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  1. #1
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    First time shock oil change - What I learned

    I wanted to post this for anyone who is new to RC and changes their shock oil for the first time. This is because of this post of mine

    https://forums.traxxas.com/showthrea...ut-Options-now

    It's going to take longer than you think it will the first time.

    Be patient and don't rush. Give yourself some time to do it.

    Old oil: This is my daughters and she MAYBE has 5 hours on it and it's never even been wet or muddy. I was astonished how dirty the oil was.

    I worked on this on my computer desk. Next time I'll do it in an area where I have room to put everything I need on the desk.

    The bladder: This is the one area I struggled with the most. Some people put the bladder on the shock and use the shock as suction to hold it on and screw the cap on. Others put the bladder in the cap and use the allen wrench method to ensure it's even in the cap. I tried both ways. For me the bladder in the cap was FAR easier to work with. I changed the rear with the suction method and the front with cap method.

    Shock rebound amount: This is an area I could never find a straight answer. I guess it all depends on what you're using it for. The only thing that seemed to be consistent is all four should be the same. I wasn't sure how much to do so I probably ran 3/16" of rebound. I'll see how it goes and adjust if needed.

    Shock oil weight: Another area that was all over the map. The 2WD slash is 30W all around. Talking to a few people I decided to try 40W in the front shocks and keep the rear at 30W. I'll see how that goes.

    Bleeding the air bubbles: Go slow with the shock shaft. This falls under the patience category. Some people button up after they bleed for a minute or two. Others will let it sit for 10-15 minutes before topping off. I'm not sure which way is correct, but there are enough videos to figure out what direction you want to go.

    Cleaning up: Some people use brake cleaner or window cleaner. I didn't have brake cleaner so I used window cleaner. That seems to work fine.

    Aside from that I learned a lot and next time I could do it in probably half the time.

    Thank you for anyone that gave advice. I listened to all of it and tried to pick a direction and go with it. We'll see how it goes.

  2. #2
    RC Qualifier Calebs0615's Avatar
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    Quote Originally Posted by kantonburg View Post
    I wanted to post this for anyone who is new to RC and changes their shock oil for the first time. This is because of this post of mine

    https://forums.traxxas.com/showthrea...ut-Options-now

    It's going to take longer than you think it will the first time.

    Be patient and don't rush. Give yourself some time to do it.

    Old oil: This is my daughters and she MAYBE has 5 hours on it and it's never even been wet or muddy. I was astonished how dirty the oil was.

    I worked on this on my computer desk. Next time I'll do it in an area where I have room to put everything I need on the desk.

    The bladder: This is the one area I struggled with the most. Some people put the bladder on the shock and use the shock as suction to hold it on and screw the cap on. Others put the bladder in the cap and use the allen wrench method to ensure it's even in the cap. I tried both ways. For me the bladder in the cap was FAR easier to work with. I changed the rear with the suction method and the front with cap method.

    Shock rebound amount: This is an area I could never find a straight answer. I guess it all depends on what you're using it for. The only thing that seemed to be consistent is all four should be the same. I wasn't sure how much to do so I probably ran 3/16" of rebound. I'll see how it goes and adjust if needed.

    Shock oil weight: Another area that was all over the map. The 2WD slash is 30W all around. Talking to a few people I decided to try 40W in the front shocks and keep the rear at 30W. I'll see how that goes.

    Bleeding the air bubbles: Go slow with the shock shaft. This falls under the patience category. Some people button up after they bleed for a minute or two. Others will let it sit for 10-15 minutes before topping off. I'm not sure which way is correct, but there are enough videos to figure out what direction you want to go.

    Cleaning up: Some people use brake cleaner or window cleaner. I didn't have brake cleaner so I used window cleaner. That seems to work fine.

    Aside from that I learned a lot and next time I could do it in probably half the time.

    Thank you for anyone that gave advice. I listened to all of it and tried to pick a direction and go with it. We'll see how it goes.
    This is a good read.

    Keep us updated on how it goes.

    Working on stuff for the first time is always hard. Maybe not hard every time, but time consuming at the very least. I love working on things and gaining that knowledge. Cause the next time you do it, its gonna take half the time. And at a certain point of doing things so many times, your going to find shortcuts to make things easier for you.

    Bleeding bubbles in my opinion the longer you wait the better i would think. But after say ten minutes your probably just waisting time.

    As for cleaning up, probably the best bang for buck would be isopropyl alcohol. And q tips. Or cotton swabs. Brake cleaner works awesome for bigger areas but it has quite a bit of pressure so its not ideal for some things.

    I'm looking forward to what people say about rebound. Cause i dont think i put any rebound in mine.. I just left them extended all the way and filled them to the top. Pumped it a dozen times or so. Waited for bubbles to go away. And topped off with fluid.

