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  1. #1
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    Slash 4x4 Ride Height and Preload

    so I have a slash 4x4 lcg that I have been tuning for the track and am not sure how to best get the desired ride height without putting to much preload into my rear shocks.

    I am using the SCTE Ten Rear Springs (red) on my GTR shocks with 35wt oil.

    The issue I am bumping into is:

    Set ride height to 26mm, roughly 15mm of preload required - shocks are so stiff that the rear end is bouncing all over the place.

    I have been trying to soften by backing out the preload on the rear shocks so that it does not bounce when I do a drop test; however, the rear end still bounces. I have filmed this in slo mo and it is not bottoming out but is not settling like I want it to.

    Here are some pics and video. Ride height at the time I took the pics/video below is at 22mm.

    Apologies for the exceptionally bad video editing.







    Last edited by enare_vta; 11-23-2018 at 11:57 PM.

  2. #2
    RC Turnbuckle Jr. Squeegie's Avatar
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    Try here for some track tuning tips:
    https://forums.traxxas.com/showthrea...g-on-the-track
    Creativity is intelligence having fun. -Einstein

  3. #3
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    thanks squeegie. ive read razors post many times. he inspired pretty much my entire setup...however, i just cant get this one problem solved...

  4. #4
    RC Turnbuckle Jr. Squeegie's Avatar
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    Something is seriously wrong with your setup. When you pick your rig up, you have no droop. What holes are you using to mount your shocks on the shock towers and a-arms?
    Creativity is intelligence having fun. -Einstein

  5. #5
    RC Champion RazorRC22's Avatar
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    I never used springs that soft and always used front springs from LOSB2959 in the rear shocks. Try Blue or Green springs in the rear. I also set rear ride height to around 27-28mm.
    youtube.com/c/RazorRCvideos

  6. #6
    RC Turnbuckle Jr.
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    Rear arms level, and front chassis just slighty higher than level

  7. #7
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    Quote Originally Posted by Squeegie View Post
    Something is seriously wrong with your setup. When you pick your rig up, you have no droop. What holes are you using to mount your shocks on the shock towers and a-arms?
    That was it!!! good eye squeegie. I was wondering why the rear end felt so weird when I would push on the shocks compared to the front where I am running the rear shocks as well.

    My rear sway bar is taking 10mm of droop out of the rear shocks. How do I deal with that? Should I lengthen the rod ends?

    Also, when I remove the sway bar with the extra droop, the rear still bounces quite a bit when I do the drop test. any clues as to how to keep that down?

    Max Droop With Sway Bar Installed:


    Max Droop with Sway bar removed:
    Last edited by enare_vta; 11-24-2018 at 10:59 AM.

  8. #8
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    Quote Originally Posted by RazorRC22 View Post
    I never used springs that soft and always used front springs from LOSB2959 in the rear shocks. Try Blue or Green springs in the rear. I also set rear ride height to around 27-28mm.


    Razor, the amount of preload I needed with the fronts on the rear compressed the black fronts all the way to the end of the threads on the GTR shocks just to acheive a 26mm ride height, when I put the Losi rears on, I needed 15mm or preload or more. Stiffer will likely help and maybe when I can dial in the droop, that should also help. I think the rears springs will work once I figure out the sway bar situation.
    Last edited by enare_vta; 11-24-2018 at 10:46 AM.

  9. #9
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    You could also try some different weight shock oil. 40-50 weight might help some. It takes time to dial in things for track use. And everyone will have a little different way of going about that. The sway bars help a lot with body roll and such, but at the cost of suspension travel. Try using some different shock oil weight and see if it helps. Something heavier weight but not too heavy.

  10. #10
    RC Champion RazorRC22's Avatar
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    Swaybars should not limit droop on any kit I’ve owned. I don’t have my Slash 4x4 anymore, but yes make sure the suspension is completely free and the rod ends should be all the way to the end to start. Maybe go in a little bit, but they SHOULD NOT be limiting your suspension travel when both arms are hanging at full droop.
    youtube.com/c/RazorRCvideos

  11. #11
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    thanks guys. I was able to extend the rod ends so that they do not limit the suspension travel. With that fixed, the truck still bounces quite a bit from 18".

    Do you think I need go up in oil and spring rate or down in oil and spring rate?

  12. #12
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    Also, could the shock position on the arms made a difference as well in the rebound?

  13. #13
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    Slash 4x4 Ride Height and Preload

    Try to understand what shock is doin. RC shocks are pretty , same hole for compression and rebound. use heavier oil to bouncing shox (rearones in your case), to make em rebound slower. BUT....it also affect compresion (cuz of one way design). Btw ure bottoming on video, heavier oil can stop this

    Position on Aarms wil not affect rebound, it will affect mailnly shock compresion curve

    Traxxas has a strict language policy. A word filter operates to change inappropriate words to *s. When you see these in your post, you MUST edit them out. -ksb51rl
    Last edited by ksb51rl; 11-24-2018 at 05:53 PM.

