Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: 901 Trans Intermediate Plate Gasket Thickness

  1. #1
    Member
    Join Date
    Feb 2013
    Location
    Retired in the Seattle area.
    Posts
    33

    901 Trans Intermediate Plate Gasket Thickness

    I am resealing a 901 transmission with about 80K miles that was leaking from the intermediate plate area. Transmission was working well and was quiet, just leaking.

    I have the nose cone off and intermediate plate/gear cluster removed. There was one gasket between the case and intermediate plate. It is about 0.17mm thick based on an average of several mic readings (readings 0.16 to 0.18mm). The Erling gasket set contained 3 x gaskets all 0.22mm thick uncompressed - I would have thought it might have include 0.1mm, 0.15mm and 0.2mm - oh well.

    The original gasket came off undamaged in one piece so my question is:

    A) do I clean and reuse the original gasket with sparing use of Curil T on both sides; or
    B) order a new 0.15 mm gasket; or
    C) use 1 x 0.22 mm new gasket and hope it compresses 25% to 0.165mm?

    Advice appreciated. I am a transmission newbie.
    Bill Sargent
    Seattle area
    67 912
    64 356 C cab
    59 356 A carrera cab
    64 904 in the works

  2. #2
    Bill, you can re-use the original gasket, but it would be better to use a new one.
    In the old days, the 0.15 mm IP gaskets were usually green. I'm surprised that the Elring set didn't have a proper selection.

    Jon B.
    Vista, CA

  3. #3
    Member
    Join Date
    Feb 2013
    Location
    Retired in the Seattle area.
    Posts
    33
    Thanks Jon!

    Unfortunately looks like I will need to order a gasket anyway. When I went back this morning to clean up the case side on the intermediate plate and I found a second gasket there I had overlooked. It was well stuck and I was not able to save it. It was a little thinner than the first one. First one was 0.145mm compressed and 0.21mm uncompressed (~ 30% compression). Second gasket was 0.125mm compressed and 0.155 uncompressed (~ 21% compression). I think the factory originally used a 0.2mm and a 0.15mm. So I need to order a 0.15mm gasket. That, with one of the 0.22mm ones I have, and assuming 25% compression, gives me the correct compressed value. So before I order that gasket I need to do a enough reassembly to pull the side cover and check that gasket thickness too.

    The original gaskets were the factory tan paper ones. The 0.22mm gasket in the Erling kit is a gray paper like material.

    Does anyone know how much the current gray (or green) gaskets compress? In the absence of better input I an going to assume 20% to 25% based on measurements if the original gaskets.

    On the positive side I am learning a lot.
    Bill Sargent
    Seattle area
    67 912
    64 356 C cab
    59 356 A carrera cab
    64 904 in the works

  4. #4
    Senior Member
    Join Date
    Oct 2008
    Location
    Burford, ON, Canada
    Posts
    4,237
    The cover gasket should be a standard thickness, but the gaskets between the case and the intermediate plate need to be carefully measured on removal. There are often 3 gaskets used to make up the pack. These gaskets are like shims to set the pinion gear depth so it is important to get the total thickness the same as the factory pack; the factory assembler went to a lot of trouble getting the pack JUST RIGHT.
    Porsche Historian, contact for Kardex & CoA-type Reports
    Addicted since 1975, ESR mbr# 2200 to 2024 03
    Researching Paint codes and Engine Build numbers

  5. #5
    Quote Originally Posted by Bill Sargent View Post
    First one was 0.145mm compressed and 0.21mm uncompressed (~ 30% compression). Second gasket was 0.125mm compressed and 0.155 uncompressed (~ 21% compression)...
    Does anyone know how much the current gray (or green) gaskets compress? In the absence of better input I an going to assume 20% to 25% based on measurements if the original gaskets.
    Bill, I haven't examined your gaskets or even seen a picture of them, but it's very unlikely that they compress that much from their new dimensions.
    It's more likely that they'll saturate with oil and swell where not completely compressed on both sides. The intermediate plate has several open areas where this can occur.
    Furthermore, the factory didn't use sealant on these, and you didn't mention any on them. Any sealant added to both sides can add a small amount to the dimensions.

