Packard Forum Index » V-8 (1955-56)

Hello all, I have a PB Twin Ultra and Low and D no longer actuate. I am seeking some advice before I put it on the hoist. It still selects H and the other positions fine and has always been a very positive selection to L and D previously. The 56 Patrician has done 52,000 miles and the PB on the Steering Column has not been changed, but I replaced the trans a few years ago and Land D were always strong and positive. I have checked the terminal block from the Push Button control at the back of the dash and the terminal block is secure. I assume that selecting L or D should step the motor to the L position on the side of the box. The box should shift from L to the H position when the governed speed is reached to change from D to H, even though the PB will still be in the D position. I am looking for my next step. Should I remove the side plate from the step motor and check voltage from the PB control. Has anyone had this issue and what should I do next please? Peter T

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A little more info is necessary: Is the problem that the shifter isn't shifting--that is that the shifter motor is not doing anything when you select those buttons--or is it that the transmission is not doing anything when you press those buttons?

You can check for the first problem by listening carefully as you press the buttons with the engine switched off but the ignition on. You can tell by the sound and by the brief slight dimming of the courtesy lights that the motor is working or not. If not working, I suggest that the contacts inside the shifter gearbox have failed if all other positions work normally.

If the motor is operating and you are just not getting the gears that you want then there are two very likely culprits. The first and easiest is that the setscrew that attaches the PB unit to the transmission is loose and you are a victim of lost motion. The second and much more likely cause is that the shift lever inside the trans that operates the valve body has come loose on its shaft and you are again a victim of lost motion. Then you must drop the pan and tighten that set screw. Afterwards, drill clean through the lever base and the shifter shaft and install a tight fitting roll pin, or spring pin.

My first boss after college taught me that one never secures an oscillating load with a set screw. He was right. John Delorean did not have the benefit that wisdom.

Here is a video showing what Ross is describing. Once the linkage gets loose enough, the trans can "skip" gears.

If this is the problem, then it is more likely, but no guarantee, that if you first shift into Reverse and test the gears in order, you can hit all the gears. RLDHNP

youtube.com/shorts/8VWbsWP6gmA

And if it does turn out to be electrical and the actuator is not moving when D or L is pushed, before going under to check fingers check the contacts on the back of the pushbuttons. A flat leaf contact on either side of a button is connected together when the button is depressed and a spring clip around the button stem touches the two of them simultaneously. The vertical leaf has a sharp bend and metal fatigue has been known to weaken so one cannot make contact or one completely breaks off. A faulty leaf contact will only disable that particular button.

Someone long ago devised a repair using miniature microswitches to replace a broken leaf. Riki did the mod on one of his switches a couple of years ago but used a piece of aluminum angle for the support rather than bending the recommended shim stock. While the aluminum is a bit thicker than the original design called for it worked out. He also made a change in the way the reverse lights and starting relay is activated. Some photos are in his blog.

I would post the original design paper which has some detailed instructions but as I recall it came from something PI published in the 70 or 80s so may still be copyrighted.

If they published an original PMCC drawing or document then they don't hold copyright to it. Just crop it to original PMCC material (without their notes or article) then it's OK to post.

Quote:

It's not PMCC. Hand drawn page with instructions and now defunct Radio Shack part #s for switches. In the linked blog photo of his bad PB assy you can see a partial view of a printout of the copy I emailed him under the switch.

Microswitches are no big deal as Amazon and ebay vendors sell virtually the same switch for a low price frequently packaged by the dozen. Shim stock might be a bit more difficult if finding a single sheet which is why Riki probably chose the aluminum angle. The also not very common to be locally stocked tiny screws and nuts to go thru the switch holes are also easily available mail order but are usually sold by the box.

After 40 or 50 years there is a chance the person who came up with the mod is no longer with us but PI used to be very protective and probably still are. It would be nice if there was a way Kev could add a copy to the electrical or how to section archives though. If Riki acknowledged the original work and documented the materials changes he needed to make to the those instructions that might work for posting too.

Thanks, do you happen to know the specific issue that that was featured in?

I'm curious, because I might have it.

Don't remember and it might not have been in the magazine but in one of their other pubs. Sent you a PM.

Post. #444

Has my diagram

Riki I think your posts there show very clearly how to do that install.