[DML] Door service overview

[deloreanernst@xxxxxxx]

Group, here's a sample of updated DeLorean Repair Manual online content. I just posted it to the DMCTech group as well, under the heading of "Files"   
http://autos.groups.yahoo.com/group/DMCTech/
Comments or corrections?


                                                                                                   
DeLorean Door Service & Repairs – Overview

Those cool gullwing doors that we all love have caused a lot of suffering. They’re beautiful, but they can be frustrating and high maintenance until you get them adjusted right. In fact, there are several specific reasons that DeLorean doors have functional problems that other car doors don’t. It’s all in the design. Any one of the following well-intentioned design features- or the lack of proper adjustment of them- can causes door malfunctions. Fortunately, all these problems can be eliminated if you understand how to properly adjust your door components!


To avoid confusion, let’s define some terms:

The terms “door locks” and “door latches” are often used interchangeably. The Latch holds the door shut, until you pull on a door handle to release the latch, allowing the door to open.  The Lock prevents the Latch from opening the door when locked. Mechanically, the latch and lock functions are in one hunk of hardware, which we can broadly call the Door Latch, to avoid confusion. All the locks, handles etc. that lock or open the doors are actuated by Control Link Rods connected to two pivoting Bellcranks. If the Link Rods are not properly adjusted, the doors will not open, or won’t stay closed, or won’t unlock.  Some of these Link Rods have Turnbuckles to adjust the length of the Link Rods for proper operation of the doors.

The Upper Bellcrank releases the Latches to allow the door to open. The Lower Bellcrank operates the Locks, to prevent the Latches from releasing and opening the doors when they’re locked.

In addition, the Lower Bellcrank is connected to a set of electrical contacts called a Wiper Switch and a Solenoid (or actuator) to make the doors lock or unlock electronically in tandem. 

Design: each of these features contributes to the function- or malfunctioning of your doors:

Dual Latches: The DeLorean has 2 Latches per door, as compared to the 1 per door found on other cars, or big minivan tailgates, or even the DeLorean prototype. They come in two styles, mirror images of each other, one on the front edge of each door, one on the rear edge. The front one on each door is the same as the rear one on the opposite side. The door Latches are capable of closing independently. If a door is closed unevenly, you might damage the edge of a door Latch. Since they both must be adjusted correctly, having 2 latches gives twice as many opportunities for misadjusted latches.

Striker Bolts: Each of the door Latches hold a door shut by gripping on a Striker Bolt. (Also called Striker Pins.) If these bolts are not positioned correctly, the door may not close fully, or fit too tightly. And closing the door improperly and violently can knock them out of whack. Other cars commonly don’t have striker bolts with adjustable positioning. Since the DeLorean does, it also means they can be out of adjustment. And there are 2 per door, unlike other cars.

Central Locking System: These are pretty common now, whether key operated or remote controlled. In a typical current car design, you click the remote, (or turn the driver side door key,) once to unlock the driver door, and once again to unlock the other door or doors. On the DeLorean, unlocking or locking one correctly operating door always instantly does the same to the other one, without clicking twice, or flipping a separate switch.  The only problem with this is the fact that it depends on several trouble prone components, so if one door is messed up, the other will typically have problems. Since the doors will work without the Central Locking System powered up, many owners avoid problems by either disconnecting or better yet, upgrading the original Door Lock Module that causes problems.

The Door Lock Module in the car’s Fuse and Relay Compartment is the central brain of the electronic central door locking system. The relays in the module that feed the high current appetite of the door lock Solenoids are prone to burn out. The factory tried to correct this by installing self-resetting Circuit Breakers. So, if you can’t get your doors to open, wait about a minute, and they may work just fine... a few more times. But if this happens, your OEM (original equipment) Lock Module is failing. You need to replace or at least disconnect it. If you don’t, your Solenoids WILL eventually fry, and you could get stuck in your DeLorean. The doors will work just fine individually without the Door Lock Module. They just won’t both lock or unlock simultaneously. To disconnect the Lock Module, tip the passenger seat back forward, and fold back about two feet of carpet on the rear Parcel Shelf. Lift open the triangular bulkhead cover that covers the electrical Relay Compartment, and set it aside. Identify the Door Lock Module.  It’s a black square with two side mounting screws and a short wire harness and big white connector coming from it, plus a single fat red wire with a black connector. Be careful… danger of electrical shock! Disconnect the single big red wire and be sure it doesn’t flop into contact with something it shouldn’t touch. Now close up your Relay Compartment. The door locks can now be operated purely mechanically using the key, and you’ve eliminated a major source of problems. The other good news is that not only can you get along fine without it, but there are also upgraded replacement door modules available which allow you to use the locks as intended, or better yet, install a remote door lock/unlock system. The only downside is that you have to lock or unlock each door individually if you don’t install an upgrade, but that’s a small inconvenience compared to the alternative.

The Door Lock Solenoids: The Link Rods and even the door lock Rocker Switch on the armrest are flipped from lock to unlock position by large electromagnetic Solenoid plunger units. If your Door Lock Module electrical relays fry in the “on” position, they will try to pass on the joy by frying the windings of the Solenoids. Fortunately, there are replacements and even upgraded alternatives for these. 

