mechanism. Inspect pushrod tip for wear or damage. On early 451 models, pushrod can wear a hole in clutch throw-out bearing arm requiring additional repairs beyond actuator replacement. If excessive wear is visible on pushrod or bearing arm, these components require attention before installing new actuator.
6. Prepare the new actuator for installation. Before installing replacement actuator, apply silicone grease to internal mechanism following manufacturer instructions. Early 451 actuators were inadequately lubricated from factory leading to premature failures. Proper lubrication of replacement actuator helps prevent repeat failures. Some technicians recommend disassembling new actuator to apply grease internally though this voids warranty. At minimum, lubricate pushrod and external moving parts.
7. Install and adjust the new actuator. Position new actuator aligned with mounting holes ensuring pushrod engages clutch release mechanism correctly. If actuator uses slotted mounting holes for adjustment, position actuator to place clutch approximately in center of available adjustment range. Thread in all three mounting bolts finger-tight initially. Some sources recommend adjusting actuator position "out one notch" from center to compensate for clutch wear. Tighten mounting bolts to proper torque specification ensuring actuator is securely mounted.
8. Reconnect electrical connector and perform clutch re-teach. Reconnect electrical connector ensuring it clicks firmly into place. Lower vehicle to ground safely. The transmission control unit requires a "re-teach" or "reset" procedure after clutch actuator replacement to recalibrate clutch position. This requires Star diagnostic tool (Mercedes dealer equipment) or compatible aftermarket scanner like iCarsoft. Follow diagnostic tool instructions to perform clutch adaptation procedure. Without proper re-teach, transmission may not function correctly or may display warning lights. Some owners report vehicles working without re-teach but proper calibration is recommended.

Important Notes: Clutch actuator replacement costs £286-£900 depending on whether using aftermarket or genuine Mercedes parts. Dealers typically charge £900+ for genuine actuator while aftermarket units available from £286 though quality varies. Early 451 models (2008-2009) had particularly problematic actuators that frequently failed requiring replacement. When symptoms include gear selection problems, jerky shifts, or "three bars of death" dashboard warning, always check wiring condition before replacing actuator as chafed wires can cause identical symptoms at much lower repair cost. Some Smart owners report actuators lasting over 100,000 miles while others fail under 30,000 miles highlighting inconsistent quality.

Browse Smart Clutch Actuators →

How to Replace Smart Body Panels

Smart fortwo and forfour models feature distinctive Tridion safety cell with removable plastic body panels that can be replaced relatively easily. This modular design allows owners to change colors or replace damaged panels without extensive bodywork, making Smart vehicles uniquely customizable and repairable after minor accidents.

Step-by-Step Instructions:

1. Identify the panel to be replaced. Smart body panels are modular and include front panels, rear panels, side panels, door skins, and various trim pieces. The Tridion safety cell is the structural element painted in contrasting color (typically silver or black) forming the "skeleton" visible externally. Colored plastic body panels attach to Tridion frame using combination of bolts, clips, and screws. Each panel can be removed independently allowing targeted replacement of damaged sections.
2. Remove any adjacent trim or components blocking access. Depending on which panel is being replaced, you may need to remove bumper sections, lights, mirrors, or interior trim pieces for access to mounting points. For example, front panels may require headlight removal, while rear panels need taillight access. Work systematically removing only necessary components to access panel fixings. Keep all removed parts organized by location.
3. Locate and remove all panel mounting screws and bolts. Smart panels typically use Torx screws (T20, T25, or T30) and some 10mm bolts for mounting. Panel fixings are located around perimeter where plastic panel meets Tridion frame. Carefully inspect entire panel edge for all fixings as missed fasteners will prevent panel removal and may crack plastic if forced. Typical panel uses 8-15 fixings depending on size and location.
4. Release plastic clips securing panel. In addition to screws and bolts, panels use plastic push-clips at various points. These clips require careful removal using trim tools to press center pins before pulling clips out. Forcing clips without properly releasing them will break clips necessitating replacements. Smart panels are designed for removal but require patience and proper technique to avoid damage.
5. Carefully remove the old panel from vehicle. With all fixings and clips removed, gently pull panel away from Tridion frame. Panels may have locating tabs or pins requiring slight manipulation to disengage. Support panel weight to prevent dropping and damaging panel or vehicle. Inspect Tridion frame mounting points for damage, rust, or missing clips that need addressing before installing replacement panel.
6. Prepare the replacement panel for installation. New or used replacement panels should be cleaned and inspected for proper fit. If installing used panel from different color Smart, ensure it's the correct panel for your model year as slight variations exist between generations. Check that all mounting holes align with Tridion frame fixings. If reusing existing clips and hardware, ensure they're in good condition and not damaged during removal.
7. Install the new panel in reverse order. Position replacement panel aligned with Tridion frame ensuring all locating pins and tabs engage properly. Start all screws and bolts finger-tight before fully tightening any to allow adjustment for proper panel gaps. Work around perimeter systematically tightening fixings to secure panel evenly. Ensure panel gaps are consistent and panel sits flush with adjacent panels. Install any clips required and verify panel is secure.
8. Reinstall adjacent components and check panel alignment. Reinstall any lights, trim pieces, or components removed for access. Check panel gaps around entire perimeter ensuring consistent spacing. Smart panels should align cleanly with Tridion frame and adjacent panels. Minor adjustments possible by loosening fixings and repositioning panel before final tightening. Stand back and visually inspect overall appearance ensuring replacement panel matches surrounding panels.

