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Lower Hatch Receiver - Problems for all!

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Old 01-11-2007, 10:13 AM
  #16  
heinrich
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It doesn't make it work but you can't beat the ghetto vsalue ... just kidding. Don't know ... Ken:confuzzled:
Old 01-11-2007, 10:21 AM
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Ed Hughes
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Jim: Great detail on how to diagnose and repair! I'm saving it, in fact. But, do the words "multiple paragraphs" mean anything to you?
Old 01-11-2007, 10:37 AM
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Panzer9
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I miss the catfish
Old 01-11-2007, 10:55 AM
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chaadster
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Okay, I've determined that the hatch release mechanism is the most complicated system on the 928.

Good Lord. I've read dozens of writeups on "the fix," everything involving adjusting, shimming, trimming, replacing and greasing.

The hatch release deserves its own volume in the repair manuals; its own chapter in Project 928; there has got to be a story behind this mysterious and complex (verily, incomprehensible) device!
Old 01-11-2007, 11:00 AM
  #20  
Ed Hughes
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Originally Posted by Panzer9
I miss the catfish
He's still here, and will popup from time to time.....
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Old 01-11-2007, 11:05 AM
  #21  
ErnestSw
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Jim seems to be enjoying his new wide band internet connection!!!!
Old 01-11-2007, 02:04 PM
  #22  
PorKen
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Yes. No. (Here's another thread.)

Originally Posted by aggravation
Is the function of the zip ties to make the cam bigger, to extend it's reach toward the catch and do you leave the excess tie dangling like in the photo?
The cam wears down, so it takes a little extra to get it going.

Kinda of like when you turn 40. H?
Old 01-11-2007, 02:08 PM
  #23  
heinrich
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Wouldn't know Ken, not there yet old man
Old 01-11-2007, 02:22 PM
  #24  
SharkSkin
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Originally Posted by Jim M.
You asked for it:
The nylon actuator on the hatch should be centered. Is the hatch release hitting the nylon release completely? I used a magic marker to mark the nylon piece. I then actuated the release to visually check if the striker was hitting the release.

Porsche used a plastic catch on the upper latch that’s designed to wear. It’s a replaceable, but be sure to get the pin with it. The upper hatch piece is cast and cracks, flexes and becomes inop. Check the sides of the upper latch, often the metal of the latch gets a hairline crack on the side and prevents the motor from releasing the catch.

Shim about 1/16"between the rear side of the male part of the latch and the hatch. This moved the lower end toward the front of the car, so it works. Use carbon paper to see where it’s contacting. When the catch is moved aft, the latch releases and the spring in the lower piece lifts the hatch about ¼" above where the catch holds the hatch down.

By moving the motor further down the release cam pushes the catch further in, allowing the release. A ribbed rubber insert in the lower half of the latch holds the tongue in position allowing the release. The rubber is soft, shrinks and wears with age. I inserted a 1"x1¼" shim between the rubber insert in the lower piece and the rear of the lower housing. Loosen the motor mount bolts, and slide the motor up all the way. This relieves stress on the tongue and prevents cracks.

On the lower part of the latch, push the rubber cup at the rear, forward into the latch area. Slide the shim between the rubber piece and the rear of the housing. This moves the tongue forward so the catch is moved into the tongue. Tighten the motor bolts at the top and test.

Follow the manual by incrementally moving the motor down until the hatch starts working. With the hatch closed, move the motor down until the release cam just touches the catch. If the hatch fails to release with the motor adjusted to the bottom, start over.

The sheet metal that the upper lock assembly bolts to gets bent so the black post is pointed toward the rear. Shim to adjust the angle of the upper hatch mechanism to point it farther back. This helps engage the lower mechanism and pop the hatch.

When the rear hatch lock breaks internally, to open the hatch crawl into the rear, take the tool kit off, peel up the carpet at the center top section of the panel behind the tool kit. Drill a ¼”hole in the very center of the panel as high as possible still on the main body. Then insert a screwdriver to push back the white plastic latch on the black post. It helps if someone pushes down on the hatch to release the tension. The carpet covers the hole.

The internal cast metal arm of the lock isn’t sold separately. Tried many adjustments without success, until I read this tip: tape a piece of paper over the receiver; put some grease on the tip of latch, and gently lower it until it makes a mark on the paper. Note how far off center, and in which direction, the mark is; then adjust the latch with shims until it comes down dead center.


