texasSlick
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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.
1) Remove outer and inner primary chain case covers.
2) 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.
3) 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.
Before going further, it is necessary to discuss sealing materials. If you intend to run oil in the primary, most sealants and adhesives are satisfactory, and you are probably okay with your old favorites. On the other hand, if you plan to run ATF (automatic transmission fluid. my preference), then all the popular sealants including silicone such as RTV, are unsatisfactory. ATF has detergents which degrades the adhesion of RTV, and most sealers and adhesives. A sealer especially formulated for use with ATF is Permatex 81880. Use only this with ATF.
4) Separate the sliding discs. I did mine by drilling out the spot welds that held them together. I advise buying two new discs, AN part no. 06.0769. They are reasonably inexpensive, and new will assure you will have flat surfaces after reassembly.
5) Bond a 1/16” synthetic cork gasket to the inside of the inner cover as shown in Figure 1. I used Gasgacinch which failed after about a year with ATF, and redone withPermatex 81880. The purpose of this gasket is for its thickness (1/16”) to create a drain channel for any oil which may run down and get between the sliding discs, directing the oil fore and aft of the transmission shaft.
6) Drill four holes for 4 #4-40, or #6-32 pan head machine screws to reassemble the sliding discs, replacing the original spot welds. Saturate a new felt washer (pt. No 012443) with oil or ATF, and place it in the cavity on the outer sliding disc. Invert the inner sliding disc so that the pocket meant for the felt washer faces the clutch basket. Assemble the inner and outer discs with the inner primary cover between them 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. The felt washer does little to keep oil in the primary case, but it may help to keep dirt and grit out.
7) 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, or fasten with #4-40 machine screws, nuts, and lock washers, 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 or Permatex 81880.
8) 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.
9) Clean the threaded 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, made in Step 8, 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 swelling of the band 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.
10) 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 #81880.
11) Install the inner cover with gasket made in Step 8. Use a thread sealer on the 3 screws threaded into the drive side crankcase half.
12) 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.
13) Now install the stator basket, using thread sealer on the 3 screws. Route the stator wires thru a grommet sealing the gap with silicone, or Permatex #81880.
14) As instructed in Step 6, the felt washer pocket is facing towards the clutch basket. Inside that pocket, I JB Welded a shaft grease seal (McMaster Carr #5154T61, or 1 1/8" ID x 1 3/8" OD). The seal lip just barely closes over the transmission shaft, when the inner primary cover is fitted (Atlas anyway).
The felt washer is compressed by flipping the inner disk over. This also helps prevent oil migration. Commandos should respond to this treatment as well, although the shaft circlip may be a problem.
15) Install the drive components. Now would be a good time to install one of DynoDaves clutch rod oil seals. His website <<http://atlanticgreen.com/>> shows them to be sold out, so try to contact him by email or phone. Ludwig on this Forum tells how to make your own <<https://www.accessnorton.com/NortonCommando/clutch-rod-seal.36817/#post-617608>>. Check pressure plate lift off, chain tension, etc.
Adjusting the primary chain requires some care: since the grease seal is pliable. When the gearbox is adjusted, the transmission shaft will push the seal and sliding disks off center. The primary chain should be adjusted over-tight, about 1/4" up/down play, then the gearbox moved 5 flats on the adjuster nut towards the front (loosening the chain). The 5 flat turn of the adjuster bolt should re-center the disk and seal. Vibration will help perfectly center the disk and seal.
16) 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.
17) Degrease the oil drain hole in the outer primary cover, and install the drain plug, part # 06.7630, with thread sealer.
NOTE: The following instructions are written for running oil in the primary, and call for using silicone. Many Featherbed fettlers dislike silicone in this application because it tends to "glue" the outer cover on. Red rubber grease is preferred as an alternate. It is your call. If you are running ATF in the primary, you have no choice but Permatex #81880. Apply it as per instructions for silicone.
18) 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.
19) 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.
It is a joy to look under my Atlas and see no oil spots. I hope this works for you!
Questions or comments to make this tutorial better, PM me.
texasSlick
1) Remove outer and inner primary chain case covers.