    The relevant gasket measurement is in between the fastener holes, where the gasket was completely compressed and not against any open areas.
    That was the effective spacing dimension between the two housing pieces.

    The best thing to do, of course, is to check the pinion depth with new gaskets. You can factor in some allowance for possible compression versus any added sealant if you wish.

    Jon B.
    Vista, CA

  6. #6
    Quote Originally Posted by Jon B View Post
    The best thing to do, of course, is to check the pinion depth with new gaskets.
    Like this...

    Name:  DSCN0332.jpg
Views: 300
Size:  68.4 KB

    Jon B.
    Vista, CA

  7. #7
    Senior Member
    Join Date
    Oct 2010
    Location
    Southern Ca.
    Posts
    1,166
    Jon's description of the gasket variations is perfect , your lucky to have his expertise . So measure accordingly and get the correct thickness's . You probably don't have a pinion depth gauge as pictured , so you have to duplicate the original thickness ,

  8. #8
    Member #226 R Gruppe Life Member #147
    Join Date
    Feb 2009
    Location
    Portland, Oregon
    Posts
    2,343
    Bill is correct, the black gaskets are all the same thickness. I just use those, and set pinion depth with pinion shims. The gaskets are actually very good, not fragile gaskets. You will have to go somewhere else to get measured gaskets, Porsche or Wrightwood maybe.

  9. #9
    Member
    Join Date
    Feb 2013
    Location
    Retired in the Seattle area.
    Posts
    33
    Thanks Jon - I am very thankful you are active on the Early S Resistry (and the 356 Registry). I had not even thought about oil making the paper gasket swell where it was not contacted on both sides. What you describe is exactly what I saw - thicker gasket where the intermediate plate had voids.

    This makes my gasket ordering easier. I need 0.26 to 0.275mm compressed gasket between the case and intermediate plate. So a 0.15 and a 0.1mm will give me 0.25mm. Sparing use of Curil T should put me in the range I need. I think I would rather do this than use a 0.1 and 0.2 mm with no sealer and hope for 10%+ compression of the gaskets. Stoddard and others sell the intermediate plate gaskets in 0.1, 0.15 & 0.2mm.

    I have the same issue with the side cover gasket. The one in the kit is 0.22mm while the compressed original is 0.12 to 0.13mm. I think a 0.1mm with sparing use of sealant should get me in the range. Using a 0.15mm and no sealer would require ~20% compression which is probably not reasonable. Hopefully the side cover gaskets are also available in 0.1mm and not just 0.22mm.

    Thanks again for the good advice and please let me know if there is a problem with my plan.
    Bill Sargent
    Seattle area
    67 912
    64 356 C cab
    59 356 A carrera cab
    64 904 in the works

  10. #10
    Quote Originally Posted by Jon B View Post
    In the old days, the 0.15 mm IP gaskets were usually green. I'm surprised that the Elring set didn't have a proper selection.
    Quote Originally Posted by Bill Sargent View Post
    The 0.22mm gasket in the Erling kit is a gray paper like material.
    Quote Originally Posted by gled49 View Post
    Bill is correct, the black gaskets are all the same thickness... You will have to go somewhere else to get measured gaskets, Porsche or Wrightwood maybe.
    Interesting, I've always bought gaskets from Porsche and rarely used the Elring sets, but their old sets were fine.

    A few sellers are still using this stock file image of an old Elring set.
    You can see that the gaskets were previously tan or green...



    Now, apparently, you might receive a new Elring set which is not similar to the file image they use.
    Bill, as Gordon said you can still get properly sized individual gaskets from Porsche, I think Stoddard/NLA too, and the Wrightwood kits have been excellent as well.

    Jon B.
    Vista, CA

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.