The driveshaft of the e30 needs to be shortened by several centimeters because the transmission will be positioned slightly further back in the 335i than in the factory e30 setup. The exact size of the driveshaft will vary from car to car, as the engine position will be slightly different in each case.  Three possibilities are available: Fig: The perfect result.  Here a shortened e30 M3 driveshaft is shown.  This particular unit was manufactured by WANA GmbH of Berlin

Variant 1:  Shortened e30 Driveshaft (not recommended)

The e30 driveshaft can be shortened and used for the 335i conversion. The flange at the front of the driveshaft is much smaller than that of its M30 counterpart.  In order to use the M20 driveshaft the flange must be changed at the transmission.  In this setup the M20 universal joint will be left unaltered.  The M20 driveshaft is often broken at the universal joint in the standard M20, so the use of this joint in an application that will be applying more torque is unfavorable.  It is likely that frequent changes of the universal joint would be required in this application. Fig. (right): M30 Transmission with the smaller e30 flange

Variant 2: M30 Flange Welded to an e30 Driveshaft
In order to account for the significantly increased torque of the M30 it makes sense to use the universal joint from that driveshaft. The flange from this driveshaft must also be welded to the front of the e30 driveshaft.  This is not a significant problem, as the driveshaft must be shortened anyway.  If such a flange is available it is highly recommended that it be used. (Exchanging the flange at the transmission now becomes unnecessary). Note: Not all machine shops can do this modification, as the diameters must be made to match exactly.  
 

Fig.: Size Comparison of the M30 and M20 flex disks

Variant 3: The e30 M3 Driveshaft 
The best option is to use the e30 M3 driveshaft.  This driveshaft fits in Engine Position I without any modifications. In Engine Position II the driveshaft must be shortened by around 4-5 cm. If using the motor mount brackets from www.e30.de to fix the engine in Engine Position III the driveshaft must be shortened by around 7 cm, in all it should measure about 193 cm. 

Addresses:
All the work described above should be done by a certified machine shop. An improperly balanced driveshaft will cause significant vibrations within the drive train and could severely damage the vehicle. To avoid such damage all work must be done by a professional.  A few German companies capable of doing such work are listed below.  American, or companies located in other countries, must be located on an individual basis.

Möller&Och GmbH **
Sorststr.11
30165 Hannover
0511 / 352 43 28/29

Heinrich WANA GmbH **
Sophie-Charlotten Straße 40
14059 Berlin-Charlottenburg
030 / 32 69 32 - 0
(Example: e30 M3 Driveshaft shortened by 7cm and with a larger flex disk: $218.87)

HB-Fahrzeugtechnik **
Juliusstraße 5
12051 Berlin
030 / 684 50 34
 

**Available in German Only

Questions, Comments?