Anyone else snap a center suspension pivot arm?

[jewill4]

I was taking out my skid last night because I wanted to re valve my center shock again since I was bottoming a little to frequently. In the preoccess, my front pivot arm was snapped in half just to the left of my center shock attachment point. It was a holy S$^t moment! This happen to anyone else? Did you weld it and beef it up or buy a new one for
SKU: 8HK-47331-00-00
ARM, PIVOT 1 1 $202.15

J-Rod

 

[stopdropanroll]

FYI, I have a customers 08 RTX shocks at HyGear for a basic revavle and rebuild, I recieved a call from them Monday saying the center shock was junk. They told me the shock body was "balloned" at the bottom and had to be replaced. They told me that the shock hose on those sleds is extremely restrictive and causes damage to the shock when the sled lands hard or is driven aggressively. I know that this is a issue because my good buddie had a 08 RTX with a 136 and Carver revavle and it destoyed 2 shocks in one season by blowing the banjo fitting off the shock hence the restrictive hose. I would guess that this has something to do with your issue. I would recomend calling HyGear and talking to them about your shock and broken part.

 

[Alatalo]

I cracked a center swingarm on my -08 RTX 40th, but not in the place you are talking about. My left side tube (connecting the upper tube and the left side rail) started to show a crack straight across the tube at the end of the season (approximately 5000 kilometers).

They told me the shock body was "balloned" at the bottom and had to be replaced. They told me that the shock hose on those sleds is extremely restrictive and causes damage to the shock when the sled lands hard or is driven aggressively.

This happens because the shock absorber is building too much pressure between the main piston and the seal head. This is caused by the pressure build-up in the restrictive hose, by questionable shock absorber pressure balance (creating too much compression damping at the compression adjuster and not enough compression damping at the main piston) or by too much rebound damping (not very likely).
If the hose can survive a "balloned" cylinder tube, one way to go around this problem could simply be to get a revalve that improves the pressure balance (increase the compression damping at the main piston or reduce the compression damping at the compression adjuster).

 

[Crewchief47]

The question is, what came first, the bad shock or the broken shaft....

SDAR has some excellent points that I haven't read about to date.

 

[stopdropanroll]

I cracked a center swingarm on my -08 RTX 40th, but not in the place you are talking about. My left side tube (connecting the upper tube and the left side rail) started to show a crack straight across the tube at the end of the season (approximately 5000 kilometers).

They told me the shock body was "balloned" at the bottom and had to be replaced. They told me that the shock hose on those sleds is extremely restrictive and causes damage to the shock when the sled lands hard or is driven aggressively.

This happens because the shock absorber is building too much pressure between the main piston and the seal head. This is caused by the pressure build-up in the restrictive hose, by questionable shock absorber pressure balance (creating too much compression damping at the compression adjuster and not enough compression damping at the main piston) or by too much rebound damping (not very likely).
If the hose can survive a "balloned" cylinder tube, one way to go around this problem could simply be to get a revalve that improves the pressure balance (increase the compression damping at the main piston or reduce the compression damping at the compression adjuster).

Yes, very high pressure in the shock body. Luckly they had 1 spare new body left, factory shock is around 600 and a Axis shock is 799. The Hyflo hose does what your talking about:

http://www.hygearsuspension.com/hyflo_hose.html

 

[Grimm]

Do you have a pic of the breakage?

 

[jewill4]

What happened first?? Well I had it revalved by Bruce @ Pioneer last fall. All four shocks actually, reason for better stutter bump and I was bottoming BAD in the rear. Much better however I was bottoming in the center to much last winter but is that a result of the revalve being too stiff causing the metel to snap? IDK but as you guys are saying, its a good guess. I don't know when it broke unfortunatly. Inspecting the shock afterwards it seems really stiff about 45% into the stroke and I can't push it any further plus it appears the shaft is tweaked to the side that didn't break. The shaft isn't bent but its leaning to the right no matter where I spin the shaft to. I didn't notice any balloning. I'm going to call Bruse today and maybe Hygear as well..

 

[jewill4]

picture

Broke Pic.. looking backwards. Sorry about the quality. Cheap phone.

 

[arteeex]

Popsicle sticks and duct tape and you'll be back on the trail.

It looks to have failed at the transition leading into the gusseted area. In this case the gusset acts as a stress riser in the system limiting the ability of the tube to flex (strain) and redistribute applied stresses. A shock absorber should help attenuate the stresses by dissipating some energy and slowing the rate at which it is transferred. If the shock and/or spring is too soft both of these attributes are diminished and the tube will see higher peak loads and a increased rate of applied force when the shock is bottomed. Neither is good.

A similar problem would occur if the shock and spring were incompressible. But if this was the case it would have sucked to ride the sled.

It could also be that there was a flaw in the material. My bet is on the shock and spring being too soft.

 

[welterracer]

Re: picture

Broke Pic.. looking backwards. Sorry about the quality. Cheap phone.

Looks like that skid has the same problem the MONO shock skid has..

The shocks rebounds too fast which causes the arm to snap when the limiter strap grabs it and yanks on it..

If you buy a new one.. i would love for you to send me your old arm and i might work on a beef up kit for that model sled..

Thanks

Brian

 

[2008FxNytro]

i broke TWO of them....hope my new sled holds up better

 

[AttakDog]

Very common on the mono skid, go to the Apex forum and check it out!

 

[nytro44]

i had same thing happen to my 09 rt. took the skid to dealer and they covered it under warranty.

 

[stopdropanroll]

i broke TWO of them....hope my new sled holds up better

Change the shock hose! Call Leein at HyGear, he will tell all about that shock.

 

[2008FxNytro]

does this need to be done on the 09 FX nytro too?