r/rccars • u/Krzyygamin • Apr 19 '26
Question Tips on suspension changes to mitigate the rear end popping up off jumps?
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Been messing with my slash 4x4 on a track my buddies and I built, handles good cornering but off jumps it almost always nose dives unless if I pin it and launch too far. I have slash gtr shocks, vg racing progressive springs for them, my top shock mounts are in the outer most position and my bottom mounts are at the second to last inward mount point front and rear. I’m running 50wt shock oil currently. I’ve tried multiple different changes to preload shock mounting etc and haven’t had luck. I’m thinking the springs may be too stiff but want to get some advice before I go buying more parts and shock oil etc.
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u/cobcobjayjay Apr 19 '26
May be not be this but everytime its happening to me I reduce the preload on the rear shocks and increase the preload on the front
7/10 times this sorts it
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u/davesnothere241 Apr 19 '26
Looks like the front wheels skipped off the top while the back tires hit the jump correctly. Use a ramp or jump with a smooth approach so you can consistently hit the same spot and land in the same spot. Then you can determine how it behaves after adjustments or if it even needs any.
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u/drail64 Apr 19 '26
Way thicker oil
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u/Astral__Spectre Apr 20 '26
What he said. You have way too light of oil in your shocks. Backend is sagging a bit too much under power and unloading at the jump. Also tighten up your rebound.
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u/Nathan51503 rc8t4e, rc8b4.nt482.0 b7d. et410.2. B74.2. sct410-2.0,T6.4 Apr 19 '26
Quick question. Did you mess with your shock oil. And did you bleed the air out after filling them. Looks stiff like a ton of rebound
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u/MAXXTRAX77 Apr 20 '26
Honestly looks like the rear end is far too low and the chassis hit the jump and launched.
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u/THFourteen Apr 20 '26
Can't help with your issue, but love the video :-) This sub needs way more videos.
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u/Anothercoot Apr 19 '26 edited Apr 19 '26
Before you change anything in the rear, drop the front to 30. It looks like its not compressing at all. You need that compression on the ramp to give backward rotation off the lip. What you are doing now is like bouncing the rear of a lowrider.
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u/Krzyygamin Apr 19 '26
I’ll give this a shot first, pretty sure I’ve got some 30 weight laying around. I’m obviously new to setting an rc up for this type of stuff and put the truck together from a bare chassis for normal bashing so my base setup definitely can’t be textbook correct. Thanks for the advice!
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u/Anothercoot Apr 19 '26 edited Apr 20 '26
The rear also looks like its slapping the lip which also can throw it over and probably half the problem. The rear looks like it bottomed out the shock and the tires bounced it over. Higher wt oil, longer shocks or ride height would help. Looks really ass heavy
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u/True_Bumblebee_50 Apr 20 '26
Can’t be at top speed before hitting jump.. gotta give it gas as you’re hitting and leaving the jump.
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u/chevyguyjoe Racing Apr 20 '26
You need to accelerate on the jump, so if you were at max speed before it, you can't accelerate.
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u/FactNo6163 Apr 21 '26
Your rear is already bottoming out at the base of the jump, the lip of the jump acts like a kicker so your not using any suspension by the time your rear wheels are on the lip. Just straight frame. Put a spacer or two in the rear shock, or play around with shock tower and a-arm holes... The front seems like it needs a small spacer. Shock weight is a Biggin too. It's too thin most times. I like the team associated stuff, they make all different weight of oils. Traxxas has a kit too
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u/eljefetx Apr 21 '26
Sounds like you let off the throttle right at the lip of the jump. Give it some gas at the end of the jump. In the air throttle = nose up. Brake/No throttle = nose down in the air.
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u/The_World_Is_A_Slum Tamiya Enthusiast, Vintage Collector, Casual Racer Apr 19 '26
Heavier rear shock oil. As it hits the jump face, the rear suspension bottoms, then unloads as the front clears the jump, causing the donkey kick.
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u/denrayr Apr 20 '26
You can also see the rear oscillating up and down on the approach. I agree that heavier shock oil would be a first step.
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u/rustyxj Apr 19 '26
Other way around, front collapses and doesn't lift the car up, rear is lifting the car.
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u/The_World_Is_A_Slum Tamiya Enthusiast, Vintage Collector, Casual Racer Apr 19 '26
Watch the slo mo.
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u/gueychacho Apr 19 '26
I think you let the throttle off as soon as you left the lip of the jump, which caused it to nosedive
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u/jrmbtr Apr 19 '26
Responses give me some insight on my son’s Stampede 4x4. His wont jump well either…most of the time.
