Used ZF 8HP gearbox: 8HP45, 8HP50, 8HP75 — which one for your BMW?
Since 2009, the ZF 8HP has been the automatic gearbox at BMW. It is fitted to everything from the 1 Series to the M5 and from the X1 to the X7, in petrol, diesel and plug-in hybrid versions. Being everywhere is good news when you are looking for a used part — there is plenty of supply — but it also creates a trap: behind the same “8HP” name there are three case sizes and a dozen or so variants that are not interchangeable.
Three sizes, one maximum torque figure
The number after “8HP” is not a generation: it is the maximum permissible torque, in decanewton-metres. It determines the physical size of the gearbox.
8HP45 — up to about 450 Nm. The “medium” case and by far the most common: 3 Series, four-cylinder 5 Series, X1, X3, X4 in 18d, 20d, 20i and 30i.
8HP50 — the evolution of the 45, introduced around 2014 on the same ranges. Same external dimensions, different electronics and ratios.
8HP70 and 8HP75 — the large case, up to 700-750 Nm: six-cylinder diesels (B57, N57), V8s, M Performance and M5.
8HP76 and 8HP80 — the reinforced versions for the M3, M4, X5 M and X6 M.
An 8HP45 will never replace an 8HP75: the casing, bell housing and shafts have different dimensions. Nor will an 8HP50 replace an 8HP45, despite similar dimensions — the control unit and gear ratios are different.
The X and Z suffixes: don't ignore them
This is where most buying mistakes happen. The letters after the number describe the architecture:
X — gearbox designed for xDrive all-wheel drive, with the mounting for the transfer case. An 8HP45X will not fit a rear-wheel-drive car, and the reverse is just as true.
Z — denotes the manufacturer's generation and electronic interface variant. An identical casing can carry incompatible software.
GA8HP... — the “GA” prefix is simply BMW's naming for the same ZF gearbox. GA8HP45Z and 8HP45Z are the same product.
In other words: “8HP45” on its own is not a usable reference. You need the full string, suffix included — which is exactly what we show on every one of our product pages.
Reading the ZF plate: the ten-second method
On the side of the casing, a metal label carries three pieces of information that are enough to identify any 8HP:
the BMW part number with seven digits (for example 8692976 or 8638291) — the most reliable reference, the one any parts counter will understand straight away;
the ZF parts list with seven digits in three groups (1102 026, 1070 401 606) — it describes the exact internal configuration;
the model, written out in full: GA8HP-45XZ, GA8HP75Z…
Some gearboxes also carry a six-character code such as 250WFW or 233ZCB: this is the software version identifier, useful for diagnostics but not enough on its own to order.
Our rule is simple: we never list a gearbox unless we have read its plate on the photo. A listing title can be wrong; an engraved label cannot.
What to check before ordering
Note the seven-digit part number on your gearbox, not from a registration-number database: BMW changed references during production.
Check whether the transfer case output (xDrive) is present or not — you can see it at a glance on the photos.
Plan an oil change and replacement of the filter built into the oil pan when fitting: the ZF 8HP is reliable, but it does not like tired oil.
After fitting, the adaptive values must be reset so the gearbox relearns its shift points.
If you are hesitating between two references, send us a photo of your plate: we will reply with the compatible gearbox or gearboxes actually in stock.
🔧 Need a ZF 8HP gearbox for your BMW?
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👉 See the BMW gearboxes in stock — or write to us at contact@allomoteur.com, reply within 24 business hours.
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