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Thread: Shock rebound

  1. #1
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    Shock rebound

    Hey guys so I got a new summit a couple weeks ago and I haven't even played with it yet. I know it sucks One thing that I dont like much is how the back sags a bit, Im sure it might be better for crawling but i would just like to see a little less sag. So yesterday I went to the hobby store and purchased a set of front springs to install in the rear #5469 they have a higher spring rate 5.4 then orginal stock rear which I believe is 4.9. So any ways I took the rear shocks off and removed the spring just for inspection I decided to test the rebound of the shock so I pushed in the shaft and I was really surprised at how the shock barely moved back out. This is my first Traxxas ever and maybe its normal for this kind of truck. I just wanted to confirm if this is accurate, plus does anyone know the shock weight for the stock Summit shocks?

    Here are some pics.


    shaft fully extended

    max rebound after pushing in the shaft


    What shock weights are you running?
    Thanks in advance!
    Last edited by nsousa; 02-13-2012 at 09:52 AM.

  2. #2
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    The spring is what creates the rebound...

    No spring = No rebound.
    Whatever it is I just said... I could be wrong.

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    Quote Originally Posted by Jimmie Neutron View Post
    The spring is what creates the rebound...

    No spring = No rebound.
    +1. Don't know what more to say, but I have to say something .
    This is a signature.

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    If you liked it then you should have put a spring on it, don't be mad because you didn't put a spring on it. oh oh oh

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    Quote Originally Posted by Jimmie Neutron View Post
    The spring is what creates the rebound...

    No spring = No rebound.
    I might have explained it wrong but let me explain a little better. On my previous RC that I owned RC8T when we we filled the shocks with fluid we would have to test the shock shaft by pushing it in and see how far it would come back by itself.
    I believe on the Rc8t it was about 1/2 to 3/4 inch the shaft would comeback out, with the Summit shocks its looks like it less then 1/4. Im not saying that there is something wrong with the Summit shocks I just want some to confirm if thats all they come out.

    Watch this video its called rebound when the shock comes out.
    http://www.youtube.com/watch?v=HNJy7kreK90

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    Quote Originally Posted by nsousa View Post
    I might have explained it wrong but let me explain a little better. On my previous RC that I owned RC8T when we we filled the shocks with fluid we would have to test the shock shaft by pushing it in and see how far it would come back by itself.
    I believe on the Rc8t it was about 1/2 to 3/4 inch the shaft would comeback out, with the Summit shocks its looks like it less then 1/4. Im not saying that there is something wrong with the Summit shocks I just want some to confirm if thats all they come out.

    Watch this video its called rebound when the shock comes out.
    http://www.youtube.com/watch?v=HNJy7kreK90
    thats absolutly right. They should rebound about 1/2 to 3/4 when compressed without springs.
    Revenge 1/8 buggy

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    well I just checked all 4 shocks and they rebound about the same....just a little over 1/4. Im really surprised the trucks never been used. I might empty them and adjust that.

    I installed a pair of front springs in the rear Wow! it looks a lot better. It evens out the stance of the Summit.

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    Quote Originally Posted by nsousa View Post
    well I just checked all 4 shocks and they rebound about the same....just a little over 1/4. Im really surprised the trucks never been used. I might empty them and adjust that.

    I installed a pair of front springs in the rear Wow! it looks a lot better. It evens out the stance of the Summit.
    change the weight to 50 wt and try that again. you will see a better performance in rebound
    Revenge 1/8 buggy

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    Shock rebound

    That makes no sense. I too thought its the springs that are soley responsible for the rebound. If you have the shafts rebounding as well, that can't be ideal for dampening, can it?

    I was told early on you want zero rebounding of the shaft when you fill the oil up, that way you know the shock is completely filled with oil and maximizing the dampening.

    And from the op, the squatting you see is a known issue with the summit, erevo and mini erevo. I think its mentioned on all the official faq pages. . You can even see it squatting on the main promo pic on the erevo product page. I just jack the preload up on the rear springs and it helps, but still sags with throttle.
    Last edited by varunaX; 02-13-2012 at 07:37 PM.

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    Quote Originally Posted by OnebadTMAXX3.3 View Post
    change the weight to 50 wt and try that again. you will see a better performance in rebound
    Thanks im going to try that tomorrow.

    Cheers!

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    Quote Originally Posted by varunaX View Post
    That makes no sense. I too thought its the springs that are soley responsible for the rebound. If you have the shafts rebounding as well, that can't be ideal for dampening, can it?

    I was told early on you want zero rebounding of the shaft when you fill the oil up, that way you know the shock is completely filled with oil and maximizing the dampening.

    And from the op, the squatting you see is a known issue with the summit, erevo and mini erevo. I think its mentioned on all the official faq pages. . You can even see it squatting on the main promo pic on the erevo product page. I just jack the preload up on the rear springs and it helps, but still sags with throttle.
    Shocks Have to have some rebound as the help the spring have a controlled compression and decompression as its going throught the bumps. Basically they will try to keep the tire down after it goes on a bump so that they are not bouncing all over the place giving you traction.
    You ever see a car go over bump on the highway and even a little after its passed that bump the car is still looks like its moving up and down. Usually that same car when hits a bump the tire looks like its ready to fall off because the shock has no rebound to keep the tire on the ground.

