Header nut size

[Robby]

What is the exhaust header nut size and pitch? Lost one on a ride Sunday. 06FXSTI, TC88
Thanks
Robby

[OldBikerGuy]

I have the same engine. It's as smooth as butter (TC88B - B for Butter). How do you think the header nut got loose? Vibration? Seems weird. Especially if any Loc-tite was used, as it should've been.

[Horse]

Flange nut hd p/n 7593 5/16 24 (i think) no loc-tite use anti-seize (i believe)

[OldBikerGuy]

Well, some of that goopy shit of some sort. I never heard of one coming loose, especially if some goopy retention shit was used.

[Horse]

OBG seen it before I buddy had new Bub's installed and both rear flange nuts came off. Likely the headers were not correctly seated. Removed the rear view mirrors and used the acorn nuts to secure the exhaust to get him home.

[Robby]

Thanks Horse. OBG, heat is what is used to get loc-tight to release so it would not be effective on exhaust. Heat expansion and contraction may be the cause of them coming loose.

[arthureld]

HD doesn't seem to believe in them but a lock washer might help.

[OldBikerGuy]

I think I'll check along with other critical nuts and bolts. I've never had an exhaust flange come loose but I'd like to keep it that way. Be a good time to check the main steering head bolt, too. Those also wreak havoc when they go loose.

[Heretic]

some exhaust pipes get just the right vibration to work them loose...keep and eye on the exhaust bracket. if it is flexing, that is the problem. If locktite is used on the exhaust bolts, and that bracket flexes, the pipe will eventually crack