  14. #14
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    Also adding larger holes in the compression rings can help. Not saying to do it, that is up to you. I believe some one makes some 4 hole compression rings for the shocks. Canít remember who off the top of my head. But like above poster said, as well as I, try some heavier shock oil first and see if it helps.

  15. #15
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    i have the 4 hole gtr variable tuning kit installed. i think that is what you are referring to. i will try thicker shock oil aafter i can get this setup back out on the track to test it.

  16. #16
    RC Champion RazorRC22's Avatar
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    I recommend going to 1.5mm hole pistons from the front Long GTR shocks and using them in the rear. These are actually smaller holes and I used 35wt Associated oil with these smaller pistons in the rear to get enough pack when landing jumps. It’s in my setup sheet. Else maybe try 40wt oil in the rear, but it will be more bouncy down the straights.

    Red is also the softest TEN-SCTE rear springs, I definitely would go stiffer:

    Rear:
    2.7 rate Red springs
    3.0 rate Orange springs
    3.3 rate Silver springs
    3.6 rate Green springs

    Front:
    3.6 rate Green springs
    3.9 rate Blue springs
    4.2 rate Black springs
    4.5 rate Purple springs

    You are running way lighter springs than I was running (Green/Blue in rear), and you have a heavier truck (Castle motor and aluminum motor mount), so you should be starting with Green Rear springs at a minimum IMO.

    Also make sure everything is nice and free in the arms with wheels and shocks removed. They should flop up and down easily with no binding.
    Last edited by RazorRC22; 11-24-2018 at 06:32 PM.
    youtube.com/c/RazorRCvideos

  17. #17
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    Thanks razor. I know some of you guys have spent countless hours tuning for the track! It is a lot of hard work to make these truck track sufficient!!

  18. #18
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    Quote Originally Posted by RazorRC22 View Post
    I recommend going to 1.5mm hole pistons from the front Long GTR shocks and using them in the rear. These are actually smaller holes and I used 35wt Associated oil with these smaller pistons in the rear to get enough pack when landing jumps. Itís in my setup sheet. Else maybe try 40wt oil in the rear, but it will be more bouncy down the straights.

    Red is also the softest TEN-SCTE rear springs, I definitely would go stiffer:

    Rear:
    2.7 rate Red springs
    3.0 rate Orange springs
    3.3 rate Silver springs
    3.6 rate Green springs

    Front:
    3.6 rate Green springs
    3.9 rate Blue springs
    4.2 rate Black springs
    4.5 rate Purple springs

    You are running way lighter springs than I was running (Green/Blue in rear), and you have a heavier truck (Castle motor and aluminum motor mount), so you should be starting with Green Rear springs at a minimum IMO.

    Also make sure everything is nice and free in the arms with wheels and shocks removed. They should flop up and down easily with no binding.

    Thank you razor. i replaced the can today too and went back to using the 3800kv until I can improve my driving.

    I am going to change the piston, that is a good idea and makes sense. I wanted to avoid going up in shock oil if I could.

    I also put the silvers on the rear as well.

  19. #19
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    so we had our first race since making some changes to the suspension and i could not be happier. although i finished fourth, i had the second fastest lap time of the main and the truck was handling great...the other trucks were losi,teknos and associated. the truck was very predictable in corners. i need to get more consistent as a driver but that will come with time.


    a couple of notes that i am curious for your feedback...

    1. there is a turn at the end of the straight away that the truck wants to traction roll on.

    2. i have the suspension setup with 37.5 in rear and 35 in front and the truck definitely bottoms out way more than the flatter chassis trucks. should i try to increase spring rates or shock oil to help with the landing? i dont want to lose the predictability in the turns but wonder what changes would help. springs are losi ten rear silvers ams blue fronts.

  20. #20
    RC Champion RazorRC22's Avatar
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    Go to Green rear springs, and the 1.5mm pistons with 35wt Associated oil if you haven't already. Get ride height to at least 27mm front and rear.

    For the traction rolling, make sure the front camber links are on the lowest hole on the front shock tower. Maybe try the soft front sway bar (I think it's silver?) set to the lightest setting, but your low speed steering will suffer.

    What kind of track surface are you running on and what tires are you using?
    Last edited by RazorRC22; 12-19-2018 at 04:16 PM.
    youtube.com/c/RazorRCvideos

  21. #21
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    right on! Seriously, thank you so much Razor for all you do for the RC world, not to mention traxxas owners.

    I think rear ride height in the rear is a big one for me. I did go to the 1.5mm piston in the current setup but will move to the stiffer spring and see what that does.

