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Discussion Starter #1
I just pulled my V&H Bigshots (Retro model), pulled one stud with the acorn nut attached, and I read all of the posts on this and related problems. I think the stud/acorn nut combo is lousy, so I decided to replace the combo with S/S allen head bolts (someone else's recommendation -- can't remember who). Previous threads, however, didn't answer my Q"s below:

Q1: The stock studs are 8mm x 25mm. Is there any reason why using the same size allen bolt won't work, with or without the use of washers to ensure proper depth, i.e., 8mm x 25mm allen bolt?

Q2: Is there any problem with using S/S bolts in the Al heads, even with the use of high temp never-seize? If so, are there any problems using chromed bolts instead, w/ or w/o never-seize?

Q3: Would you recommend using "button head" allen or standard allen head bolts?

Sorry if the answers are obvious. I'm a rank beginner wrencher and I'm doing my best to learn from scratch.

Thanks,
Steve
 

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The problem you may run into is bottoming out that bolt before you tighten the exhaust. Just get new studs and some stainless nuts(not acorn) and a washer to use. Never have to worry about bottoming anything out that way. 8)

But , yes, doing that would work if the bottoming out doesn't happen again.
 

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Dr. Reid,
I had the same thing happen- all (4) of the studs came out, as I was removing the exhaust to black out the engine and file and polish the fins (looks FANTASTIC!).. The crown nuts were ALL securely bottomed and jammed on the studs. I tried breaking just (1) loose, but it was so bad, decided to get all NEW instead. Go to ACE HARDWARE: They have the studs you need (m8 x 1.25). They are black, and hardened. They may be a hair shorter, not sure. They also have chrome M8 crown nuts, which have a full .500" of M8 threads. Using these (4) new sets, and anti-seize on EVERYTHING, first double-nut all the new studs and tighten them into the block...tight...15-20 ft./lbs. min. Now, with new exhaust gaskets, and the STOCK exhaust back in place, I had .200" sticking up above the exhaust flange. (it felt like a little less). And the exhaust gaskets can compress NO MORE than .150", and also the flange can't tighten toward the head more than .150" before hitting the machined faces near the studs,.....SO.......300" available thread to tighten down the crown nuts; and .150" either to smash the gasket or for the flange to hit the next surface (even if the thick flange bends just a little). THE 1/2" THREADED M8 CROWN NUTS FROM ACE, COULD NOT BOTTOM OUT.
It's the way I went to re-mount the stock headers, all thread lathered with anti-seize, and have re-torqued about 4 times over the last 2 days to 17 lbs. works great.
Oh, and here's a very important point: The torque values were designed to occur with studs first mounted to the manifold, then torquing only the prepared crown nuts against the flange. THIS IS GIVING YOU A TORQUE VALUE OF STEEL AGAINST STEEL (Nut against the stud), and not throwing in a SECOND value, of the steel studs threading in the aluminum! Also!... if you were to fully thread the studs into the crown nuts first, you'd be bearing down, pretty hard, on SHORTER threads, going into the ALUMINUM block. Not good. Bottom and tighten the studs FIRST.
Ace has your stuff.
 

