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Primary/Transmission/Driveline/ClutchFind answers to general powertrain, primary and transmission. Have clutch issues and need suggestions? Post them here.
So, got to go for a little ride yesterday, and had been wanting to change the case oil since I changed the engine and tranny awhile back and didn't do it at the time for whatever reason. The derby cover bolts seemed pretty loose, and when removed I didn't find an o ring, but a raised flat gasket. Is that a better choice? Seemed so to me, I believe it's an HD part, anyone have the number so I can get a spare or will they know what I'm talking about? Anyway , refilled with a quart minus spillage, 2003 heritage, I tried to torque the derby cover screws to spec with a ft lb wrench, and they started getting really tight, so I stopped, I'll borrow an in lb wrench today, and maybe dab some blue loctite on, or is that needed. Also, How in the world are you supposed to estimate the drain plug? It gives a depth in the manual, for crying out loud. I just tightened it rill it felt ok, right or wrong, it certanly won't fall out, but I didn;t want to get it to far in to interfere with something inside.
Something is not right. Engine (oil bag drain in frame crossrail) and transmission oil drain should have a o-ring but no telling what's been done in past.
O-ring seals in a bevel and a metal to metal enables a torque value to be used on plugs.
On my primary, 04 Softail Deuce, it was a tapered pipe plug. I use tape and just snug. If its tapered , use a sealant for pipe, snug and maybe another tweak.
Some are like the transmission and engine oil bag in frame rail.
The derby cover OEM screws have a torque of 84-108 in-lbs. I use the flat gasket with the red rubber on it.
I just snug them with a 1/4 drive T handle torex socket drive between my fingers and double check warm. I don't use any loctite. Some covers require a face gasket.
Harley dealers usually use new fastners with the white epoxy coat type locking sealant on the derby cover.
That makes them a real hassle to get out.Level the bike and upright and make sure oil level is correct in primary.
It should just touch the outer edge of diaphragm clutch spring. My 04 only required 26 ozs.
It's difficult to see oil level. It's about 1/2" to 3/4" down below derby opening as I recall.
Need a picture of the primary drain plug. What kind of service manual do you have that gives a depth? I have see that a few places on tapered pipe. You definitely do not want to overtighten them. It will crack the part it's screwed in.
Last edited by Jackie Paper; Feb 3, 2026 at 08:09 AM.
NO loctite......and just snug on the derby covers, they dont have any great thing to do except hold back oil.
I also just snug up the drain plugs, no torque or loctite.
He was referencing the oring for the derby cover. There is groove in the primary cover for an oring. Harley also sells a flat gasket you can use as well.
I don't use a torque wench for the primary and oils drain bolts. I just stung them down and a small turn after. Back in the 60's I had a auto shop teacher always say " Don't get strong in the back and week in the mine when tighting bolts" As far as the primary bolts I always change them to Allen bolts
Torx head has more wrenching surface than Allen head.
The biggest issue with Torx heads is a lot of people use the wrong size bit, and also don`t keep the bit straight in the screw head.
To help keep the bit straight in the screw head, use a long extension with the ratchet.
I don`t like any fasteners with internal wrenching, I have replaced all the screws in my primary covers with ARP 12 point stainless fasteners, I use anti seize and decrease the torque to about 70 in lb.
Last edited by Dan89FLSTC; Feb 3, 2026 at 10:12 AM.
I find the derby cover screws one of those that seem to tighten themselves up over time. It always feels like it takes quite a bit more effort to undo them than it did to do them up.
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Primary oil change
