1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Rope Or Neoprene?

Discussion in 'Early CJ5 and CJ6 Tech' started by red61cj5, Jan 19, 2020.

  1. Jan 19, 2020
    red61cj5

    red61cj5 Just fell off the turnip truck!

    wv
    Joined:
    May 16, 2011
    Messages:
    136
    Rear main seal, that is. I have the rope one, watched a video where they rolled it with a socket and slipped it right in. Didn't go that way with me, no surprise there. So reading around the net and find there's a lot of back and forth as to which style is better, from an installation and reliability standpoint. What is the general consensus, if there is one?
     
  2. Jan 19, 2020
    rejeep

    rejeep Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Rochester, NY
    Joined:
    Nov 5, 2009
    Messages:
    1,691
    Neoprene
     
  3. Jan 19, 2020
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
    Joined:
    Apr 4, 2010
    Messages:
    7,110
  4. Jan 19, 2020
    red61cj5

    red61cj5 Just fell off the turnip truck!

    wv
    Joined:
    May 16, 2011
    Messages:
    136
    Easier to install? Or just superior overall?
     
  5. Jan 19, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    red61cj5 likes this.
  6. Jan 19, 2020
    Dave Deyton

    Dave Deyton Member

    Fuquay-Varina, NC
    Joined:
    Oct 12, 2003
    Messages:
    847
    Got some of both in the shop. Waiting for time to install. Good information. I think I'll try the Neoprene seal when I get back around to the 64 F Head.

    Dave
     
  7. Jan 19, 2020
    red61cj5

    red61cj5 Just fell off the turnip truck!

    wv
    Joined:
    May 16, 2011
    Messages:
    136
  8. Jan 19, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
    Joined:
    Jan 23, 2014
    Messages:
    4,170
    I think the neoprene seal is superior. I have cheated when installing one. I loosened all the main bearing caps slightly, allowing the crank to drop a very small amount. This only works with the transmission remove too.
    -Donny
     
  9. Jan 19, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    We got by installing it by having one guy work the seal while the other turned the crankshaft with a wrench on the pulley nut.
     
  10. Jan 19, 2020
    red61cj5

    red61cj5 Just fell off the turnip truck!

    wv
    Joined:
    May 16, 2011
    Messages:
    136
    Engine is out, so hopefully wont have to do that.
     
  11. Jan 19, 2020
    CHUGALUG

    CHUGALUG Member

    Silverton, OR
    Joined:
    May 11, 2019
    Messages:
    238
    ALL depends on the condition of the seal surface on the crank and its diameter. Most machine shops can not grind such a narrow surface I had to go to a true Crankshaft grinding out fit the OLD school kind. And this was in the Portland Oregon Market. Make sure the Diameter falls within the recommended size (do some google searching for Willys Rear main seal crank diameter there is actually an industry alert on this out there to be found). My crank could not be made perfect and remain larger then the min given so I went to the Rope on advise from the Crank grinder.
     
  12. Jan 27, 2020
    red61cj5

    red61cj5 Just fell off the turnip truck!

    wv
    Joined:
    May 16, 2011
    Messages:
    136
    Was trying the neoprene (best gasket 3b71) in the cap and block without the crank in place, just to check fit. Gasket halves stand a little proud on both cap and block. Keeps the cap from sitting flat. I didn't torque the bolts. Is this normal? Anyone ever have to trim? Also, why are the round rubber plugs in the holes on either side not used with other seals? Am I missing something?
     
    Last edited: Jan 27, 2020
  13. Jan 27, 2020
    John Gedde

    John Gedde Been around the block once or twice...

    Middle Island, NY
    Joined:
    Oct 23, 2019
    Messages:
    125
    You didn't say for what engine, but if it's the 225, Neoprene for sure. Not only is Neo just better, but the rope seals from Fel-Pro are too big. I tried several sets and none fit without jamming the crank. The diameter they used is quite a bit thicker than OEM. I gave up with the ropes and went Neo.

    John
     
  14. Jan 28, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    I also had to compress the seal halves a bit to seat the bearing cap. I think this is to help give it a snug seal all the way around. If it was a loose fit you would get leaks.
    I also suspect the rubber plugs are used with all seal types, you need something in there. Perhaps the seal kit you purchased is more complete than some others.
    We used Permatex Aviation #3 on the top surface of the bearing cap between the rubber plugs and the main seal. Just a very thin coat.
     
  15. Feb 5, 2020
    red61cj5

    red61cj5 Just fell off the turnip truck!

    wv
    Joined:
    May 16, 2011
    Messages:
    136
    Im having trouble getting the rubber dowels in on the sides of the rear main. Do you set them in before or after putting the cap on? I cant get mine to go in either way. And still not sure about the seal, seems to be holding the cap up.
     
  16. Feb 6, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    Hmm I don't exactly recall how I set the rubber dowels. I think I got them started before I pushed the cap in. Certainly I drove them up before I fully tightened the cap. Do you have photos of what you are dealing with?
     
  17. Feb 6, 2020
    red61cj5

    red61cj5 Just fell off the turnip truck!

    wv
    Joined:
    May 16, 2011
    Messages:
    136
    I finally got them in. Had to set them in the block side grooves and slide the cap down them. Also smoothing the edges of the cap groove with a file helps, mine were rough and kept catching the rubber. Do you just trim the excess sticking above the deck?
     
  18. Feb 6, 2020
    CHUGALUG

    CHUGALUG Member

    Silverton, OR
    Joined:
    May 11, 2019
    Messages:
    238
    No the Rubber plugs should compress when you tighten the rear cap down.
     
  19. Feb 6, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    Are you asking what to do with the tails of the cylindrical rubber plugs that hang below the block? Like where the oil pan mates? Mine hung below enough that had to do something to be able to install the oil pan. I trimmed them so there was maybe 3/16-1/4" sticking out. That way the oil pan compressed it a bit.
     
    ITLKSEZ likes this.
  20. Feb 6, 2020
    Greevesman

    Greevesman Member

    Napa, Ca
    Joined:
    Oct 12, 2014
    Messages:
    417
    Did you read the FSM? Section D-77 says "do not trim these packings. the packings are of predetermined length that will cause them to protrude approximately 1/4" from the case." I figured Felco or whoever could be depended on to make them the correct length. How can you cut them square or smooth enough to seal. Good luck.
     
New Posts