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Discussion Starter #4
GA_VTXTC said:
Dr. Reid,
I had the same thing happen- all (4) of the studs came out, as I was removing the exhaust to black out the engine and file and polish the fins (looks FANTASTIC!).. The crown nuts were ALL securely bottomed and jammed on the studs. I tried breaking just (1) loose, but it was so bad, decided to get all NEW instead. Go to ACE HARDWARE: They have the studs you need (m8 x 1.25). They are black, and hardened. They may be a hair shorter, not sure. They also have chrome M8 crown nuts, which have a full .500" of M8 threads. Using these (4) new sets, and anti-seize on EVERYTHING, first double-nut all the new studs and tighten them into the block...tight...15-20 ft./lbs. min. Now, with new exhaust gaskets, and the STOCK exhaust back in place, I had .200" sticking up above the exhaust flange. (it felt like a little less). And the exhaust gaskets can compress NO MORE than .150", and also the flange can't tighten toward the head more than .150" before hitting the machined faces near the studs,.....SO.......300" available thread to tighten down the crown nuts; and .150" either to smash the gasket or for the flange to hit the next surface (even if the thick flange bends just a little). THE 1/2" THREADED M8 CROWN NUTS FROM ACE, COULD NOT BOTTOM OUT.
It's the way I went to re-mount the stock headers, all thread lathered with anti-seize, and have re-torqued about 4 times over the last 2 days to 17 lbs. works great.
Oh, and here's a very important point: The torque values were designed to occur with studs first mounted to the manifold, then torquing only the prepared crown nuts against the flange. THIS IS GIVING YOU A TORQUE VALUE OF STEEL AGAINST STEEL (Nut against the stud), and not throwing in a SECOND value, of the steel studs threading in the aluminum! Also!... if you were to fully thread the studs into the crown nuts first, you'd be bearing down, pretty hard, on SHORTER threads, going into the ALUMINUM block. Not good. Bottom and tighten the studs FIRST.
Ace has your stuff.
GA, thanks for such a detailed reply, which again raises the question, several times entertained on this board before, of whether (1) to torque the studs into the heads, as you recommend, or (2) merely thread them into a specified depth (finger tight or ~ 5ft/lb), as I have read about before. (If I read your reply right, you were concerned primarily about the acorn nuts themselves 'bottoming' out on the studs. I was interested by contrast in avoiding bottoming out the bolt -- my alternative method -- in the cylinder head.)

I believe that scenario (2) pertained, with the added provision that tightening the stock acorn nuts would 'tension' the threaded portions of the studs within the heads. Have I got that wrong?

If not, then I am still interested in my alternative solution to avoid the hassle of acorn nuts, or using any nuts for that matter. Just one bolt not long enough to hit the end of the hole in the head. Seems like an 'ok' idea. I ordered 8x25mm bolts today. Should have them by the weekend, when I will see if they work. I asked Q1-Q3 to help me avoid making any dumb mistakes (worse than dumb questions, I guess :lol: ).

Steve
 

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Just get a regular nut that has a hole in it for the threads to pass through and nothing will bottom out. Ace hardware has the ehaust studs in stainless, bring the old ones to be sure you get the right size and get stainless nuts to go on them. No problems with anything bottoming out. 8)
 

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Are you guys using a standard stainless hex nut or the ones with the lock flanges? Do you need to add a lock washer with a standard flangeless nut? Is it worth getting stainless studs if I have already ordered the factory studs from the "stealer"?
 

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Sorry for the long reply,
I would use the stock hardened(non-stainless studs). Stainless has a habit of galling after being subjected to extreme heat. The next time you go to take it apart it WILL pull the studs again. It is NOT a good idea to thread bolts in to replace the studs. The pupose of studs is ease of replacement and torque loading. If you use the hardened studs with a stainless washer and acorn nuts, you'll have the perfect setup. As far as locktite, you can and I would use Blue(very low strength) locktite, on the end that screws into the head. Hand tighten the studs into the head and reinstall the exhaust. Use only a small amount of anti-seize on the acorn end, no need to slather it on. A little goes a long way.

The biggest problem with using bolts instead of studs is if you accidentally cross thread a bolt, you are screwed. The studs will allready be in place, nothing to crossthread into a very expensive engine. There is a reason why almost every engine manufacturer uses studs and NOT bolts. There is also a reason why most don't use stainless. JMO from 20+ years of turning wrench.

Jon
 

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I lost track of this thread and meant to post an "Oops". The studs I got at Ace are not stainless, just hardened like Jon's1800VTXC has said. Just the nuts and washers are stainless. 8)
 

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Discussion Starter #10
Jon's1800VTXC said:
Sorry for the long reply,
I would use the stock hardened(non-stainless studs). Stainless has a habit of galling after being subjected to extreme heat. The next time you go to take it apart it WILL pull the studs again. It is NOT a good idea to thread bolts in to replace the studs. The pupose of studs is ease of replacement and torque loading. If you use the hardened studs with a stainless washer and acorn nuts, you'll have the perfect setup. As far as locktite, you can and I would use Blue(very low strength) locktite, on the end that screws into the head. Hand tighten the studs into the head and reinstall the exhaust. Use only a small amount of anti-seize on the acorn end, no need to slather it on. A little goes a long way.

