Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: 911/01 Disassembly and Post Mortum - Comments Welcome

  1. #1
    Senior Member
    Join Date
    Apr 2013
    Location
    Clayton, NC
    Posts
    381

    911/01 Disassembly and Post Mortum - Comments Welcome

    Hi All,

    I purchased a core 1971 911/01 5-speed transmission (S/N 771xxxx) from an Early S member for my '70 Targa project that I plan to rebuild. The seller didn’t have any history on the trans, as it was from a parts car that was parted out a long time ago.

    I had hoped that the trans had not been previously opened, but probably wishful thinking for something 50+ yrs old. Anyway, I started the teardown yesterday and unfortunately started seeing a few things that did not look correct to me. I’m hoping the experts on the forum can provide some guidance on what needs to be replaced and what can be reused. I am on a limited budget, so I want to make smart decisions on which parts to replace, but avoid stupid one that save me a few bucks.

    I drained the fluid which looked very clear, but upon opening the transmission I saw a black film/slime over some of the internal parts and inside the case. The magnetic plug was filled with sludge and magnetic fur, but no solid particles. I have not started to clean the parts yet, so the pictures below are not very good. My plan is to start cleaning the parts as my time allows over the new few day to better determine the state of the parts and start taking measurements.

    The Transmission:
    Name:  20230724_121542.jpg
Views: 1105
Size:  78.3 KB


    Intermediate Plate and Gear Clusters

    Name:  20230724_142006.jpg
Views: 1092
Size:  117.7 KB

    Name:  20230724_142029.jpg
Views: 1032
Size:  72.2 KB

    Name:  20230724_142726.jpg
Views: 1065
Size:  104.2 KB


    Items that Caught My Attention

    Marks on 1st Gear Sleeve
    Name:  20230729_134433.jpg
Views: 965
Size:  58.1 KB

    Chipped Tooth
    Name:  20230727_135622.jpg
Views: 958
Size:  51.7 KB

    Score marks on Bearing faces - this seems very odd to me. what would cause this?
    Name:  20230729_131304.jpg
Views: 891
Size:  68.0 KB

    Name:  20230729_131635.jpg
Views: 679
Size:  87.7 KB

    Broken Bearing
    Name:  20230729_131234.jpg
Views: 694
Size:  110.3 KB

    Main Shaft is stamped "FB" and PET stated it should be "GA". If GA is correct, then mainshaft was swapped out.
    Name:  20230727_132849.jpg
Views: 679
Size:  67.7 KB


    Thanks for input and more to follow....
    Last edited by denniso; 07-30-2023 at 06:01 AM.

  2. #2
    Restoration newbie.
    Join Date
    Jun 2007
    Location
    San Francisco
    Posts
    1,491
    Can you post more pictures of the pinion gear. There seems to be some damage but hard to tell exactly from the end picture posted.

    andy
    67S in pieces
    EarlyS: 1358
    [SIGPIC][/SIGPIC]

  3. #3
    Senior Member
    Join Date
    Apr 2013
    Location
    Clayton, NC
    Posts
    381
    Hi Andy,

    Thanks for taking a look.

    I'm having a hard time taking pictures of the pinion gear, as I keep get reflections that make it appear there are bad spots on it. I've looked at the pinion gear with a magnifying glass and it looks perfect to me. There are no signs of galling or even scratches. Here is another attempt at a picture:

    Name:  20230731_132356.jpg
Views: 592
Size:  52.9 KB


    Both sides of the differential around the bearings have wear makes which seems odd to me. Here is a picture of the wear marks (it's the same on both sides of the differential).
    Name:  20230731_132519.jpg
Views: 604
Size:  106.1 KB

    Also I see some wear marks on the outside of one of the gears - also seems odd to me:
    Name:  20230731_132624.jpg
Views: 592
Size:  106.1 KB


    Does anyone know if a 911/01 came with "FB" Mainshaft? I only see "GA" in PET.

    Any recommendations on a good bearing supplier for these transmissions? I'm real concerned about getting counterfeit bearings. I may need to but at Porsche unless someone has a solid recommendation.


    Thanks for the help!

