Mathews can bearing failure - lesson learned

ZDR

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The bottom cam bearing on my traverse failed a few weeks ago and luckily my LBS was able to expedite a new one from Mathews. My bow is shooting perfectly now but I wanted to share my lesson from this: don't over tighten your axle keepers! @Billy Goat has shared this multiple times on here but here is an example of the failure. My top hats were unusually worn due to my over tightening of the axel bolts keepers. My LBS immediately knew that was the issue before they disassembled my bow.
Here is a pic of the cam and another of the top hats that were removed. The top hat photos don’t do justice to how rough they are.

image.jpgimage.jpg
 
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Come on ZDR, we know it's just cause it's Mathews junk.




In all seriousness, it would be nice if they had a listed torque spec or tightening sequence.
 
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ZDR

ZDR

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Come on ZDR, we know it's just cause it's Mathews junk.




In all seriousness, it would be nice if they had a listed torque spec or tightening sequence.
Ya…a torque spec would be great. I’m surprised bow manufacturers don’t do that…at least to my knowledge.
 
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Ya…a torque spec would be great. I’m surprised bow manufacturers don’t do that…at least to my knowledge.

Years ago I argued with Hoyt about that.


Fastener sizes have torque spec, so it's kind of implied I guess, but sure seems it would be simple to just put something on it.


And loctite, well that's great, til you want the bastard to move. That's the benefit to torx head, it is stronger than allan heads.



Interesting fact for those who don't know, phillips head was engineered to strip. Made for assembly line product. Strip at torque value
 
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The cam failure has highly likely nothing to to with over tightening the axles bolts. There is an edge between the inner race and the bottom of the cam socket to provide a gap for the outer race so the outer race has always enough play (the collar of the top-hat pushes only against the inner race) - thus over-tightening IS NOT the cause for the bearing failure (also Mathew may want you to believe this).

Conversely, if the "clamping" of the limb-top-hat-inner-race system is not firm: this can actually cause real issues as it allows the top-hat and the cam to move along the axle.

The top-hats are damaged when the bearing is collapsing and allowing the axle to tilt as the bore in the middle of the cam is approx. 0.6 mm wider compared to the bore of the inner race. This together with the debris from a collapsed bearing will cause the wear and tear of the top-hat. The damage of the bearing is caused by nothing else than poor quality of the bearing balls: take a bearing ball, look at it under a magnifier and you will see that it is covered in pitting marks - looks like every shot I made left a pitting mark, some of the bearing balls look like hammered. I looked a little bit deeper in this issue when the already replaced cam for my Traverse failed again after approx. just 3,000 shots. Long DL, high poundage ...and there is a 50% chance that the bearing will fail prematurely due to the poor quality of the bearings balls.

If you want to replace the bearing: the bearing can be easily pulled out (you can't push it through like you can do with some of the Elite) when you warm them up a little bit with a heat gun (don't go overboard!) and a snap ring / circlip plier.
Thousand dollar bow

2c bearings.

Wonder how much the cost would've went up to use the $5 bearings?

Nah can't have that, that'll cut too much into our profits!!
 
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bigW

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Thousand dollar bow

2c bearings.

Wonder how much the cost would've went up to use the $5 bearings?

Nah can't have that, that'll cut too much into our profits!!
the comment from me you quoted is not 100% correct - the edge at the bottom of the socket of the cam is actually supporting the outer race, so from this you actually could over-tighten it - if there wouldn't been this small lip / collar on the washer for the axle bolt that reaches into the limb thus defining the actual axle length. ...so yes, over-tightening seems to be not possible....but the soft bearing balls are real and likely due to lack of quality control - I also have a TOPOINT, and pretty sure this one has Chinese bearings too, but no issues here and I shot the hell out of this bow.
 

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bigW

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My comment cited by Jeff was not 100% correct, hence I deleted it - while he quoted it 😀....here the correct details:

If you would be able to over-tighten the axle bolt thus applying too much clamping pressure you actually could push the top-hat too hard against the inner race that has no support from the cam socket. In the cam socket there is at the outer diameter a small edge that defines the position of the outer race thus giving the inner race theoretically some play.
However, the axle has a defined fix length, and when you remove the axle bolt you see that it reaches just approx. 1-2 mm to the edge of the limb, and these 1-2 mm are taken care for by a collar on the washer for the axle bolt. Thus the clamping length is fixed.
I get this that the limbs may have some tolerances (especially due to slightly varying the coating thickness), however, this in order of micro meters, not millimeters. And lets not forget that it gets tighten with a 5/64 Allan key ....I use a little bit of blue Loctite and tighten it till I feel a slight / minimal resistance (I would be scared ruining the little bolt head if I would do it otherwise).
IMO if it is too loose it can do more damage as it would allow the top-hat and the cam to move on the axle - that's definitely not a good thing to happen.

The damage I could recognize when observing the ball bearings under a magnifier clearly points to ball material that is too soft!

I also experienced some wear and tear on the top-hat the first time I had the issue with the cam. The damage was clearly from the collapsed bearing. The top-hat was damaged as the axle was tilting (excessive cam lean! watch out for this) as the bore in the middle of the cam is approx. 0.6 mm wider compared to the bore of the inner race. This together with the debris from a collapsed bearing will cause the wear and tear of the top-hat.

