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Discussion Starter · #1 ·
'97 flhtci I am replacing studs because a couple of them are pulling out of the cases. I've never used helicoils before and it looks like I can stack 2 of them to get enough threads for the studs. I'm wondering how to break the tab that is used to screw the threads in and not have it go into the bottom of the engine being as the holes go clear through the cases.
 

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2004 FLSTCI, 1993 FXDL
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There is a longer helicoil made just for head bolts but I'm not sure I'd use it. I believe they still stack. Google that up and see what they say.
 

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Helicoils are not recommended for repairing those stud holes. Drilling the hole out weakens the case, and the coils don't add any strength back to the repair.

Time Cert sells a kit(s) for fixing those threads. It's a set of thin wall inserts in the length your case requires as well as the tools to install them in the case.

Time Cert

With that said, you still need to be able to keep the hole parallel to the spigot bore. If it ends up off center or crooked, the corner can crack from the stress induced. Jims makes a tool for drilling them free hand, and many indies can do it in their mills using the spigot boring jigs.

Jims stud repair jig

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You can use the old studs at least two or three times. Yes, they stretch. Ive personally done several builds using the old studs with no head gasket failures so far. Just oil the threads and the bottoms of the bolt flanges so you wont get a false torque reading. Now, since youre removing em to repair damaged case threads, why not get new studs, of course.
 

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Studs are elastic. That's why you tighten them some additional amount after they reach a given level of tightness. Think of it as a bungie cord. That lets them give a little when the jug grows with heat, and still be tight after it cools back down and shrinks. In normal use the studs get hot, the exhaust studs get hotter than the intake side. This repeated cycle of heating and cooling hardens them and takes away the elasticity. So, they will not retorque properly.

I suspect that this loss of elasticity and the extra heating that happens to the exhaust studs is why the most common place for pulled stud threads is the front and rear set of stud holes.
 

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I was looking around and found this blurb on Feuling's web site. It was in the middle of their parts description.

Stock Cylinder studs are designed as a stretch to torque stud with a one time use only lifespan
Feuling studs are installed to a torque spec can be reused

They were talking about studs that they have ARP make for them. I'm not selling, just FYI.

Although this is for TC studs, I believe stock EVO studs are the same.
 

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Discussion Starter · #17 ·
You can use the old studs at least two or three times. Yes, they stretch. Ive personally done several builds using the old studs with no head gasket failures so far. Just oil the threads and the bottoms of the bolt flanges so you wont get a false torque reading. Now, since youre removing em to repair damaged case threads, why not get new studs, of course.
I changed both head gaskets and base gaskets last spring being as the front head was leaking compression. It went about 4500 miles and started seeping from the rear head and base gasket. Also one of the head nuts was very loose when I tore it down, that's why I think the studs are pulling. I cant see that the treads are damaged but I guess it wouldn't take much to make the head loose. I'm just going to change the studs and time sert all of them. I hope this takes care of it. Also going to get rid of the mm injection and put a carb on her.
 
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