    What are benefits to rebound?

    Sent from my LGL722DL using Tapatalk

  3. #3
    RC Racer
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    Bleeding - The thicker the oil, the longer you wait. Also, I made a shock building stand by drilling 4 holes in a scrap piece of 2” x 2. The holes are just big enough for the shock shafts to fit into, without the ball end. It’s way better than the shock stand I actually paid for. I overfill them, so the oil forms a slight bulge above the top of the shock body. This makes assembly a bit messier, but pretty much eliminates the chances of air getting into the oil.

    Rebound - I like zero rebound. It makes setup more predictable for me. I accomplish this by drilling a really small hole, 1/16” perhas, up through the centre of the shock cap, so it exits at the bottom of the ball end. This allows the bladder to simply be an oil seal. I still push the shaft all the way up (minus the threads) into the shock body.

    I hope this helps you a little.

  4. #4
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    Quote Originally Posted by monkeyracing View Post
    Bleeding - The thicker the oil, the longer you wait. Also, I made a shock building stand by drilling 4 holes in a scrap piece of 2” x 2. The holes are just big enough for the shock shafts to fit into, without the ball end. It’s way better than the shock stand I actually paid for. I overfill them, so the oil forms a slight bulge above the top of the shock body. This makes assembly a bit messier, but pretty much eliminates the chances of air getting into the oil.

    Rebound - I like zero rebound. It makes setup more predictable for me. I accomplish this by drilling a really small hole, 1/16” perhas, up through the centre of the shock cap, so it exits at the bottom of the ball end. This allows the bladder to simply be an oil seal. I still push the shaft all the way up (minus the threads) into the shock body.

    I hope this helps you a little.
    I've seen some higher end shocks have the bleeder hole. I have the aluminum caps on her shocks so I could do that too.

    My only question is by drilling the hole it causes the oil to exit at the ball end? I thought it just bled out the top and that was it. Not the case?

  5. #5
    RC Champion zedorda's Avatar
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    Quote Originally Posted by monkeyracing View Post
    Rebound - I like zero rebound. It makes setup more predictable for me. I accomplish this by drilling a really small hole, 1/16 perhas, up through the centre of the shock cap, so it exits at the bottom of the ball end. This allows the bladder to simply be an oil seal. I still push the shaft all the way up (minus the threads) into the shock body.

    I hope this helps you a little.
    This is not zero rebound this is negative rebound. When your suspension is as full extension you have high negative pressure in the shock. Only when your shock is fully compressed is your shock at zero pressure.

    Zero rebound stands for zero pressure when the shock is in the middle of its travel. This condition reduces the pressure/rebound in both directions.

    With that said there is not a wrong setting for rebound but there are some side effects of going extreme in either direction.

    High negative rebound causes the shock to suck in dirt passed the seals and stretches out the diaphragm.

    High positive rebound will cause leaking and possible blow-out of a seal or the cap.

  6. #6
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    Quote Originally Posted by zedorda View Post
    This is not zero rebound this is negative rebound. When your suspension is as full extension you have high negative pressure in the shock. Only when your shock is fully compressed is your shock at zero pressure.

    Zero rebound stands for zero pressure when the shock is in the middle of its travel. This condition reduces the pressure/rebound in both directions.
    So does that mean that as the shock sits in your hand with no spring half the shaft should be out?

  7. #7
    RC Champion zedorda's Avatar
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    Yes exactly. It should not push out harder than it pulls back from full extension. True zero rebound is pretty hard to get perfect.
    Last edited by zedorda; 09-20-2020 at 02:58 PM.

  8. #8
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    Quote Originally Posted by zedorda View Post
    Yes exactly. It should not push out harder than it pulls back from full extension. True zero rebound is pretty hard to get perfect.
    Thank you for the explanation

  9. #9
    RC Racer
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    Quote Originally Posted by zedorda View Post
    This is not zero rebound this is negative rebound. When your suspension is as full extension you have high negative pressure in the shock. Only when your shock is fully compressed is your shock at zero pressure.

    Zero rebound stands for zero pressure when the shock is in the middle of its travel. This condition reduces the pressure/rebound in both directions.

    With that said there is not a wrong setting for rebound but there are some side effects of going extreme in either direction.
    I end up with zero rebound. The shaft will not move away from any position it’s put into. That tiny hole in the shock cap prevents the bladder from maintaining any effect on the fluid at all. It works for me.

    I think I just compress the shock out of habit. I have built shocks at full extension and the ne5 effect is the same.

  10. #10
    RC Turnbuckle Jr. rag6's Avatar
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    If talking about ultra shocks or big bores step 1 is...

    Match oil to springs. Stiffer/softer springs = heavier/lighter oil.


    Sent from my moto e5 cruise using Tapatalk
    Ya can't polish fertilizer...

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