Top Tips: Smart's modular panel design is one of its cleverest features allowing easy color changes and damage repair. Panels are available in various colors from Smart dealers and breakers, with some owners swapping panels to create custom two-tone schemes. Plastic panels are more forgiving in minor accidents than steel panels and won't rust. When buying used panels, inspect carefully for cracks particularly around mounting holes as overtightened screws can crack plastic. Panel prices vary from £50-£200 depending on size and whether buying used from breakers or new from dealers. The Tridion safety cell is structural and should not be modified or have mounting points damaged as it provides crash protection.

Browse Smart Body Panels →

Common Smart Parts Problems & Solutions

Smart vehicles, particularly the fortwo, are iconic city cars known for innovative design, compact dimensions, and quirky character. However, Smart's reliability record is mixed with the brand ranking dead last out of 32 manufacturers in the 2013 Driver Power owner satisfaction survey. While some Smart owners report trouble-free motoring with vehicles reaching high mileages, others experience significant problems particularly with the automated manual transmission and early engine designs. Understanding common Smart problems helps buyers make informed decisions and current owners address issues promptly. Here are the most commonly reported Smart parts problems based on verified owner experiences and technical specialists.

Automated Manual Transmission Problems (Major Issue Across Most Models):

• Jerky, Harsh Gear Changes: The automated manual transmission (AMT) represents Smart's most controversial feature and most common source of owner complaints. Unlike conventional automatic transmissions with torque converters or modern dual-clutch systems, Smart uses automated manual gearbox where electronic actuators operate a conventional manual transmission and clutch without driver input. The system exhibits harsh, jerky gear changes particularly between first and second gear, delayed shifts with noticeable hesitation causing forward-backward lurching, rough engagement from standstill, and generally unrefined shifting compared to proper automatic transmissions. Many reviewers describe shifts as feeling "like a beginner learning manual transmission" with abrupt clutch engagement. The issue affects fortwo models with automated transmission across 450, 451, and to lesser extent 453 generations. Some owners adapt to transmission's quirks and accept its character while others find it frustrating and unacceptable.
• Clutch Actuator Failures: The clutch actuator is an electric motor mounted on transmission that physically operates the clutch. Early 451 fortwo models (2008-2009) particularly notorious for clutch actuator failures due to inadequate factory lubrication. Symptoms include complete inability to select any gears with "three bars of death" (three horizontal lines) displayed on instrument cluster, intermittent gear selection problems where some gears work while others don't, jerky or delayed clutch engagement, and transmission warning lights. Clutch actuator replacement costs £286-£900 depending on parts choice with dealers charging premium prices. Many Smart owners report actuator failures under 50,000 miles though some last over 100,000 miles. The actuator includes position sensor that sends feedback to transmission control unit, and sensor failures can cause similar symptoms to actuator motor failures.
• Gear Selector Actuator Issues: In addition to clutch actuator, Smart transmission uses separate gear selector actuator that physically moves gears. This actuator can fail causing inability to select certain gears, getting stuck in one gear with inability to shift, rough or grinding shifts, and transmission error codes. The gear selector actuator is separate component from clutch actuator requiring its own diagnosis and replacement. Both actuators work together to operate transmission and both are prone to failures particularly on higher mileage examples or vehicles used extensively in stop-and-go city traffic.
• Transmission Control Module Faults: The transmission control unit (TCU) or automated manual transmission control unit (AMTCU) is the computer that orchestrates gear changes and clutch operation based on inputs from speed sensors, position sensors, and driver inputs. TCU calibration faults cause improper shift timing, delayed or hesitant gear changes, and transmission behaving unpredictably. Software updates from Mercedes dealers can sometimes improve transmission behavior though problems often persist. TCU hardware failures require replacement costing several hundred pounds. The TCU location varies by model year with some located under driver seat and others integrated into transmission housing.