    -Dennis

  4. #4
    There is no FB, count the teeth, 18/32 is GA.
    Early S Registry member #90
    R Gruppe member #138
    Fort Worth Tx.

  5. #5
    Senior Member
    Join Date
    Apr 2013
    Location
    Clayton, NC
    Posts
    381
    Hi Ed,

    Hard to get good pics, but it looks like "F B" to me. I counted 18 teeth on the gear.

    Name:  20230731_154447.jpg
Views: 584
Size:  53.7 KB

    Name:  20230731_154530.jpg
Views: 588
Size:  67.4 KB

    Name:  20230731_154740.jpg
Views: 598
Size:  65.5 KB

  6. #6
    Your 1st/reverse spider and shift sleeve should ideally be replaced. Your pinion looks fine in the photos. I would not be terribly worried about any of the wear marks you note, it's 52 years old, stuff rubs. The ding to the input shaft 2nd gear in one of your later photos is a bit of a surprise. If the damage is just to the edge as shown in the photo and nowhere else, you should be fine cleaning it up with a honing stone.

    Just rebuild the transmission properly, fresh bearings and factory set-up, should be ducky.

  7. #7
    Senior Member
    Join Date
    Oct 2010
    Location
    Southern Ca.
    Posts
    1,202
    !st gear sleeve is usable , chipped tooth on reverse 1st gear slider would work but would be noisy , the important part is the wear in the inside of the slider . Broken ball bearing is fairly normal . If money is an issue , buy new ball bearings and use the existing roller bearings and use the 2nd and 3rd gear synchro components for 4th and 5th and vice versa .

  8. #8
    Senior Member
    Join Date
    Apr 2013
    Location
    Clayton, NC
    Posts
    381
    Thanks all for the continued comments.

    I'm wondering if the broken bearing caused the shaft to move and contributed to the wear marks??

    Yeah, this rebuild is going to be pricey. My current plan is to replace:
    4-5 synchros
    4 dog teeth
    2 Shift Sleeves
    Maybe 1st gear slider and shift sleeve. I need to clean and look more closely for wear
    4-6 bearings. I need to clean and look at rear shaft bearings, but suspect they will also need to be replaced. This would make all 6 replaced :-(
    I'm not sure about the stop bands and blocks yet, as I haven't inspected yet. There are threads about upgrading to the later design for these transmissions.

    -Dennis

  9. #9
    Senior Member
    Join Date
    Oct 2010
    Location
    Southern Ca.
    Posts
    1,202
    If you are concerned about money , why would you replace 4-5 synchros ? Shifting to 5th is never an issue and 4th is rarely an issue . Also , do not replace 4th 5th shift sleeve , spend money on 2nd ,3rd and 1st .
    Why spend money on new roller bearings ? You definitely need some guidance . Who's checking the ring and pinion specs or wear pattern ? You are not inspiring any confidence in the rebuild .

  10. #10
    Quote Originally Posted by Richy View Post
    If you are concerned about money , why would you replace 4-5 synchros ? Shifting to 5th is never an issue and 4th is rarely an issue . Also , do not replace 4th 5th shift sleeve , spend money on 2nd ,3rd and 1st .
    Why spend money on new roller bearings ? You definitely need some guidance . Who's checking the ring and pinion specs or wear pattern ? You are not inspiring any confidence in the rebuild .
    Dunno how you can give this advice without seeing what those synchros look like, and how they and their dog rings measure. Same goes for the bearings.

    Just for an example, I just rebuilt a 902/1 for a customer upgrading his 912 from a four to five speed. Although the replacement five-speed was sold to us as low mileage and looked great, the years had taken their toll on everything inside. All bearings, dog rings, synchros, and shift sleeves needed replacement. Some of the bearings were corroded (it had been sitting for many years), others were pitted from use. Except for first gear, the dog rings all looked great... but measured well out of spec with new synchros. As you probably know, with the Porsche-design balk ring synchros, the sleeves wear with the synchros, so they were also replaced. Bottom line is that 901-series transmissions are all fifty or more years old, and unless they've seen some TLC in the meantime, they need it now. Cheers,

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.