Renault JB / JC / PK / UN-1
5-speed manual · transverse · 1980–present
Also known as: m5p, m5d, m3p, un-1, un1, pk5, pk6, jb1, jc5, jh3, renault 5-speed manual
Renault's transverse manual gearboxes — the JB, JC, PK and UN-1 families, and the M-coded variants of them.
⚑ Renault names one gearbox several ways — a family code, a variant code and a fitment code — so M5P and JB1 can be the same unit described from different catalogues. Establishing which system a code belongs to comes before any parts search, and it is the commonest reason a Renault gearbox order goes wrong.
These are light cable-shifted units and the linkage is the first suspect in almost every complaint: worn cables and a perished gearbox mount produce a change that feels like synchroniser wear and is not.
The UN-1 is the odd one — a longitudinal transaxle used in mid-engined and rear-engined cars, sharing its name with the transverse boxes and almost nothing else.
Fifth-gear and reverse selection problems are the pattern that recurs, and on the higher-mileage units they are usually the selector mechanism rather than the gears.
Cars fitted with this gearbox
3 generations. Only where a source names the model and the generation together — a gearbox is documented as a product far more often than as a fitment, so this list is deliberately shorter than the truth.
Lotus
Renault
Volvo
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