I am planning to connect the '69 spiral-wound interlock cable that runs from the reverse shifter linkage to the firewall and connects to the steering column. It has never been connected since we bought the car years ago. Don't know why? Are there any tricks or pointers to be aware of like shift **** inside the car has to be in the Reverse Position prior to connecting the spiral-wound cable to the steering column? Be sure the rotating bowl on the steering column is all the way to the left? Be sure the linkage from the Backup Light Switch is connected to the reverse linkage on the transmission prior to pulling the spiral-wound cable up and hooking it to the steering column near the firewall?

Does not seem to affect anything from a driving, starting, operating standpoint so I'm not sure why it was disconnected except that perhaps other owners liked or needed to shift the transmission while the car was off and the keys were out of the ignition? It is something that I do from time-to-time if I am sitting in the car and the keys are not in the ignition....just an old habit to run through the gears with the car off and then make sure the transmission is in the Neutral Position before exiting the car while it is sitting in our garage. I always leave the car in gear when I am parked outside, at cruise-ins, car shows, etc.

 

Either someone disconnected it to remove something and never put it back or it didn't work correctly so they bypassed it.
Check that the cable is free to actually move and not rusted in-place or kinked somewhere, they are fairly stiff but should still move easily
Here's the Jim Shea paper on the system and has the operation and adjustment bits on it


M

 

Hello Mooser,
Wow, really appreciate passing along the technical information on the operation and adjustment of the Steering Column to Transmission Interlock System. Really helpful!!! Someone has worked on the transmission / 4-speed shifter linkage in the past. The green/pink wire that runs from the backup switch to the clip on the firewall was missing the rubber-coated J-clip to secure the wire at the upper left bolt on the transmission side plate. The heat deflector shield that is positioned under the rubber-coated backup switch is missing. The backup light linkage was not connected at the reverse shift linkage. I put all of these back like they should be.

The spiral-wound cable moves okay but I would not call it "freely" or "moves easily". It does move but requires a bit of elbow grease to push/pull so I have started to put some PB Blaster garage lube on the wire cable at the firewall on the high side of the cable with the hope that gravity will pull the lube down through the reinforced spiral-wound sleeve...eventually, getting to the point where the cable exits and connects to the reverse shifter linkage. Perhaps the PB Blaster lube that will help free the cable up so it moves inside the spiral-wound sleeve easier.

Thanks again for the help,

Kevin

 

Easily was probably not the right word to use. It's a thick stiff cable so maybe just plain move without binding would be a better description
M

 

Hey M,

10-4 on description easily. Yep, pretty stiff wire cable. It does move manually with a little elbow grease. I guess that's good news. It's not frozen in place.

Per the Jim Shea paper, I have the 4-speed shifted into Reverse position. The loop end of the wire cable at the firewall is almost high enough to slip onto the steering column - just shy of slipping on the steering column pin by perhaps a 1/16" or so. Might have to adjust it a little per the instructions or maybe just give the cable a bit of a pull to see if the wire cable will move enough to slip on without forcing it too much.

Did notice a slight kink at the end of the wire cable just before the loop where it attaches to the reverse shift linkage. Car has never really shifted clean/crisp/positive like other cars I've had with M-21 close-ratio manual transmissions. Maybe one of the reasons the interlocking steering column was disconnected?

Thanks again for your help.

Kevin

 

Update:

Connected the steering column to tranny interlocking cable. As mentioned to Mooser, the cable was a tad short by about 1/16" to maybe 1/8" in order to slip easily onto the steering column with no tension on the wire cable, was able to pull the cable a bit more and slip the eyelet end of the cable over the steering column. Not the result I was hoping for:
1. once connected, the 4-speed shifter would not move easily out of reverse without forcing it....so I left it alone and did not force it out of reverse
2. I put the key in the ignition switch, rotated the steering column about an inch counter-clockwise to release the locking steering wheel and move the key into the accessory position but I was not able to get the key back out of the ignition, and not able to lock the steering column again

Looks like I'll need to spend more time trying to make some adjustments to the steering column (per Jim Shea paper attachment) to eliminate all tension on the cable so that the steering column coupling remains in a relaxed state and the key locks and unlocks the ignition switch easily. Hopefully, that will fully release the shifter and allow me to easily move the shifter out of reverse.

To be continued....

