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hvac vacuum actuator replacement diaphragms

 
Old 08-21-2006, 11:21 AM
  #31  
heinrich
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btw I would greatly prefer electric servos
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Old 08-21-2006, 12:21 PM
  #32  
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Gordon,
I agree with H - it is far easier to change out the diaphrgm than the complete unit as they are rivited in place.
Roger
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Old 08-21-2006, 01:24 PM
  #33  
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Originally Posted by ROG100
Gordon,
I agree with H - it is far easier to change out the diaphrgm than the complete unit as they are rivited in place.
Roger
We still on for this weekend?
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Old 11-19-2007, 07:12 PM
  #34  
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Thanks John for the HVAC Actuator replacement write up on your site, it has been invaluable.

Thanks to Roger for supplying the large diaphragms.
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Old 11-19-2007, 11:25 PM
  #35  
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Did the guy ever make the smaller ones?
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Old 11-20-2007, 12:07 AM
  #36  
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Did the guy ever make the smaller ones?

The "guy" was me - [email protected] - and no I did not due to the high tooling cost.
I have the rights to the sale of Porsche Recirc. diaphragm - for what that is worth.
They are $10 each including shipping in the USA in most cases.

Still working on the smaller diaphragms and I WILL get them made somehow!!
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Old 11-20-2007, 12:15 AM
  #37  
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Impressive Rog Yes, it is amazing to have an inexpensive source here locally for those silly diaphragms!!
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Old 07-23-2018, 10:22 PM
  #38  
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I know that this is a pretty old thread but I'm getting started with restoring an 83' 928 which has the riveted attachment method. I've read that the part #928-573-077-04 is a replacement for part #928-573-077-03 which I'm beginning to think might be the riveted part. Does anyone know whether the diaphragms are interchangeable? And if not, how in the heck does the later part attach?
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Old 07-24-2018, 11:10 AM
  #39  
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Originally Posted by RubinRot928 View Post
I know that this is a pretty old thread but I'm getting started with restoring an 83' 928 which has the riveted attachment method. I've read that the part #928-573-077-04 is a replacement for part #928-573-077-03 which I'm beginning to think might be the riveted part. Does anyone know whether the diaphragms are interchangeable? And if not, how in the heck does the later part attach?
They are not interchangeable, your choices are to take your chances with a correct used vacuum pod, replace the entire recirc box for a 84' and up, or retrofit the new style vacuum pod into your recirc box. I chose the latter.

New style diaphragm on left.


Old style vacuum pod attachment method. Pry off the metal retainers with a screwdriver.


New vacuum pod clips onto the recirc box with four plastic protrusions


I applied a pattern to enlarge the center hole and for the mounting points


I did my best but it is awkward to get at with the ledge above.




It was a pretty secure fit but for piece of mind I JB welded the base of the vacuum pod to the recirc box. If the diaphragm ever goes bad again you just replace the innards anyway.


Retrofit complete.

It works perfectly.
After I wrote this out I found the discussion thread https://rennlist.com/forums/928-foru...acuum-pod.html
Attached Images
File Type: pdf
Recirc vac pod pattern.pdf (6.8 KB, 12 views)
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Old 07-24-2018, 04:10 PM
  #40  
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Nice work Mr. Moose. I say never be too proud to use JB Weld in the right circumstances.

I hope Roger will chime in here and correct me if I am wrong, but I believe he has the "smaller" diaphragms for the comb and footwell actuators made out of a superior silicone rubber but only has the entire actuator for the "larger" defrost and recirc flaps. For cars with the "snap in" recirc actuator old threads indicate that a Mercedes "single" diaphragm available here - http://www.perfanalysis.com/climate-...acc-version-i/ - will fit the recirc actuator. I have not verified this but have an example being shipped to my hacienda.

Are the diaphragms for the recirc and defrost interchangeable?
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Old 07-26-2018, 12:35 PM
  #41  
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Alex & the Group --

From your pictures it looks like the diaphragm for the replacement actuator is a tad shorter in the cup than the original, has same length rod/link attached, and same diameter as the original. If this is correct, does the new part have the same available stroke as the original? I'm trying to remember if/how this might be important for the recirc flap especially. I think that's the only one I haven't replaced.
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Old 07-26-2018, 06:09 PM
  #42  
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Originally Posted by Eplebnista View Post
Are the diaphragms for the recirc and defrost interchangeable?
I cannot say for sure, I replaced the whole unit. I could take apart the old defrost vacuum pod and measure the diaphragm if that helps.

Originally Posted by dr bob View Post
Alex & the Group --

From your pictures it looks like the diaphragm for the replacement actuator is a tad shorter in the cup than the original, has same length rod/link attached, and same diameter as the original. If this is correct, does the new part have the same available stroke as the original? I'm trying to remember if/how this might be important for the recirc flap especially. I think that's the only one I haven't replaced.
The new part has the exact same stroke and fully opens and closes the recirc flap.
If this is for your '89 then it should be a direct swap, no retrofit needed.
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Old 07-26-2018, 06:59 PM
  #43  
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I used to sell the diaphragm for the recirculation actuator - Mercedes part and it was similar but not exact dimensionally to the defrost diaphragm.
Some were able to fit it and get it to seal in the defrost position but many others could not.
As the recirc. and defrost are relatively inexpensive as complete actuators I have not really looked for a replacement diaphragm.
I do have the diaphragms for the footwell and center actuator (in the center console) for $56 each.
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