Broken Penske Clevis.

[majicmaker]

Lol, no not shear. The failure surface would be different than these failures. You should reread what I wrote as I am saying it is likely driven by clevis bolted joint design.

Ok, no problem. We can just agree to disagree. Finding metal failure and what causes them has been my profession for thirty five years. Just trying to lend a helping hand here. All is good. Continue, Please...

 

[Ignacio]

Iggy, your #1 failure lasted the longest (cracked) of any shown in this thread. It is also very peculiar that it has iron-based oxides on it. Was it stored in a humid environment after failure, next to iron-based metals? Your #2 failure was shorter in life, but still lasted a while cracked. Many other's failures shown in this thread were very small cracks (or NO cracking) and sudden instantaneous failure of nearly the entire failure area.

Yes, it was in a hostile and unknown environment after failure and one shouldn't look at the rust as part of the issue. I think it may have been under a toolbox in the drafty and moist part of my garage for years.

The "long" failure time makes my ego smart a bit less in that maybe they failed shortly before I discovered them, but then reinforces that mine may have been failures more related to my blowing off relay arm bearings

 

[Fred W]

I used a clamp to hold the clevis together to obtain these measurements.

First off, thanks very much for providing the photos and measurements. Your photo above tells the entire story, which is unfortunately exactly as I expected.

The width of the yoke is ~ 1.180", and the width of the inner bearing race (some are calling it a spacer) is slightly less than that so it will fit inside of the clevis yoke. Rayzerman measured the race as being 0.181" but I think he left off the first 1", so lets just say that the race is exactly the same length as the width of the yoke, as that would be the best case.

The thickness of the right side leg (side with larger hole) is 0.225" and per Rayzerman's prior measurements the width of the shoulder on the stock bolt is 0.210" . This means that the hex head of the bolt will contact the outside surface of the large hole before the shoulder contacts the inner race inside the yoke. You will have to bend and compress the two legs of the yoke together before the bolt shoulder presses the inner race into the left side leg as it is supposed to.

The thickness of the stock steel yoke is only 0.195" so the head will remain .005" proud of the right side when it is clamping the inner race against the left side leg. This is what we want to eliminate lateral tension on the brittle alloy clevis joint.

To fix this we would either need to find or make a new shoulder bolt with a wider shoulder on it (I'd want it to be at least 0.235" wide), or to install a shim over the smaller diameter of the bolt that has an OD the same size as (or slightly smaller than) the shoulder's diameter.

 

[08FJR4ME]

I have one question, is that bolt in the picture stock OEM or from Penske?

Dave

 

[Fred W]

That is the stock shoulder bolt, which is what Penske says to use

 

[HelzBelz]

I have another question -

On my 8975, that I installed in June - my bolt slides all the way in and the head rests against the clevis, leaving none of the shoulder exposed.

I also have about 2 threads showing after tourqing it to spec.

That is with a the OEM washer between the nut and clevis on the bolt.

And one giant caveat to this, I did not take pictures on install (DUMMY) but I do have a post as proof, there was a slight gap between the clevis and linkage that worried me. That gap disappeared when I tightened those bolts to spec. I actually thought about putting the washer in that gap instead of on the outside. (seems like It could work, binding problem ignored for the sake of this point for now, and I get more threads visibile by removing the washer?)

So - I am under the impression that I COULD have a clevis failure in my future, since I apparently bent it to remove that gap.

But is my bolt different? is my clevis different? why does my bolt head rest on the clevis? should it be able to see small amount of shoulder between the head of the bolt and clevis?

 

[Fred W]

But is my bolt different? is my clevis different? why does my bolt head rest on the clevis? should it be able to see small amount of shoulder between the head of the bolt and clevis?

No, yours is how they would all be. The bolt should slide into the large end until the shoulder butts up against the inner bearing race. As I pointed out above, there should be a small gap between the head of the bolt and outside surface of the yoke, but there is none because the yoke is too thick. This results in you bending the yoke legs together and stressing the part.

The small end of the bolt shouldn't stop when the threaded part is used up. Don't know why frushlorton's is stopping. I bet if you put a nut on there it would pull through.

 

[HelzBelz]

Ok, who is going to start machining the part to fix this?

or maybe find a high strength collar to be used as the shim suggested by Fred? and what would we do to fight the possible binding that someone mentioned earlier?

