Rear Shock Mount Broken

[Mangiples]

Hi guys, recently (less than 1000klms old) CT125 Trail in Thailand I’ve had the room mount bolt/pin break off, not sure if it’s due to an overloading situation or over torquing the exhaust mount when fitting a Diablo system, issue is it looks like it’s press fitted to the frame (through the frame) and is only available as a complete new frame, anyone experienced the issue and has a resolution?

 

[Kritou]

It’s unclear from your photo but can that bolt stub not be removed? Judging by the colour and state of your bike would this not be a warranty fix?

 

[m in sc]

that whole lug is welded onto the frame as 1 piece. time to drill and tap or weld o a new lug of some sort, or replace the frame. that 'center section' does NOT come out. man, that sucks.

 

[Cpd419]

That’s a weird fail.

 

[eastema]

Yeah, that is a strange fail? Should be able to drill out and replace stud if u have the capabilities yourself. It will be tough to find a shop to do that repair and assume liabilities. If it were mine, I would drill out and replace stud myself. Other than riding double, overloaded with gear and bottoming out rear suspension hard I don't understand the fail. If it was way overtorqued that could cause the fail. Like with a three foot cheater bar and all of your weight on it you could shear the bolt.

 

[MisterB]

This is a total hail Mary since I can't see exactly how it's made, but if you whack the end that broke off with a 3/8 or so punch and a 5 pound hammer does it move?
As I mentioned I can't see enough but hoping it's a rod that extends all the way through.
(edit: see if they'll warranty repair first!)

 

[TrailBoss]

This is a total hail Mary since I can't see exactly how it's made, but if you whack the end that broke off with a 3/8 or so punch and a 5 pound hammer does it move?
As I mentioned I can't see enough but hoping it's a rod that extends all the way through.
(edit: see if they'll warranty repair first!)

My guess is that rod is one piece and goes all the way through the frame, with an interference fit to keep it in place. If you could confirm that's the case, then theoretically he could press the old one out and press a new one in. Problems I see though are that part is most likely non-existent (not sold separately), and being able to press it out/in would be a nightmare.

 

[oldskool]

Have you talked to Honda? Are you sure that it is pressed in and the through rod is not available? That seems like a poor design. Hard to tell from the photo but it looks like threads going into the socket? If that rod is pressed into place they may have used liquid nitrogen to shrink it first. If so it will be difficult to press back out without stressing ruining the frame. If it can be pressed out a clever lad could come up with a suitable substitute if Honda willnot/cannot provide the rod. If the rod cannot be removed without causing damage you will want to find a skilled welder/fitter. Doesn't look like too bad of a job for a skilled hand. May not be that cheap but far cheaper and easier than buying a whole frame and rebuilding the whole bike.

 

[m in sc]

guys, its not pressed in. its a turned part that was welded onto the frame. the -correct- way to repair it sans replacing the frame, is to make another one and grind the weld off, and weld on a new one. IF it were me, and i have done this on other bikes, I would turn down a bar of steel and tap it with an m10x1.25 and weld it onto the frame, then use a bolt to mount the exhaust/shock . But i do this sort of work all the time so... To me, it looks like somebody hit that with a 1/2" air impact wide ass open and wrung the stud pretty good.

 

[aka_hellcat]

According to a Japanese Facebook group, most of the damage was caused by Diablo mufflers. The genuine parts are supposed to tighten two bolts, but Diablo and a few mufflers use only one bolt. I think this is the cause of the damage. The vibration of the engine is concentrated there. Takegawa or Moriwaki have two fixing points, and no damage has been reported.

 

[m in sc]

I find that extremely hard to believe. actually, I find that to be complete BS speculation on their part. I have a bunch of 2 strokes that run long pipes hung on by an M6 or M8 bolt that vibrate -way- more that that does. My trail exhaust only uses the back bolt and the head pipe, its been on for a few hundred miles and zero issues. the muffler tab will crack and break long before that stud will IF that was the cause. Id bet a dollar to a donut it was over tightened. its not easy to shear a bolt that diameter, sorry. and looking at it, it looks like the failure started to wards the back of the frame (direction). if it was vibration, would have been top down.

 

[ShieldArc]

My guess would be that the machined rod was slid into the pipe on the frame and spot welded in a drilled hole in the pipe.

 

[dmonkey]

I'm not sure if it's something that's accessible in Thailand, but a machine shop that does metal disintegration machining (MDM) would likely make quick work of removing the broken stud.

 

[m in sc]

its NOT pressed into the bung, its one turned piece.

 

[MisterB]

Kinda looks like one long rod pressed into tube welded to frame. Take a punch and hammer to the broken part and see if it moved. If so then you can try to hunt down a replacement or have one made.
As ShieldArc suggested it may have a hole in the tube where the insert was secured. More pics available?

 

[m in sc]

if it was a pressed in insert, the od of the black part would be larger. if it was a pressed in insert, the outer part would have cracked on the 1st bump. that 'lip' is where it was masked off for frame painting.

 

[dmonkey]

@Mangiples it seems you're not the only one who's had this issue. There are mentions from Japanese Hunter Cub 125 owners of it happening with the K-Speed Diablo exhaust and other aftermarket parts that share the shock mount. It has also happened with the OEM rubber mounted exhaust though

CT125ハンターカブのフレームが折れた件 - 黒ウサギ外伝

今年に入ってCT125ハンターカブのマフラー側サスペンションのシャフトが折れる事例が数件耳に入ってた。ここが折れるとは、どういう事だと思いましたよ。（SNSから転載）いろいろ検索してみたら、社外マフラー（K-SPEEDのDiabloが多かった）を付けた車体で発生してました。（SNSから転載）1番に考えたのが、社外マフラーによる振動でシャフトが折れた？2番に考えたのが、取付時にオーバートルクで締めた事でシャフトにクラックが入っての破断です。マフラー側（右）は、サスのシャフトにマフラー固定用延長シャフトを付ける構造。（サス左右の締め付けトルクが44Nで、マフラー取付部分が27N、考えずに締め...

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CT125 ハンターカブ リヤサス取付部が折れる問題 - モトボッチ

2022年1月、リヤサス取付部のボルドがフレームの根元から折れたという情報がFacebookに投稿され話題にな

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Here's a YouTuber I follow, Ozu-san, explaining how a shop recently did the frame repair on his:

I have very little comprehension of what's being said, but from the illustration it looks like the shop may have drilled and tapped both sides of the broken piece, installed a dowel stud, screwed it back together, ground down a bevel or v-groove at the butt joint, and then welded that. If that is what they did, it seems like a pretty weird fix to me, maybe just what they were comfortable with trying? @m in sc 's suggested fix sounds sturdier to me.
Ozu-san attributes the issue to his extensive customization of the motorcycle and emphasizes that he does not blame Honda for it (he's got a few videos talking about the issue). The exhaust he switched to after the repair, a Dirtfreak Delta 4-S Mini, uses more mounting points than the prior aftermarket one which used one less mount point than the OEM exhaust, and no rubber mounts. His "long" seat has a bracket that attaches to the shock mount which also looks suspect to me.

Here's someone checking for defects in the mount and then changing their aftermarket exhaust to use a tab welded to the rear rack instead as a preventative measure:

 

[m in sc]

if they tapped both sides and came in from the back side of the frame rail as well it will def be fine. still pretty ridiculous it broke in the 1st place. No, didn't/not going to watch video.