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Discussion Starter · #1 ·
Out riding on my 2008 SC Heckler today and snapped the DHX shock where the shaft meets the smaller end. On inspection it seems that the mounting bushes have siezed preventing the shock from rotating so its not surprising it snapped!

Help please:

Background: Riding a few months ago I found that the mounting bolts had come a little loose and could see the shock mounting hardware moving relative to the bolt through the frame. I tightened up the mounting bolts (nice-and-tight :nono: ) as I thought that the mounting hardware prevented the shock and bushes from ever being captive causing them to sieze. Is this not the case? If not, how do you prevent the shock ratling on the mounting bolts.
 

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billyboy197 said:
Out riding on my 2008 SC Heckler today and snapped the DHX shock where the shaft meets the smaller end. On inspection it seems that the mounting bushes have siezed preventing the shock from rotating so its not surprising it snapped!

Help please:

Background: Riding a few months ago I found that the mounting bolts had come a little loose and could see the shock mounting hardware moving relative to the bolt through the frame. I tightened up the mounting bolts (nice-and-tight :nono: ) as I thought that the mounting hardware prevented the shock and bushes from ever being captive causing them to sieze. Is this not the case? If not, how do you prevent the shock ratling on the mounting bolts.
Doesn't sound like you did anything wrong just sounds like a defect. Only way I could see a shaft breaking under neglect is if the main pivot is loose then you would be putting side loaded stress on the shaft (not good) but I have seen this and still the shaft didnt break so it would have to be pretty loose. This is on reason CCDB uses heim joints.
 

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not that it is an issue here, but this is why some mfg (and it is a GOOD idea to) put a scissor link up near the shock on simple single pivot frames where the pivot is far from the shock.

A frame lay out like the heckler could apply some serious side loading to a shock...
 

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davep said:
not that it is an issue here, but this is why some mfg (and it is a GOOD idea to) put a scissor link up near the shock on simple single pivot frames where the pivot is far from the shock.

A frame lay out like the heckler could apply some serious side loading to a shock...
This is true in theory but I have been working in a Santa Cruz shop for 8 years now and still have not seen one snap even when people who are totally oblivious to the fact there main pivot is loose and probably has been for a while and there bike is in total crap shape the shocks still seem to hang on. Not sure what kinda long term damage may be done to the inside like the rod bushing and piston glide ring but no broken rods so far.

It is not real common for the main pivot to come loose on them but not a bad idea to check every now and then. I would think people would be able to feel when there rear end is all over the place but then some really just cant.

And on a last note it would be nice if shock manufactures starting following with Cane Creek and using the heim joints then you dont need to worry about your shock getting any sorta unwanted load.
 

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It sounds like the bushes wore out (they're designed to wear before your actual shock eyelet does so you only have to replace your bushings and not the shock) producing that movement. I'm guessing you really cranked up those mounting bolts to get rid of the play? And this extra bolt tension was enough to prevent the shock from rotating, which over stressed the shock eyelet and resulted in catastrophic gear failure?

That early play in the mounting hardware was probably worn bushings that are readily available and easy to replace. Next time you'll know.....
 

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Elitest thrill junkie
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billyboy197 said:
Out riding on my 2008 SC Heckler today and snapped the DHX shock where the shaft meets the smaller end. On inspection it seems that the mounting bushes have siezed preventing the shock from rotating so its not surprising it snapped!

Help please:

Background: Riding a few months ago I found that the mounting bolts had come a little loose and could see the shock mounting hardware moving relative to the bolt through the frame. I tightened up the mounting bolts (nice-and-tight :nono: ) as I thought that the mounting hardware prevented the shock and bushes from ever being captive causing them to sieze. Is this not the case? If not, how do you prevent the shock ratling on the mounting bolts.
Adding to what's already been said, the heckler design tends to side-load the shock that is fitted on the bike to a much greater extent than other designs, it shouldn't snap in two but when you add a few of these factors together, that may have been enough to do it.
 

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noMAD man
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Jayem, I'd agree on Heckleresque high forward single pivot style bikes having more flex at the shock without stiffening links, but this just sounds relatively unusual. Has anyone else seen any report around here about a full blown break like this? I'd think the untreated loose condition of shock hardware would just about have to get to the stage where the clanking would be so noticeable that you'd be ashamed to ride the thing...LOL! That's a really chunky spot on a DHXC...I'm guessing from the OP's description it's the place where the shock shaft screws into the mount. I'm not saying it couldn't happen with just loose eyelet hardware, but I'm speculating that a defect at this juncture of the shock may have been present. My opinion and $3.50 will get you a cup of coffee at Starbuck's...along with free wireless internet...but not in Canada.

Can the OP post up a closeup pic of this shock?
 

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Master of None
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billyboy, with the eyelet of the shock still attached to the reducers and bolted in the frame, can it be rotated? My guess is no.

