I have question about how to hold a rubber sealing ring in place when closing two halves of an electronic component.  I'm trying to assemble a backup controller for my ebike.  I want to match up the good front from one controller with the good back from another.  There is a rubber seal to go between them.

The problem I'm having is that the seal won't stay in its groove dry.  Would it be ok to use something like a bit of Vaseline to hold the ring in place?  Maybe something else?

 

Oil degrades rubber.

Not as much as me trying to assemble with a misplaced seal.

Can you suggest something else?  In the meantime, I'll keep looking.

High vacuum grease is the grease to use. Use a small amount in the groove to retain the seal. Also, put a small amount between your thumb and forefinger and coat the entire seal.

If the seal has shrunk, stretch it slightly so it fits naturally in the groove. If it has stretched, place the seal in the groove all the way around with the excess hanging out. Put the two halfs together and while holding them together with slight pressure, push the remaining seal into the groove between the halfs.

 

2 hours ago, Looser101 said:

High vacuum grease is the grease to use. Use a small amount in the groove to retain the seal. Also, put a small amount between your thumb and forefinger and coat the entire seal.

If the seal has shrunk, stretch it slightly so it fits naturally in the groove. If it has stretched, place the seal in the groove all the way around with the excess hanging out. Put the two halfs together and while holding them together with slight pressure, push the remaining seal into the groove between the halfs. 

Yes it´s correct.

We used a little vaseline in the workshop to adjust the rubber seals on the engines that we repaired.

I've dug a little more into the problem.  I was able to insert the seal correctly into the "bad" back.  It lays there correctly but is not held.  So it comes out with any false move.  The seal is the correct size so that's not a problem.  The channel that holds the seal was damaged a bit in the "good" back.  I'll try to clean it up and see if I can make it work.  As I intend to use this controller as a backup, I don't really care that much if it's water proof.  So if I can't fix the channel on the "good" back, I'll just assemble it without the seal.

Thank you everybody for your help and suggestions.

Could you seal it with some silicone caulk?

2 hours ago, dsavitsk said:

Could you seal it with some silicone caulk? 

We used Nural 60 too 

Could you seal it with some silicone caulk?

Silicone would be a great substitute for the rubber seal. Many silicones are acid cure and are corrosive to electronics. You would want to use a neutral cure silicone. GE Silicone II is easy to find and is inexpensive. It's much cheaper than electronic specific silicones.