Primary Case Oil Leak Suggestions

I have a new rubber gasket for the primary case but the case still leaks a tiny bit (I know this is pretty normal) I'm wondering if it's a good idea to ad a little bit of gasket seal to the case while remounting it as well? Has anyone tried this with success or do you have any other suggestions? Also if sealer is a good idea, what type of sealer should I use? Thanks!

People freak out when they see the word "silicone" but this is a good place for some. Also Permatex's Right Stuff which hardens more like a good stretchy rubber would be a nice choice. But the trick is to take out the O-ring, run the bead of goo around the groove, replace the O-ring and then put the cover on finger tight only. This squeezes excess goo out from behind the O-ring and allows the O-ring to form to the not so perfect face of the primary cover. Allow goo to harden, remove the cover, clean away excess and replace the cover, this time tightening it down enough to compress the O-ring. The reason you can get away with silicone or Right Stuff in this kind of application is because you are going to clean off the excess and if some where to break free inside the primary, it doesn't block any oiling passage.

I've used sealant to good effect here but it was a real pain to fully remove the sealant when I decided to change the rubber seal. This time I've used Hylomar gasket dressing compound which doesn't set...like a very tacky grease. No leaks.

I remember when I bought my Norton (It was delivered by van) and as it stood in my yard a pool of oil started forming. I though what have I bought now!
Anyway to the point the old seal was hard and square and the new one will more likely be end to end glued with a diameter of 5.5 mm in EPDM which is pretty soft and gives a good seal. You should place the joint of the seal at the highest position to eliminate seepage. Do a dry fit to make sure the primary case seats.
If you have a seal where the excess glue has been sanded off then again the seal will be thinner at that point.

rvich said:

People freak out when they see the word "silicone" but this is a good place for some. Also Permatex's Right Stuff which hardens more like a good stretchy rubber would be a nice choice. But the trick is to take out the O-ring, run the bead of goo around the groove, replace the O-ring and then put the cover on finger tight only. This squeezes excess goo out from behind the O-ring and allows the O-ring to form to the not so perfect face of the primary cover. Allow goo to harden, remove the cover, clean away excess and replace the cover, this time tightening it down enough to compress the O-ring. The reason you can get away with silicone or Right Stuff in this kind of application is because you are going to clean off the excess and if some where to break free inside the primary, it doesn't block any oiling passage.

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Did you put a release down before the silcone to make it so you could take the cover off?

keep joint to top , line bottom half with grey gasket maker , easy off/on and clean up .... works for me

I put red rubber grease on mine and get no leaks.

Plus do not over tighten the centre bolt, a over tighten outer case will cause the cover to warp and hence cause it to leak, but rubber grease works a treat as well and is easy to remove the cover when need to.

Ashley

CraigT said:

Did you put a release down before the silcone to make it so you could take the cover off?

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Silicone under the seal on one half only.

As Ashman said the Key to all of this is shimming the center bolt so that no warpages can occur. All British bikes need shimming. The primary outer cover once shimmed on the support bolt with washers to size should be problem free.

A belt drive solves the oil leak!

CraigT said:

Did you put a release down before the silcone to make it so you could take the cover off?

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No. To be honest, I never thought about it. The high temp silicone actually peals off aluminum pretty easily, which is partly why it doesn't work well for application where it might break off and get into oilways. The Permatex "Right Stuff" is a lot harder to get off. I've not used it in the manner described for the primary oil seal. If one where to choose it for this, some precautions might be in order. Like a spray film of lube on both surfaces. I have been highly impressed with "Right Stuff" for making gaskets for various other items and it forms a nice stretchy rubber. Like any of these products, figuring out what precautions to take with it is appropriate. It's possible this is not a good spot to use it, as it might be hard to clean off, but its good shit.

I realize while writing this that there are things I do as habit that I don't always think about. Making sure a surface is clean when I want a gasket to stick. Wiping down a surface with oil when I don't want it to stick. Stuff like that.

If you put a thin bead of sealant into the o-ring groove, then put in the o-ring but not such that it pushed out excess sealant, and then sprayed or wiped on a lube before compressing. I might have actually done that. It certainly wouldn't hurt the clean up process.

I use regular clear RTV on the outer primary cover. It has to be scraped off with a knife next time it comes apart.

I do not disagree with the use of compounds but we are talking about the O-ring seal the paper gasket is another kettle of fish.
If it was me I would get my cases plan by a machinist the you can forget all sealing compounds.
When I think how often I have my primary open I would be going stark stareing bonkers.
Here is a tip for the adventurous, if you can source O-ring by the meter then make your own.

John

I just use regular silicone, and wipe off any that squishes out. Once applied, I let set for a day before I fully tighten center bolt. I find the silicone easy to remove with a wooden popsicle stick scraper and tool cleaner spray.


Gataby