My idea is that the manufacturing tolerance on the reducers was off, thereby clamping the shock on the shoulders of the reducer before the reducers touched in the middle. If the eyelet/reducers wore it would not clamp on the shock more, it would be less; along with the fact that your frame is a 2008 model.

The reducer tolerances are quite tight. I've made a few on my lathe and I've also scrapped a few due to missing the tolerance.
 

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Discussion Starter · #10 ·
I'll try and get a photo on tonight. Now the parts are removed from the frame the bushes still don't rotate on the failed end. They do on the other end though even if I clamp them in the vice (can't do any more damage now! :D )

Now for the full story where I gets lots of abuse :rolleyes:

I did fail to point out was that the DHX was from another bike of mine. I swapped it out as soon as I got the Heckler about 9 months ago (It came with the stock Fox float). I kept the old bushes (as they looked fine :nono: ) but used the new mounting hardware. When assembling them in the vice they moved as I expected without any play and the shock functioned fine full travel when checked without the spring fitted. Then after a number of months I noticed the movement as I mentioned in the original post.

The ride yesterday when it failed was mainly cross country seated and it failed catastrophically as it sheered striaght through, fortunatly I was going very slowly over a bumpy uphill secton.

Anyway - if it was poorly manufactured hardware I have got no warranty claim as it was not the original shock. This is not my first full sus but from now on I will be checking my bush more often. :blush: oo errr!

Thanks for the responses. Now let me have the abuse..........................
 

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billyboy197 said:
I'll try and get a photo on tonight. Now the parts are removed from the frame the bushes still don't rotate on the failed end. They do on the other end though even if I clamp them in the vice (can't do any more damage now! :D )

Now for the full story where I gets lots of abuse :rolleyes:

I did fail to point out was that the DHX was from another bike of mine. I swapped it out as soon as I got the Heckler about 9 months ago (It came with the stock Fox float). I kept the old bushes (as they looked fine :nono: ) but used the new mounting hardware. When assembling them in the vice they moved as I expected without any play and the shock functioned fine full travel when checked without the spring fitted. Then after a number of months I noticed the movement as I mentioned in the original post.

The ride yesterday when it failed was mainly cross country seated and it failed catastrophically as it sheered striaght through, fortunatly I was going very slowly over a bumpy uphill secton.

Anyway - if it was poorly manufactured hardware I have got no warranty claim as it was not the original shock. This is not my first full sus but from now on I will be checking my bush more often. :blush: oo errr!

Thanks for the responses. Now let me have the abuse..........................
well I still dont see this as your fault really. Like I said I have seen plenty of abused bikes and yet none snaped the rod as you describe. As for the warranty well really it just depends on how in depth your receipt is since the DHX is an option for the Heckler as long as your receipt doesnt mention what shock it came with then I would just have to assume it came with a DHX :D

even if not it did come of another bike of yours that did come with a DHX so use that ones receipt.

Bare minimum fox should meet you in between since there is a little liability in there and it is a very odd thing to have happened (what if you had been doing a drop?).

P.S. if you are going to test the bushings in a vice dont rotate the shock too much there really isnt alot of pivot motion in them and going too far will just prematuraly wear them out.
 

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Old man on a bike
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You weren't experimenting with a DHX other than an 8.5 x 2.5 were you? Fox is a pretty solid customer service oriented company, and I don't think you'd have to resort to fraud like someone suggested to get some help from them.
 

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Well actually fox is a stickler on your receipt so no they won't just help you out. I know this for fact as my friend had one of their dropouts break off when his dad was riding the fork on the Lexington park course trial (super duper easy relaxing ride) and you could visually see a pores casting bubble where it broke. Fox's first answer was well you cant use a rack that clamps the fork dropouts because this puts more stress on them than they were designed (retarded as it is if you ask me since most racks back then were all fork mount racks), but he wasnt even useing that kind of rack he has one of the basic strap on trunk racks with the two poles so their next answer was if your receipt doesn't show the fork then you have no warranty regardless of the fact this could have caused serious injury and a nice lawsuite if it had happened on a technical trail. So they offered him new lowers at full retail nice huh?

So no fox is not some easy laid back company on their warranty process and if you have to lie to get something that is that obviously a defect then no I don't see that as wrong.
 

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Your experience isn't even yours let alone being comprehensible and in any case it's not a good excuse to present a fraudulent case just to get what you want. What are you, 12 years old or something?
 

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Well being that "I" was handling the warranty claim I guess you could say it was "my" experience. So you think that if you bought a fork but you lost your receipt and even though fox has your serial number on hand to know the date it was manufactured and there is no way it is older than a year old and that the failure could have cost you all your front teeth but no its ok to not be warrantied because you dont have a stupid peice of paper to proove you originally owned it even though there is an obvious casting bubble. :confused:

Not saying they dont make good stuff his was just a fluke and this sounds like a fluke and I would think it would be in their best interest to fix it as quietly as possible I am just saying don't show all your cards and screw yourself.
 

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billyboy197 said:
Out riding on my 2008 SC Heckler today and snapped the DHX shock where the shaft meets the smaller end. On inspection it seems that the mounting bushes have siezed preventing the shock from rotating so its not surprising it snapped!