Edit- I just called Penske and spoke to Eric , only because I wanted to ask about this. (they rebuilt and resprung my 8975 that I had bought used here on the forum in may 16). I gave him a link to this thread, and advised he might need to seek membership to see it. He told me that they are dedicated to researching and determining what the fix might be. He told me they ordered a bunch of Yamaha parts to investigate. I told him that since I know I had a gap before I torqued the bolt I might set up a camera and take video/pics of me loosening the bolt to see what happens. Although its been 4+ months and close to 3k miles since then. It be interesting to see if it tries to bounce back to original width...

 

[Fred W]

Good on ya' for getting Penske into the loop. I'd suggest they do the same measurements with a brand new, stock Yamaha shoulder bolt and one of their clevis yokes. It should be a fairly quick and easy analysis.

And if they do get registered here and want to discuss anything I've posted here they can just send me a PM. I'd be glad to help.

 

[exskibum]

Ok, who is going to start machining the part to fix this? or maybe find a high strength collar to be used as the shim suggested by Fred? and what would we do to fight the possible binding that someone mentioned earlier?

Edit- I just called Penske and spoke to Eric , only because I wanted to ask about this. (they rebuilt and resprung my 8975 that I had bought used here on the forum in may 16). I gave him a link to this thread, and advised he might need to seek membership to see it. He told me that they are dedicated to researching and determining what the fix might be. He told me they ordered a bunch of Yamaha parts to investigate. I told him that since I know I had a gap before I torqued the bolt I might set up a camera and take video/pics of me loosening the bolt to see what happens. Although its been 4+ months and close to 3k miles since then. It be interesting to see if it tries to bounce back to original width...

Much prefer that Penske fix this, since they already have a liability position that their insurer would likely defend and indemnify.

As to the first sentence (I bolded and underlined): I love it that the members of this forum bring technical diagnostic and fabrication skills to bear on problems like this, and it's why I am drawn to reading threads like this, even though I am not running a Penske shock on this bike (had one on the Blackbird my good friend now owns, however). BUT . . . designing and/or machining a part like this (integral to the bike's safe functioning) could result in real liability to the well meaning engineer or fabricator, and that liability very well might not be covered by any of his existing insurance policies. I hate to throw a wet blanket on the idea of jumping in to do what needs to be done, but helping and encouraging Penske to fix this is the best way to go, IMO.

 

[Fred W]

If we come up with a readily available shim and recommend that people install it (or something like it) before the Penske clevis breaks, all with the understanding that they do so at their own risk, I don't see that anyone will be assuming any liability.

On the other hand, if WynPro were to start turning out replacement shoulder bolts... then I see your point. For Penske to try and rectify all of the parts that it has shipped throughout decades of shock sales would be tough. I think they may want to go the shim / added spacer route as well.

 

[exskibum]

If we come up with a readily available shim and recommend that people install it (or something like it) before the Penske clevis breaks, all with the understanding that they do so at their own risk, I don't see that anyone will be assuming any liability.
On the other hand, if WynPro were to start turning out replacement shoulder bolts... then I see your point. For Penske to try and rectify all of the parts that it has shipped throughout decades of shock sales would be tough. I think they may want to go the shim / added spacer route as well.

Penske likely has insurance and legal counsel addressing the advisability of making any such decision, in addition to an already existing stake in potential failure liability.

Having spent 30 years arguing with people for a fee (aka keeping other shysters out of my clients' wallets), I'm not going to argue with you or dispute that your proposal probably diminishes the risk of a liability judgment. Having said that, there are a couple practical considerations from tort lawyers' perspectives:

Assume a failure of the suspension that results in death or catastrophic injury (thus, the potential award is high enough to motivate all on the plaintiff's side of things - widow, heirs, attorneys, etc.). Preliminary investigation and discovery turn up everything that was done to that suspension and by whom. Defendants (shock manufacturer, Yamaha, maintenance providers, etc.) can all predictably be expected to point at someone else whose service or parts might have been wholly or partly culpable. Experts will be hired who posit different conclusions on that issue. Plaintiff's attorney either sues e.v.e.r.y.o.n.e. or defense attorneys cross complain against them, probably both. Either way, the fear of legal malpractice for failing to do so drives that result because there is likely "probable cause to believe that a cause of action exists" until the evidence (including disparate expert testimony) is weighed and the issue of comparative liability is decided, very likely at trial.

