Help me understand the AAR please.

[siteunseen]

How come your finger nails aren't all nasty? You must have a hand model for the pictures. Just messing with ya'! You do some amazing things Captain.

[Captain Obvious]

FastWoman, The trickiest part was drilling and tapping for the screws to hold the clamshell back together. There isn't a lot of meat to work with there.

I held the two clamshell halves together with a clamp and drilled the hole right on the seam between the two halves. That means for the first few turns of the screw, there are threads in both the front and back of the clamshell. Then, of course, once you get deeper, the front part of the shell ends and you've got a full hole in the back half. Doing a pretty shoddy job of describing that, I'm sure...

What else? I used 2-56 screws for the clamshell. Small is more important than strong. The bottom hole is blind. Don't remember what size I used for the flat head screw on the shutter blade or the retainer for the bending element.

How come your finger nails aren't all nasty? You must have a hand model for the pictures.

Haha! Yeah, I use a stunt double for my photos. This is what my hand look like. It's kinda embarrassing...

[TomoHawk]

He uses Grandma's sure-fire cure-all lye soap

[FastWoman]

Yeah, Captain, I can see there's not much room for threading a hole!

I'm wondering about a service method that's not nearly as good, but infinitely easier: Looking at the anatomy of the thing, it looks as though I can shoot some oil onto the shutter, let it drip down to the pivot post, and then wiggle the shutter open with a screwdriver blade, essentially working out any rust that might be causing the thing to stick/hang. The problem I'm having with my AAR is that it hangs up and gives me an irratic idle. One day the idle will be running a bit high (when warm), and the next day it will be too low. Then sometimes the cold high-idle doesn't even work. I'm guessing the mechanism is just getting sticky/rusty. Do you think that would be a fair assessment?

[TomoHawk]

I didn't have any problems washing out my unit. I plugged one tube with s paper towel, and sprayed carb cleaner into the other to fill it, then watched it drip slowly out. Mine is new, so the fluid was clear...

I'm still interested in that rubber boot tho...

[Wade Nelson]

Hey, Fast. Id suggest you completely block off yer AAR and CONFIRM that it ALONE is the source of your erratic idle. Make sure you don't have a vacuum leak anywhere else, spray around the injectors / manifold with brake cleaner, both hot and cold, looking for an rpm increase.

You knew that, but sometimes we focus too hard on one avenue and miss some other possible streets.

I got a lot of gunk out of my AAR doing what you're about to, but found, no matter how much I tried to adjust it, out of the freezer or nice and warmed up, just couldn't get enough travel. It only makes about a 100-200 rpm difference hot vs cold. I'm just gonna replace it with a fresh one.

Unless I can get Captain to do a magnificent rebuild for me like he did on his own. One possible idea, instead of tapping 3 tiny holes, just have a really good TIG guy weld a couple of dots to hold it back together. You can always grind 'em off if you ever have to go back in -- unlikely!

[TomoHawk]

By drilling a small (1/16 inch) hole you could probably get a little hitch pin in, and it just might hold it together! You'd probably need two or three pins tho.

Edited November 16, 2012 by TomoHawk

[Captain Obvious]

FastWoman, I think what you described to oil the pivot pin would work fine, but I'm not sure there is anything in there to rust. The shutter is aluminum, and I believe the pivot pin is chromed steel. Of course, there's the possibility that you have worn through the chrome plating on the pin and have developed some rust, but I think that's unlikely. Mine wasn't rusty inside, but did have some sticky oil residue from the PCV system.

As for getting oily stuff out, the first thought is some kind of solvent, but I'm not completely comfortable with that approach. I know others (TomoHawk for example) have had good success doing that, but it worries me a little for two reasons. a) I don't know what kind of insulation they used on the resistive heating element and I don't know if it would like the solvent, and Some of the shutter blades I've seen have a coating on them that I assume is supposed to provide a thin elastomeric surface to better seal against the inside face of the high vacuum side of the clamshell.

Problem is that I don't remember if that rubber type coating was on the Z car AAR, or another one from a different car. I've got a few of them I've messed with at this point, and I don't remember which had coatings and which ones didn't. If I had to guess, I believe the Z was uncoated so it should be OK, but you should take a look inside through the holes first to confirm that all you see is aluminum. Maybe just try to keep the heating element on the uphill side so it doesn't soak in the solvent?

I'm wondering if your pivot pin has creeped out some like mine did.

You could file the crimped lip off, poke around inside, and then epoxy it back together. Wouldn't be quite as field serviceable as what I've got, but you could file the epoxy off again in the future if you needed to get it open again. A little heat would soften it up too.

Do you have a spare AAR or just the one that's on the car?

[Captain Obvious]

Wade, Yeah, you should be getting more than 100-200 RPM difference out of the AAR. Wonder what's wrong with yours...

Haha! So you're thinking that I should get into the AAR rebuild business? What's a new AAR cost these days?

[TomoHawk]

New ones are about $90 or so, IIRC.

[FastWoman]

Thanks, Captain! Yes, I do have a spare AAR. This project might have to wait, though. Although I have two AARs, I only have one toilet and zero showers (but one bath tub). I also have a stack of cement board in the garage and boxes of tile in the living room. I already removed the last remaining rusty bits of 1980 toilet flange, the old rotted bath/shower, the old tile, and the rotted subfloor. Before I start on the AAR, I'm really looking forward to a nice shower.

[FastWoman]

Wade, my intake is all pretty well gone over. There's no way I have a vacuum leak anywhere, although I admit that's a common problem in these old cars. Everything is removed, cleaned, reconditioned, checked, re-checked, and reassembled. New intake/exhaust gasket, obviously. New injectors and O-rings. The only old working parts I simply cleaned, checked and reinstalled were the cold start injector, throttle position switch, and AAR. She runs like a champ. The only remaining issue is the idle. Oh, and FAIW, my AAR is only good for a couple hundred RPM variation (just like yours), if that. I just live with the idle around 1100 RPM. Sometimes it will drop as far as 800. If I drop idle to 900, it will sometimes dip to 500. It's never died there, but it's "wanted" to.