Chrysler A404 / A413 / A470 / 31TH

Chrysler's A-series transaxles — the three-speed automatics in the K-cars, the minivans and everything built on them.

⚑ It is a TorqueFlite turned sideways, and that is the useful route in: the rear-drive TorqueFlite is one of the most thoroughly documented automatics ever built, and much of its behaviour and its hydraulics carry across. The A413 is the common one, and the A670 is its heavier relative in the front-drive minivans.

They are entirely hydraulic and mechanically governed — no computer, nothing to read, and a road-speed governor rather than a sensor. Diagnosis is fluid condition, band adjustment and line pressure, in that order.

Band adjustment is a real service item and one most modern technicians have never performed. A slipping second gear on one of these is frequently an adjustment rather than a rebuild.

⚑ Chrysler renamed the whole family 31TH in the 1990s — three speeds, Transverse, Hydraulic — and the parts trade still sells A413, A470, A670 and 31TH as one unit. A Neon or a minivan quoting a 31TH is quoting this gearbox, which is worth knowing because the newer name looks like it belongs to the electronic Ultradrive family and does not.

⚑ The same A series numbers the manual transaxles too. The A523 and the heavy-duty A568 from these cars are five-speed manuals, on their own page here — so a number in this series settles nothing until somebody says which kind it is.

The A604 Ultradrive that replaced them is electronic and a completely different proposition — it has its own page here, and its reputation should not be read backwards onto these.