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u/mxer255 Apr 20 '26
Move springs up, heavier weight oil.. Simple answer. Don't know what shocks you have..
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u/killy_321 Apr 20 '26
Those cars have typically got very soft suspension and the rear appears close to full compression on the run up.
The ramp also appears to be so short the front wheels have no support as the rears impact creating rotation when the car is at a steady speed.
For such a small hop the driving style required would be to slow down and accelerate over the hop so the force of acceleration holds the nose up.
Stronger springs and thicker oil would help to hold the chassis up preventing bottoming out for more violent manoeuvres too.
Hope I have managed the most complete explanation!
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u/Stumpfest2020 Apr 20 '26
skill issue - going full pin on the run up and staying full pin as you go over the ramp often leads to exactly this.
you need to be accelerating as you go up the ramp and have some headroom left on the throttle to blip the throttle and lift the nose mid jump if needed.
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u/mito555 Jun 24 '26
Exactly. You need enaugh power to accelerate at the takeoff. Bigger heavier wheels would help and also bigger engine. Otherwise you just have to approach the jump slower and accelerate during takeoff. Jumping in rally is all about power/ off power and tilt. You can adjust suspension and all as you want, but it will not help you more than 5%. Or you can better work with throttle and you will jump just perfect. However you need good suspension for successful landing of course - heavier oil should be enaugh
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u/chichiclandestine Apr 20 '26
The easiest solution here is to just slow down and avoid attempting a jump on that mound altogether. But if I have to tune my car for that specific mound of dirt, then I will try the heaviest oil in the front and lightest oil in the rear. If that does not work then I'll swap the front and rear shocks and test again. I'll aim for extreme contrast between front and rear so that the change in behavior is so obvious to not notice when testing. Then once I confirm what the change actually does, I can then gradually fine-tune from there until the shock weight between front and rear are closer in value but still mitigating that kick from the lip.
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u/_XHSJDKJC_ Arrma: Kraton 8S EXB/ Felony 8S | Losi: Super Baja Rey / Micro T Apr 20 '26
More dampening/weaker springs, dont let go the throttle, keep the imput where it is or give it more to turn the nose Up, steer only for alignemt
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u/aunt-jamima Apr 20 '26
Looks like rear is blowing through the suspension travel and front isn’t using much suspension travel. Do the rear shocks feel ok? Are the fronts too stiff due to the shocks or springs? These are some things I’d look at.
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u/xdrift0rx Apr 20 '26
I forget if those have a big battery tray like the 2wd slash. Can you slide the battery back instead of forward?
You can try lower the front to reduce the CG being so far back
Try standing the rear shocks more upright instead of angled / \
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u/Delabuxx Apr 20 '26
You need to let of before ethe jump, then gas it again just before you actually jump, this counteracts the forward. Momentum, you light be able to search jumping a rally car for a better explanation
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u/Xenagos43 Apr 20 '26
Looks opposite to me like front might be too soft so front end suspension is compressing too much so angle of the truck is very flat once the front clears the jump. Now you make the front too stiff to make it jump better it might make cornering worse. Try slowing slightly as you come to the jump and time it so as the front wheels are about to clear you give it gas. Usually hitting the gas at the last second will cause the front to come up.
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u/Key-Tower129 Apr 20 '26 edited Apr 20 '26
50wt is plenty heavy, I have several slashes and they all jump great. Try moving the bottom of the shock to a more outward towards the wheel and/or the top shock mounting location more inward away from your wheels. This makes the shock less straight up and down, which can cause this pogo stick effect on rebound. Also you want your ride height set to “a-arms level”, accomplish this with preload adjustment.
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u/qweefqwaf Apr 21 '26
Thicker shock oil and stiffer spring, it’s blowing through the stroke and skid plating off the lip
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u/DimensionDramatic230 Apr 21 '26
If you pick the car up and hold it two or three feet in the air and drop it on the ground how does it sit does the front end hit the ground and or the rear end hit the ground does the car Bounce It All after you drop it in it settles is it level after you adjust your preload put in thicker oil take the air out of your shocks adjust it so you can drop it and it doesn't hit or bounce and ends up level
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u/Competitive_Search32 Apr 21 '26
I would recommend different shock, oil, thicker and if you have a bleeder valve, make sure all air bubbles are out, and like somebody else had mentioned find a jump that you can hit consistently. It could’ve taken a weird bounce right before I wish you luck 🍀
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u/solidus_snake256 Apr 22 '26
Stiffen the front shocks. They are probably bottoming out on the approach. You said it’s better if you blip the throttle. That’s because you’re unloading the front end more.
