Leaking Shock Cap - Suggestions Needed

[ChisaiKuso]

Maybe some of you have encountered this before...

One of the rear shocks on my late model (all black) RC10 Worlds car will not stop leaking between the cap and body. I have replaced the O-ring three times, but doing that has not helped. No damage or defects have been noticed on the cap or body. What is really frustrating is that the shock is leaking while the car sits on the shelf. The car is not a runner, and the shocks are not getting cycled.

Any ideas or suggestions (other than replacing the shock body and/or cap)?

[GoMachV]

I personally would swap caps with another known good shock, that will tell you if it is the cap or the body that is at fault. Just my $.02

[RC10resto]

I would rather have oil in my shelf queens.................but if they don't have oil they can't leak

[ChisaiKuso]

I personally would swap caps with another known good shock, that will tell you if it is the cap or the body that is at fault. Just my $.02

I was planning to do that very thing unless someone has a suggestion that doesn't involve opening two shocks. I'm not sure why, but working on shocks has always been the least enjoyable part of building and racing RC vehicles for me.

[ChisaiKuso]

I would rather have oil in my shelf queens.................but if they don't have oil they can't leak

I'm with you on that thought process. I've often contemplated leaving shocks empty and bushings/bearings dry on my shelf queens, but it just wouldn't be right. Nearly all of my RC cars are kept in a "ready to run" state even though over half of them will likely never leave the shelves again.

[GoMachV]

I personally would swap caps with another known good shock, that will tell you if it is the cap or the body that is at fault. Just my $.02

I was planning to do that very thing unless someone has a suggestion that doesn't involve opening two shocks. I'm not sure why, but working on shocks has always been the least enjoyable part of building and racing RC vehicles for me.

+1 on that, shocks are the last thing I build!

[Percymon]

you could always take the pressure off the shocks and the tyres by displaying the car with wheels off the ground - a plastic margarine tub sprayed up to match the cars colour scheme works well if you don't want to shell out on car stands or perspex boxes.

[teman]

Have you tried green slime yet? I've always got a kick out of that product name

[ChisaiKuso]

you could always take the pressure off the shocks and the tyres by displaying the car with wheels off the ground - a plastic margarine tub sprayed up to match the cars colour scheme works well if you don't want to shell out on car stands or perspex boxes.

All of my RC10s sit on old E-Maxx wheels.

[ChisaiKuso]

Have you tried green slime yet? I've always got a kick out of that product name

LOL! I am forced to admit that during all of my years in this hobby I have never once used the stuff ... maybe because of the product name.

[Charlie don't surf]

If your fluid is leaking out of the shock while it's wheels down, then you have positive pressure inside the shock, which is increased as the shock is compressed under vehicle weight. ie- way too much shock oil, and since pressures are always trying to equalize, yours are succeeding at that process.

[ChisaiKuso]

I personally would swap caps with another known good shock, that will tell you if it is the cap or the body that is at fault. Just my $.02

Curiosity got the better of me. I'm in the process of swapping caps on the rear shocks now. I'll also replace the O-rings (again!) just to error on the safe side. In a few days I'll hopefully know which part is actually causing the problem. In the meantime, please keep the suggestions coming...

[ChisaiKuso]

If your fluid is leaking out of the shock while it's wheels down, then you have positive pressure inside the shock, which is increased as the shock is compressed under vehicle weight. ie- way too much shock oil, and since pressures are always trying to equalize, yours are succeeding at that process.

This is turning into a fun discussion. My car probably has a defective shock cap, but let's continue as if that isn't the case...

I completely understand your logic, but I don't see it as being a possibility in this case. On any given RC10 I always build the shocks per the exact instructions for the specific model (even though some of the older building methods really suck and can cause exactly what you mentioned). The Worlds car instructions have the rear shocks filled to 1/16" from the top of the bodies. Before screwing on the caps, the shafts are pushed all the way into the bodies until the pistons are just below the surface of the oil. This would logically mean that once the shafts are then extended back out there should be a vacuum created inside of the shocks.

[RC10th]

Can you see the black o-ring sitting properly in the cap as you tighten it down? Also make sure the o-ring isn't twisted when you put it on, and use a drop of oil when putting it on the shock body as a sharp thread can cut it. You should be able to push the shock shaft in till it bottoms out, if you cant there is too much oil.

[Lonestar]

Charliedon'tsurf is right, still... if it leaks from the top at "idle" then it's overfilled, assuming there is no obvious defect on one of the parts AND the oring sits properly (on the body... not in the cap... just want to be sure, as this is a common mistake )

How to bleed top-loaders optimally: with orings greenslimed, piston down, fill to the top (with practice you will learn to not waste oil by filling less later on), fill a couple of drops in the cap, be quick and screw it on until there's like two threads showing, slowly push piston fully up, should bleed all over the place, wait for it to be done, then tighten up (RPM tools is a BIG help here).

Like this, no air, only oil (max volume before hydro-lock) ; this means vacuum , as vacuums don't exist outside of NASA labs, when you start operating the shock air gets in via the bottom orings until there is just enough air inside to not overcome the orings stiction with the vacuum, and then you're all set with minimal rebound (always some on an emulsion shock... 100% vacuum dont exist...) with perfect emulsion shocks that will last 3 packs and then you can rebuild at the track

if it leaks from the top after you built them like this (ie with a slight vacuum), then some part is really defective (or oring is in the cap, not on the body)

Good luck

Paul