2) 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.
3) 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.
Before going further, it is necessary to discuss sealing materials. If you intend to run oil in the primary, most sealants and adhesives are satisfactory, and you are probably okay with your old favorites. On the other hand, if you plan to run ATF (automatic transmission fluid. my preference), then all the popular sealants including silicone such as RTV, are unsatisfactory. ATF has detergents which degrades the adhesion of RTV, and most sealers and adhesives. A sealer especially formulated for use with ATF is Permatex 81880. Use only this with ATF.
4) Separate the sliding discs. I did mine by drilling out the spot welds that held them together. I advise buying two new discs, AN part no. 06.0769. They are reasonably inexpensive, and new will assure you will have flat surfaces after reassembly.
5) Bond a 1/16” synthetic cork gasket to the inside of the inner cover as shown in Figure 1. I used Gasgacinch which failed after about a year with ATF, and redone withPermatex 81880. The purpose of this gasket is for its thickness (1/16”) to create a drain channel for any oil which may run down and get between the sliding discs, directing the oil fore and aft of the transmission shaft.
FIG. 1
6) Drill four holes for 4 #4-40, or #6-32 pan head machine screws to reassemble the sliding discs, replacing the original spot welds. Saturate a new felt washer (pt. No 012443) with oil or ATF, and place it in the cavity on the outer sliding disc. Invert the inner sliding disc so that the pocket meant for the felt washer faces the clutch basket. Assemble the inner and outer discs with the inner primary cover between them 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. The felt washer does little to keep oil in the primary case, but it may help to keep dirt and grit out.
7) 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, or fasten with #4-40 machine screws, nuts, and lock washers, 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 or Permatex 81880.
FIG.2
8) 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.
9) Clean the threaded 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, made in Step 8, 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 swelling of the band 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.
10) 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 #81880.
11) Install the inner cover with gasket made in Step 8. Use a thread sealer on the 3 screws threaded into the drive side crankcase half.
12) 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.
13) Now install the stator basket, using thread sealer on the 3 screws. Route the stator wires thru a grommet sealing the gap with silicone, or Permatex #81880.
14) As instructed in Step 6, the felt washer pocket is facing towards the clutch basket. Inside that pocket, I JB Welded a shaft grease seal (McMaster Carr #5154T61, or 1 1/8" ID x 1 3/8" OD). The seal lip just barely closes over the transmission shaft, when the inner primary cover is fitted (Atlas anyway).
The felt washer is compressed by flipping the inner disk over. This also helps prevent oil migration. Commandos should respond to this treatment as well, although the shaft circlip may be a problem.
15) Install the drive components. Now would be a good time to install one of DynoDaves clutch rod oil seals. His website <<http://atlanticgreen.com/>> shows them to be sold out, so try to contact him by email or phone. Ludwig on this Forum tells how to make your own <<https://www.accessnorton.com/NortonCommando/clutch-rod-seal.36817/#post-617608>>. Check pressure plate lift off, chain tension, etc.
Adjusting the primary chain requires some care: since the grease seal is pliable. When the gearbox is adjusted, the transmission shaft will push the seal and sliding disks off center. The primary chain should be adjusted over-tight, about 1/4" up/down play, then the gearbox moved 5 flats on the adjuster nut towards the front (loosening the chain). The 5 flat turn of the adjuster bolt should re-center the disk and seal. Vibration will help perfectly center the disk and seal.
16) 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.
17) Degrease the oil drain hole in the outer primary cover, and install the drain plug, part # 06.7630, with thread sealer.
NOTE: The following instructions are written for running oil in the primary, and call for using silicone. Many Featherbed fettlers dislike silicone in this application because it tends to "glue" the outer cover on. Red rubber grease is preferred as an alternate. It is your call. If you are running ATF in the primary, you have no choice but Permatex #81880. Apply it as per instructions for silicone.
18) 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.
19) 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.
It is a joy to look under my Atlas and see no oil spots. I hope this works for you!
Questions or comments to make this tutorial better, PM me.
texasSlick
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