Generator to Alternator Swap

by Jim Thompson and images thanks to Dale Mueller

Assuming a 68-71 bus with a 1600cc engine going from a generator to the typical BOSCH AL82X Alternator that's been coming with the alternator kits for the past several years:


Your regulator is mounted on the right-side firewall and yes, there's several wires going to and from your old generator, but there's really only two on the regulator that are important for correct hookup to the alternator.

Terminal B+ on the old Voltage Regulator - that's the heavy 10 gauge RED wire coming usually directly from the Battery. Usually has a Push-on Female terminal that is generally useless with Alternators, as they have a stud protruding on the top right side (as the Alt is mounted in the engine) that acts as the B+ terminal. So, change the Push-on to a Ring terminal on this wire and mount it on that stud. (Note: if you have more than one wire going to B+ on the old Regulator, put them ALL on this stud). Use a little vaseline to prevent corrosion on the connections as well.

Terminal 61 on the old Voltage Regulator - usually a small BLUE wire, this is for your Dash Generator Warning Light. On top of the Alternator is a small Male Push-on terminal the SAME size as the Female terminal of your harness. Might even have the number 61 right next to the terminal, I can't remember. Connect that wire to that male terminal. The rest of the wires and the regulator can now be removed and properly recycled or disposed of.

Note: Some Alternators, Motorola in particular had an additiona real teeny-weeny Male Push-on terminal. Don't hook anything up to this terminal (this was for the diagnosis harness on the 75-79 Beetles/Convertibles). Motorola Alternators haven't been available new for quite some time, so the chances of you getting one with the kit are very slim. Motorola's can be identified by the small white plastic Voltage Regulator/Rectifier Assembly mounted directly on the top of the Alternator. (Ha! - try finding that regulator nowadays, Motorola hasn't made these in almost 9 years - I think I still have one in my stash somewhere's)

If there is a grounding screw on the alternator case (some do), run a wire from that to a good ground. If possible, stay within the color code and use BROWN, 16 gauge wire's fine.

Note to 69-71 Bus owners originally equipped with the 38amp GR17X Generator - This generator uses the infamous and very expensive cast-iron backed pulley which is NOT useable with the Alternator Conversion. This is because this particular Generator is a little longer than it's 30amp GR15X cousin and required this bastard pulley to "step" the belt properly back in line with the crankshaft pulley. If you try to use this pulley on the Alternator, you'll pay hell very shortly because the belt won't stay on, the pulley assembly will make a gawd-awful noise and possibly come apart, damaging the Alternator Shaft and Housing and that can ruin just about anyone's day. Hopefully a new pulley was provided with your kit (most are not), so if this is the case, hop on down to your FLAPS and ask for a 12 Volt Beetle Generator Pulley. It's stamped steel on the inner and outer halves. Stay away from the chrome ones - chroming weakens the integrity of the metal and this piece needs all the strength it can get with the stresses it puts up with, not to mention that your cooling (i.e. fan) department depends heavily on it's strength. 67-68 Buses normally came with the GR15X Generator and you can use the pulley from that one however, because it is the same for all 12 Volt Beetles/Ghias as well.

Trivia note: The 12 volt Generator Pulley (stamped steel) was used on the large diameter 6 Volt Generator (105mm OD). The 6 Volt Pulley (differently stepped) was used on the smaller diameter (90mm) 6 Volt Generators (GR11X) back to 1959. An even smaller pulley was used on the 36hp varieties because the Crank Pulley was was larger than it's descendants'

Ron Van Ness writes:

Alternator conversion kits typically come with an alternator pedestal (the stock generator pedestal will not work with the alternator without modification), three fan mounting tin pieces (which are very thin compared to the original German pieces), an alternator clamp, and a 55 watt alternator with internal regulator (Kymco does sell a higher output alternator). Because of the poor quality of the tin and problems some have fitting the cheap alternator pedestal casting that are included with the typical aftermarket kit, it is often wiser to locate the better made German pieces from a '73-'74 bug which came stock with an alternator. Also, to clear the alternator, a '73-'74 alternator charged bug fuel pump is required (113 127 025G) as well as a shorter push rod (113 127 307A) to match the pump.

Dale Mueller provides the following:

1. Modifications to fuel system with Alternator

With the installation of an alternator, the fuel system has had to be modified as follows:

a - Pump inclined 15 degrees to the left
b - Pump push rod length: 100 mm (3.937 in.), previously: 108 mm (4.252 in.)

click on image:

c - Carburetor with modified accelerator pump linkage (the adjusting segment is towards the accelerator pump).

click on image:

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