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How to Make the Atlas/Dominator Primary Oil Tight

Discussion in 'Other Norton Motorcycles' started by texasSlick, Jan 7, 2019.

  1. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    I don’t think anything has sold more belt drives than the Atlas/Dominator chain case proclivity to leak. The pressed steel chain case can be made oil tight.

    Remove outer and inner primary chain case covers.

    Inspect the inner cover sealing flange. There should be no dents or ripples, and the flange should be at a right angle to the back plane. If you hammer out small dents and ripples, do not consider yourself done! The sealing flange must be smooth and free of peaks and valleys. Apply a smear of JB Weld (scrupulously cleaning and de-greasing the surface first) and sand smooth.

    Inspect the outer cover. Most likely, PO’s overtightened the big nut in an effort to quell the leaks. If the cover appears to be “dished in” around the foot rest hole, press it back with an arbor press.

    Separate the sliding discs. I did mine by drilling out the spot welds that held them together.

    Bond a 1/16” synthetic cork gasket to the inside of the inner cover as shown in Figure 1. I used Gasgacinch. The purpose of this gasket is for its thickness (1/16”) to create a drain channel for oil which may run down and get between the sliding discs, directing the oil fore and aft of the transmission shaft.


    InnerPrimaryCover5.png


    FIG. 1​


    Saturate a new felt washer (pt. No 012443) with wheel bearing grease and place it in the cavity on the inner sliding disc. Assemble the inner and outer discs with 4 small pan head screws, 4-40 or 6-32, using red Loctite and tightening the nuts until there is a snug sliding fit

    This is a convenient time to do a modification that does nothing to keep oil in the chain case, but will keep the drive side of the crankcase clean from rear chain oil and lube that is flung forward as the chain rounds the transmission drive sprocket. Pop rivet a “U” or “L” shaped extension to the inside flange of the inner cover as shown by the red highlight in the following Fig. 2. Pop from the inside and seal the rivet heads with silicone.

    upload_2019-1-7_14-15-45.png

    FIG.2​

    Make a gasket of 1/32” synthetic cork for pt. No. 06.7779. I have found synthetic cork seals when all other materials, even with sealers, fail. I used the same 1/16” cork that I bonded to the inner cover as explained above, but had a slight interference fit when mounting the stator basket. The interference was easily rectified with a Dremel tool, but 1/32” thickness material will avoid the problem. MSC, and McMaster-Carr stock 1/32” synthetic cork, whereas 1/16” can be found in any auto parts store.

    Clean the treaded holes in the crankcase with an oil solvent (3 for the inner cover and 3 for the stator basket).

    I do not think synthetic cork requires a sealer, but it is your call …. If I were to use sealer, I would bond the gasket to the inner cover. That way, a future removal of the cover will leave the crankcase surface clean. If you opt to bond the gasket to the inner cover, wait until the completion of the next step.

    Now, let us digress into a discussion of the sealing band, pt. No. 06.7627. These bands “stretch” after being in service. Even the Norton Owner’s Manual suggests removing about ½” to bring the size down, placing the cut on the top of the inner cover flange. I have long mused over why these bands stretch so much …. It is only necessary to stretch them about 1/8” to pass over the flange, so why do they stretch as much as ½”? I recently concluded, rightly or wrongly, that the elastomer material that the bands are made of, is intentionally selected to swell on exposure to heat or oil, or both. When the band is sandwiched between the inner and outer covers, the swelling can go nowhere, but the band is under compression which increases the sealing pressure on the mating parts. When the outer cover is removed, the band expands in all directions, giving the appearance of having stretched. Thus, if the band is reused by removing a piece, one should not expect the band to continue swelling, and the additional sealing pressure from such swelling is lost. Therefore, always use a new band!

    RGM sells a band that has an additional 1/16” sealing lip on the outer edge of the band. I do not know if this lip is effective at increasing the band’s sealing quality, but I installed one in my Atlas.

    Next step: Bond the band to the inner cover flange. Do not use a contact type adhesive, at least not in contact mode. The band must have the stress of being stretched over the flange evened out by working and smoothing all around the circumference. I used Permatex High Tack Sealant.

    Install gasket Pt. No. 06.7779 and the inner cover. Use a thread sealer on the 3 screws threaded into the drive side crankcase half.

    Install the outer cover temporarily to provide clamp pressure on the band. As you tighten the big nut, tap all around the circumference of the outer cover with a rubber mallet or the palm of your hand. Tighten the big nut until 1 ½ to 2 threads are visible. Allow 12 to 24 hours for the band adhesive to dry.

    Now install the stator basket, using thread sealer on the 3 screws. Route the stator wires thru a grommet sealing the gap with silicone.

    Install the drive components. Now would be a good time to install one of DynoDaves clutch rod oil seals. Check pressure plate lift off, chain tension, etc.

    Install felt washer Pt No. 042055 inside cover to foot rest tube. Make a synthetic cork gasket to replace Pt. No. 06.7882, the sealing washer under the inspection cap. Be sure to put a small vent hole in it.

    When all is ready for fitting the outer cover, place a generous bead of silicone around the circumference of the sealing band on the outer edge, the 3/8” thick edge.

    The outer cover has a shoulder which, when assembled, comes in close proximity (about 1/8”) to the edge of the sealing band. Place a bead of silicone on that shoulder. The object is to have both beads merge and fill that 1/8” void. If that gap is successfully sealed, no oil can get to the flat wide part of the band that should do the sealing work. Just for good measure, smear silicone on the lower flange of the outer cover, and half way up each side.

