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Hi Guys, Hope I get my car back together this sumer for some high speed autobahn-storming and on my list of things to acquire is an OD Trans, but since my car has been converted to 12 Neg Ground, will I have to get a particular solenoid or relay for the trans?
For the relay I bet something can be found as an easy substitute, but the solenoid is attached to the side of the trans from what I see. Did the 55/56 cars come with the R11 OD Trans? If so, then I guess that makes things easier.

Car is currently a 3speed man without OD.

Dankesch?n!
Tobs

There is a question as to exactly which OD unit was used in 55-56 -- if R11 or maybe R12 and what are all the differences. One for sure is no lockout switch in 55-6. I can't say if solenoids are the same construction. Probably so, but am sure others can say for sure. One thing to watch for is solenoid travel length. Once you find the trans/OD unit to install you can tell. Others have made the conversion so surely not a big deal finding one.

One place you might check for a solenoid is 5th avenue garagefifthaveinternetgarage.com/ They have repro OD items for standard BW units which might be easier to chase down than a 55-6 item. Their solenoids are not inexpensive but then neither are Packard vendors. Making sure theirs has the correct travel length is the issue.

Also have repro relays but as you said, those can be substituted quite nicely with a Bosch 30 or 40 amp headlight type relay from the parts store. Just won't have the metal can and fuse looks if that matters.

Cool website, I wonder if the solid state generator cutout would work on our systems also? I only see 2 terminals and I know my voltge regulator has 3 terminals....

G'day all, My 1938 120 ( running a 327 and R6 OD) has been converted to 12V neg. I use a 1955/56 ballast resistor to drop the voltage on the "voltage sensitive' items such as OD solenoid, radio, instruments etc. I have not had any problems. I did not bother changing the 6V starter or solenoid and it still works fine. Petet Toet

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Interesting...so do you have for each one of those things a porcelain resister inline? Do you still have a Generator or a modern alternator?

More movement on the OD Front. Ross worked out a 12 Stude Solenoid for me (Dankesch?n!), and I am looking into what I actually need for the relay. Most Relays that I know (headlight etc) switch when the signal line gets 12V. Then the output gets bridged to the Battery terminal. The OD relays have 4 terminals, which confuses me.
1)To Batt 12ga
2)To Solenoid on OD 12ga
3)Ignition switch 16ga
4)Switch (kickdown and govenor in series) 16ga

How do the switches work? Do they give the relay a 12v signal to make it switch or do they complete a ground to make the relay turn on? Ignition switch gives 12V to the relay to 'arm it' but then does then what happens? Not certain which modern relay I can hook up here.
Thanks guys!

An ordinary 12v 30/40 amp relay such as this oneparts-express.com/pe/showdetl.cfm?Partnumber=330-073&utm_source=googleps would work. Would think any number of European parts stores should carry the Bosch or equivalent type. If you want one that looks original, reproductions are available from Fifth Avenue Garagefifthaveinternetgarage.com/parts/parts_counter_3.html but they are not inexpensive.

Kev drew a schematic using one of the same type Bosch relays for fog lights.packardinfo.com/xoops/html/modules/newbb ... ic.php?post_id=25761#forumpost25761 The overdrive would use it the same way.

In place of the lights would be the 12ga solenoid wire on 87. The fused 12ga battery source would still go to 30. The 16ga wire from ignition switch would go to 86 and the 16ga kickdown and governor wire would go to 85. 87a would not be used.

It works like the original relay except it doesn't have a fuse on the side so you do need to add an inline fuse. When ign switch is on, power is available to one side of relay coil at 86. When speed is at OD point, the governor closes and supplies ground thru the kickdown switch at 85 to bring in the relay. Relay connects battery to solenoid via 30 to 87 and OD is ready to engage when you let your foot off. When you want to drop out of OD, the kickdown switch interrupts the ground from governor and relay drops out, letting the solenoid drop out.

Have included a wiring diagram with the overdrive. As Howard mentioned, the switchgear on the overdrive provides a ground to operate the relay.

The solenoid measures 0.8 ohms in the pull in mode, so your relay needs to handle about 20 amps for a brief moment, then about 4 or 5 continuously.

Howard and Ross, thanks for the help! Now everything is clear with relays and wiring. I already bought a relay and a small harness at a place called 'Conrad' here in Munich. It is like Radio Shack, except 4 times the size, and the people there really know what the are talking about. The harness/connector has 18awg wire in it, so I will swap that out for some thicker wire, and also put an inline fuse holder between the terminal on the starter solenoid and the relay.