Caps Popped out after jump. Wondering why

Thread starter #1
Messages
42
Likes
17
Location
Spain
I have two shocks per wheel and use big Joe tyres. Yesterday, after landing from a jump, both shock caps from a rear side had popped out open. This never happened to me before.
Could it be caused because of using heavy wheels?
I would like to prevent it from happening again (don't like cleaning silicon oil from all around).
 
Messages
8
Likes
0
More than one reason comes to mind and maybe there are more reasons out there :

1. Changed to thicker shock oil, maybe too thick.... the plastic caps can only hold so much pressure

2. Improperly bled shock oil after refilling, Too much oil will definatly cause busted caps or busted O rings because of hydrolock

3. Over tightening the caps can cause cross threading

4. Improperly screwing in the caps can cause cross threading
 
Thread starter #4
Messages
42
Likes
17
Location
Spain
More than one reason comes to mind and maybe there are more reasons out there :

1. Changed to thicker shock oil, maybe too thick.... the plastic caps can only hold so much pressure

2. Improperly bled shock oil after refilling, Too much oil will definatly cause busted caps or busted O rings because of hydrolock

3. Over tightening the caps can cause cross threading

4. Improperly screwing in the caps can cause cross threading
Thanks for your response. I am using 45W (575 cst team associated) silicon oil. Maybe that is too thick. I have refilled both shocks again with 45W but will get some 37W for future use.
One thing I have found out is that the shock expansion travel is not limited by the arm movement. This could also cause the pull out of the shock caps. Big bore shocks have the same length as the narrow type so the same happens when using them. Attached is a picture showing that arm movement is about 5mm longer than shock length.
 

Attachments

Messages
8
Likes
0
Shock extension limitation will only cause the caps to pop if the truck lands upside down and the wheels hit some object before the top of the body hits the ground, so hence somthing pulling down on the wheel, usually unlikely.
Standard shock oil used i beleive is 10wt, its either 45wt is too heavy to be used or most likely you had too much oil in shock, hence uncompressable shock shaft = popped caps no matter what oil weight used...

Id imagine if the truck lands at forward motion no matter oil weight used, it shouldnt cause popped caps... if the truck free falls vertically down then heavier oil might cause popped caps....

Big note: after filling shock with shock oil and screwing the cap, make sure the shaft can completly compress, no hydrolock, otherwise re-bleed and test again
 

olds97_lss

Well-Known Member
Messages
1,673
Likes
288
Location
Dekalb, IL 60115
Are you using big bore plastic or the smaller plastic shocks?

I was only able to go up to 40wt associated in my big bores running white front/yellow rear springs on my flux hp. Any more than that and I was busted shock ends every time I bashed. I think some of my issue was due to the RPM arms I had twisting too much causing them to break, but I never increased the weight beyond 40 anyway and it's taking some pretty big air with pro-line trencher 3.8's, which are pretty big and heavy tires.
 
Top