Having the engine/transmission out I took the opportunity to look in through the throttle body and see if the variable intake flaps were actually operating. The pivot arms were free, but the flaps were not moving so I knew they were broke. There is practically nothing in the Bentley about it, so I decided to just begin disassembling it. I started by pulling of the arms off. Here is the where they were broken:
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC_0957.jpg">



This is the part that broke off, it keys the flapper pivot rod into the control arm.
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC00317-1.jpg">


I had to apply some serious force to press the rod out of the end guides. These things were really frozen in!
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC_0962.jpg">


Now what to do with this?!
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC00302.jpg">

After searching every online resource I could for a replacement part to no avail and then mulling it over for a day or two, this is what I came up with. First I set up the arms and used an external boring tool to turn down the end to .375 diameter. You cant see the boring tool because it blurred out from motion:
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC00303.jpg">


Here are the parts after machining, I went about 0.800 down from the end with the turn-down. The base rod is aluminum. Then from the measurements of control arms, I fabricated these pieces to fit on the turned-down ends. They are made of 12L14 CRS (screw machine stock), the back side is bored 0.375 diameter to fit over the turned down rod ends.
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC00306.jpg">


Originally I planned to cross-drill these and add a roll pin to keep the radial orientation of the new part from slipping. But they pressed on so nicely that I decided to forgo that step.
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC00308.jpg">


Here is the re-assembly. I used an emery cloth strip attached to a ¼" mandrel on a die grinder to clean out the ID of the end guides. Because I am concerned about corrosion from dissimilar metals, I made sure the metal part is about 0.005" smaller in diameter than the plastic part that is left, so the plastic part should touch. I also lubed it heavily with anti-seize paste on the rod end.
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC00313.jpg">

That's it!. After cleaning the deposits out of both halves of the manifold, I lovingly reassembled and torqued the top part back in. The arms operate freely...for now at least.
<img src="http://i48.photobucket.com/albums/f202/G1968Y/2000_A8_intake_fix/DSC00318.jpg">

Hope this helps somebody!
Greg

 

Fabulous work and outstanding write-up! Can you describe any driving difference w/ the repair?

 

Wow that's hugely impressive - was this on the 'A' or the '//S'??? Hoping 'A', I don't wanna do this

 

Car is not fully re-assembled yet, but I will report back when it is.

 

I "fixed" them the first time - trying to free them up. I am not sure if I could have pressed them out with the ends intact anyway as frozen as they were.

If you pull the arms off (pretty easy to do), you should be able lube them. If they are sticking at all, I would pull the end guides and ream them with some emery cloth on a drill or die grinder, being careful to not hit the seal, and then you should be good to go for a long time.

 

Nice parts! I've got a small machine shop in my garage - I do have a mill, but not a Bridgeport!

 

...freely. But if you just pull the arms off (the black actuating levers?) to lube then maybe I'll give that a go for some preventitve POM.

Anyone have any ideas on what causes the sieze? Thinking it's pretty obvious that the (guaranteed) busted acuator connectors are just the symptom of the bigger issue then. Hmmm.

Great job, tx for sharing.

 

I would buy your fabricated pieces in a second. I've held off trying to fix my wife's car for this reason.

I don't want to take it all apart and have one break. I already did that on my car!

Nice fix!

Bob

 

Love it! Will add to the FAQ

 

WOW, that's really impressive. Thanks for the excellent write-up.