• Reluctor Ring Corrosion (451 Models): The 451 fortwo uses reluctor rings (toothed metal rings) on transmission shafts that work with magnetic sensors to determine gear position and shaft speeds. These reluctor rings prone to rust and deterioration causing sensor reading errors. Symptoms include blinking gear number on display, inability to select certain gears, and transmission error codes indicating faulty speed sensors. The actual problem is corroded reluctor rings rather than faulty sensors themselves. Replacing reluctor rings requires partial transmission disassembly and is labor-intensive repair. This issue particularly affects vehicles driven in winter conditions where road salt accelerates corrosion.
• Clutch Wear and Adjustment: The physical clutch disc wears over time like any manual transmission clutch. On 2008 and early 2009 451 models, clutch disc was too tight on transmission input shaft and could stick causing delayed clutch disengagement. Most common symptom is failure to select reverse gear. Mercedes issued software patch allowing more time for clutch disengagement as temporary fix but proper repair requires clutch replacement. Clutch actuator includes adjustment capability and should be adjusted periodically as clutch wears to maintain proper engagement. Failure to adjust actuator results in poor clutch engagement and accelerated wear.
• Solutions and Workarounds: Many Smart owners learn to adapt driving style to transmission's characteristics by lifting slightly off accelerator during upshifts to allow smoother engagement, using manual mode (where available) for more predictable shifts, and avoiding aggressive acceleration from stops that exacerbates jerky first-to-second shift. For mechanical failures, replacing failed actuators addresses immediate problem though underlying design means repeat failures possible. Regular transmission servicing using proper fluid maintains actuator function. Software updates from Mercedes dealers can improve shift quality though transformation into smooth automatic is unrealistic. Some owners describe transmission as "part of Smart's character" while others consider it a fatal flaw. Electric Smart models eliminate transmission issues entirely with simple electric motor drive.

Engine Problems (Particularly Early Models):

• High Oil Consumption and Engine Wear (450 and Early 451): The 600cc (0.6L) and 700cc (0.7L) three-cylinder engines used in 450 fortwo (1998-2007) and early 451 models (2007-2010) notorious for problems around 70,000 miles. Issues include excessive oil consumption requiring frequent top-ups between service intervals, melting spark plugs due to excessive combustion temperatures, burning out exhaust valves requiring expensive cylinder head repairs, and general loss of compression and power. The root cause involves inadequate piston ring sealing allowing oil into combustion chambers. One-way valve in engine breather pipe always fails permitting boost pressure into crankcase, not helping ring sealing problem. This valve costs only £16 and worth replacing preventatively.
• Spark Plug Accessibility: Smart engines use six spark plugs (two per cylinder) due to small combustion chamber design. Three spark plugs are relatively accessible but three toward rear of engine require removal of rear panel making them commonly neglected. Neglected rear spark plugs can fail causing misfires, rough running, and catalytic converter damage. Full spark plug service requires removing rear panel (five minute job) but many service centers skip rear plugs leading to incomplete maintenance.
• Later Engine Improvements: The 451 fortwo from approximately 2010 onward used improved engines with better longevity. The 451 Brabus models used uprated engines with oil coolers and improved components showing better durability. Later 453 generation (2014+) uses Renault/Nissan engines with generally good reliability. Diesel engines (all generations) show superior longevity often exceeding 200,000-250,000 miles due to tighter tolerances and oil coolers. First-generation 454 forfour (2004-2006) uses reliable Mitsubishi engines with excellent longevity avoiding problems plaguing fortwo engines.