Now, setting aside the aggravation of even being a party to a lawsuit, IF the maker of any of those parts gets sued and doesn't have a liability policy that will provide (pay for) a defense of that action, then the question of whether the part maker will win (be held not to be liable) isn't the only real world consideration. What most failed to ask me when they wanted a preliminary guesstimate of whether they would win a case in litigation was: "can I afford to get to the point of winning?" I usually had to raise the issue and go through the practical and financial considerations so that a year and $50,000 later I wouldn't have an angry client asking me why I didn't tell them that the resulting parade of horribles might occur. Attorneys fees and costs have not gone down from when I retired at the end of 2012, so . . .

I'm not saying don't fabricate a fix, just cautioning that you be damned certain that such a fix fully remedies this known defect and be aware of the financial risk accompanying it. For reasons I won't belabor, I'm not so confident that mere acknowledgement that users use the washer or part "at their own risk" is an effective prophylactic, despite there being ways to strengthen, though not bulletproof it. (E.g., I have drafted numerous "express assumption of the risk" forms for skiing, snowmobiling, golf and other sports related provider clients.) And please don't shoot the messenger just because he has a different type of expertise than engineering. This is not intended to be taken as legal advice and you are just as free to disregard it as any of my clients were.

 

[Fontanaman]

I am really enjoying this discussion. It is a diverse group of people we have here and it certainly is an asset to the forum.

For my two bits. I replaced the factory washer with a very thin washer and put it under the nut. I used blue loctite and tightened the nut snug. (I did not use a torque wrench.) Just snug enough keep the nut on the bolt. I will inspect this periodically and contact Penske in few months.

 

[Constant Mesh]

Maybe should use a variation of one of these?

https://www.tractorsupply.com/tsc/product/countyline-red-head-hitch-pin-grade-5-4-in-usable-pin-length?cm_vc=-10005

 

[Fred W]

@exskibum - First, I appreciate your expertise and advice. And I fully understand what you are saying. Although I do have an engineering background, that being in the medical devices industry makes me wary of any and all liabilities resulting from designs and their modifications. I live it every day.

That said, someone's advice on how to make a particular modification found in the public domain on an internet forum, and then carried out by the owner / operator individually can never receive the kind of liability scrutiny that a seller of parts, modifications, or the original products would receive. I think that is a fairly safe position.

So, we should be safe in making the measurements (done), and figuring out a way to avoid the clevis failures with a couple of simple off the shelf spacers, and propagating that "fix" online for those who want to do it themselves. I doubt you'd find any shops that would be willing to install it for you, since it has never been verified or validated by either the bike or shock manufacturers, but that shouldn't bother us as individuals.

Now when (or if) Penske finds a solution, they would have to do the V&V on the fix, and assume all the liability of it as it applies to their product and their installed base. But they are already liable for a product that we have recently determined has an identifiable problem, one possibly resulting in a safety concern. So in that light, doing nothing may not be a good option for them either, if you catch my drift.

 

[Bounce]

Remember that waivers and caveats abound and only add to your defense. None of them prevent the situation where you end up PAYING to defend yourself.

 

[exskibum]

Remember that waivers and caveats abound and only add to your defense. None of them prevent the situation where you end up PAYING to defend yourself.

Exactly so, sir! Succinct, too.

That said, someone's advice on how to make a particular modification found in the public domain on an internet forum, and then carried out by the owner / operator individually can never receive the kind of liability scrutiny that a seller of parts, modifications, or the original products would receive. I think that is a fairly safe position.

I'd quibble over the bolded and underlined language (lawyers get sued for bad results obtained by clients following our advice with some regularity). I would agree, however, that in the abstract, it is LESS likely. Whether a lawsuit is filed and how vigorously it is pursued against each defendant depends largely upon the facts and the identities (and tragic circumstances) of the plaintiff(s), who may be under severe financial and emotional duress. The amount of the potential damage award, the depth of the defendants' pockets and their available defenses are also significant factors. An example:

Assume that "Doc" is a member here, is a young and promising heart surgeon only a few years out of med school and has a lifetime of serious earning potential ahead of him. You know him to be a stand-up guy who would never sue a friend, and he relies on your engineering background and expertise to choose the inexpensive self performed fix you offer, foregoIng the alternative of buying an Ohlins replacement. Seems safe to do - for him and for you.

Though you know that Doc has a new wife and two young children, you don't know that he has an ex to whom he has been paying much of his earnings over a term that is to expire shortly. Consequently, he has yet to follow through on a financial plan for his new wife and kids. And when Doc's suspension fails and kills him, they are strapped - life insurance beneficiary is the ex and everything they have is mortgaged. A future that looked bright is suddenly trying and desolate.