Hatch release: The catch edge of the latch wears and prevents the hatch from closing completely. With the remote release a small metal flap driven by a motor pushes the catch back. The flap rotates 360° on each activation. This causes the catch to clear the metal catch on the lower latch and then the spring in the lower latch pushes the hatch up to clear the lower latch before the motor releases the upper plastic catch. If there isn’t enough clearance due to wear on the upper plastic catch it won’t release.

Also if the latch or hatch is binding then the spring doesn’t have enough strength to push up the hatch. Eventually between the flap wearing into the plastic catch and the top edge wearing away the flap cannot push the catch far enough back to release the hatch. There are several fixes for this, but the best, easiest and most reliable way is to replace the plastic catch in the top latch.

Check that the fasteners are tight on both the top and bottom part of the latch. There are two adjustments that may be necessary. Remove the tool panel. Loosen the two 10 mm bolts that hold the hatch release, and have an assistant trigger the release. Slide the release down until it begins to drag at the bottom of the cycle, and slide it up until it’s just free. If this doesn't cure the problem, loosen the fasteners holding the top latch to the hatch, and insert spacers under the outer edge so that the latch is tilted forward. Make sure that the alignment allows the latch to enter the receptacle cleanly.

A used rear hatch rubber (plastic?) liner solved my hatch problem where the hatch lid was squirming around and squeaking like crazy. The liner deteriorates and cracks with age and eventually goes to pieces. With all the other hatch problems that develop with age, a new unit the makes the most sense.

My symptom was the rear hatch not opening. I removed the lock cylinder from the assembly. There’s a small lock screw to remove, and then rotate the lock cylinder about 20°, then push. Once removed you can withdraw the white piece. Trying to spread the rivet head in the new pin is a problem. If you had some sort of press you could do it. I tried the hole-punch and hammer method; felt as though I would hurt something so stopped. I have left the pin floating in there. With the grease applied, it has not drifted at all.

Hatch motor won't park is usually the release motor is running so freely that it coasts over the cutout that should stop it. Possible cures: 1. Clean the cutout. Sometimes, there will be a build-up of copper on the disk that bridges the cutout, allowing just enough power flow to keep the motor running. 2. Pack the gearbox with grease, adding enough drag to slow the motor down so that it won't coast over the cutout. 3. I haven't tried it, but I would think that adding a power resistor in the run-on line before the motor might slow it down enough to solve the problem. Perhaps two ohms, 25 watt from Radio Shack? 4. Replace the unit!

Jim Mayzurk
93 GTS 5-spd
Better?
Old 01-11-2007, 02:40 PM
  #25  
Jim bailey - 928 International
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Yes Roger the latest batches of hatch receivers are defective....sometimes new parts from Porsche do not work.
Old 01-11-2007, 03:07 PM
  #26  
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Jim,
Are they doing anything about it though?
Thanks for the confirmation.
Roger
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Old 01-11-2007, 03:22 PM
  #27  
Jim bailey - 928 International
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NOPE ...it takes them a while to respond to such things only after repeated returned parts does someone finally decide that there just might be a problem... The green ignition wire 78-84 fiasco took them a while to get sorted out... One of the big problems for any parts business is returned parts defective parts warranty issues one well know supplier of all model Porsche parts gets about 16 % of all there orders returned ! so they just about work one day per week for nothing ! A few years ago Pelican parts was trying to hire a person to do nothing but customer service and handle returned parts. Since they try to inventory nothing getting parts returned becomes a big issue when you have no warehouse system in which to store them and must get them returned to the distributor and be sure that you get credited....Selling parts is "easy" ...
Old 01-11-2007, 04:22 PM
  #28  
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I got mine with the problem maybe a couple of years ago already, so apparently they still don't know about it or are in no hurry to change it. It's not the first time that I've gotten a brand new factory original part that either didn't work or fit as well as the one did that was originally on the car when it was new.
Old 01-11-2007, 04:30 PM
  #29  
Bill Ball
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Originally Posted by the flyin' scotsman
what did Jim say???????????????

You know, I can do a timing belt in my sleep and install a supercharger in a day, but the rear hatch mechanism has me totally baffled and Jim M's discourse lost me. I guess I just need to take one apart and see what makes it tick, err, not tick but release. Mine has refused to fail, so I'm not too motivated yet.
Old 01-11-2007, 04:32 PM
  #30  
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Originally Posted by Bill Ball
You know, I can do a timing belt in my sleep and install a supercharger in a day, but the rear hatch mechanism has me totally baffled and Jim M's discourse lost me. I guess I just need to take one apart and see what makes it tick.
Be Careful. I don't want to see you end up with a shell and a garage full of parts in 30 days.

Small things like this are like a gateway drug.


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