Rear hatch pulldown motor/gearbox... what a POS!

[Gokou]

Driving down the road today in 105 degree heat (boy, does this car HATE hot weather, it had to be down at least 50hp!), I hit a very small bump in the road, hear a muted pop, then I notice some wind noise, look back, and see the rear hatch is sitting open about 2". Crap!

I go home, yank the rear trim panel, and find that the amazingly brittle plastic GM used to mold the gearbox out of cracked at the bolt holes. All 3 of the torx-headed self-tappers pulled right out and severely damaged the plastic gearbox. What a terrible design... a critical item that sees abuse from people slamming the decklids, jars from road hazards, etc, and they use the plastic gearbox to hold the darn thing to the car?

What the heck was GM thinking molding a stressed item, especially one that holds down the rear hatch, out of such a brittle plastic? There's a nice metal bracket that the motor attaches to, why not have the stamped steel bracket bolt to the latch plate in the car instead of that really brittle plastic? Argh. I guess being a mechanical engineer I'm quick to anger about poorly designed parts which would have taken very simple steps and minimal efforts to improve.

(end venting)

After getting a price on a new assembly from my local GM dealer (my price was $320 for a new latch assembly, including the pulldown motor... I was told I cannot purchase just the motor and gearbox. List was $428!), looks like tomorrow I'll hit up the local wrecking yards. I plan on getting as many good ones as I can-- 4 or 5 if possible! I have a little reinforcement plate I made out of .125" aluminum for the two upper bolt holes-- rather than let screws tap into the plastic and cause stress risers, I'll use some 10-32 nuts and bolts and clamp the sucker in place.

What a pain in the butt...

did I mention my rear main is still leaking?

Still, I love this car...

Also, is this (see pic below) the buildsheet, or is there another? If there's another, where should I look? I found this particular sheet under the carpet after removing the rear trim to get to the pulldown motor.

Is this the build sheet?

[89SandBagger]

Try to find some early 90's Cadillacs, im sure it the same setup.

[Gokou]

From what I've found, all 82-92 F-bodies use the same rear pulldown motor, so I figure I have a good chance of finding them in the junkyard. Finding a good one that isn't cracked however might be difficult if my 2500 mile one cracked, and it hasn't seen one ounce of abuse...

*update*

Got back from the junkyard... I'd say that the stats look pretty good! There were 39 F-bodies in the yard which had the power hatch pulldowns. I only found 2 with the pulldown motors left in, because those 2 cars had their hatches shut and it was a real PITA to get them open. Gee, I wonder if other people have problems with their motors breaking? 1 of the motors (the cleaner one) was cracked, and the real dirty one (looks like the hatch leaked) was the one without cracks. Argh. I snagged it anyways for $10...

I tried to repair mine last night using some extra aluminum and a whole lot a 2-part adhesive I borrowed from work (which is typically used in bonded aluminum aircraft and satellite structures). I'm hoping my repair holds.

[Razor]

Gokou,the number one things that people pilfer on these Fbods are the rear pull down motor assy and the headlamp motors.

Keep an eye out forthese items..great to have spares

[Gokou]

No doubt!

I actually think my repaired piece is stronger than an original, so I'm going to put that back on and keep the other one I got for a spare...

I also plan on acquiring 3-4 more spares over the summer, because I have a funny feeling this is going to be one of those "once a year" jobs, along with fresh coolant and brake fluid

[Razor]

I dont run coolant in my car.Just distilled water with the addition of water pump lubricant/antirust which is .99 cents at you local autoparts store..

Reason is if you blow a head gasket and coolant/antifreeze goes into your oil..the bearings are toast..

HTH

[Gokou]

Good point there Razor... being in the middle of CA I don't run much antifreeze. I usually run about 80% distilled water, 20% antifreeze, and one bottle of WaterWetter for the water pump lubrication it provides.

I might have to drain my cooling system this weekend and replace it with just distilled water and an antirust additive. Not that these cars ever blow headgaskets

My repair holds. YAY!

However I think I found part of the problem: the rear latch was adjusted WAY too low. The decklid would hit the bump stops but the motor would keep pulling. You could then watch the motor and the bracket bend upwards. It was nearly impossible to turn the key to open the deck there was so much tension on it! I adjusted the entire latch mechanism 1/8" upwards to relieve some of the tension-- now when the decklid hits the stops, the motor only pulls down a tiny bit more, and then it stops. The key is much easier to turn now. I think the adjustment problem was putting way too much stress on that plastic gearbox, which is why it broke so early. I mean the car has less than 3000 miles on it, the rear deck has probably been opened less than 30 times over the life of the car, and it already broke?

[Pace 1989]

Take a look at this month's High Performance Pontiac, they address the rear hatch pull down and ways to fix it. Interesting stuff!

Ken TTA#1426

[Gokou]

Excellent! I'll have to go pick up a copy.

I wonder if they did anything similar to what I did... I felt I did a pretty darn good job of not only repairing my damaged box, but improving on the way it fastens to the rest of the latch mechanism.

[Gokou]

Pace 1989 -- I sent you a PM. My local newsstand didn't have the right issue. What month was the article in? Think you could scan it for me?

Thanks.

I read this thread at 12:00 noon today, and at 9PM my hatch pull down motor quit working. The TTA has 38,000 miles on it and I've owned it 2 days. I think it's possessed. Can anybody help by
(1) telling me how to fix it from the Pontiac magazine article

(2) Providing me with the part number so I can see how much it costs at gmpartsdirect.com

(3) selling me a spare at a reasonable price

I'll call junk yards and see what I can find.

Thanks

[The Swede]

Hey!

Fellow TTA owner Lon Salgren runs TDS, check out attached link what he has for the hatch down!

http://www.top-downsolutions.com/def...09 72f5a01268

[Lee_Burough]

Thanks Goku, This is an important repair for all of us.

I'll be making it a FAQ in our TTA forum, with the link provided by The Swede