Unforeseen by all when we were discussing a simple fix, it turns out that Doc's sympathetic widow is the liability lawsuit decision-maker whose priority in life (having lost Doc's future income and support that the economist expert pegs at 8 figures) is taking care of her children's welfare, education and the family's support. She sues because she feels she has no alternative. This widow and her children scare defense attorneys because she is so sympathetic in her efforts to care for and raise Doc's children - a jury could go nuts. This drives settlement discussions with a multi-party dynamic that can give the little guy defendant heartburn.

Penske may have deep pockets, but their attorneys note that they never recommended a different sleeve, spacer, washer, bolt, whatever. They claim that Doc installed this unauthorized fix in a way that caused the failure and his death, whether or not that was the way the outside advisor/part maker instructed. If it's Doc's fault, his widow's recovery from Penske is reduced wholly or partially by his own comparative fault. If it was the fault of the outside advisor's part or recommendations, his widow's recovery from Penske is reduced in whole or in part by the comparative fault of the outside vendor. Guess who she must seek compensation from? Yep. And even if the advisor/parts supplier does prevail, that will cost significant fees if an insurer is not covering it.

Moral of the story, then: when you have desperate parties playing for keeps within this adversarial legal system, and when you are the outside advisor/part supplier who is uninsured for this risk and you have significant assets, watch out! Arguments can be made that you are responsible, and as Bounce rightly notes, the cost of defense can be a large gorilla on your back. Settlements are made in many cases simply because it makes more bottom line sense to make a deal than to put all of your lawyer's kids through college and grad school.

In the abstract, is that the probable result? No. Have I seen that sort of thing happen? Oh hell yeah! They're not called "war stories" for nothing and they're often sad. My ex was a bankruptcy attorney, btw, and she lost two clients to suicide in her first nine years of practice. Holes can be that deep. Again, I'm not telling you what to do, but the legal system is broken and unfair results that seem to defy common sense occur.

On the bright side, I seriously doubt that Penske is ignoring this issue. Furthering one of the best traditions of the FJR Forum, you guys have done a hell of a job developing information they can use. I'd suggest that everyone with this shock contact Penske and alert them to this thread and your concern. Ask if they are contemplating a fix, to keep you in the loop, and what they recommend in the interim. (Maybe an interim fix like you suggest, Fred - but on their dime and insurance coverage.) Thank God no one has yet been hurt and winter will be reducing miles while they address the problem.

 

[mikerider]

Exskibum, awesome post from another perspective! Thank you!

 

[Fred W]

Yes, thanks for the insight. But, God help us, what a sad and sorry state our society is in.

In retrospect, I see that I have been naive about this sort of possibility in the past. Not that I am unaware of it ever having happened, rather just thinking that "it couldn't happen to me." I look back at some of the advice I have given, both here and other similar places, and think about what you have just laid out; it gives me a shiver to think of what could have resulted.

It's truly unfortunate that any people are this way. Consider that in this case there are a large number of these parts that were designed with a minor flaw that could have a failure, and that failure could result in injury or worse. Someone that recognizes the flaw and a quick and easy way to eliminate it can't even share that helpful information with others for fear that they would be the target of a viscous law suit, so instead the population at large is left in the original higher risk state. Is that really better for anyone?

What else falls in scope here? What about the advice to put a car tire on the back, or to run tire pressures higher than the manufacturer's specs, or what super bright auxiliary lights to run, or how to install spacers in the windshield to alter it's angle, or a zillion other things we discuss nearly every day? Aren't these all advice that could be latched onto by some law parasite bent on judiciary financial extortion?

What has happened to personal responsibility? When "Doc" decides to follow the internet advice to shim his own pivot bolt with parts he buys from the True Value hardware store down the road, based on the information he garnered from an internet forum, how is it anyone else's responsibility for his actions or his decision or any unforeseen result.

It just makes me shake my head.

I guess I'll be shimming my son's shock clevis, and share my thoughts with the guys at Penske, but the rest of you are on your own.

 

[eflyguy]

I might set up a camera and take video/pics of me loosening the bolt to see what happens. Although its been 4+ months and close to 3k miles since then. It be interesting to see if it tries to bounce back to original width...

I posted earlier, mine had no gap at the bottom and a very small gap at the top with the bolt tightened. When I removed the nut, it had about 1mm total. The clevis is definitely bending inwards and "bouncing back"..