Broken Penske Clevis.

[Mr Bill]

Here is the link to my old post pic again. Break looks like it's on the big hole side.

 

[eflyguy]

I agree on the stress point at the thread/clevis joint, but perhaps that alone isn't the fault. Look at the "bottom" of the inside faces of the clevis, especially the broken piece = that is a significant amount of wear from the linkage. Those parts should barely contact if the spacing is correct.

All the aforementioned hardware.

 

[Fred W]

The bottom of the shock is free to move laterally (left/right) until it contacts the inside of the clevis as it is only attached to the inner race of the bearing by the roller needles in the bearing.

 

[eflyguy]

Thinking more on this - It would be interesting to assemble the broken part around the linkage, and measure (feeler gauge) the gap. I bet there is none - incorrect spacer length.

The bottom of the shock is free to move laterally (left/right) until it contacts the inside of the clevis as it is only attached to the inner race of the bearing by the roller needles in the bearing.

Understood, but that is a significant amount of wear for something that moves freely. I've replaced shocks and bearings in linkages, I don't recall seeing that kind of wear - but I don't claim to be right, just offering an additional opinion.

 

[BikerGeek99]

Dumb question: what were the ride / handling characteristics that changed and led to investigating all of this?

 

[majicmaker]

Ask Tom, Andy. He rode with a cracked one for 150 miles on a leaf peeping loop.

 

[Ignacio]

Dumb question: what were the ride / handling characteristics that changed and led to investigating all of this?

I'v broken two of these and the reason I found them is I took the shock off for service each time. That means I rode 20,000 - 30,000 miles each time with it cracked at some point in between including one 11 day Iron Butt Rally.

 

[TomInPA]

I noticed nothing, even on the ride where I reassembled the broken part. No noise, no different handling, nothing but a bit of anxiety. I learned about the fracture when Cav47 posted this thread, and I figured it would be easy to help by pulling the bottom bolt and observing what was there. At the time we were speculating on incorrect mounting hardware. The part fell into my hands. Keep in mind I had the shock rebuilt by GP, so all was good this Spring, and it has not been a punishing year.

Here is the photo of the fracture I took at that time before having the clevis removed from the shock. I don't have that wear on the bottom of the clevis, but you can see where both parts were in contact with the bolt shoulder (not the race). This photo also shows how perfectly flat the top of the clevis is, with no hint of a crown, which might add some structural strength. In fact, the only radius is on the bottom below the bolt when mounted.

 

[Cav47]

Dumb question: what were the ride / handling characteristics that changed and led to investigating all of this?

Andy, I had a separate issue that was causing me to investigate. I had a problem with the ride height. (it was a rebound issue, the dial was all the way closed. Therefore not allowing the shock to return to regular ride height. I think my kids were messing with the shiny red dial. But they won't admit to it) I started poking around and initially did not even see the crack as it was not separated. I pushed on it and it widened a little. No symptom presented otherwise. I just got back from Arkansas and had been using the FJR for commuting and did notice some harshness of the rear suspension coming home one day on the interstate. We have a spot that is down hill crossing a bridge where a certain set of bumps causes the spring to compress and not have time to rebound. The problem is exacerbated at speeds over 80. I might have been over that trying to get around some trucks on the way to the exit. When I set the bike on the kickstand in the garage, something was not right.

I am not a hooligan when I ride. I used the right bolt, must be a defect.

 

[wheatonFJR]

...We have a spot that is down hill crossing a bridge where a certain set of bumps causes the spring to compress and not have time to rebound. The problem is exacerbated at speeds over 80. I might have been over that trying to get around some trucks on the way to the exit...

Heavy shock load...but nothing a shock assembly shouldn't be able to handle really.

 

[BikerGeek99]

Interesting...

Thanks for the feedback.

 

[TomInPA]

...We have a spot that is down hill crossing a bridge where a certain set of bumps causes the spring to compress and not have time to rebound. The problem is exacerbated at speeds over 80. I might have been over that trying to get around some trucks on the way to the exit...

Heavy shock load...but nothing a shock assembly shouldn't be able to handle really.

I agree with you Mark. In this case, his shock was packing down and his ride was becoming almost hard tail. Gotta have rebound.

 

[Steve in Phx]

Is it feasible to weld this? Could a good welder reinforce it to make it stronger?

 

[wheatonFJR]

Is it feasible to weld this? Could a good welder reinforce it to make it stronger?

Not if you want peace of mind. It looks like the material failed in fatigue, the same material you would be welding to.

Sure, you could "weld the piss out of it" and make it work...but the replacement part is a better way to go.

 

[Steve in Phx]

Understood. Just curious. I'm still running the stock shock but wanting a replacement. Man, these things are pricey.

 

[Cav47]

Good Idea Steve, but welding it is not something I would be able to do and I do not know anyone who would do it for free. And since Warranty parts are free, I am all about that FREE life.

A better design is coming from someone that knows this stuff.

 

[Fred W]

Thinking more on this - It would be interesting to assemble the broken part around the linkage, and measure (feeler gauge) the gap. I bet there is none - incorrect spacer length.

^^^ This may be true. If the inner race is exactly the same width or, more likely, slightly narrower that the inside dimension of the clevis' yoke then the shoulder of the bolt needs to be considerably longer than the thickness of the material the yoke is formed from at the side with the larger of the two holes, otherwise the hex part of the bolt's head will contact the outer surface of the clevis and put lateral tension on it. When assembled correctly there should be a visible gap between the outside of the clevis and the bolt's hex head.

Here is the photo of the fracture I took at that time before having the clevis removed from the shock. I don't have that wear on the bottom of the clevis, but you can see where both parts were in contact with the bolt shoulder (not the race).

Actually, the bolt shoulder should have been on the other side where the larger diameter hole is. The side in the photo was contacting the end of the bearing inner race that is away from the bolt shoulder.

It may be a bit early in the investigation of these failures to jump to any conclusions, but the part could easily be redesigned using a more fracture proof material (like the steel one that the stock shock uses) or a CAD re-designed, CNC milled alloy piece that reinforces the horizontal part of the clevis yoke.

 

[TomInPA]

Good Idea Steve, but welding it is not something I would be able to do and I do not know anyone who would do it for free. And since Warranty parts are free, I am all about that FREE life.
A better design is coming from someone that knows this stuff.

A better design is really up to Penske. I suspect the FJR is one of the heavier "sport" bikes they manufacture this part to fit. The shock may be used on multiple models, but this clevis is adapted specifically to the FJR.and they CNC mill it in-house. If enough break, they will look at design changes.

 

[majicmaker]

Good Idea Steve, but welding it is not something I would be able to do and I do not know anyone who would do it for free. And since Warranty parts are free, I am all about that FREE life.

A better design is coming from someone that knows this stuff.

A better design is really up to Penske. I suspect the FJR is one of the heavier "sport" bikes they manufacture this part to fit. The shock may be used on multiple models, but this clevis is adapted specifically to the FJR.and they CNC mill it in-house. If enough break, they will look at design changes.

I agree, Tom. The picture of RaYzerman's Race Tech Clevis in post # 70 looks solid as a rock with the way they designed theirs. Their transition radius will handle the loads with no problem at all.

 

[ionbeam]

^^^^^^

I agree, Tom. The ...Clevis in post # 70 looks solid as a rock...Their transition radius will handle the loads with no problem at all.

So, at the next EOM are you going to bring your specialty tools and run a shock Clevis X-Ray clinic?