Poor Fuel Economy (Widespread Across Models):

• Real-World Consumption vs Claims: Smart marketed as ultra-efficient city car but actual fuel economy frequently disappoints owners. The 1.0-liter engine reportedly achieves only 38-39 mpg even on motorways, far below claimed figures approaching 64 mpg. Owners report real-world economy of 30-40 mpg versus claimed 50-65 mpg representing significant discrepancy. One forfour owner complained getting only 38 mpg compared to their previous Vauxhall Meriva achieving 40 mpg despite being larger vehicle. The poor fuel economy stems from small but highly-stressed engines, automated transmission losses, and poor aerodynamics. Electric EQ models achieve approximately 63-68 miles of range with quick charging addressing efficiency concerns but limiting range for longer journeys.

Brake Component Wear:

• Accelerated Brake Pad and Disc Wear: Smart owners report brake pads and discs wearing faster than comparable city cars. Some owners report replacing brake pads every 8-12 months versus typical 35-40,000 mile lifespan on other vehicles. Smart cars should average 25,000-30,000 miles before brake pad replacement but some models wear components much faster. The issue likely stems from heavy braking in city traffic combined with relatively soft brake pad compounds and small brake components with limited thermal mass. Rear brake drums on some models prone to rusting particularly on forfour. Regular brake inspections essential to catch wear before safety compromised.

Suspension Problems:

• Rapid Suspension Component Wear: Smart's short wheelbase and city driving patterns accelerate suspension wear. Common issues include knocking or clunking noises from front suspension indicating worn bushings, shock absorbers wearing prematurely causing bouncy ride, ball joint wear requiring replacement, and front springs breaking particularly on 450 models. One forfour owner reported suspension knocking at only 8,000 miles highlighting quality concerns. Suspension repairs typically cost £80-£200 per corner for component replacement. Regular suspension inspections important to catch worn components before they affect handling or safety.

Electrical and Electronic Issues:

• Various Electrical Gremlins: Smart vehicles experience range of electrical problems including flat batteries particularly on vehicles with infrequent use, false dashboard alarms and warning lights without corresponding faults, infotainment system freezes requiring resets, and various sensor failures. One forfour owner reported flat battery from day one, false dashboard alarms, and ongoing electrical issues. Smart's connection to Mercedes means parts can be expensive despite small car status. Electrical diagnosis requires proper diagnostic equipment as multiple systems interconnect.

Convertible/Roadster Specific Issues:

• Water Ingress and Roof Problems: Smart fortwo cabriolet models and Roadster sports car suffer water ingress through convertible roof seals and mechanisms. Symptoms include wet carpets and footwells after rain, electrical issues from water damage, and mold or mildew in interior. The Roadster particularly notorious for water ingress and subsequent electrical problems killing more Roadsters than engine failures. Cabriolet soft-top mechanisms can malfunction preventing roof operation. These issues require careful inspection when buying convertible Smart models and prompt attention to any water entry to prevent escalating damage.

Design Quirks and Practical Issues:

• Boot Heat from Rear-Mounted Engine: Smart's rear-engine layout places engine directly under boot/luggage area. Engine heat transfers to boot making it unsuitable for temperature-sensitive items like frozen food or chocolate. Owners report boot getting hot enough to cook food en-route requiring use of tilting rear seats for storage of items requiring cool conditions. This is design characteristic rather than defect but catches owners by surprise.
• Washer Fluid Access Requires Bonnet Removal: Filling washer fluid on some Smart models requires removing bonnet or significant disassembly making routine maintenance unnecessarily complicated. Multiple owners describe needing "offsite training" to access washer fluid reservoir. This represents poor design prioritizing styling over serviceability.
• Limited Storage and Impractical Features: Drivers report nowhere to store items with no glove box or useful storage pockets. Glass panoramic sunroofs on some models don't actually open making them "wholly pointless" according to owners while creating greenhouse effect in sunshine making inadequate air conditioning work harder. When opening boot in rain, water cascade greets driver requiring preparation to get wet. These design choices prioritize aesthetics over functionality.

Smart Reliability Assessment:

Dead Last in 2013 Driver Power: Smart's ranking of dead last (32nd out of 32 manufacturers) in the 2013 Driver Power owner satisfaction survey tells a concerning story about owner experiences. This "wooden spoon" position reflects widespread dissatisfaction with reliability, running costs, and practicality despite Smart's innovative concept. While Smart didn't appear in subsequent years' surveys due to low sample sizes, the 2013 result remains damning indictment of the brand's reliability during that era.

