Stripped Shock Mount Stud

So I'm trying to remove the upper shock mount acorn nut, and I'm turning it for what feels like 5 minutes before I figure out, this thing is stripped...so I grab a vicegrips, clamp on, and start pulling and twisting the nut off....now I've got s stripped stud....what are my alternatives?
Oh yeah, it's on my '83 XJ750 Seca
Thanks

 

Somebody else just went through this.

I don't remember what was finally done; but essentially you can cut off the threaded part, and carefully drill and tap it and then Loctite in a new threaded portion or switch to a bolt.

Or cut the whole thing off, drill it out and replace with a through bolt from the inside and a collar and/or spacer for the mount.

 

I have to replace one of mine for the same reason, with the difference that mine is also missing half its length. I will be cutting the whole thing off and making a new through bolt, and rewelding it in place. But I am a machine builder/repairman so it will be no cost, just an hour or two of my time.

 

you can try a bungie from one shock over to the other

 

Or a big C-clamp. Yes, much better.

 

I'm in the middle of doing that right now......... I just ground the threaded parts off flush with the stud and will be drilling holes today if all goes well.

I also had an issue where a PO had welded the shock right to the stud since the threaded section had previously broken. As it turns out, when I pulled the lower shock end off, the top moved freely. WTF?!?! Turned out that the PO put the shock in place, then welded a bolt to the stud, backward so the head was to the stud and the threads stuck out. The weld was terrible, didn't hold to the stud, and was welded only to the shock. The stud weld probably broke as soon as he sat on it. I broke the weld from the shock with a twist of a screwdriver...........good thing he didn't ride it !

Anyway, my plan is to drill holes and then tap them for the right size threaded rod or bolt. I will not put a bolt in as I want to put the correct acorn cap on again.

I have looked at different options:

Here's what you can consider, too....

1. grind the end off, drill and install a bolt

2. drill all the way through and run a threaded shaft all the way through

3. drill part way through, and install a shorter stud, like a hanger bolt---

4. grind the whole stud flat to the frame, drill it out completely and install a replacement. Keep in mind that Yamaha does not make these anymore, they are unavailable from any source that I know, INCLUDING CHACAL......as of last conversation on it with him. SO.....the replacement part would be a car dealer where you would get the drum brake wheel studs. You woould have to measure for diameter, and length. Then once it is is in, re-weld the stud to the inside of the frame.

Personally, I"m aiming for option 4. I do know one person that suggested just drilling and installing a bolt and washer. That will be effective, but I want it to look as close to original as possible.

Dave F

Dave Fox

 

Exactly. It looks like the Yamaha setup is a one piece through stud with a large flat flange approximately in the middle (I will be taking precise measurements), the shock stud, and then the threaded portion. Mine is welded on the inside of the frame on the smaller diameter through pilot, and around the large diameter flange on the outside of the frame. I imagine that there is a hole manufactured in the frame and Yamaha had a jig to align the studs when welding.

It's going to take some skill to cut it off without cutting into the frame, and to make sure I keep the stud aligned.

I'm not just doing it that way for cosmetic reasons, it also looks to be the most secure. There CAN'T! be enough stock in that area of the frame to safely drill and tap for a screw.

 

that's not going to be easy. if the last size bit breaks through the side of the stud, you might end up with a crescent shaped piece of the stud left in there and a oval hole in the frame.
how about grind the original stud flat and make your own new hole just in front of it, then weld your stud in. the angle of the shock would change slightly but not enough to matter

 

peganit2, you would drill and tap into the center of the original stud, after it's ground flat

 

Yes exactly, that's why the last step in removing the through stud wouldn't be hand drilling. I'm good at that stuff, but I know the limitations.

There are usually witness marks to grind to. :wink: I've done it successfully quite a few times. It amazes boys and men alike.

Skill baby!

 

The through stud looks to be about 3/8' in diameter. How much stock is going to be left after drilling and tapping?

 

if the shoulder was .375 and we use a .250 bolt, there would be .0625, that's 1/16 inch wall
but
the .375 is really .560, now how much stock is left?
even those of us with lesser skills can hit that

 

.560?!?! Easy breezy!

But still that leaves some engineering questions.

 

Quick question. Why aren't you just cutting new threads on the existing stud so you can use an undersized fastener?

 

In MY case, it because a PO cut the threaded section off after he removed the standing handles. In restoring the handles, there is not enough thread to install the washers and acorn nuts.

Dave

 

that's a 10X1.25 thread on there, so if we file or grind off the original threads the stud would be 8.75 mm dia.
somehow that would have to be made 8mm and kind of round to get it in a die

 

You use an adjustable die to cut new threads to the next undersize. It's been standard shop practice for at least 5 decades. No grinding is needed. You take multiple passes with the adjustible die, taking a small cut each time, and re-lubing between passes. Once the die reaches the limit of adjustment you have a new thread that is exactly one size under the stripped thread.
The current (stripped) M10x1.25 should be rethreaded to M9x1.25, and a suitable washer used to account for the difference in OD of the new nut so there is no undue wear on either the fastener or the shock eyelet.
A decent adjustable die is a bit spendy for a one-time job, but still costs less than my labor for the time that replacing the stud would take ( 15 min job to re-thread, vs. two hours(est.) to cut/drill/weld/paint), and there are fewer operations that could potentially be messed up.

I realise that most people don't think of their time costing anything when doing hobby work, but I do. Spending money on a tool that saves me time is usually worth the cost. I can make more money, but I can't make more time.

 

i see you have it all figured out so that's what everyone should do, good job

 

Same hear, the stud is too short on mine, otherwise it's rethreading to a smaller nut size.

I just don't have that option.

I HAVE to remove mine completely and weld a new fabbed one back in it's place.

The only question I would ask is what steel I should make it out of?