shock oil

[RobH]

First, know that I've looked in my instructions and all over on-line. I don't just come running here when I have any question.

How do I change the oil in my shocks? I found an article that explained how to take them apart (suspension tuning article on r/c car action) but he never said how to put it back together.

I accidentally got 50 wt oil, which is a bit high for my off-road rig but I figure I should have 40 in the back so 50 is ok for now. (I'm only changing the oil in the back anyway).

I took my shocks apart and I do have holes on either side of the plunger. I cleaned out the old oil and dropped the plunger all the way to the bottom. I then filled em all the way to the top and put the lid back on. (just guessing how it's done)

The only problem is that my shock hardly moves now. I push it in and it only moves like 1/8 to 1/4 of an inch before I hit major resistance... press any harder and the rubber cap on the bottom gives and oil shoots out.

any info would be greatly appreciated.

-rob

 

[NCNitro]

You have to bleed them. Heres a pretty good explanation of how to set them up.

Shock Setup

 

[RobH]

EXACTLY WHAT I NEEDED!

thx nc

 

[NCNitro]

No problem, just take your time and make sure you get ALL the tiny little air bubbles out of the shock fluid.

 

[SkyMaxx]

My question for you is why do you feel that 50wt is too heavy for an off road rig? I run 60wt in mine, and it is just right. Just curious.

 

[nitro dave]

I got 60 in mine too. The thing about shock oil, is you can experiment and see what works best for where you run. I know you don't race so you just need to find one that works best all around. It might be 50wt it might not.

 

[SkyMaxx]

I am familiar with the shock oil selection stuff; was just curious as to why he felt 50 wt was too heavy...but I think I can figure out why now. I just noticed the RC in his signature (kind of a light weight RC compared to my mostly metal Maxx).

As for me not racing, maybe I don't on a track, but it is always a race between Pirata and I as to who can get running first and stay running the longest. I win most of the time =devil .

 

[RobH]

yeah my max st is a light weight compared to youor t-maxxes. I read someplace that 40 in the back and 30 in the front runs well in my setup. The instructions also say I should use from 30-40wt.

I did the shock bleed thing. I have a question though. If you're supposed to fill them 3/4 full of shock oil, you'll never get all the air out right? I found if you fill them all the way and try to bleed them, you end up with shock that bounceces right back out when you are done. Maybe I still did it wrong.

 

[NCNitro]

Rob, you fill them 3/4 so you can move the piston up and down to get rid of the air without spilling oil, then top off before you put the cap on. They should compress fully and rebound a little with no spring on it, then you know you got it right.

 

[nitro dave]

Originally posted by SkyMaxx
I am familiar with the shock oil selection stuff; was just curious as to why he felt 50 wt was too heavy...but I think I can figure out why now. I just noticed the RC in his signature (kind of a light weight RC compared to my mostly metal Maxx).

As for me not racing, maybe I don't on a track, but it is always a race between Pirata and I as to who can get running first and stay running the longest. I win most of the time =devil .

Sky, my comment wasn't directed to you, but to Rob. I know that you know all that stuff, I was just giving a little info to Novice. I should have been more clear as to who the post was intended.

 

[SkyMaxx]

Once you have completed the bleed off process (with 3/4 cylinder of oil) you top it off as NC mentioned. As for rebound, when the shock is properly bled, filled, and capped; you should get rebound from full compression. This rebound should be between 1/4 and 1/2 an inch. Any more and you might have managed to overfill the shock. Any less and you still have air in the system.

NitroDave, I figured as much. I was just taking advantage of the ambiguity to ding Pirata.

 

[John Clark]

I know this a little off topic, but I figured it was close enough. I've got a full set of big bores on my Maxx, and since the day i put them in, I've had 2 caps leak. I've tried cranking them, leaving them finger tight, and about 1/2 turn past finger tight, and they still leak. I tried thread tape this last time, and still no go. Should I use a little silicone?

 

[SkyMaxx]

You can, but my question is this: are you sure it's the caps that are leaking?

If you have a bad o-ring on the cap or bad o-rings around the shaft, you will get oil from either source. You might consider buying some replacement o-rings (usually sold as a rebuild kit) and rebuilding those two shocks.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX2604&P=7

This is similar to what you want. It might actually work out for you, but I am trying to find the Big Bore rebuild kit.

 

[John Clark]

Thanks Sky. Yes oil is definitely leaking from the caps, but they don't have seals (in the caps), just bladders. Now, I did notice that the bladders were displaced a little bit when I pulled the caps off (ie pushed in a little bit). Do thay act as seals as well?

 

[SkyMaxx]

They can, but they are more a dampener against what is referred to as a waterhammer effect.

My recommendation, based on this new info, would be get some new diaphragms (the things you referred to as bladders), some large o-rings for the area around where the cap threads onto the shock body, and possibly some new o-rings for around the shaft. That should seal everything up nice and tight. If you replace all of the above and still have leakage, then there might be something else wrong (though I can't think what that might be, other than a size mis-match cap to body).

Either way do a search for "shock rebuild kit" or "shocks" at most on-line hobby stores (TowerHobbies is a good place to start), and you might find everything in one package. The link I posted above has everything for two shocks except the diaphragms. I know TRAXXAS makes a rebuild kit for their shocks that has everything you need. I'm just having a hard time tracking down the part number or a link.

Here's the only TRAXXAS rebuild kit I could find:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJJ17&P=7

It does not include a large o-ring for around the neck of the shock body. Might need to find them separately. Anyone with Big Bore shocks that can add to this please jump in.