Need door lock advice for 1981 F150

[JohnnyD]

I have an 81 F150 two-door, 2WD, just turning 200K that is having problems with one door latching and I suspect the other is on the way out, too. I replaced both of the pins (with the plastic insert) that mount in the door jam several years ago and these look like there in good shape. The passenger door only latches if you slam the heck out of it, and then if you pull in and out it has slop in the mechanism. The new door rubber is all that keeps it from rattling. I suspect the lock mechanism itself is dead. The driver's side latches OK, but it also has slop in it when closed.

My question is if there is only one type of lock mechanism in 1981. I have the sliders and think that the pin-type locks do not have interchangeable lock mechanisms. When I look at, say, LMC Truck, they only show one. I don't want to shell out $160 to do both sides only to find that I have to send the part back because it doesn't work with the slider mechanism.

Advice? Perhaps a recommended source?

Thanks

[Gary Lewis]

The pin locks were phased in during '81, but the latching mechanism is interchangeable with one minor difference: if you put a pin style lock in it'll lock in the unlock position and vice versa.

To say it differently, if you put a slide-style lock in a pin style door lock will be with the button pulled up and unlock with be with it pushed down.  Similarly, a pin-style lock in a slide-style door will have it locked in the unlock position.

But otherwise the locks are identical and can be swapped.

[JohnnyD]

Thanks, Gary, for the prompt and informative reply.

[Gary Lewis]

Let us know what you do and how it goes, please.  That's how we learn.

[FuzzFace2]

JohnnyD wrote

I have an 81 F150 two-door, 2WD, just turning 200K that is having problems with one door latching and I suspect the other is on the way out, too. I replaced both of the pins (with the plastic insert) that mount in the door jam several years ago and these look like there in good shape. The passenger door only latches if you slam the heck out of it, and then if you pull in and out it has slop in the mechanism. The new door rubber is all that keeps it from rattling. I suspect the lock mechanism itself is dead. The driver's side latches OK, but it also has slop in it when closed.

My question is if there is only one type of lock mechanism in 1981. I have the sliders and think that the pin-type locks do not have interchangeable lock mechanisms. When I look at, say, LMC Truck, they only show one. I don't want to shell out $160 to do both sides only to find that I have to send the part back because it doesn't work with the slider mechanism.

Advice? Perhaps a recommended source?

Thanks

Am I reading this right?
You installed new door weather seals and now the doors don't close right?
If so this is normal till the seals "break in" and flatten out some.

What you are seeing with the latch is it has 2 locking positions and I bet with the new seals it is only catching the first catch. You can see this if you open the door and using something to push the latch to close it will click for the first catch (that I think you are getting now) and if you push it a little more it will get to the second catch.

Now make sure the latch will work right clean it and re-lube first.
Then you will need to adjust the post out just a little so both catches catch.
You may need to slam the doors till the seals flatten out and adjust the post in a little again so both catches catch. Keep adjusting the post inover time till the door fits right.

BTW my truck I had to slam the right door a few times when I installed new seals.
Been almost 2 years and I dont need to slam it as much now that the seals have flatten.
Dave ----

[JohnnyD]

Dave, thanks for this input. I think the door seals are well squished after a year. Also, when I first put the seals in, I couldn't get the doors to latch at all, so I adjusted the post until it latched. At that point, there was a 1/4" gap between the door edge and the cab. Now they'll close without the gap. The symptom that the doors both have some give when I pull on them when locked makes me still think the mechanisms are just worn out from 40 years of work.

I already ordered the parts, so we'll have to see what plays out. I'll keep y'all posted.

[JohnnyD]

Perhaps someone has some advice for a work-around for this problem. My RH door latch (81 F150) is barely functional, requiring heavy slam to secure, and then still loose on the jam pin. I have replaced the pin and adjusted it with no improvement (details in original post). I suspect internal wear (200K mi). I bought the replacement latch from LMC Truck after discussing my concerns with the sales rep. My concern is that I know my version with the slider inside lock was only produced within a narrow production window, and even some of the 81s have pin-type locks on the window sill. I was assured this lock would fit; there is no alternative I can find. Gary also indicated that he thought the only problem was that the lock/unlock position might be reversed (I can live with that).

So I bought a new latch and dug the old one out of the door (note, remove window channel first for better access). At first glance they look the same. Figure 1 compares the two (sorry it needs to be rotated CCW 90 deg; maybe lay down to view?). This is viewed as if you were inside the door panel, so the actual latch is on the back side to the right.



Figure 2 shows the Ford original one with the operator rods attached. The outside door handle and outside lock rods (left side) move straight up and down, parallel to the back of the latch chassis. The inside handle and lock rods (right side) move perpendicular to the back of the latch mechanism, toward the viewer and slightly to the right. You can see that the inside lock rod connects to a rotating plate that has a notch at the lower left that engages with the actual locking mechanism in the main latch chassis.