 

M

 

Mine on my 69 gets finicky every now and then and I have to pull up on the lever by the steering column under the hood to get it into reverse or get the key out. Try it and see if it helps. I think the cable has lost some of its flexibility and it slightly binds. Ike

 

In addition to Jim Shea's paper, you might look at the 1970 Chassis Service Manual. GM called the interlock system the "backdrive" (?) system, why, I don't know. As I remember, they give a definite procedure for installing the cable.
It's a very problematic system, and the slightest drag on the cable will cause the connecting-end to kink, and the "system" will be a problem in some way. I'm restoring my '69, had Mike Denapole restore my steering column, and I found an NOS cable. When I install the cable, I'm going to follow the exact procedure from GM, and use Jim Shea's paper as an enhancement.

Bottom line is that this system was a GM failure. Cables were meant to pull, not push, as the backdrive system does.

 

The fine tuning for the cable is done through the column mounting plate on the firewall. The openings are slotted so you can adjust to get the eyelet perfectly placed when in reverse(or park).

 

Update 11-6-2021
I did notice that the adjusting plate on the interior of the car was adjusted as far as it would go and there is still tension on the cable, enough tension for the ignition key not to unlock and for me to remove the key from the ignition switch. One thing I did notice while working on the steering column lever inside the engine bay is that the lever was very hard to move manually even when the cable was not connected so I spent a few hours cleaning, PB Blaster penetrating oil, bunch of Q-tips, old tooth brush, PB Blaster garage door lube and 3 in 1 oil to free up the steering column lever so it would move more easily. It worked and the steering lever moves much easier this morning.

I did check the interior adjustment plate inside the car under the steering column per the Jim Shea paper that Mooser passed along and the stud plate was already adjusted as far as it will go. So, I removed the stud plate from the firewall side and I am going to try and lengthen the hole on the inboard side of the plate to see if I can lift the cable another 1/16" to 1/8" to see of that allows me to easily slip the loop of the wire cable over the pin on the lever.

Have not given up yet and gone with general ike's method of raise the hood and just pull up on the steering column lever manually to get the key out of the ignition.

Certainly agree on the bad design conclusion. Cable works great for pulling....not so great for pushing!

 

Almost like it should have had a spring to help “push” the cable back up to the correct position. Ike

 

Hello Ike,

There is a spring, photo attached. My spring does absolutely nothing in terms of return tension to pull the steering column lever back up to a neutral position. Good point you make though. Up until you mentioned it, I did not consider that perhaps the spring in the photo is broken. After considerable cleaning, the steering column lever moves reasonably easy compared to where I began. It was not frozen but it certainly took some effort to move the lever prior to cleaning.

Think my project may have taken a new turn. With the wire cable loop off of the end of the lever pin, can anyone verify for me that "yes" this is a return spring for the lever and "yes" with a reasonably free moving lever the spring will pull the lever all the way back to a neutral position which allows the key to be removed from the ignition switch.


If this spring is suppose to pull the lever all the way back up to neutral position (about 12 O'Clock), then I think my spring is broken?

 

Or after 50 plus years it has lost some of its tension strength. Ike

 

No, the spring does not bring the lever up to the high position. If it did, we wouldn't have to secure it in the up position to drive the car without the interlock cable installed to remove the key. I think it's just a spring to keep tension against the lever.

 

Hey Green 454,

That is GREAT to know. I was not looking forward to taking the clip, collar, spring, and lever apart to replace the spring because that looks like a PIA job.

Hoping today to paint the firewall-side stud plate, clean up the interior adjustment nuts, and put this back together later today. Fingers crossed.

Continued to clean and lube the collar, spring, and lever yesterday and it is moving even better now that I'm getting all the crud out. I'm a little optimistic now that once reconnected, with the lever moving more freely, that the wire cable will be able to push the lever all the up to neutral and I can get the key in/out of the ignition switch care-free without having to resort to opening the hood and pulling on the lever... or leaving it disconnected.

 

When you look at the transmission end of the cable, make sure you have the hold down bracket shown on the last photo.
From Alan71's photo collection.

 

Hi 71 Green 454,

Confirmed. Both of the upper transmission brackets for the spiral wound interlocking cable are in place. Wow, miss Alan's posts. What an incredible resource of knowledge and experience. And, holly cow is that car immaculate!

Thank you for the continued ideas and suggestions.

 

Might be a good idea to invest ~$40 for a new interlock cable at this point.
As others have mentioned, "pushing" the cable is half of this system's function, and any internal binding will affect its performance.
It IS a finicky system, and needs fine-tuning of the adjustment bracket, but a new cable will at least eliminate sluggish movement internally.

 

Certainly worth considering especially if I cannot get the one on the car working effectively. Appreciate the suggestion.