Sinclair C5 Parts

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====== The Hoover service network ======

Hoover plc assembled the C5 at Merthyr Tydfil, and its domestic-appliance service division was also the C5's **exclusive service and parts organisation**. This page draws on the confidential //C5 Service Engineer Training Notes// used at Hoover's **Doncaster Training School** in late 1984. A scanned copy is archived on c5owners.com under Resources › Internal Documents. A separate set of //Control Clerk Training Notes// (54 pp.) also survives.

===== The arrangement =====
  * **Sinclair Vehicles** appointed Hoover exclusively to carry out service work and to buy, pack, store and supply replacement parts. Sinclair reimbursed warranty work and transit damage.
  * **Hoover** committed to:
    * visit within **3 working days**;
    * complete at least **90 % of jobs on the first visit**, and the rest within 15 days;
    * keep parts available "throughout the reasonable life of the vehicle";
    * guarantee charged work for 12 months;
    * keep at least **2 control clerks** at each District Service Office;
    * report service and reliability statistics to Sinclair.
  * **Not Hoover's responsibility under warranty:** the battery and charger (these went to Sinclair Battery Centres) and accessories (referred to the accessory supplier). Hoover would fit accessories as a charged job.
  * Sinclair also allowed Hoover to set up a "service-related" **owners' club**.
  * Hoover planned for production "geared to 4,000 machines per week" and an assumed **12 % call rate**. That works out at about 480 warranty calls a week, or about **12 jobs a week for each of ~40 trained engineers**.

===== Course outline (two days) =====
  * **Day 1:** introduction to the C5 and its concept; commissioning and "on the road"; construction and components, with the instructor stripping and rebuilding a vehicle; trainee practical work.
  * **Day 2:** servicing and general fault location; the circuit diagram and electrical fault finding; technical specifications; legal requirements; administration.

The engineers were taught the vehicle was **top secret**. Production had started "behind closed doors" at Merthyr Tydfil with a pilot batch of five vehicles, ahead of the early-January 1985 launch.

===== Component notes from the training slides =====
  * **Body:** two polypropylene halves welded by passing a high current through a special tape laid along the joint.
  * **Instrument pod:** "will be changed as a complete unit – we will not repair."
  * **Chassis:** a fabricated steel box frame.
  * **Front wheel:** **12-spoke glass-filled nylon**.
  * **Front brake:** a standard cantilever-type caliper, but with **special blocks for the nylon rim**. **Normal bicycle brake blocks must not be fitted.**
  * **Rear brake:** a heat sink was added during development.
  * **Motor/gearbox:** 13:1 ratio. The motor casing is **eccentric** to allow belt adjustment.
  * **Thermistor:** fitted in the motor; "must ensure probe does not foul armature shaft." The **thermal overload cut-out (T.O.C.)** is clipped to the motor casing.
  * **Battery:** "essentially a fork-lift truck battery", able to deliver high starting currents and to be discharged to 80 % without damage. **Do not use an ordinary car battery.**
  * **Security (master) switch:** a simple **double-pole** device with a red-button isolator.
  * **Wiring diagram:** this version shows a **20 A in-line fuse** in the brown battery feed, as well as FS1 (5 A) and FS2 (1 A) in the control box.

===== Servicing positions and tools =====
Engineers were issued a **service frame** and taught three working positions:

  - **Parked:** crank assembly and steering control.
  - **Rear raised on a half frame, boot off:** rear wheels, rear brake, drive belt, drive gear and splined sleeve, axle, motor, gearbox, motor mount, bump rubbers, body hoop and control box.
  - **Vertical on the full frame, battery out:** front wheel, tyre and tube, wheel axle, front caliper, fork and steering bearings.

Each engineer was also issued a **multimeter** and a **battery tester**. They were warned **never to use a Metrohm insulation tester on its 500 V range** on a C5, because it destroys the 12 V and 5 V electronics.

Major strip-down sequences covered in the practical exercises:
  * **Body shell removal and harness replacement.** Remove the battery, release the harness from the chassis, separate the motor harness, disconnect the leads at the control box, remove the steering bars as one unit, then remove the crank set.
  * **Motor.** Disconnect the motor leads (mains and protection) at the box and remove the motor from its mounting. Remove the thermistor, T.O.C. and brush assembly. Split the gearbox from the motor and strip and rebuild the planet gears.
  * **Motor mount.** This needs the near-side (left) rear wheel removed. On refitting, check the belt tension, the control-box connections, the thermistor and T.O.C. positions, and the harness ties.
  * **Body.** Four body securing bolts with **bump rubbers**. Check the screw and bump-rubber alignment when refitting.