The damage of the bearing is caused by nothing else than poor quality of the bearing balls: take a bearing ball, look at it under a magnifier and you will see that it is covered in pitting marks - looks like every shot I made left a pitting mark, some of the bearing balls look like hammered. I looked a little bit deeper in this issue when the already replaced cam for my Traverse failed again after approx. just 3,000 shots. Long DL, high poundage ...and there is a 50% chance that the bearing will fail prematurely due to the poor quality of the bearings balls.

If you want to replace the bearing: the bearing can be easily pulled out (you can't push it through like you can do with some of the Elite) when you warm them up a little bit with a heat gun (don't go overboard!) and a snap ring / circlip plier.
 
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bigW

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Both of my cams failed on my vxr..
how many shots approx. at which poundage and DL? ...

While it is a PITA, now that I know what causes the issues and that it can be relative easily fixed I feel much better - life time warranty is fine, but having to wait till the spare parts are coming from US to down under takes the fun out of it. I will get the best quality ball bearings I can find and put them in and that should do the trick....
 

bigW

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...the bearings SSR4 2RS TRITAN used by Mathews in my Traverse cost between US $4 and US$ 4.50 per bearing for a normal mortal - that's US$ 16 ...18 in total (4 bearings) - a better quality bearing with a significant higher static and dynamic load cost approx. 100% more ...that's US $ 18 more in total (or even less considering Mathews may get a discount...) .....so they saved approx. $18 on production costs for a flagship bow....:(
 

Trial153

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Extrapolate 18 per bow over the entire production and unite frankly it’s a huge margin. Considering how few failures production bearings have in cam compared to the number of bows built and sold it seems fairly reasonable model.
 
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However, the axle has a defined fix length, and when you remove the axle bolt you see that it reaches just approx. 1-2 mm to the edge of the limb, and these 1-2 mm are taken care for by a collar on the washer for the axle bolt. Thus the clamping length is fixed.


I'm 99% certain this is not correct. The washer is shouldered to locate it, not to draw down on the axle.

I can mic everything at a later point.


Pretty certain it's got an 1/8" of play in there.
 

gelton

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Had to replace my bearings in both the top and bottom cam of my V3 and used this guys approach and replaced the Chinese bearings used by Mathews with the Japanese ones that he recommends in the description of the video.

No issues so far, but agree that a bow that is "Made in the USA" and is their flagship offering shouldn't have such sub-par components. All four of the bearings pulled were grinding and one of the four the bearings were totally crushed.

 
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Extrapolate 18 per bow over the entire production and unite frankly it’s a huge margin. Considering how few failures production bearings have in cam compared to the number of bows built and sold it seems fairly reasonable model.
No issues so far, but agree that a bow that is "Made in the USA" and is their flagship offering shouldn't have such sub-par components. All four of the bearings pulled were grinding and one of the four the bearings were totally crushed.

Its $18 bucks a bow... I'm sorry, you're supposed to be selling a superior product - this means you either pass along the extra $18 in expense to the customer or you eat it.

Not to mention those prices he quoted are for regular folks buying one or two - Mathews calls up and says they want to order 100,000 and those prices go down.
 

Johbran

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I’m curious, what did you experience
That made you look in to it? Excessive noise at the shot, a squeak or creaking during the draw? I own a vxr 28 and just want to know what to watch for if need be.
 

gelton

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I’m curious, what did you experience
That made you look in to it? Excessive noise at the shot, a squeak or creaking during the draw? I own a vxr 28 and just want to know what to watch for if need be.
For me, it was a clicking noise during the draw cycle. I thought that the limb pockets needed to be lubed and took the bow apart threw some lithium grease in the limb pockets and the clicking sound didn't go away.

Looked further into it to find that the bearings could be the cause so I proceeded to check the bearings and found that they were wanting to bind up. Replaced them and the noise went away.

If you have a press and want to check yours it's a fairly easy process, just remove the cams and hold them between your thumb and forefinger, and spin...it will be fairly obvious if yours need replacing or not. Either they will spin freely or not.
 

D S 319

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how many shots approx. at which poundage and DL? ...

While it is a PITA, now that I know what causes the issues and that it can be relative easily fixed I feel much better - life time warranty is fine, but having to wait till the spare parts are coming from US to down under takes the fun out of it. I will get the best quality ball bearings I can find and put them in and that should do the trick....
I would guess 2000 first cam, another 500 or so later the other cam started doing the same thing. I am at 29.5 at 75 lbs. thankfully my friends over at Scheels took cams off of bows to just replace mine on the spot. One of them went bad couple days before a hunt we were going on.
 

bigW

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I'm 99% certain this is not correct. The washer is shouldered to locate it, not to draw down on the axle.

I can mic everything at a later point.


Pretty certain it's got an 1/8" of play in there.
when I get my upgraded bearings and swap them over I will take precise measurements -

but somethings else comes to my mind: these little black washers with the collar lip are really tiny, sometimes they stick to the limb and you might take them of - now if you put it back together and you rush and you overlook that this little tiny washer has the lip / collar that should fit INTO the limb, and you fit them the wrong way, and it happens at both sides --> suddenly your axle is 2 mm too short!
Something definitely everyone should be aware of when taking the cams out!!!

Eta: that can also happen in a bow shop - not every bow mechanic might have the time to get familiar with every bow that goes through their hands, hence I highly recommend to check the fitting of these washers - both sides, top and bottom - anyway.
 
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