Help with derby cover leak
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Intermediate
Joined: Oct 2010
Posts: 34
Likes: 0
Help with derby cover leak
Good evening folks,
Bought my 98 Fat Boy in Oct/10 knowing that it had a leak from the derby cover. Assumed that it was an easy fix with a new gasket but since the bike would be sitting all winter, just got around to changing it last week. Had to order one of the 3 hole disc type gaskets from the dealer. Upon removal of the cover, I found that the old gasket (not disc type but a paper gasket) was pretty trashed. There was also a large o-ring in a channel on the inside portion of the primary. The derby cover is one of the ones that has "Harley Davidson Motor Co" in large black letters. So I re-seated the o ring and installed the new disc type gasket, put the cover on and hand tightened the bolts. Was installing my new detachable windshield tonight and had the bars turned to the right and it caused the bike to lean further to the left and after a while I noticed a puddle of oil on the floor so it's still leaking.... Don't think I over tightened them but is it possible that I still didn't tighten them enough? Should I have removed the o-ring all together?
Any suggestions are appreciated!
Thanks
John
Bought my 98 Fat Boy in Oct/10 knowing that it had a leak from the derby cover. Assumed that it was an easy fix with a new gasket but since the bike would be sitting all winter, just got around to changing it last week. Had to order one of the 3 hole disc type gaskets from the dealer. Upon removal of the cover, I found that the old gasket (not disc type but a paper gasket) was pretty trashed. There was also a large o-ring in a channel on the inside portion of the primary. The derby cover is one of the ones that has "Harley Davidson Motor Co" in large black letters. So I re-seated the o ring and installed the new disc type gasket, put the cover on and hand tightened the bolts. Was installing my new detachable windshield tonight and had the bars turned to the right and it caused the bike to lean further to the left and after a while I noticed a puddle of oil on the floor so it's still leaking.... Don't think I over tightened them but is it possible that I still didn't tighten them enough? Should I have removed the o-ring all together?
Any suggestions are appreciated!
Thanks
John
Last edited by Johnny423; Apr 6, 2011 at 10:07 PM.
Road Warrior
Joined: Jan 2007
Posts: 1,276
Likes: 8
From: Minneapolis Area, MN
As Havoc said...it either the o-ring OR the gasket (frisbee style).
Chance are you now need a new derby cover as yours is likely tweaked from over tightening. Pull it off and lay the sealing surface on a fairly flat surface and check for warpage. A little warp will seal, but too much and you get the leak. It is possible to get it flat enough for the gasket to seal if you just tighten the screws enough. If warped beyond just a little, the o-ring will never seal it.
If you can't get the gasket to seal you'll need a new derby cover. If you get the type that has a wide sealing surface I'd recommend sealing with the o-ring. The o-ring is more forgiving to over tightening of the screws without warping the derby cover.
The problem that I have with the gasket is that you have to be extremely careful about not torquing the screws too much. If so, you end up with a warped derby cover.
Chance are you now need a new derby cover as yours is likely tweaked from over tightening. Pull it off and lay the sealing surface on a fairly flat surface and check for warpage. A little warp will seal, but too much and you get the leak. It is possible to get it flat enough for the gasket to seal if you just tighten the screws enough. If warped beyond just a little, the o-ring will never seal it.
If you can't get the gasket to seal you'll need a new derby cover. If you get the type that has a wide sealing surface I'd recommend sealing with the o-ring. The o-ring is more forgiving to over tightening of the screws without warping the derby cover.
The problem that I have with the gasket is that you have to be extremely careful about not torquing the screws too much. If so, you end up with a warped derby cover.
Road Captain
Joined: Mar 2009
Posts: 734
Likes: 0
From: Southern Missouri ( ozarks)
I'm a little confused over the 2 different gaskets there.My 98 only has the rubber O ring.Last winter when I changed the fluids,I had a hard time getting it sealed.I finally added just a tad of gasket sealer to help hold the O ring in place,carefully put the cover on ,tightened,and all was ok after that. Look at that O ring carefully,if the cover was put on and the O ring slipped out of the groove,it may have flat spotted the O ring enough to let fluid leak out at that spot.
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Outstanding HDF Member
Joined: Aug 2010
Posts: 3,486
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From: Union,Ms
I worried with my derby cover for years leaking. I left the o-ring on with the gasket on top of it. Problem leak stopped.
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Road Captain
Joined: Mar 2009
Posts: 734
Likes: 0
From: Southern Missouri ( ozarks)
Like I said Mike,mine never had a "gasket",just the O ring,what's it look like?
Outstanding HDF Member
Joined: Aug 2010
Posts: 3,486
Likes: 6
From: Union,Ms
It's a gasket the Harley shop sells now that's the same size as the inside cover. You can only use it one time. I guess the reason the TC's went to the 5 hole cover was all the trouble the evo guys have with that derby cover leaking.