===== Service schedules =====
**Commissioning** (Hoover would unpack and prepare the vehicle as a paid job):
  * unpack and check for damage;
  * fit the charger plug and put the battery on charge;
  * check tyre pressures (30/35 psi);
  * do the rolling check, install the battery, and do the operational check;
  * fit any accessories;
  * show the owner the controls, the legal requirements and the safety notes;
  * sign them up for a servicing contract and fill in the ownership data in the handbook.

**6-monthly service:**
  * inspect for damage;
  * tyres;
  * front and rear brakes;
  * clean and lubricate the chain;
  * inspect the drive belt;
  * axle retaining bolts;
  * front and rear hub bearings;
  * steering head bearing and alignment;
  * steering control bearings;
  * chainset bearings;
  * electrical components;
  * rolling check and operational check;
  * lubricate.

**Functional test** after every repair (allowed time 5 minutes):
  - Lights, indicators and horn.
  - Pod lights.
  - Key to D: the cut-out button should click out.
  - Press the button, then return the key to D.
  - Pedal and test each brake.
  - Power on.
  - Instrument display.
  - Full lock each way, bearing adjustment and wheel alignment.
  - Visual check of the tyres.

Engineers were told to carry out this test **on the road**: "C5 is not a washing machine in a kitchen, it's a vehicle on the highway."

===== Fault-finding chart (summary) =====

==== Mechanical ====

^ Symptom ^ Check in order ^
| Front: vibration or steering play | Brake binding; wheel/tyre damage and alignment; hub bearings; steering control bearing; head bearing; steering linkage; stem; control levers |
| Front brake weak | Blocks; cable; caliper action; lever |
| Rear left (driven side) noisy | Motor including the planet gears; drive belt; wheel bearings; rear-axle bearing surface; chain drive and sprocket; wheel/tyre; **chassis-to-body bump bush** |
| Rear right noisy | Brake binding; wheel bearing; wheel/tyre; boot assembly; rear axle |
| Poor performance or short range | Free movement of the rear wheels (forward only); chain and drive; tyres; **is the user pedalling when needed?** |
| Stall protection operating too often, or a single segment flashing with the buzzer too often | **Transmission binding** (making the motor overheat); belt condition |

==== Electrical ====

^ Symptom ^ Check in order ^
| Immobile, pod and lights dead | Key switch closed; battery and connections; wiring battery → control box (the 12 V feed is missing) |
| Immobile, pod and lights OK | Battery; **bi-metal trip circuit**; motor switch wiring; motor circuit; then change the pod, then the control box |
| Immobile, all pod segments lit | **FS2** fuse; wiring to the pod; pod; control box |
| Immobile, all current segments flash (mechanics OK) | Wiring to the pod; **thermistor circuit (about 10 kΩ when cold)**; pod; control box. This is a false stall |
| Runs, but no pod display | Wiring to the pod; control supplies to the pod; pod; box |
| Runs, single segment flashing with buzzer (mechanics OK) | Thermistor and wiring; pod; box |
| Runs, single segment flashing, no buzzer | Faulty buzzer, so change the pod |
| Fuel gauge never drops | Battery connections; battery supply to the control box; pod; box |
| Last fuel segment goes out but the vehicle doesn't lock out, or it restarts after a low-fuel lock-out | Pod or box. **Raise a serious fault report** |
| Motor doesn't stop when the switch is released | Motor switch and wiring for a short; motor negative for a short; control box. **Serious fault report** |
| Cut-out button doesn't work | **Change the key switch. Serious fault report** |
| Stall protection doesn't work | Control box. **Serious fault report** |
| Headlamp or rear lamp out | Bulb; continuity from the control box to the lamp holder |
| Both lamps and horn out | **FS1**; negative auxiliary return |
| Indicators flash fast | Bulbs; flasher unit |

===== Labour charges (Dec 1984) =====
  * Single-item changes were charged in time bands, from **£13.50 + VAT (5–14 min) up to £40.50 + VAT (95–104 min)**.
  * Commissioning cost **£14.00 + VAT**. A maintenance contract (the 6-monthly service) cost **£27.00 + VAT**.
  * The charge list gives pack numbers that match the handbook part numbers. It also shows **C5674 350, "Control box – reconditioned"**, which is not in the owner's handbook list.

===== Sources =====
  * //C5 Training Notes – Service Engineer// (Hoover plc, confidential, c. Nov–Dec 1984), 67 pp. Scan on c5owners.com.
  * //Control Clerk Training Notes// (Hoover plc), 54 pp. Scan on c5owners.com; not summarised here yet.