Are some of the e28 and e34 gearboxes same?

[Turbo Ready]

Hi Guys,

I am a bit confused, no its not normal

I am doing an E34 M30 engine swap into my 87 325is E30.

I know that e28 gearbox fits the e34 m30 engines so I bought a e28 with a blown engine for the tranny and diff.

I was always told that the e28 535i had a weaker gearbox than the e34, so after hunting, I found an e34 5 speed which we pulled the gearbox from this morning.

When I looked at the gearbox from the e28 and that of the e34 they look IDENTICAL, same Zetrag numbers, style, shape and out put flange size etc.

I know my e30's fairly well, but the conflicting info on the 5 series stuff is making me bonkers

I think the Zetrag 260 was made for the later e28's and was implemented into
the e34 535i as well.

I have attached pics of both gearboxes, any confirmation will help.

Thanks so much.

[Turbo Ready]

Pics of the fins on both gearboxes.

[Kalevera]

The front halves of the transmission are essentially the same. Period cars use the Getrag 260. There's a variation in them -- 260/5 and 260/6. There is a 260/6 that crosses between early E32 735 5 speed cars and late E28 cars. I think the early E32 735/5 driveshaft is different from the later unit, though. That is the only transmission that I know of that crosses between the E23/E24/E28 generation and E32/E34. Not saying that the E28 trans can't be made to work....

You will also see similar number interchanges on parts of the G280 used in E24 M6/E28 M5/E34 M5 and parts of the G260.

The thing that makes using an E28/late E24 G260 difficult in an E34 is that the shift console style changed in mid production on those cars, so the back half of the transmission housing can be different. To interchange, you essentially have to rebuild the transmission, as everything is pressed into the rear half of the unit.

SOME earlier cars (and the E30 M3) use a Getrag 265, which is more robust than the 260 and has a detachable front bellhousing, but it's getting hard(er) to find a good used 265 that doesn't need some kind of work.

The E34 G260/6 does not retrofit onto E23/E24/E28 M30 cars without an upgrade to motronic 1.3, as the early cars used crank position sensors in the bellhousing, not on a tone wheel at the hub dampener.

[Dave M]

Yeah.......what he said, except way less informative.

Someone knows their transmissions

[Turbo Ready]

Hi Whit,

Thanks for the reply, seems as though I struck gold seeing that the 87 e28 parts car I bought had the 260/6 tranny in it. The car had really low mileage on it so the transmission is awesome. It also has the rod style shifting linkage instead of the sheet metal plate style.

The only disappointment I had with this car is finding out that the 3.25 diff in it was open instead of an LSD I was hoping for. I was told that I can swap the LSD clutch components into the open diff, just awaiting some more information.

Thanks again,

Raph.

[Kalevera]

Yes, you can transfer a limited slip into an open diff, but why do you want a 3.25 to begin with? The limited slip unit bolts to the ring gear, fairly easy to swap it over.

[Turbo Ready]

Whit I would like to use the 3.25 LSD because I am turbocharging the m30 B35 for my e30. The 3.73 LSD it came with will be too low for that motor even naturally aspirated, so I would like to go higher with the 3.25 LSD

The 3.25 LSD is a bolt on fit for the e30 with the output stub axles swapped along with the backing plate.

While in there I will change all the seals and try to get a higher lock up ratio, I heard that the dealers sells the thicker shims for this.

Thanks again for your help, I will venture into doing the open to LSD swap and will let you know my progress.


Regards,

Raph.

[grave77]

OK ... housing is a little different ... clutch system for E28 are discontinued, and really hard to find, also noise from the engine will be heard more than the newer E34. I have tried both on my car, the newer tranny is way quiet than the E28. fitting the new clutch system on the old E28 was really hard so better you get the E34 tranny

you will need to modify the shifter system for sure to fit inside your car.

[Turbo Ready]

OK ... housing is a little different ... clutch system for E28 are discontinued, and really hard to find, also noise from the engine will be heard more than the newer E34. I have tried both on my car, the newer tranny is way quiet than the E28. fitting the new clutch system on the old E28 was really hard so better you get the E34 tranny

you will need to modify the shifter system for sure to fit inside your car.

Hi Bud,

I do think I have the e34 tranny, it's the whole reason I started this thread I was looking for the 5 series Gurus like Whit to confirm this.

I got a tranny from an e28 but it's the same 260/6 which came with the e34 535i 5 speed.

I had both tranny's here to compare and the both are identical including the shifter system.

The e30 shifter system I think will work on the 260/6 for my application.

Thanks for the reply.

Regards,

Raph.

[Jeff N.]

Carefully check the output shaft on your E28 vs. your E34 tranny. I tried to swap in an E28 M30 gearbox to my E34 and it didn't work. The output shaft (centers to the driveshaft) was about 20mm longer (IIR) and had a different taper. Wouldn't bolt up to the stock E34 driveline.

Of course, this may all be irrelevant if you're putting into an E30.

Jeff