====== Restoring a C5 ======

See [[guides:buying|Buying a C5]] for what to check before you buy.

===== Restoration workflow =====
This follows the typical "budget restoration" written up on c5owners.com, cross-checked against the Owner's Handbook and the Hoover training notes.

==== 1. Strip ====
  * Remove the boot: open it, pull the two retaining clips down off their bosses, spring the wheel arches outward and lift the boot away.
  * Remove the battery and the master switch.
  * To take the body off, release the harness at the control box and steering stem, the brake cables and grommets, and the **four body bolts with bump rubbers**.
  * The Hoover training course stripped the body, harness, steering, crank set, rear wheels and brake, belt, axle, motor, gearbox and front end in that order. See [[history:hoover_service|Hoover Service Network]] for the three servicing positions.

==== 2. Chassis and mechanicals ====
  * Lightly sand the Y-frame and rear frame, treat with a rust converter, and repaint.
  * Clean and regrease:
    * the **steering ball bearings** (head and steering-control bearings);
    * the **crank bearings** (cotterless chainset);
    * the **front hub** and **right rear hub** (cup and cone);
    * the **gearbox** (5 ml of semi-fluid lithium grease, e.g. Castrol LMB).
  * Set all bearings, steering height (15–20 mm above the tunnel) and torques to the handbook figures. See [[guides:specifications|Specifications]] and [[guides:driving_and_maintenance|Driving and Maintenance]].

==== 3. Brakes ====
  * **Always replace the original brake cables.** Replace inner and outer together.
  * **Front:**
    * Generic bicycle side-pull calipers have been used successfully.
    * Hoover's notes warned that **normal bicycle brake blocks must not be used on the nylon rim**. Use blocks suitable for plastic or composite rims.
    * Set the block clearance to 1.5–3 mm, and make sure the blocks don't touch the tyre.
  * **Rear:** inspect the shoes and the backplate. Reproduction rear-brake bearing brackets are available. Front and rear disc-brake conversions are popular modifications.

==== 4. Electrics ====
  * **The control box:**
    * Check **D1, the commutation diode**. It's often blown, usually from the C5 being pushed backwards.
    * Check **FS1 (5 A)** and **FS2 (1 A)**.
    * Check the relay contacts, and look for **corroded connectors**.
  * **The pod:**
    * Clean the **red pod connector** pins with contact cleaner.
    * Re-flow any **cracked solder joints**, especially on the LEDs.
    * Handle the ULA with anti-static precautions. If the ULA is dead, see [[guides:modifications|Modifications]] for Arduino replacement modules.
  * **Lights:** fit **LED bulbs** in place of the 5 W W10/5 bulbs. They save power and stop the front housing overheating. LEDs are polarity-sensitive, and the flasher must be an LED type.
  * **Battery:**
    * A modern sealed or leisure lead-acid battery of a suitable size works.
    * A **LiFePO4** pack (for example a 12 V 20 Ah golf-trolley battery, about 2.5 kg) dramatically improves acceleration and hill climbing because of the weight saving. Use a charger matched to the chemistry; the original Sinclair charger is lead-acid only.
    * With non-original batteries, fit **quick-release terminals** and keep an **emergency cut-out** in the circuit, since a welded relay can make the motor run away.

==== 5. Wheels and tyres ====
  * **Tyre sizes:**
    * Front: **12½ × 2¼ (ISO 57-203)**. Kenda and others make this size.
    * Rear: **16 × 2 (ISO 54-305)**. Schwalbe Big Apple and City Jet, and Raleigh Chopper-style tyres, have been used.
  * Original pressures are **30 psi front / 35 psi rear**.
  * The plastic wheels need no maintenance, but check the front rim for heat distortion.

==== 6. Body ====
  * Clean the polypropylene with a strong cleaner and a soft brush. Light sanding removes scuffs. **Don't paint it unless you know what you're doing**, because polypropylene needs special primers.
  * Replace the yellow side stripes with **high-intensity reflective tape** of a similar pattern; it's about 0.5 cm taller than the original. The stripe also hides the body weld line.
  * **Decals:**
    * "C5" on the headlamp surround;
    * "sinclair" on the boot;
    * the stripes.

Reproductions are available.
  * **Small plastic parts:** many are available as 3D-printable reproductions. See [[guides:modifications|Modifications]].

==== 7. Test ====
Follow the handbook's commissioning sequence: rolling check, battery installation, then operational check with the rear wheel off the ground. Then do Hoover's 5-minute functional test, including a road test. See [[guides:driving_and_maintenance|Driving and Maintenance]].

===== Costs =====
The c5owners.com budget restoration of about 2014 bought a C5 for **£200** and spent about **£76** on parts. The parts were rust treatment, paint, brakes and cables, diode D1, contact cleaner, a relay, a key switch, LED bulbs, tyres, tubes and stripes.

===== Sources =====
  * c5owners.com: "What to Look for When Buying a Sinclair C5"; "Restoring a Sinclair C5 on a Budget"; forum threads on LiFePO4 batteries, tyres and gearbox inserts.
  * Sinclair C5 Owner's Handbook (1985); Hoover Service Engineer Training Notes (1984); //The Unofficial Sinclair C5 Service Manual//.