Broken shock spring?

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6/14/2021 9:36 PM

Ever seen this? 4.0 spring on an ‘18 fc350 ridden by a 155 lb novice. Not exactly highly stressed. All pivot bolts greased and torqued properly.

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Hammer 663s

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6/14/2021 10:48 PM

Looking the wear marks, it looks like the spring has been running on the body. Something seriously not right going on before it failed

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6/14/2021 10:50 PM

I can't see the codes properly. Are you sure it's the correct spring type for that shock?

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6/15/2021 6:38 AM

Yes, I've seen broken shock springs before. It happens. I think most of the rubbing on the shock body happened after the spring broke and got cocked sideways on there.

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Powerband in every gear !

6/15/2021 7:00 AM

Ive seen it on cars a lot but never bikes.
The wear looks like it is just from riding when it broke.

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6/15/2021 7:17 AM

I have broke a few shock springs, mostly Ti, and fork springs,, it happens

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6/15/2021 8:53 AM

Thanks all. I've never broken a spring before. Yes, the wear is from after it broke. We didn't catch it till later, unsure how long he rode it like this - maybe an hour or 2 max. Damn near wore thru the shock body in that time.

It's a 4.0 kg spring rate 260 length, one rate lower than the stock 4.2.

Kreft makes a shock body ($150) and I'll get a new EE spring from AOMC and have it rebuilt. All good after that!

Anyone have the shim stack for the 21 AER? I'll have that done too while the fork is getting serviced.

Hammer 663s

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6/15/2021 1:15 PM

Hammer 663s wrote:

Thanks all. I've never broken a spring before. Yes, the wear is from after it broke. We didn't catch it till later, unsure how ...more

The 21 fork midvalve is totally redesigned, so settings won't work on the older forks. Plus, they moved the air pressure blow by on the air side as well.

Strange why it broke, but its not like it's never happened as people pointed out

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6/15/2021 4:44 PM

I use Diverse Springs now. Small company that produces lightweight chrome silicone springs.

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6/16/2021 12:57 AM

When my spring broke, it had similar hours to yours looking at the wear. So yes it happens. It is steel, and under stress it becomes weaker with time.

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6/16/2021 2:00 PM

Exact same thing happened on a friend's 17 SXF 350 a few weeks ago

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UK Vet rider - 2020 KX450

6/20/2021 11:18 AM

Looks like that is correct spring (aftermarket 39 NM x 262). Older link shocks were coming with 247mm WP springs and we have seen a few of those break as well. All bikes now come with 260mm length. You should be be able to acquire just the shock tube from a WP authorized centre as KTM/Husky dealers can only get the whole upper shock (much more expensive).

We stock them but we are located in Canada. Don’t have the part number with me here (at home).

Make sure that you don’t have more than 5mm of preload on the spring after you set sag. Also make sure the upper shock spring washer (that goes between spring and preload collar) is not worn or packed with dirt. When shock spring compress they do slightly twist so this minimizes side loading of spring and change of breaking.

Stuff happens but you will be back at it with a few parts!

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6/21/2021 6:38 PM
Edited Date/Time: 6/21/2021 6:41 PM

My riding buddy broke his 4.2 shock spring on his TX300 the exact same way. He goes 165#. Vet A off road. The spring dropped down into his linkage and locked the assembly. I had to use my cutoff wheel the cut the spring into pieces to get it off.

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6/22/2021 10:04 AM

canuck250f wrote:

Looks like that is correct spring (aftermarket 39 NM x 262). Older link shocks were coming with 247mm WP springs and we have ...more

Is there a way to find WP part numbers? I work at a Husky dealer and only need the shock tube for a 2016.

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Unleaded tastes a little tangy. Supreme is kinda sour, and diesel tastes pretty good.

6/22/2021 2:05 PM

Rickyisms wrote:

Is there a way to find WP part numbers? I work at a Husky dealer and only need the shock tube for a 2016.

Did you decide on doing the bladder conversion kit? I ask because. to me, if I am already in there going through the trouble of spinning off the stock reservoir and I am going to spin off the body, I am putting that sweet Kreft one on there!! I ain't going through all that trouble to put a boring non-Kashima body on there ! haaa I just did another bladder conversion last night and it was even more of a pita than the others I've done. Barely got the thing broke loose.

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Powerband in every gear !

6/22/2021 2:13 PM

We'll check with Factory Connection and get a price on the stock body tube. If the Kreft isn't a whole lot more he'll get that instead. It's a young guy's bike and his Dad is a cheap Dutchman. wink If it was my bike I'd do the kreft tube and a MX Tech can and piston upgrade. I generally don't do a bladder since I don't service the shock every 25 hours.

Hammer 663s

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6/22/2021 7:10 PM

canuck250f wrote:

Looks like that is correct spring (aftermarket 39 NM x 262). Older link shocks were coming with 247mm WP springs and we have ...more

Rickyisms wrote:

Is there a way to find WP part numbers? I work at a Husky dealer and only need the shock tube for a 2016.

FGR01 wrote:

Did you decide on doing the bladder conversion kit? I ask because. to me, if I am already in there going through the trouble ...more

Still playing with the idea, I think I’m going to run what I have now, and do the bladder conversion next time the bike is apart. I’m scraping by on cash at the moment because I just paid for a full bottom end rebuild along with a cylinder replate and have 3 other project bikes on my hands haha.

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Unleaded tastes a little tangy. Supreme is kinda sour, and diesel tastes pretty good.