    Install the outer cover as was done to apply clamp pressure above. Allow 24 to 48 hours for the silicone to cure before adding oil.

    I use Type F ATF. With the bike on the center stand, add oil and rotate engine with the kick starter (spark plugs removed for ease), while checking for oil to appear on the upper chain run. Check with a finger thru the inspection hole. Stop adding oil as soon as the chain begins to pick up oil. The right amount of oil is about 7 oz. or 200 ml.

    I hope this works for you!

    Slick
     
    Last edited: Jan 7, 2019
  2. norton bob

    norton bob

    Joined:
    Nov 29, 2013
    I have done the job the same way but found the case very difficult to remove later and scraping rubbery sealant off the surfaces a real pain. I have refitted mine using only Red Rubber grease (bought a 500g tin for £8 .) Seems to resist oil, no leak worth a worry. No pool under bike.
     
  3. Gilesy

    Gilesy VIP MEMBER

    Joined:
    Aug 27, 2017
    Me too, red rubber grease and no leaks. Also easy to remove and refit.
     
  4. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    @norton bob and Gilesy

    I appreciate your comments and welcome those of others. The purpose of this thread is to get leak tight Atlas/Dominator primaries. A combination of techniques may prove to be best.

    FWIW ..... The cover is not difficult to remove with my method, most of the stuff ends up concentrated on the 3/8" edge of the band. The smear I suggest applying to the outer cover flange ends up there as well (squeegied there by the lip of the band). That smear is for those who might have dented or distorted outer covers. After removal of the cover, the silicone peels off easily and cleans up readily with mineral spirits.

    I am not familiar with your red rubber grease, but I intend to look into it.

    Slick
     
  5. Gilesy

    Gilesy VIP MEMBER

    Joined:
    Aug 27, 2017
  6. norton bob

    norton bob

    Joined:
    Nov 29, 2013
    Red Rubber grease still working , did get a leak from front of case when bike carried in van and left in nose down attitude. Think the band could do with shortening. All working too well to disturb.Up to ears in Atlas engine at present. I will try Slick's oil deflector next time .
     
  7. Peavey Jeltz

    Peavey Jeltz

    Joined:
    Jan 12, 2019
    Red Rubber grease for the short term win. It's not 100%, if I wipe the bottom of the chaincase after a run, it's a little wet. Somewhere around 6oz type F ATF. I'll probably give in and use glue, but I'm gonna put a couple hundred more miles on it first and see.
     
  8. Bodger

    Bodger VIP MEMBER

    Joined:
    May 9, 2017
    FWIW I think the key is to make certain that the chain case cover is not deformed. All of these bikes are over 50 years old. At some point some owner has succumbed to the urge to put a couple of extra turns on the large nut that secures the cover. I mean who hasn't thought, at one time or another, despite the no more than 2 threads showing rule, that a couple of extra can't hurt? (And don't think I'm holding myself out as the exception.) If the cover is flat it may weep a little but it will be more than acceptable no matter what grease, magic elixir, or other sealing solution you use.
     
    texasSlick likes this.
  9. Bodger

    Bodger VIP MEMBER

    Joined:
    May 9, 2017
    BTW I also use Type F ATF. Every once in a while when I get paranoid I push a stiff electrical wire with white insulation down through the inspection cover to the bottom of the chain case and check it like a dip stick just to make sure all the ATF hasn't escaped.
     
    Peavey Jeltz likes this.
  10. elefantrider

    elefantrider VIP MEMBER

    Joined:
    Apr 6, 2013
    I think the best solution is no oil in the case while using an o-ring chain.
     
  11. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    AMC type clutch has rollers and requires oil.

    Absolute best solution is belt drive, but I meant this discussion to be a solution for the original set up.

    Thanks for posting anyway.

    Slick
     
  12. Peavey Jeltz

    Peavey Jeltz

    Joined:
    Jan 12, 2019
    Bodger, Indeed my outer primary had been over-tightened. As advised by Slick, I pressed out the area around the footrest hole just a bit. The rest of the outer primary and inner looked fairly straight. Haven't bothered with the rest of the mods yet. Maybe someday I'll switch from the 19T sprocket to something bigger. Good idea about the "dipstick" for the primary.
     
  13. elefantrider

    elefantrider VIP MEMBER

    Joined:
    Apr 6, 2013
    There are many Manx and Dominator Atlas racers running o-ring chains with open primaries so I don't think clutch lubrication is a problem.
     
    Last edited: Jun 14, 2019
  14. Bodger

    Bodger VIP MEMBER

    Joined:
    May 9, 2017
    Elefantrider, curious about your experience running an o-ring primary. How many miles? I tried it for a while but got nervous about the chain running hot and lack of cooling (assuming there is any) from oil or ATF on the alternator and lack of lubrication on the clutch . Not at all certain that my concerns were justified so would like to hear your experience.
     
  15. 1down5up

    1down5up

    Joined:
    Oct 17, 2014
    I have been running an x-ring chain for about 5 months now, I did put some atf in the chain case as I was concerned that the chain would run to hot up against the motor and with no airflow, but it proceeded to run out after my first ride like it normally does (new band but believe my outer is warped)

    I prob haven't done enough miles on it to form a solid opinion but so far so good, minimal if any real stretch.

    I will prob run an open primary to increase airflow when I get around to making one
     
  16. elefantrider

    elefantrider VIP MEMBER

    Joined:
    Apr 6, 2013
    I was just responding to the clutch lubrication concern. This thread is for those who wish to seal up their Atlas case. I have the same chain and clutch but a Matchless case which has been detailed in other threads.
     

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