wolfe10 wrote:
As far as I know, the primary issue will be whether the transmission is lubricated adequately from just the OUTPUT shaft or whether it needs the INPUT shaft turning to properly lubricate the transmission.
A good BMW tech who overhauls the manual transmissions should be able to give you guidance.
Exactly! Many manual shift transmissions are splash lubricated by the rotating cluster gear. That cluster gear only rotates when the INPUT shaft is turning. When being towed, only the OUTPUT shaft is turning. No splash lubrication is taking place. Eventually, the output shaft bearings will dry out and begin to self destruct. It may take a while, but when it happens the repair cost will not be covered by ANY warranty!
IF that is true of the transmission in your vehicle, there are ways to get around it:
1. Stop every 100 to 200 miles, run the vehicle in Neutral for 5 minutes to distribute the lubricant.
2. Tow the vehicle with the engine running, transmission in Neutral. This will keep the lube stirred up and the bearings coated.
3. Replace the filler plug with a "street ell" pipe fitting, with the elbow pointed up. Fill the tranny with lube until it runs out of the elbow, then install the plug in it. This will flood the upper half of the gear train with lube. It will also cause some of the excess lube to puke out of the vent plug, so you will have to check the level often, and your vehicle will be "marking its territory" with oil spots.
Of course, you COULD just believe the Owners Manual when it says "Recreational Towing: ONLY on a dolly or trailer! Do NOT tow four down!"
Good luck.
CM1, USN (RET)
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