Re[2]: Wastegate Diaphrams

[BSWANN@arinc.com]

Jim,

I appreciate your reply, and I'm posting it for the list.  I do recall the 
original post which I found rummaging through the archives.

I understand what Orin say's below, and I'm sure he's quite correct - a 
fabrication facility for these to be worthwhile may have to charge a premium.  
Law of supply and demand.

As for me I'd try some innertube stock and try to fabricate one before I pay 
$100 dollars or more.  For every hundred dollars, I already paid Uncle Sam more 
on top of that.  I know that some folks can't justify this time/effortwise, and 
consider it money well spent - I wish it was me.

Hope this can do some good for others on a budget.  Sounds like it should work -
it just may not last 150k miles.

Disclaimer - I'm not advocating this as a tried and true solution. Your results 
will vary based on how good you are with a leather punch, exacto knife or razor 
blade.   What you do with your or someone elses car is not my responsibility.


Best Regards,

Ben Swann
'85 4ksq
'86 5kcstq (rebuilding)
'87 5kcstq Wagon - still tracing down the overboost fuel pump shutoff problem


_________________________________________________________________________

Hi Mr. BSWANN,
     
I sometimes monitor the Quattro list but usually just look at the archives 
occasionally.
     
About 6 years ago I suspected that my waste gate was defective and 
replaced it with one from a wrecking yard that wasn't any better.  In 
the process I became very familiar with the diaphragm and the fact 
that it's vented to the atmosphere and water condenses within it 
corroding everything and causing the waste gate diaphragm to rot.  I 
attempted to find a replacement then with no success.  
     
Over 2 years ago I had to replace the diaphragm because it was 
disintegrating.  I looked around and could find nothing;  I also tried 
the Bendix Airbrake people for a piece of material but that didn't 
work out, for I thought the material had to be special.  At the time 
several people had them for sale in the $50 to $100 range and I 
thought it was a ripoff.  Orrin was out of stock and expecting some 
soon.
     
In desperation I made one of a piece of an old innertube.  I posted 
the method I used to Dan Simones, but I don't know if it made it to 
the list.  Essentially, you use the top of the waste gate as a 
template and mark the rubber with a pencil.  Remove the top and use a 
straight edge to draw lines though diametrically opposed holes which 
with result in 3 lines that intersect in the center.  I extended the 6 
screw holes outward about 1/4 inch, and then used a leather punch, 
3/16 maybe, to puch the peripheral holes and the center holes.  Then I 
trimmed the rubber around the periphery.
     
I installed it expecting it to burn up immediately;  however, it's 
still working with about 40K miles on it.  I even did the boost 
feedback trick which gives tremendous boost but I didn't feel good 
about boosting an engine with over 250K on it too high.  It now has 
slightly less than 300k.
     
Mine worked;  total cost was my time.
     
BTW, I'm sending this from HP where I'd doing a job.  If you feel the 
need to contact me further, please do so at "superba@pacbell.net".
     
HTH.
     
Cheers!
     
Jim Jordan

______________________________ Reply Separator _________________________________
Subject: Re: Wastegate Diaphrams
Author:  orin@WOLFENET.com (Orin Eman) at SMTPGATE
Date:    6/17/99 2:35 PM


> I have a hard time swallowing that a round piece of rubber with some 
> holes punched in it costs over $5 much less over $100.

It's more than just a round piece of rubber.  It's a special 
rubber (expensive) with a fabric reinforcement which makes it 
hard to mold.

Setting up to make these will cost $3k to $4k... then you have
a limited market.  Unless they found a new supplier, I had those 
that TAP are selling made.  His price is probably rising because 
he doesn't have many left.  I have none.

Ned Ritchie at Intended Acceleration may have some.

Orin.