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Discussion Starter #1
I've been slowly working on filing and sanding the fins so that I can eventually paint the engine (I figure I'll be done in 2011 at the rate I'm going). I decided to take a quick break and pull the crush gaskets out of the exhaust ports and clean them up a bit while I was at it (the previous owner had a dealership install the VH BigShots, and they used Red Permatex over top of the crush gaskets).

When I had taken the pipes off in getting ready for the engine paint project, the inside stud had came out due to the acorn nut being stuck solid on the stud. I didn't look at it further at the time. What to my wondering eyes did I see when I started to clean up the gasket rim? A hairline crack in the stud mount.

How serious is this? Do I need to put some JB Weld on it, find somebody who's good with a welder, or not worry about it?

I'm still a long ways off from getting to the point of getting the stud back on and reinstalling the pipes, but I figured it would be better to know now if this is gonna be serious.

Thanks,

TRU


 

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If it's just the top few threads of the stud boss you might be OK. If it goes any deeper you mihgt have to get it welded and re-tapped.
 

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Is your flange bent pretty bad ? If the bolts were over tightened as the flange bends it probably going to pull the bolts toward the pipe and cause something like that . Quite often holes are not tapped all the way to the bottom of the hole . I would buy a bottoming tap and see how much threaded area you can get below that crack . Im sure you will be OK
I dont know how much deeper you can drill before hitting water but that is another option..try tapping first
 

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Discussion Starter #4
I believe the crack is actually before the threads start. I was more concerned about whether the crack would spread when I would put the pipes back on.

You've got me thinking about the flange. I don't know if it's bent, and I guess the question is - how would I be able to know? Should I be able to put a straight-edge on the flange and have it make contact for the whole surface?

I'm thinking I'll need to do something to address it. I'm wondering if a little bit of JB Weld would be ok.

Need some more opinions, guys.

Thanks,

TRU
 

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Discussion Starter #5
Shameful bump

:oops:
 

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Think I would just use Loctite............Hydraulic Loctite. It's made to seal threads for pipe and hyd. fittings. Wouldn't hurt to squeeze some in the crack too and let dry.
Just a suggestion.
 

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I too would run a bottoming tap in the hole, get a new stud and acorn nut, use loc-tite as Smokin-Joe suggested, and forget it. Slapping some JB weld on the exterior of the stud boss won't do a damn thing. No need for a straight edge on the pipe flange. just looking will tell if it was overtightened. If the flange is bowed toward the exhaust port, it was overtightened.
 

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Discussion Starter #8
Thanks to both Jim's on the advice for the bottoming tap. I've never used one and will have to find out the size I need. I thought the studs were supposed to have anti-seize on them for easy removal. So, I guess with putting the loctite on there the stud is going to be set permanently.

Here's where I have my next question - based on a stud thread depth diagram provided by Bare, it looks like ALL of my studs are sticking out way more than the diagram shows. Since this stud is going to be set permanently, I really can't afford to screw (no pun intended) this up. Are the Big Shots exhaust flanges thicker than stock to require more threads sticking out of the boss? I'm trying to figure out why all my studs are sticking out farther than they should be based on Bare's diagram.

Forgot one more question - if the exhaust flange IS bent how do I fix that without risking any damage/scratches to the rest of the pipes?

Thanks again,

TRU
 

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If you can screw your studs in as far as the threads on the stud itself allow, as all mine are, you're good. Tighten 2 nuts against each other on the stud and put a socket on it, if you can get the studs in as far as studs threads allow without forcing it, a tap isn't needed, unless you want a longer deeper stud in the cracked hole. I think the BS flanges are slightly thinner if anything. It's possible crack was caused because your studs just weren't screwed in far enough. The first time my exhaust was off I screwed studs into head to end of studs oiled threads and snugged them up, no loctite, then I put anti-seize on studs outer threads for acorn nuts, and since then I've had exhaust off and on several times with no problem, studs stay put, only nuts come off, and also no washers, with Big Shots. Good Luck!
 

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just a suggestion...
Replace the studs with stainless steel,and avoid seize-up issues..
stainless steel nuts too....
That's a great idea! I am going to make a note to do that on my own bike. A good way to staighten the flange is to use a pair of adjustable wrenches as brakes. Set them so they just slide onto the flange over the stud holes (flanges widest part), bring them in till they are about 1/4" from the header.Pull them backward at the same time opposite the bowing until straight.
 

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Discussion Starter #13
Thanks for all the responses, guys. Do acorn nuts come in stainless versions? Am I going to the dealership for both the nuts and the studs or do I need to go somewhere else?

I don't think I need to tap the hole (the more I think about it), and will definitely run the studs down as far as the threads allow to confirm that.

Should I loctite all the new studs when I put them on? I'm assuming anti-seize on the nut side of all of them, but wasn't sure about putting loctite on the block-end of them.

Jimbo, I'm hoping I can visualize what you're talking about if I have to straighten the flange. Are the adjustable wrenches you're referring to crescent wrenches or something else? I'm hoping whatever is needed (actually I'm hoping I don't need to do it) won't scratch up the flanges too much.

Thanks,

TRU
 

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Thanks for all the responses, guys. Do acorn nuts come in stainless versions? Am I going to the dealership for both the nuts and the studs or do I need to go somewhere else?

I don't think I need to tap the hole (the more I think about it), and will definitely run the studs down as far as the threads allow to confirm that.

Should I loctite all the new studs when I put them on? I'm assuming anti-seize on the nut side of all of them, but wasn't sure about putting loctite on the block-end of them.

Jimbo, I'm hoping I can visualize what you're talking about if I have to straighten the flange. Are the adjustable wrenches you're referring to crescent wrenches or something else? I'm hoping whatever is needed (actually I'm hoping I don't need to do it) won't scratch up the flanges too much.

Thanks,

TRU
http://www.thomasnet.com/michigan/fasteners-stainless-steel-27790559-1.html
 

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I also have an exhaust stud hole crack. My concern is not that the stud will hold torque. My concern is that the crack will propagate until it reaches a water jacket or oil passage and ruin the engine.

Does anybody have some experience with this issue? Will I have some major problems down the road?

I just spent more money than the bike was worth fixing all kinds of other problems, I would hate to sell her.

172847
 

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I had an issue with bending the aftermarket flange on my HK 3". Didn't hurt the thread bosses though. After straightening the flange in a bench vise with big channellocks, I re-installed with correct torque on the hex nuts that replaced the acorns. There is enough thread left after the hex nuts that you can install the acorn atop the hex, w/ just a little dab of BLUE loctite. You can also use a flat washer under the flange to make a better fit.
 

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No concerns about bent flanges, I'm installing a new exhaust pipe.

I'm a skilled TIG welder on aluminum Does anybody know much about welding on aluminum cylinder heads? I wouldnt want to warp it. I think the only "right" way to do the job would be to remove the head, preheat it, weld new material on and drill and tap new threads.

If I were going through the effort of removing the head I think I would just replace the da*n head haha

That being said, this sounds like a monumental task.

Maybe I should let this sleeping dog lie?
 

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Is that the crack at 3:00.....If possible might drill a small hole so crack cant travel...Ive done similar but not on a mc...good luck
 
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