Transmission Remains Major Weakness: The automated manual transmission represents Smart's Achilles heel with many reviewers and owners describing it as barely acceptable. Even high-performance vehicles like Maserati GranTurismo using similar single-clutch automated manuals receive complaints using identical descriptive words as Smart reviews. The technology inherently jerky compared to torque-converter automatics or modern dual-clutch systems. Smart's implementation particularly troublesome with frequent actuator failures and control module problems creating expensive repair bills. Owners either adapt to transmission's quirks accepting it as "character" or remain perpetually frustrated. Many recommend avoiding automated transmission entirely and choosing manual where available or waiting for dual-clutch equipped later models.

Engine Longevity Varies by Generation: Early 600cc and 700cc engines in 450 and early 451 models show concerning failure patterns around 70,000 miles requiring expensive reconditioning or replacement. Later engines show improvement with some examples reaching 150,000-200,000 miles. Diesel engines demonstrate superior longevity regularly exceeding 250,000 miles. The 454 forfour benefits from reliable Mitsubishi engines avoiding fortwo engine problems entirely. Buyers should research specific engine codes and model years as Smart's engine reliability varies dramatically across generations with some powertrains reliable and others problematic.

Mercedes Connection Doesn't Guarantee Quality: Despite Smart being division of Mercedes-Benz, vehicles don't benefit from Mercedes reliability reputation. Parts often carry Mercedes pricing without Mercedes quality or longevity. The brand represents failed experiment attempting ultra-compact car utilizing Mercedes engineering resources but never achieving reliability or profitability targets. Smart's closure of conventional production and shift to electric-only future under Chinese ownership reflects the brand's struggle to succeed in competitive city car market.

Electric Models Show Promise: The EQ fortwo and EQ forfour electric models eliminate troublesome automated manual transmission replacing it with simple electric motor drive. Fewer moving parts reduce maintenance requirements and potential failure points. Electric Smarts suit urban commuting perfectly with 80-100 mile range adequate for city use and lower running costs than petrol models. Reliability data for electric models limited but early indications suggest improved dependability versus combustion counterparts. For buyers wanting Smart experience with better reliability prospects, electric models represent safer choice.

Buying Recommendations: Prospective Smart buyers should avoid early 450 and 451 models with 600cc/700cc engines particularly those approaching 70,000 miles without documented engine rebuilds. For automated transmission models, budget for clutch actuator replacement (£286-£900) as failure is common rather than exceptional. Consider manual transmission where available eliminating automated system problems though manual Smart cars rare in UK market. First-generation 454 forfour (2004-2006) offers Smart quirky character with reliable Mitsubishi mechanicals though production run was short making examples scarce. Later 453 generation (2014+) shows improvement over earlier models particularly with Renault/Nissan engines. Electric EQ models avoid engine and transmission problems entirely representing most reliable Smart option despite range limitations. Diesel models suit higher-mileage users with superior longevity though automated transmission issues still possible. Always obtain pre-purchase inspection from Smart specialist who can check transmission function, actuator operation, engine compression, and common problem areas. Join Smart owner forums to research specific model year problems and realistic ownership costs before purchasing.

Overall Assessment: Smart vehicles offer unique urban mobility proposition with iconic styling, ultra-compact dimensions, and innovative design. However, reliability concerns particularly automated manual transmission jerky operation and frequent actuator failures, early engine problems requiring expensive repairs, disappointing fuel economy versus claims, and dead-last ranking in 2013 Driver Power survey make Smart difficult to recommend for reliability-focused buyers. The brand works best for urban drivers willing to accept quirky character and potential reliability compromises in exchange for easy parking, distinctive styling, and city-friendly dimensions. Enthusiastic owner communities provide support and knowledge for addressing common problems. Electric models represent significant improvement eliminating worst reliability concerns while maintaining Smart's urban focus. For buyers prioritizing dependability over character, mainstream alternatives like Toyota Aygo, Volkswagen up!, or Fiat 500 offer similar city car practicality with better reliability track records though without Smart's unique personality.

Find Replacement Smart Parts →