Where to Find Replacement Parts
Renault themselves still support the Renault 4 very well. Many Renault dealers are unhelpful, but we've found a tame one: Lifestyle Renault (formerly Whitehouse Renault). George Thomson in the parts department can be reached on 01892 524655. He's incredibly helpful, can accept credit cards and post the parts!
Lifestyle Renault (Tumbridge Wells UK) can post parts. Parts are sometimes original quality and are sold at Renault prices.
Service Parts in the UK
Your local Motor Factors should still be able to supply most mechanical bits (brakes, balljoints, exhaust etc), but often the Renault 4 isn't listed in their new catalogues. Look up the part numbers using these links and ask the motor factor to order them.
Mechanical parts apart from engine internals
Quinton Hazell make a lot of aftermarket parts available through motor factors.
Also well worth checking on eBay for old stock that people are selling off.
Most Other Parts (from Europe)
Renault 4s have a greater following in France and Germany. Many parts are being re-manufacturered, and some parts are from the original suppliers.
Body panels, seals, engine parts, trim:
Der Franzose (Germany) Click union jack flag at top for English version). Many body and trim parts. Includes photos of parts. Traffic lights on the site show when they are in stock.
Melun Retro Passion (France) Various panels and other parts.
reno4er (Germany) Good range of parts, often new original bits but not many photos.
Warny body panels (Belgium) Only supply body panels - not all of them will be in stock, but they make new ones every now and again. Trade only - email them for your nearest dealer.
Windclassics (Netherlands) A limited range of new and used parts.
AutoNordic (Denmark) Various panels and lighting parts
Klokkerholm (Denmark) Body and chassis parts. Trade only, but will presumably direct you to a dealer.
Gordini Engine Parts
Not really Renault 4 parts, but these engines are surprisingly easy to fit by accident:
Failing all that try asking on the forum. Others might be able to point you in the right direction or help with used parts.