    The interesting thing about the traction roll is that it seems to come more from the rear than the front. I will have to pay attention to it more. Either way, I can mess with the camber links and depending on what that does, ill play with sway bars as well. Maybe a stiffer sway bar in the rear would help as well...

    Is adjusting the camber links to the lower setting in an effort to stiffen up the roll center by raising it?

    The surface is outdoor, hard pack and varies from loamy or completely dry. I have been running calibers, and just purchased a set of blockades for the next race.

  22. #22
    RC Champion RazorRC22's Avatar
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    Quote Originally Posted by enare_vta View Post
    right on! Seriously, thank you so much Razor for all you do for the RC world, not to mention traxxas owners.

    I think rear ride height in the rear is a big one for me. I did go to the 1.5mm piston in the current setup but will move to the stiffer spring and see what that does.

    The interesting thing about the traction roll is that it seems to come more from the rear than the front. I will have to pay attention to it more. Either way, I can mess with the camber links and depending on what that does, ill play with sway bars as well. Maybe a stiffer sway bar in the rear would help as well...

    Is adjusting the camber links to the lower setting in an effort to stiffen up the roll center by raising it?

    The surface is outdoor, hard pack and varies from loamy or completely dry. I have been running calibers, and just purchased a set of blockades for the next race.
    You're welcome, glad to hear you're getting your truck working better. I didn't realize you were traction rolling from the rear, forget what I said about the front swaybar. I would guess your truck is body rolling too much in the rear, the stiffer rear springs should help, I'm guessing you are getting mad forward traction when yanking the throttle?

    Lowering the inner camber link location will raise the roll center which will help it to resist rolling as much, you are right on that. A stiffer rear sway bar would also help, but if you're already running the silver it should be enough IMO. Another thing you can do is move the upper shock mount to the outer hole on the shock tower, this will make the shock less progressive and feel a tiny bit stiffer.

    Let me know how the Blockades are compared to the Calibers, I've been thinking of getting a set of those -- I've used Calibers on my Slash 4x4 in the past but am thinking blockades might work better on the loose, loamy stuff.
    youtube.com/c/RazorRCvideos

  23. #23
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    Remember this is the Traxxas forum. Donít think they want you to be speaking much about other companies vehicles here. Just some food for thought.

  24. #24
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    Quote Originally Posted by 222 View Post
    Remember this is the Traxxas forum. Donít think they want you to be speaking much about other companies vehicles here. Just some food for thought.
    Returning to the thread, have been beavering along working on my Slash 4x4 suspension, following the essence of RazerRC22 designs (many thanks). Still a work in progress but getting closer to a final solution. As I get closer to a good outcome, it becomes more difficult to make good gains, which is surely a good thing. Stepping back for a moment, I decided to consider the basics, there are two key elements in suspension that affect the propensity for "bounce". One is the spring the other is the shock absorber and somewhere in there is the answer to a good outcome. In classic suspension design (old school) springs are used to carry the vehicle weight, the shock absorber is used to control the speed at which the spring deviates. Its important not to use the shock absorber carry the weight. In RC domain, Slash 4x4 (like many other 4x4 RC vehicles) is heavy, in fact, its very heavy. I put my try truck on the scales and in race trim its coming in at 3.3 Kg. This is not evenly split as 50/50, its approx. 2 Kg to the rear wheels and 1.5 Kg to the front. It then occured to me that dropping it from 18" and getting it arrested and under control within approx. 2-3cm of suspension travel, is a big ask so no wonder there are problems. With that in mind, made the following changes, already using GTR long shocks front and rear with 1.5mm baffles installed, tipped out the stock shock oil and refilled with known calibrated 30 wt in front and 35 wt in rear, which gave a surprising good improvement. Next went in search of maximum possible droop so that active suspension travel would be as long as possible, the longer the travel, the more chance there will be to control the drop from 18". At full extension the shocks were found to be limiting the A Arms drop down travel, so, relocated the bottom shock mount in-board one space, so the shock was no longer limiting downward travel. This increased the droop nicely, but softened the suspension. This is fixable, I built back firmness with stronger springs. Using the strongest available Traxxas springs (blue) on the rear, and second strongest (pink) in front the slapping and the bouncing were finally controlled although only just. I use the silver sway bar (soft) on the rear, set to the softest setting right at the end of the bar. No bar in front. However, with all the shocks disconnected I found the sway bar was binding at the chassis mounting screws, almost completely limiting free travel. So, had to back off the sway bar screws a long way until the A arms would lift and drop freely, in unison. Finally the truck is now much better behaved, no bouncing, no slapping and about 4 cm of active suspension travel all round. I now want to get the truck to run nearer to the ground, while keeping it off the ground on jumps. I think the answer is with stronger springs, the SCTE TEN spring kit arrives next week, testing and experimenting will continue.

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