Why Do My Exhaust Studs Keep Breaking!!!!!
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Seasoned HDF Member
Joined: Apr 2017
Posts: 9,605
Likes: 20,758
From: Globe AZ
Prolly caused by stress in the header by either, the motor bouncing around from bad motor mounts, or strain due to improper placement of hanger bracket. For the later, snug up the studs, loosen the support bracket, and run the motor a bit. Then snug up the hanger bracket.
Im betting that the front motor mount is ****, because that is literally the only thing I havent changed since the studs started breaking..... New heads, new studs, new pipes, still breaking the studs..... hence why Im getting a bit pissed about it. Head gaskets are getting damn expensive for a $2 stud that doesnt want to play ball since there is almost no access to get to the damn thing. This time I did get a mini 90 degree drill adapter and some super shorty bits. As easy as the studs screwed in (finger tight and then a bit to seat on the bulge between thread sets) if I can get any kind of easy out in there it should come out for me. Hasnt been in there long enough to have corrosion issues. Since it broke off just behind the bulge, there should be minimal torque on the remains. Worst case, I rework one of the old heads, and swap the bastard out again if I screw up on the drilling out. I still have the old take off heads, doesnt take much to send them for re-conditioning (except time and $$$) 
Club Member
Joined: Apr 2013
Posts: 5,877
Likes: 3,853
From: Cape Cod
Broke mine too, some one.....PIA to fix, had to pull head.
Found out the front motor mount was getting soft.....
AND the exhaust mount support bracket under the motor before it goes back to the slip ons was loose.
BOTH of these problems led to broken stud.
It'll never let that happen again!!!
Found out the front motor mount was getting soft.....
AND the exhaust mount support bracket under the motor before it goes back to the slip ons was loose.
BOTH of these problems led to broken stud.
It'll never let that happen again!!!
Last edited by MURPHCC1; Aug 1, 2020 at 02:28 PM.
Thread Starter
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Seasoned HDF Member
Joined: Apr 2017
Posts: 9,605
Likes: 20,758
From: Globe AZ
Broke mine too, some one.....PIA to fix, had to pull head.
Found out the front motor mount was getting soft.....
AND the exhaust mount support bracket under the motor before it goes back to the slip ons was loose.
BOTH of these problems led to broken stud.
It'll never let that happen again!!!
Found out the front motor mount was getting soft.....
AND the exhaust mount support bracket under the motor before it goes back to the slip ons was loose.
BOTH of these problems led to broken stud.
It'll never let that happen again!!!
yeah, the front is a major PITA, there is only about 2" clearance. I had one break on the rear head once, and it can be done in-situ if careful. My rear mount on the tranny is new as of 2 years ago when I put the new style (2009+) exhaust on it. Its tight, and in good condition. Its the shitty knock off front poly mount that is what I am questioning at the moment. Ronnies site is down at the moment so finding the part number for the factory piece isnt happening at the moment. As I said above, im getting a bit sick of changing head gaskets for a damn $2 stud.....
Club Member
Joined: Apr 2013
Posts: 5,877
Likes: 3,853
From: Cape Cod
Went with the GLIDE PRO motor mount.
SO much better than stock and should last forever!!!!
Oh...and it's even MORE a pia when you break the EASY OUT IN the stud!!!!!!
A hardened steel EASY OUT inside the soft steel stud, broken off flush!!!!
NO one wants to try to get that out, went to 5 different machine shops and a good friend that is a machinist.
Was looking to get a new jug just because that.
Took a small carbon tipped bit and started drilling, very tight quarters there.
Kept going up in size.
Finally got it to the right size and installed the new stud with some blue locktite.
DID NOT go to the full torque spec tightening the exhaust bolt, didn't want to strip it if it wasn't going to hold.
That was a few years ago and it's still holding up.
GOOD LUCK!!!
SO much better than stock and should last forever!!!!
Oh...and it's even MORE a pia when you break the EASY OUT IN the stud!!!!!!
A hardened steel EASY OUT inside the soft steel stud, broken off flush!!!!
NO one wants to try to get that out, went to 5 different machine shops and a good friend that is a machinist.
Was looking to get a new jug just because that.
Took a small carbon tipped bit and started drilling, very tight quarters there.
Kept going up in size.
Finally got it to the right size and installed the new stud with some blue locktite.
DID NOT go to the full torque spec tightening the exhaust bolt, didn't want to strip it if it wasn't going to hold.
That was a few years ago and it's still holding up.
GOOD LUCK!!!
Seasoned HDF Member
Joined: Aug 2006
Posts: 24,540
Likes: 30,870
From: Pennsylvania
`Ever use a torque wrench? Even when using the proper torque, do you use the proper sequence of tightening progression? Do you run the engine, let it cool and then re-torque the bolts to make sure everything is tightened evenly? Are you sure of the quality of your studs? 
Just for reference: The lower nuts should be torqued to 9-18 in lbs first.Then torque the upper nuts to 100-120 in lbs, then torque the lower nuts to 100-120 inch lbs. 100 inch pounds is about 8.33 foot pounds, even with a 1/4 inch ratchet you may be getting them too tight.
Last edited by CoolBreeze3646; Aug 2, 2020 at 08:57 AM.
Seasoned HDF Member
Joined: Jan 2011
Posts: 157,525
Likes: 57,081
From: Michigan 15 Minutes East Of Hell
Two cents worth ... There's gotta be something we're not seeing / understanding ... Breaking a Grade 8 5/16 stud torqued to @ 10 ft pounds is not an easy task
Thread Starter
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Seasoned HDF Member
Joined: Apr 2017
Posts: 9,605
Likes: 20,758
From: Globe AZ
Ill use the torque wrench this time, but I doubt that its gonna give an accurate torque reading where I use the all steel locknuts on the studs to keep them from backing off. Heat cycling is a bitch, but still shouldnt cause enough expansion in the head/pipe/flange to snap off a grade 8 stud with alarming regularity. something else is at play here, and Ill be damned if I dont figure it out......
Seasoned HDF Member
Joined: Jan 2011
Posts: 157,525
Likes: 57,081
From: Michigan 15 Minutes East Of Hell
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Thread Starter
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Seasoned HDF Member
Joined: Apr 2017
Posts: 9,605
Likes: 20,758
From: Globe AZ
will do. its gonna take a couple of weeks until I get it done. Between ordering parts and work....... Since I have to pull one of the heads anyways, I went off the deep end and am putting 2006+ heads back on. Its only money anyways....... Ordered a new Harley front mount. will go and pick it up here tomorrow most likely. today is dedicated to day drinking and keeping the wife from finding out I spent more money on the damn bike. She about **** herself when she found out what I spent the last go round......
Seasoned HDF Member
Joined: Jan 2011
Posts: 157,525
Likes: 57,081
From: Michigan 15 Minutes East Of Hell
"keeping the wife from finding out I spent more money on the damn bike" ... Make a you tube video of your successful endeavor regarding this ... You could make a fortune :>)"