The Wiper Switch: It’s a simple copper double electrical contact switch inside each door that tells the Door Lock Module whether that particular door is in the locked or unlocked position.  When you lock or unlock a door from inside or outside, it sends an electrical signal so the Door Lock Module can make the other door move virtually simultaneously into the same position. Adjusting the setting of the Latch and Lock Link Rods affects how the Wiper Switch makes contact. If you’ve messed up the alignment of your door link rods, your Wiper Switch can get out of position, so that while you turn the key to “unlock” it still sends a message to the Lock Module to “lock” both doors. Now you’re nearly breaking your key off, but it keeps relocking. It will lock perfectly in this case, but won’t unlock. Corrosion, oxidation or loosening of the electrical contacts can also cause problems.

Door Latch Design:  Inside the Door Latch are two thick metal levers, each mounted on its own pivot: a Striker Catch shaped like a horseshoe, and a Detent Pawl shaped like a question mark. The one movable part you can easily see on a door edge is the Striker Catch.  There’s also a Lift Tab which lifts the Detent Pawl to release (unlatch /open) the door, and a spring on both the Detent Pawl and the Lift Tab. The spring on the Detent Pawl keeps the Striker Catch from releasing until the inner or outer door handle is lifted. The spring on the Lift Tab serves two purposes- it keeps the Lift Tab from lifting when it’s not supposed to, thus keeping the door latch closed until both the door is unlocked and the door handle is lifted. The spring also has a hooked end that is designed to assure that the Lift Tab is in either fully locked or fully unlocked position.

The “AntiLock” feature: Other cars can be locked whether a door is open or closed. That’s handy, but on a DeLorean, if you lock one closed door then slam the other one shut, your door will jam or malfunction. Not handy. Even if you just lock and unlock your doors with one door open, such as reaching in the open door and flipping the lock switch hoping to free up a stuck door for your passenger, without closing the open door, it could still mess up the locking mechanism. Unexpected and very unhandy.  A small triangle of plastic, an AntiLock Wedge, visible from the side of an uninstalled Door Latch near the Lift Tab, moves in the way of the Lift Tab, preventing it from moving into the lock position while the Striker Catch is in the “open door” position. In other words, opening the door makes it mechanically impossible to lock the door, even with a key. That, however, does not prevent a person still seated in the car from unnecessarily pushing the lock switch on a closed door by mistake, or someone closing and locking their door while the other one is open. On most cars this happens every day and it’s no big deal.   On the DeLorean, it can force the Control Link Rods out of alignment, which is a nuisance to correct. It doesn’t always happen, but it does happen. That Antilock Wedge is the source of major inconveniences. If you’ve ever wondered why you can’t lock a DeLorean door while it’s open, this is why.

Adjustable Control Link Rods:
Link rods are a common feature inside car doors, but the ones in a DeLorean are longer than other cars.  Instead of being just a few inches long, in the vicinity of the door handle and a nearby latch, they reach “from coast to coast” with latches on both sides, meaning the rods are way longer and more likely to flex. I took apart the door of a Plymouth Neon for comparison, and discovered that the rods in the economy Neon are significantly thicker and with less flex than the DeLorean, which makes DeLorean rods sloppier with more “play” in action. Other cars have fixed length link rods.  In the DeLorean they’re not- they’re adjustable. A mechanic at a major DeLorean vendor told me it’s not possible to replace the link rods that have turnbuckles with standardized length rods, though that would eliminate guesswork if it were a practical solution. Since as little as an eighth of an inch in length can significantly affect function, it’s a lot easier for them to be misadjusted or forced into the wrong setting than the correct one. And the floppiness flex of the link rods just aggravates the situation. Even with these handicaps, they can be adjusted to work perfectly. It just isn’t as easy as it should be.

Door Closing Guides:
At the edge of the door adjacent to the opening for the Door Latch, like shoulder pads on a quarterback’s shoulders, are the Door Closing Guides. The earlier cars didn’t have these, but were usually retrofitted. There are several styles, the later one being plastic; the earlier styles are stainless steel. They’re intended to help guide the door into the correct position and to prevent damage to the Door Latches by people who close the door violently and unevenly, resulting in torque and slight twisting of the door as it descends. Absence of the Guides can allow problems such as bent or excessively worn door latches.

Torsion Bars and Door Struts:
This tech article is primarily concerned with door closing/latching/locking issues, but the Torsion Bars and Struts do impact here. Other car doors can be closed with a sideways swipe of your hand. The only spring load on them will hold a fully open door fully open. The DeLorean gullwing doors open vertically and they’re heavy, so the Torsion Bars and Struts act to counterbalance the weight, meaning that open DeLorean doors are designed to stay open. The further you close them, the more the spring load increases and the harder they are to close. You have to guide them firmly and carefully all the way closed, not releasing pressure until the door latches, and not pressing crookedly or violently on the corner instead of the center of the door. Since no non-DeLorean owner closes their car door that way, every passenger who exits your car will close your door badly unless you leap around to the passenger door and close it for them as if you were a gentleman… or unless you’ve trained them how to do it correctly.

The Cable “Clip:”
A small part identified merely as Clip in the parts manual is also crucial. The long zig-zag shaped Control Link Rod that runs along the lower half of the door is supposed to be held in place near its middle by this looped, fingernail sized plastic cable clip, which attaches to the handle support bracket. You need this part installed and with the link rod passing thru the center of it. Without it, this long rod will flop around or flex under stress when it jerks back and forth from lock to unlock. Replacements are available from the usual vendors. Small but very necessary. 

    
There are other components in the door lock & latch assembly, but these are the ones that typically cause problems.
                            © Wayne A. Ernst   4/23/08




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