Help please:

Background: Riding a few months ago I found that the mounting bolts had come a little loose and could see the shock mounting hardware moving relative to the bolt through the frame. I tightened up the mounting bolts (nice-and-tight :nono: ) as I thought that the mounting hardware prevented the shock and bushes from ever being captive causing them to sieze. Is this not the case?
[poor English inside] From my experience - if they are two piece rdeucers then no - they don't prevent seizing. The tighter they are the harder they rotate. I saw a picture or two of shocks with broken shafts and IMO this is the reason. Besides over some time friction on the bushings increases thus something that rotated hard at the beginning may end up rotating incredibly hard after a month or so. Look at the design - the bushing/reducer contact surface_s_. One of them is inside the bushing, the other one is on side of the bushing - the reducer is pressed against this surface by a mounting bolt. There is small space between reducers in the middle of the bushing so they never meet there and can't prevent overtighting.
billyboy197 said:
If not, how do you prevent the shock ratling on the mounting bolts.
To avoid excessive tightening I use rubber o-rings + ordinary washers or "springy washers" (don't know the English name) - the idea is that mounting bolts have to be loaded all the time - something springy may help.
 

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Discussion Starter · #18 ·
I've now stripped the mounting hardware off the shock and taken some measurements with my Vernier calipers and ITS NOT MY FAULT!!! :madmax:

The shock measures 12.7mm across the bush both ends.
The hardware spacing at the end that didn't fail = 13mm. :thumbsup:
The hadware spacing at the end that failed = 12.5mm :madmax:

It's no wonder then that when I tightened up the bolts it seized and eventually failed. It was probably ok on first assembly as the hardware maybe hadn't seated fully hence it came loose.

How do you suggest I approach any sort of guarantee? I can just see how the discussion will go..... SC "Not our shock", Fox "Not our hardware", LBS "Have some replacement hardware free of charge as a good will gesture" Gee Thanks, now I've only got to find £300 for a new shock!
 

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Marcin J. said:
[poor English inside] Look at the design - the bushing/reducer contact surface_s_. One of them is inside the bushing, the other one is on side of the bushing - the reducer is pressed against this surface by a mounting bolt. There is small space between reducers in the middle of the bushing so they never meet there and can't prevent overtighting.
.
This is actually incorrect in two ways.

The shoulder of the reducer should not load on the shock eyelet at all (there is no bushing on the 'side' to contact anything..it is a simple tube (generally of steel) that is lined with a film lubricant...if there were any 'side' contact, it would be directly on the shock eyelet..aluminum on aluminum wear under pressure = very bad....galling cold welding.....

The reducers should actually contact (bottom on each other) within the bushing thus preventing over tightening and the 'side' contact mentioned above. If there is a gap between the reducers (like the OP found) then you have either the wrong sized reducer(not sure from what/where as all shocks that I can think of have a 1/2" eyelet width) or a very poorly manufactured part.
 

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davep said:
This is actually incorrect in two ways.

The shoulder of the reducer should not load on the shock eyelet at all (there is no bushing on the 'side' to contact anything..it is a simple tube (generally of steel) that is lined with a film lubricant...if there were any 'side' contact, it would be directly on the shock eyelet..aluminum on aluminum wear under pressure = very bad....galling cold welding.....

The reducers should actually contact (bottom on each other) within the bushing thus preventing over tightening and the 'side' contact mentioned above. If there is a gap between the reducers (like the OP found) then you have either the wrong sized reducer(not sure from what/where as all shocks that I can think of have a 1/2" eyelet width) or a very poorly manufactured part.
I can't make any measurements now but AFAIR all shocks I've owned behaved the same way (as described above). Shortly speaking - the tighter the bolts are - the harder is to rotate the shock. I can also recall a manual (Santa Cruz?) which described shock installation as a step by step process: tighten bolts slightly; does the reducers rotate on shock axles? if so - tighten more. It was clear they tried to avoid too much load.
IMO this is a matter of balance. Too short reducers and you end up with prematurely worn out or even broken shock. Too long reducers and you have lateral shock movement which I guess is not a good thing either. The later I've experienced by my own when tried to ride AD5 equipped with heavy duty kit without one of the "side reducers" - so I know it moves ;) . Thus side contact is a must - I can't see any other way to prevent such a movement.
On the subject of increased wear of the side surfaces - surprisingly reducer's shoulders have similar thickness to the bushings. Of course you are right - there are no sliding surfaces on the side of the bushings. Some companies put there o-rings to seal this connection. (I've never owned one of these) It would be interesting to see what is moving in relation to what.
And why they (the producers) don't use needle bearings in this application? Yes, I know about Avalanche, older DT's (ball bearing however) and have read something about Fox attempts. But generally they are chained to bushings. Maybe it is because additional friction/stiction helps preventing unwanted suspension movement or these few grams more...
So small things - so much questions. :crazy:
 
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