Community Forums

DonKarstedt · 04-20-2015, 11:30 AM

I've seen many comments around the old Internet which discourage people from flat towing a BMW Z4 (manual transmission.) But no one will say why or why not.

So why not?

(and please don't say "because it's not recommended")

--DonK

jdoc · 04-20-2015, 11:46 AM

DonK, Have you read the owner's manual. There is usually an explanation in there or you can contact BMW.

Jerry

DonKarstedt · 04-20-2015, 02:32 PM

Manufacturers are so crazy scared of liability that they won't recommend that you do ANYTHING with their products except keep them under glass and view them from a distance (and only clean with a damp cloth)

I'm just thinking that SOMEBODY in this forum has either done it or tried to do it, and i was just wondering what their experience was.

--DonK

Selah · 04-20-2015, 03:56 PM

Not specific to BMW. It more about how the transmission get lubrication. In some manual transmissions the oil gets splashed around by the cluster gear directly attached to the drive shaft. These have no problem getting proper lubrication.
Some manual transmissions require a pump to ensure oil reaches everywhere needed. If the engine isn't running the pump isn't pumping and the transmission can seize.
Not all manual transmissions are designed the same way. Some recommendations not tow tow may be because the manufacturer doesn't want to be bothered, some recommendations not to tow are because you'll smoke the tranny.
Remco might have a lube pump for your car.

DonKarstedt · 04-21-2015, 08:35 AM

Thanks. That does help explain some of the "why". I guess I always just assumed that if a manual transmission was in neutral, the the transmission was effectively disconnected.

--DonK

Roger G · 04-21-2015, 07:20 PM

I sometimes tow the wife's Z3 on a tow dolly. I talked to the service manager at my dealer and was told that the five speed was ok to tow and would lube but the six speed would not lube and required a disconnect or needed to be on a trailer. I have had no issues with the five speed but can't venture a guess about you six speed.

DonKarstedt · 04-22-2015, 08:20 AM

You're making me think there is some hope, since I have a 5 speed.

I still haven't found a definitive answer on this after checking several other sources. BMW service doesn't seem to know, and the owners manual doesn't address the issue with any useful information.

I guess I'll just have to search out some mechanics that actually know the drivetrain.

--DonK

Dave Fernandez · 04-22-2015, 09:02 PM

The reason you can not tow a vehicle 4 down is the transmission output shaft and bearings to not receive lubrication when they are being turned by the drive shaft or axel (front wheel drive). The bearing is lubricated by the transmission when the engine is running and turning the transmission from the input shaft.

Many automotive manufacturers produce transmissions that are lubricated when the vehicle is towed. This also applies to 4 wheel drive vehicles transfer cases. Something needs to lube the output shaft and bearing when being towed.

BobaLong · 05-16-2015, 09:25 PM

Roger,
I'd like to know more about your experience towing the z3. I own one and have been thinking about how to safely tow it. Seems you have already figured it out. Any pictures you would care to share? Thx.
Bob

DonKarstedt · 05-16-2015, 11:54 PM

Thanks Dave. Nice answer.

--Don

Speedjester · 05-17-2015, 05:14 AM

Couldn't you just pull the driveshaft? I know it's extra work but I would assume easy enough...

Roger G · 05-17-2015, 08:24 AM

Hi BobaLong, I don't have any pics but I towed it on a Stehl Tow dolly. I haven't towed it in two years since I bought a Jeep Wrangler and set it up to tow 4 down. It takes less than five minutes to hook the jeep and about 15 to hook up the BMW plus I don't have to store the dolly when I get to a park. Before the jeep, it was our only toad other than a golf cart on a trailer. But I will say this, even though the BMW service guy said it was OK to tow, every time I stopped I would go back and crank the car and let it idle while I was fueling the MH , eating, or whatever. It might not have been necessary to lube the transmission but it didn't hurt anything either.