The biggest problem with using bolts instead of studs is if you accidentally cross thread a bolt, you are screwed. The studs will allready be in place, nothing to crossthread into a very expensive engine. There is a reason why almost every engine manufacturer uses studs and NOT bolts. There is also a reason why most don't use stainless. JMO from 20+ years of turning wrench.

Jon
Funny you should say this: I visited my (trustworthy) dealer on Friday. He said exactly the same thing as you: don't mess with bolts, just use studs. The only difference, as noted in previous posts, is that you should use anti-seize, not loctite, on the threaded portion that goes into the engine.

Bringing my experience to a nice close: Since I had 3 good studs still in the engine, I just bought one steel stud from a local h/w store along with 4 new acorn nuts. For good measure, I bolted in my pipes using 1-2 lock washers per stud/acorn nut combo. I have put on ~150 miles so far with no problems whatsoever, after re-torqueing the nuts to 17 ft-lb following my maiden voyage.

Steve

p.s. I was clueless when I started this. Thanks for everyone's help.
 

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That is why in the industry we use Blue (very low strength) it will come out easily. I've been using the stuff for 20+ years on bikes, cars, trucks, and buses.
 

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I believe I somehow managed to cross thread the screw hole in the engine for the exhaust. I really don't know how but the stud will not go in far enough to keep the exhaust tight to the engine. I believe I can either get a shorter stud or possibly grind out the area that is cross threaded and use the old stud (it is fine). Any thoughts on which method is better or any reason I shouldn't do one, the other, or both? thanks in advance.
 

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cross thead

im not sure about the grind on it comment.what you need to do is pull out the stud, check the thead size 8mmx1.25 is the thread pitch i think,but ck. tap out the exhaust hole with a bottoming tap. get a new stud, add loctite blue to the threads & install the new stud.let it sit overnight & add exhaust,good as new.if your not sure about the thread pitch or size you can take it to any good auto parts store & they will be able to measure it & get you the correct tap.:tools:
 

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Don't try to drill out any damaged threads. Get a tap and chase the threads.
 

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Thanks guys. I'll give it a shot in the morning. Hopefully it works and I can ride all day Sunday.
 

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A Couple of year ago this same discussion came up. There was some debate about using a thread locker such as Loctite. I placed a call to their technical department and spoke with them regarding the use of a thread locker on the exhaust bolts/studs. First here's a C/P from their website...I know it's not a complete answer..

All such joints are considered to be dynamic due to vibration, changing pressures or changing temperatures. Loctite® anaerobic sealants cure to insoluble tough plastic thread fillers which prevent leakage regardless of the torque applied. Thread lockers are single component anaerobic which completely fill the microscopic gaps between interfacing threads. They polymerize (1 : a chemical reaction in which two or more molecules combine to form larger molecules that contain repeating structural units
to a tough solid when they come into contact with metal in the absence of air.

OK after you've read that (the above) think about something.....when you want to remove a bolt or nut that has had a thread locking sealant applied you use heat to soften it before removing the bolt or nut. If you don't in some cases you will twist off the head.

Now getting back to Loctite; Headers/exhaust operate a high heat temperature. How is loctite going to work when basically it's plastic and looses it's integrity when heated?

Getting back to the Loctite technician. I was told that at exhaust temperatures any thread locker will burn up rendering it useless. He also stated that he knew of no product that they made would stand up to that heat and be used as a thread locker.

Also while we are on the subject and regarding some of the above posts;
In the past I have also had some of these discussions with BigLarry. BL told me NOT to use stainless because (1) yes it galls and (2) it stretches under heat. I was told to use hardened studs made for exhausts

FWIW!
 

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i replaced the studs and used stainless flange nuts and a washer from the hardware store, torqued them a few times to 17#s. threw the acorns nuts in the odds and ends can....


ps don't forget the anti-seize
 
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