1969 Commando Gearbox Gasket

I have gone through several old gasket topics and are not finding one that addresses what I've found or a solution.
After removing the cover on the gear box to replace the o-ring around the kick starter I found the mating surfaces pretty scared up, apparently from either previous heavy handed removals or just crude machining? I have a new Andover gasket to install but am concerned about the scratches and them preventing a good seal without the use of a sealer.
The gasket looks of very good quality and may indeed form to the small scratches and seal just fine.
Should one use a sealer with the gasket? If so, would you use sealer on one or both sides of the gasket? Or should you never use sealer with a gasket?
I have Locktite 518, Permatex Blue RTV, and Permatex Ultra Blue on hand maybe non of which are recommended?

I would really appreciate hearing from you guys that have gone through this task many many more times than I.

If you dress the surfaces enough to make them flat and the scratches on the mating surfaces are not excessively deep and don't go from the inside edge to the outside edge in a straight line, the Andover gasket could work without sealant, but I would not guarantee it. If the same situation is true and you use one of the JS Motorsport fiberglass reinforced rubber gearbox gaskets, it will seal without any sealer, and they are reusable. I've only had that outer cover off 3 times, but the last two times were with the JS Motorsport gasket. No leaks. Maybe not what you wanted to hear, but the product works if you are looking for something that works.

Thanks for the info, and good to know about this supplier. I was just hoping to use what I had somehow.

That Andover gasket should work. I didn't mean to sound like it would not. I don't have a sealer recommendation though. I believe what I used with the thin paper gasket I had on it prior to using the JSM gasket was Gasgacinch. Not fun to clean off that gasket 30 years later, so not recommending it.

Thanks Schwany. I probably committed the ultimate gasket sin and put a thin bead of 518 on both milled surfaces with the gasket in between. Those scratches are really concerning and some do go all the way across. I'm guessing this gasket will not be reusable. If I have to remove it again and its trashed I'll try the one you mention. Thanks for your help!

Permatex Motoseal 1 is my gasket compound of choice. A smear of that on the surface, and it will stop just about anything from leaking. Good for between the crankcase halves as well. I have been using it for over 20 years.

Those JS motorsport gaskets certainly do work well in my experience. However if yiu want to stick with what you have any RTV gasket cement will work fine on a gearbox. I would never use it on an engine which has oil ways but on a gearbox there are no small holes to block.

Thank you for sharing your experience!

I don't recommend using any sealer on transmission gaskets. Actually, I spray paper gaskets with Dupont chain saver with teflon so they don't stick. Sprays on clear, can't tell. Hate scraping off stuck gaskets. If you need to use a sealer, Hylomar also comes off easy with brake or carb cleaner

The scratches probably come from people scrapping off gaskets with metal knifes or tools. I use plastic non marr "Bojo" brand scrapers to remove gasket material that has been glued on.

elefantrider said:

I don't recommend using any sealer on transmission gaskets. Actually, I spray paper gaskets with Dupont chain saver with teflon so they don't stick. Sprays on clear, can't tell. Hate scraping off stuck gaskets. If you need to use a sealer, Hylomar also comes off easy with brake or carb cleaner

The scratches probably come from people scrapping off gaskets with metal knifes or tools. I use plastic non marr "Bojo" brand scrapers to remove gasket material that has been glued on.

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Scratches can also come from people using milled face framing hammers and long screw drivers to separate the cases.

I should get a set of the BOJO scrapers. Thanks for the tip.

I have had some luck "filling" some nasty gouges on other things with JB Weld. Need to do some judicious clean up with q-tips and solvent before it dries and finish later with some wet dry.