Figure 3 shows the LMC replacement part (49-7241). The outside door handle, outside lock, and inside door handle appear to work identically to the Ford original. However, note that the inside lock is setup for a pin lock, not a slider and that they don’t seem to be interchangeable. Whereas the original rod pulled perpendicular to the latch (out of the picture, slightly to the right of the viewer), the LMC one pulls parallel to the latch (upward in the picture). You can see that essentially the swivel plate with the notch from the Ford one is missing.



I have already replaced the door panels with ones that have slide locks. I could buy pin-type rods and drill a hole in the top of the door panel, but this would be a second choice. Any other ideas on how to conquer the beast?

Thanks, everyone,

- John

[grumpin]

At first glance, I would think an extension on the inner door lock rod. And I have no ideas of how to accomplish that.

Man, that’s a bummer!

[JohnnyD]

Dane, unfortunately it is more than an extension of the rod. The new one operates at right angles to the old one. To unlock, you'd pull up on a pin or knob on the window sill (like most cars with manual door locks) vs the old one had a slider that slides back and forth above the inside door handle. Arghhh!

[Gary Lewis]

Let me check tomorrow, but there is a chance I have an extra slide-style lock.  I think I might 'cause Cash swapped out his sliders to pin style and he's the one that discovered that the slide style locks work backward when used with pins.

And I also want to compare the LMC lock with a factory pin-style lock as I think they may have made the locks differently.  If so, that's what your problem is.

[JohnnyD]

I'll await your reply.

[grumpin]

JohnnyD wrote

Dane, unfortunately it is more than an extension of the rod. The new one operates at right angles to the old one. To unlock, you'd pull up on a pin or knob on the window sill (like most cars with manual door locks) vs the old one had a slider that slides back and forth above the inside door handle. Arghhh!

Oh yeah, different angle. Didn’t think of that.

[Gary Lewis]

Ok, GARY IS WRONG!  

The only slide-style latches are those in Dad's truck, so I compared that to the spares I have, which are all pin style.  And you are right, I don't see a way to use the pin style with the slide locks.

The issue is that lever.  On the pin style it gets pulled up/pushed down.  On the slide style it has to be pulled forward/pushed back.  And you can't pull a slide-style lever up/down nor push a pin-style lever fore/aft.

So I don't know what I was smoking when I said you could swap them.  

Given that, I think you will either have to find someone that has a used one or find some place that has them NOS.  The part number is F0AZ 5421812-A and Motor City Muscle Cars says they have one for $63.  There may be others, but that's what I found with the first search.

[JohnnyD]

Gary, I'll let you off the hook on this one. I believe the latches setup for sliders will work equally well for pin locks, since the way the lever works, I think it will pull either way. Not so for the pin-only ones, as you have noted, which work in a different plane. Thanks for the link. I'll look it up and let you know. At least when I talked to LMC before purchase they assured me they'd take them back if they didn't fit.

Onward!
John

[Gary Lewis]

John - Thanks for letting me off the hook.  

And maybe that is it - the slider-style lock with work for either, but not so the pin-style lock.  That would explain why Cash was able to convert to pins with his slider locks, but then discovered that up is lock and down is unlock.

Good luck!

[JohnnyD]

Gary, I looked up the link you sent and it is just a spreadsheet of parts for "The Paddock" with no contact info or other information. I searched around for this outfit and the web says they went out of business. The spreadsheet appears to be an inventory clearance sale. I suspect you got this from someone's website, but I can't trace it back. Can you give me a few more clues?

Thanks, John

[Gary Lewis]

Bummer!  No, I don't have any clues.  I just found that in a search and assumed they were still around.  Sorry.

Let's see if David/1986F150Six can find something.  I'll tag him.  

David - We are looking for F0AZ 5421812-A, which is a right-hand 1980/81 door latch, meaning the one with the slide lock option.  Can you help?

[JohnnyD]

Gary, I just ordered the rest of the parts to convert to pin-style locks. However, the door panel I have doesn't have a hole for the pin, and neither does the underlying metal of the door, so I need to drill these. It looks like you have a reference truck that has been converted. Can you make some reference measurements to help me locate the holes in the proper position? Maybe distance from the closed window, and from the latch end of the door or something obvious. This is one of those cases where I want to measure twice (three times?) and drill once.

Thanks, John

P.S. - When I get all the parts I'll carefully document the procedure so someone else will have an easier time than I have had.

[Gary Lewis]

Sure!  I can do that tomorrow.  And if I don't, rattle my cage.

[Gary Lewis]

Well, this isn't the "tomorrow" I'd promised, but here are the measurements nonetheless:

Here's the measurement for the opening from the inside edge of the window opening.  Parallax distorts the inside measurement, but the hole is 5/8" wide and starts at 5/16" inside and extends to 15/16".



And here are the measurements from towards the rear of the door: 4" to 4 3/4".