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    But surely the amount of rebound help from the shafts we are talking about is trivial when you think of all the jump and bumps during a run. The springs are doing all the work imo, or should be

    When I fill my shocks, I just feel I've done a good job when there is zero rebound but I can really feel the oil doint the work during compression. If I ever see some auto rebound, I refill the shock to eliminate it. Personal pref perhaps

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    Quote Originally Posted by varunaX View Post
    But surely the amount of rebound help from the shafts we are talking about is trivial when you think of all the jump and bumps during a run. The springs are doing all the work imo, or should be

    When I fill my shocks, I just feel I've done a good job when there is zero rebound but I can really feel the oil doint the work during compression. If I ever see some auto rebound, I refill the shock to eliminate it. Personal pref perhaps
    For a shock to be fuctional it needs to have some rebound wether it be 1/4 or 3/4. Obiviously the shock with more rebound will have different characteristics. If the shock shaft doesnt come out at all when its been compressed then it really doesnt do much for performance. All shocks should have some rebound the question is whats the amount. But at the end of the day its whatever floats your boat

  14. #14
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    I learn something new every day... thank you!
    Whatever it is I just said... I could be wrong.

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    Thumbs up

    Quote Originally Posted by Jimmie Neutron View Post
    I learn something new every day... thank you!
    Its just a shame sometimes people give smart remarks without really knowing or trying to understand what the other person is saying,but at least you acknowledged the following posts.
    Thats what these forums are here for, so everyone can learn.

    Cheers!

  16. #16
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    When I read your first post...
    I was like, "Is this guy serious??? There is no spring there."

    You did a wonderful job explaining what you meant... sometimes words are just not enough, the video helped tremendously.

    Thanks again!
    Whatever it is I just said... I could be wrong.

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    Quote Originally Posted by nsousa View Post
    Its just a shame sometimes people give smart remarks without really knowing or trying to understand what the other person is saying,but at least you acknowledged the following posts.
    Thats what these forums are here for, so everyone can learn.

    Cheers!
    I thought you were the one trying to be smart with the first line of your OP. Saying the truck sucks and then mentioning that you haven't even run it yet is not an ideal way to start a new thread. I agree with varunaX to a degree, there should be a little bit of rebound from the shaft but not much. Think about it, the thickness of the oil is what gives the shaft resistance on the way in and while it does have some resistance on the way out it's not going to be the same or even close to it, that is why the spring is there in the first place. I watched that video and I noticed that he had some kind of spacer that he used with the bladder which might be the reason why his shocks have more rebound which would be good if you think that more rebound is desirable and he didn't really measure anything like how much of the shaft was poking out so I'm guessing it's not something he was worried about being precise about. If I am refilling shocks I leave the shaft fully extended while the air bubbles escape and then I put the cap on. I would feel a little dumb pushing the shaft in without putting the cap on first. I also don't fill my shocks to the brim like I have seen others do, when I have done that it's messed up the bladder and the shocks just don't feel right, just below the brim has always worked for me.
    Nice camera BTW those pics were very clear and the background was out of focus so I'm guessing you're rocking a DSLR?
    Last edited by Summit Love; 02-14-2012 at 08:03 AM.

  18. #18
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    He was not saying the truck sucks... he was saying that it sucks that he has not gotten much of a chance to play with his new toy for a couple of weeks. -Which I agree with!!
    Whatever it is I just said... I could be wrong.

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    [QUOTE=Summit Love;5059342]I thought you were the one trying to be smart with the first line of your OP. Saying the truck sucks and then mentioning that you haven't even run it yet is not an ideal way to start a new thread. I agree with varunaX to a degree, there should be a little bit of rebound from the shaft but not much. Think about it, the thickness of the oil is what gives the shaft resistance on the way in and while it does have some resistance on the way out it's not going to be the same or even close to it, that is why the spring is there in the first place. I watched that video and I noticed that he had some kind of spacer that he used with the bladder which might be the reason why his shocks have more rebound which would be good if you think that more rebound is desirable and he didn't really measure anything like how much of the shaft was poking out so I'm guessing it's not something he was worried about being precise about. If I am refilling shocks I leave the shaft fully extended while the air bubbles escape and then I put the cap on. I would feel a little dumb pushing the shaft in without putting the cap on first. I also don't fill my shocks to the brim like I have seen others do, when I have done that it's messed up the bladder and the shocks just don't feel right, just below the brim has always worked for me.
    Nice camera BTW those pics were very clear and the background was out of focus so I'm guessing you're rocking a DSLR?[/QUOTE


    No, what I meant was It sucks I havent got the chance to play with it yet, not anything about quality. The shocks have rebound I was just questioning if that was the right amount. sorry if it came out the wrong way. Its actually my fav RC i've owned, just because I havent played with this one doesnt mean I've never played with a Summit before
    And yeah I recently bought a Canon T2i great camera but lots to learn about...im sure ill never be able to use it to its full capabilites.

    Thanks!

  20. #20
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    Hello,

    the amount of rebound in a summit, it's not so much important, the most important, is to have the same amount of rebound on both pair of shocks, this set up is important in racing cars like buggy 1/8 nitro cars and it depends of the track, if the track it's flat then no rebound if it's bumpy then more rebound, in jumps you don't see any difference, this helps the wheel to stay in contact with the ground on a bumpy track, the original stock oil it's 50 wt you can try 70 or 80 wt oil and harder springs a lot of people uses orange springs in the rear if you watch, Larsens awesome video, than you have an idea of a jumping summit.

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    Sorry for the misunderstanding.

  22. #22
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    Quote Originally Posted by Summit Love View Post
    Sorry for the misunderstanding.
    Hey dont worry! know one got hurt in the making of this thread.

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