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Comet Primary Outer Case T5/4 Sealing

craig

Well Known and Active Forum Website User
VOC Member
My Comet primary cases leaks! I have resealed a couple of Comet primary cases over the past year and not had a problem. Clean, remove any dings, make sure no high/low spots, no flycut grooves , or screwdriver marks, no cracks at drain plug, ...etc. Using some Hylomar sealer, assemble...no problem, no leaks. This Comet case appears different or i am getting (or remaining) as stupid as ever. Maybe one drop per hour with case at fill level.
I have cleaned, inspected, used Hylomar, trimmed threads from new SS case screws to assure full pull, cleaned all case tapped holes for swarf, chased threads......the only suspicious item is flycut grooving remaining in the outer case T5/4.
So the advice i get is the time old standard "get glass sheet, smear with grinding compound, figure 8 the case till smooth" and this seems reasonable, but for some reason i dont like it. If you like it , i dont need a retort on the technique, i might use it, i understand it.
I want an alternate method, i do not want to drag a file across the case cover, or an autobody sander.
I am thinking of a large sheet of 400 grit glued to a surface block, but i cant find a large sheet of 400.
any help ?
Cheers
Craig M064PrimaryCaseCovers.jpg
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Craig, Try a Silicone sealer, I have a bad warp in my gearbox joint from welding years ago and it fills a big gap, I won't use it near oil feeds but it is ok for a chain case, Good Luck Bill.
 

timetraveller

Well Known and Active Forum Website User
VOC Member
If you have a surface block large enough to stick abrasive paper to then why not use it first to see if the face is flat? Lighty cover surface block with talc or very thin layer of something else which leave a witness and carefully lower the casting onto it. If not flat then glue two or more pieces of A4 wet or dry to said block and work away. The joint between the two piece of paper will not cause a problem.
 

b'knighted

Well Known and Active Forum Website User
VOC Member
If you don't have a surface plate I am told that you can use marble kitchen worksurface. To save being marmalised by the kitchen's proprieter, visit a maker of such work surfaces. Our "local" manufacturer has a scrap pile of off cuts and sink hole cutouts. they are happy to give them away so long as you are happy to indemnify them against claims for injuries sustained from lifting or sliding lumps. Go by car, you wouldn't want a big lump of marble in your tank bag.
 

vibrac

Well Known and Active Forum Website User
VOC Member
All these lemmings who want a nice marble worktop often get a lump cut out for the sink (often like the one my mum threw out in 1952) that lump is no good to anyone unless you need it as a nice flat surface plate.....
So off to the kitchen fitters with you
 

Howard

Well Known and Active Forum Website User
VOC Member
Hello Craig, Try a Silicone sealer, I have a bad warp in my gearbox joint from welding years ago and it fills a big gap, I won't use it near oil feeds but it is ok for a chain case, Good Luck Bill.

Good tip about oil feeds - I wish you'd told me that in the 70s. Silicone sealant cost me a big end - it doesn't take much to block a low pressure Vincent big end feed.

H
 

alscomet

Well Known and Active Forum Website User
VOC Member
Craig, You are putting too much oil in just put enough in to wet the bottom of the primary chain,I suspect having too much in is leaking out out the gearbox shaft area and looking like a leak from the joint.
Also try some THREEBOND silicone sealant its designed just for this application.Remember if it stops leaking it may have run out of oil , a leak is a good sign of regular maintanance. Alan
 

craig

Well Known and Active Forum Website User
VOC Member
If you don't have a surface plate I am told that you can use marble kitchen worksurface. To save being marmalised by the kitchen's proprieter, visit a maker of such work surfaces. Our "local" manufacturer has a scrap pile of off cuts and sink hole cutouts. they are happy to give them away so long as you are happy to indemnify them against claims for injuries sustained from lifting or sliding lumps. Go by car, you wouldn't want a big lump of marble in your tank bag.
Ian and Vibrac, Excellent tip for a large size surface plate - the sink cutout of a marble or granite kitchen counter top! I have used granite tile from local home repair like Lowes for smaller jobs. Thank you.
Cheers
Craig
 

craig

Well Known and Active Forum Website User
VOC Member
Craig, You are putting too much oil in just put enough in to wet the bottom of the primary chain,I suspect having too much in is leaking out out the gearbox shaft area and looking like a leak from the joint.
Also try some THREEBOND silicone sealant its designed just for this application.Remember if it stops leaking it may have run out of oil , a leak is a good sign of regular maintanance. Alan
Hi Alan, You are correct and i have added the Comet crank seal kit to a couple of Comets to relieve this condition. Let me explain tho, this primary leaking Comet is just being assembled and this is the first oil filled chamber to recieve a fill, just barely enough to meet level, so the leak is all about the bottom of this primary case. (The red tank is just a loaner for fitment puposes. I need a good tank.)
This leak would seem simple, maybe it is, i have been sparingly with Hylomar sealant. I am planning on picking up a kitchen slab and spray glue two 9x11 sheets of 400 (11x18), spray some WD40 for lube, blue the case edge and honing this outer case until it appears flat. Then use Loctite 518 for sealant. Does this sound okay to all? Thank you, Craig

IMG_5250small.jpg
 
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