Packard Forum Index » V-8 (1955-56)

Hello All!
Anyone have any tips for troubleshooting the overdrive? I have the cable in the normal position (In) and I dont seem to get overdrive operation. While driving on highway (50+) I pushed in clutch, pulled cable out, and heard some gear noise. Went back to cable pushed in.
I read owners manual on how it engages when over 22mph and you ease off gas. Is there any electrical switches involved? Vacuum switches?
Many thanks in advance

This is a VERY quick overview of the electrical setup on the R11 OD unit. Over about 22 mph the governor (on the tranny) goes to ground which activates a relay (on the fire wall) that energizes the OD solenoid (again on the tranny).

And to carry the description farther, assuming the electrical is good and the solenoid has been powered, it moves slightly and is ready to engage but has not actually moved far enough to lock into OD.

Letting your foot off the gas momentarily slows the engine and some gears in OD. Because the car is still coasting at speed, other gears in OD connected to wheels will still be going slightly faster. The speed differences causes a slight reverse motion of a component. That reverse movement repositions a locking ring which had prevented the solenoid from engaging. With the ring moved, if the solenoid is powered it will fully engage and lock the car into OD.

The movement of the locking ring depends on friction with the part that moves in a reverse direction and if either part is worn or ring damaged the movement will not happen. Even if the electrical is OK, the solenoid cannot fully engage and lock into OD if the path is still blocked by the ring. That locking or balk ring mechanism would be the place to check next if the electrical activating the relay is good and solenoid tests in good condition.

EDIT: Am assuming from your avatar you are inquiring about a V8 OD. If so the components have all been described. If on an earlier model there is also an electrical lockout switch which is operated by the cable that has to be closed to allow the governor to bring in the relay.

Great information! I will start checking the relay circuits. Has anyone set up a indicator light to indicate OD active?

R9s had an indicator light but it requires a set of contacts that open when the solenoid has traveled the full distance and engaged the OD mechanism to extinguish the light. Without those contacts the light would stay on the entire time the solenoid is powered whether OD is ready or already engaged.

R9 solenoid has contacts operated when the plunger reaches almost full extension but the R11 does not. The earlier R11 solenoids are very similar internally so it might be conceivable to maybe come up with something like a microswitch mounted where the R9 contacts used to be and operated by the plunger. Not sure on the V8 solenoids if that unused space still holds. You would still have to bring the terminal out of solenoid and then do the light part.

yes it is related to the 55 Clipper Custom Constellation with the 3 on tree and OD.

First things first: On the front of the main relay--which is the small silver box on the firewall near the distributor--is a 20 amp fuse. Check that is good and has continuity.

You will find that when the overdrive is working you will have no need of any sort of indicator light.

Excellent! Will check that today.Thanks!