Talk Morgan Forums Morgan Sports Cars Morgan Plus Four, Supersport & Plus Six (CX & CXV Generation Vehicles) Which make is the manual CX gearbox?

Does anybody knows what the manufacturer is of the manual gearboxes of the present PlusFours?

Ruut as far as I know the manual gearboxes for BMW B48 engines come from Getrag, now Magna Powertrain.

Thanks Clemens! BertR wants to know!🤷‍♂️😉

Thanks for the above information Clemens and Ruut.
The background to my question is that I just started some back ground work, to prepare for some articles on the CX-type Morgans. All this for the Dutch Morganclub magazine (FataMorgana), of which Ruut is the editor in chief. I just finished my third article on the Roadster. Now, with the PlusSix being discontinued, I thought that I could start working on another discontinued Morgan model: the PlusSix. Ruut however, pushes me to included some PlusFour info in my writings them too. Ofcourse this has nothing to do with Ruur owning a PlusFour himself… For me doing the research is most fun thing to do, I did not deny his request (yet).
So when exploring, I could not readily Identify which manual gearbox MMC employs for the PlusFour. However, the above feedback from Clemens (“it’s a Germer box”) confirms what I have found myself in the meantime, by using ChatGPT to identify the gearboxe with exactly the same gear ratio’s as in the PlusFour.
My current working hypothesis is that MMC employs the GS6-17BG transmission. This is a manual gearbox (as designated by the S), it has six forward gears (as the 6 indicates). The 17 indicates that this is, what BMW calls an I-350 turbo gearbox. The B in the name tells us that it is designed to work in combination with a gasoline engine. The last G indicated that Getrag is the manufacturer.
The GS6-17BG transmission is specifically designed for turbo engines. I found that the BMW 328i (F30) uses the same gearbox. Note does not use the B48 engine, rather it has the N20B20. This gearbox is designed to work with a maximum torque of 350 Nm. Hence, that the engine in the manual PlusFour is tuned down to that level whilst the B48 engine delivers 50 Nm more in combination with the automatic gearbox.

Good research and thanks for the useful info.

Hi Bert,
that's very interesting what you found out about the manual transmission. I am also trying to find out which manufacturer supplies engine components for the B48 and their part numbers
Maybe we can summarize this in a “components” thread.

Of course I would have thought that the actual total torque loading on a gearbox would depend on the weight it is trying to shift down (or up) the road?

Further to the above.

In my "research" for the CX-writings for the NL-Morgan-Magazine I stumbled on an interesting finding on the automatic gearboxes for the Plus Four en Plus Six.
Both use the same ZF automatic transmission: ZF GA8HP51Z - and have the same gear ratios. On the ZF 8Hp there is an extensive Wiki page https://en.wikipedia.org/wiki/ZF_8HP_transmission

Note that the transmission housing will differ to couple the ZF 8HP to the Plus Four (B48) and Plus Six (B58) engines.

The "51" in ZF GA8HP51Z, denotes that it is rated for engines up to 500 Nm.
For Plus Six owners this limits their tuning possibilities, as the B58 engine is rated at 500 Nm. Increasing it further may cause automatic transmission problems later...
I found that Litchfield offers a tune up: https://www.litchfieldmotors.com/morgan/morgan-plus-6/
I wonder what modification they recommend for the ZF box...

Good point Bert. I'll leave mine well alone!