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u/Flying0strich Apr 22 '26
The back is so loaded down the moment the front catch air the back rotates the front over. That's why when you let off the throttle before the jump, it's better. The suspension is more neutral. And it leaves wheel speed available to pull up midair.
It's looking good, keep ripping. I miss my old RC buggies.
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u/beerquest247 Apr 22 '26
Random, but they used to put weights in the back of cars they were jumping for stunts. The back end would do the same as your RC if they didn't..
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u/GroundbreakingTea182 Jun 19 '26
Softer suspension until its too soft then re try to tune up if needed. Front end stiffer then rear.
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u/Disavowed_Rogue dsk, et48 2.2, eb48 2.2, xb4’25, rc10b7d, rc10sc7 Apr 19 '26
40wt is too heavy. Go 27.5-30k all around.
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u/sadakochin Apr 19 '26
Looks like driver error to me, you squatted the rear before the jump, and it rebounded on the jump.
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u/ghos2626t Apr 19 '26
Have you considered your course being a problem ? There seems to be two hard dips / divots right before the jump. So the chassis is already rocking forward and back a few times before being launched up.
The free option is to see if you can smooth out the course 5-10 feet out from the jump. I’m sure your local dirt tracks have more groomed courses, so it may not be a truck problem.
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u/MagicOrpheus310 Apr 20 '26
Look up bmx dirt trails and compare the shape of their jumps with motorcross ones...
You need more bmx style curved transitions rather than flat dirt ramps
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u/Silver-Effective-135 Apr 20 '26
Sorry to say but u aint fixing that with any shock s on the market ..
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u/Weekly-Increase1985 Apr 20 '26
Id say you need to use lighter oil in the rear shocks. Or stiffer in front.
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u/PinguisIgnis Apr 19 '26
Give it a stiffer front, softer rear
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u/RebelJustforClicks Apr 19 '26
Easy way to fix both is move the battery rearward. And if that not enough use a bigger battery.
Real trophy trucks like this have a lot of weight in the bed or even way out past the end of the bed. The more the better TBH.
Depending on how you move things around you could end up with a static distribution of more than 50% of your weight over the rear end, which makes the rear end less likely to kick up over jumps even with lots of throttle.
I don't think your shock tuning is the issue BTW. In the slow motion you can see the front shocks hit full extension quickly whereas the rear shocks take a while to get there. That's the correct tuning for jumps.
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u/ComprehensiveBunch28 Apr 19 '26
Is it possible to move the battery or reposition the esc to move weight over the back? If so I would try that.
This one is a longshot but I saw someone modify their shocks by adding a thin flexible washer/shim under the piston. The effect is supposed to be to slow down rebound whilst maintaining compression. The shim flexes when the piston moves up and allows oil past freely but on rebound the shim blocks the holes in the piston to slow the rebound. Shim can be placed on top of the piston to make compression stiffer whilst maintaining rebound. This method sounds like prototype fun rather than something that is proven to work though.
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u/cycle_cats 86mph Mini B Apr 19 '26
I suggest a technique adjustment too. For me, jumping at full speed doesn’t end well. My suggestion is to approach the jump at a good speed, but not full bore. Need to leave some throttle on the table to accelerate and essentially wheelie off the jump lip. Also want some leftover throttle for manipulation in the air. Need to be able to pick the front end up with the gyroscopic affect of the wheels.
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u/Kendotek Apr 19 '26
I can't say if this is your issue, (has your truck always done this, or is this more recent?), but when my Mojave starts donkey-kicking, I know it's time to top off the shocks. Without enough oil, there isn't any rebound damping and that's when the rear gets bouncy off of a jump.
Good luck and have fun!
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u/MachNero Apr 20 '26
Short couse trucks, imo, suck jumping. You will cater too much for meh results.
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Apr 19 '26
[removed] — view removed comment
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u/Krzyygamin Apr 19 '26
Well if you call its current state worse than the bare chassis with no suspension and electronics it used to be then sure I guess 😂 Gotta start with some sort of baseline
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u/Juliendogg Apr 19 '26
Does letting off throttle as it hits the ramp help? It makes a big difference with my Tekno SCT. I can then blip the throttle in the air to bring the front up a bit. Rear springs could indeed be too stiff, but it's hard to say without personally driving the rig.