Exhaust Stud

[Deye76]

Doing some work on my FXR, I had to remove the exhaust, the stud on the rear intake side of the head came out, the nut stayed on the stud. Threads inside the head are OK. No big deal,  I go to the Harley dealer get a new stud. Threads that go into the head are not 5/16-18, like the one that came out. The nut side on the new stud is 5/16-24, but the coarse side must be a proprietary thread. A 5/16-18 nut won't go on it, and it's not a metric thread that I know of. Anyone know what that thread size might be.   

[Hossamania]

Sounds like they gave you the wrong stud. Double nut the old stud to remove the stuck nut to ID those threads as well.

[Deye76]

Did that, the nut side is 5/16-24 fine thread, on the stud that came out, the coarse thread size id 5/16-18, don't know what the thread pitch on the new HD stud coarse side that goes into the head, but it's not the same (5/16-18 that came out of my head). Aftermarket studs don't have the thread sizes listed.     

[Scotty]

16715-83 - 5/16" x 18 x 24 x 1-11/16"

Check what part number they sold you if it is not 16715-83 then it is the wrong stud.

[david lee]

i would have taken the old stud with me when buying a new one

[Deye76]

16715-83 - 5/16" x 18 x 24 x 1-11/16"

Check what part number they sold you if it is not 16715-83 then it is the wrong stud.

Thanks for the part # Scotty.
Who knew a simple stud would be difficult to get, didn't think I was going to need a part number LOL. The dealer parts guy must be new.

[FSG]

why not use the M8 Exhaust Stud?


Exhaust stud HD 10900015A ($0.51 ea.) on left,


[attach=0,msg1280321]

[Scotty]

why not use the M8 Exhaust Stud?
Exhaust stud HD 10900015A ($0.51 ea.)

Now you are just being cheap Gary 

[FSG]

true    but I like the hex on the end,

easy to put it in and hopefully get it out

also lets the nut sit on the end of the stud while you fiddle to get it started   

[Ohio HD]

true    but I like the hex on the end,

easy to put it in and hopefully get it out

also lets the nut sit on the end of the stud while you fiddle to get it started   

Small block Chevy exhaust manifold studs, 1960's to the 1980's were similar, just rounded at the end to let you get the nut going.     

[Scotty]

Small block Chevy exhaust manifold studs, 1960's to the 1980's were similar, just rounded at the end to let you get the nut going.     

Yes the ARP ones have the rounded end as well and easier to get the nuts started.

true    but I like the hex on the end,
easy to put it in and hopefully get it out
also lets the nut sit on the end of the stud while you fiddle to get it started   

I did not even realise that the M8 ones were different until you pointed it out.
Shows how much attention I pay 

[FSG]

Shows how much attention I pay 

I pointed them out as a good move when the M8 came out a few years ago, yeppers missed it, you may have been busy   

[guido4198]

I'm loving the hex on the end..!!
Why did it take this long to get that feature on an exhaust stud..??

[JW113]

Deye, I think the exhaust stud is SAE fine (5/16-24) on the outside, but has a SAE coarse 5/16-18 Aluminum interference thread on the inside. Meaning a 5/16-18 nut will not spin onto it. Similar to the thread type on the case end of the cylinder studs.

-JW

[Mark222]

Yeah, I lost a rear cyl stud nut on a long trip west one year (riding an EVO)

Stopped at the next dealer and the parts counter guys laughed at me for wanting a nut for an Evo stud, so deep into the TC generation.  They said they hadn't stocked them in several years.  Then looked it up on their inventory system to be sure......   

In the end, one of shop wrenches had one in his personal tool box and gave it to me for free to get me moving again.  Funny how something as small as an exhaust stud nut can be so hard to find at an HD location, lol.

Anyway, may you get it right without much drama....

Mark

[JW113]

I might be missing something, but the only thing special about the exhaust nut is the flange on it. Other than that, it's just a 5/16-24 nut. In fact, for some aftermarket exhaust pipes that don't use the floating collar (Cycle Shack, for example), you can't use the stock nuts, and have to use a plain 5/16-24 nut.

Also, I'm pretty sure the exhaust nuts on my TC are exactly the same as the EVO. Why would they be different?

-JW

[Scotty]

I might be missing something, but the only thing special about the exhaust nut is the flange on it. Other than that, it's just a 5/16-24 nut. In fact, for some aftermarket exhaust pipes that don't use the floating collar (Cycle Shack, for example), you can't use the stock nuts, and have to use a plain 5/16-24 nut.

Also, I'm pretty sure the exhaust nuts on my TC are exactly the same as the EVO. Why would they be different?

-JW

Most Evo's from 83 to 96 I think had a nut and washer not the one piece flange nut we have now. They retrofit and that is what they will sell you if you go into the dealer to buy them now. The dealer he went to obviously had a moron working the parts counter 

[JW113]

I can't speak to '90 and earlier, but my '91 had the flange nuts, same as my 2004 RK, p/n 7593.

-JW

[david lee]

i know shovels had a problem with loosing studs and stripping the head threads

[Burnout]

Shovels only have one bolt. The problem comes from folks calling themselves mechanics, expecting one bolt to hold the exhaust on!   

[Scotty]

I can't speak to '90 and earlier, but my '91 had the flange nuts, same as my 2004 RK, p/n 7593.

-JW

Did you buy it brand new?
If not there is your answer as stock on a 91 model is washer part number 6016 and nut 7577
7593 is the superseded part number that comes up on the parts database if they look for part number 7577
Also if you are looking at part microfiche on Ronnies etc they show the superseded part number 

Nut 5/16"-24 Flange
Reference: HD-7593
Brand: Harley-Davidson®
MPN: 7593
Condition: New product
Availablility: 56 Items
Supercedes: 7577
5/16"-24
Flange nut

[Deye76]

Deye, I think the exhaust stud is SAE fine (5/16-24) on the outside, but has a SAE coarse 5/16-18 Aluminum interference thread on the inside. Meaning a 5/16-18 nut will not spin onto it. Similar to the thread type on the case end of the cylinder studs.

-JW

That's likely what the dealer has. The studs that came out of the head don't have that interference thread, the nut spins on easily. So my question is, will I damage the threads inside the head installing the stud with the interference ?

[FSG]

Deye, I think the exhaust stud is SAE fine (5/16-24) on the outside, but has a SAE coarse 5/16-18 Aluminum interference thread on the inside. Meaning a 5/16-18 nut will not spin onto it. Similar to the thread type on the case end of the cylinder studs.

-JW

that they do, at some time in the past I've read it here (not on the internet) in the documentation I have

That's likely what the dealer has. The studs that came out of the head don't have that interference thread, the nut spins on easily. So my question is, will I damage the threads inside the head installing the stud with the interference ?

NO

[Scotty]

What brand of head are they? If they are stock HD then someone may have put different studs in them at one point.
Even with the slight interference fit they don't take much effort to put in.
But you will have to make the decision basd on what you see.

[Deye76]

"What brand of head are they?"

Ultima.

Thanks FSG,