Losi DBXL jump analysis

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
F

fwuzzy

Member
Messages
20
Reaction score
3
Location
London, Ontario
I did a frame-by-frame jump breakdown. Some of you probably already know how it works, but for me, it's interesting to see how the DBXL hits the ramp face, bottoms out, and essentially slides up the ramp face like a sled. Landing sequence shows the amount of abuse the DBXL goes through on landing - enough force to pancake the spare tire.

I got 5000K fluid in the shocks. I'm guessing the chassis will bottom no matter what fluid you have in the shocks. It would just be a matter of how hard it hits. Whether or not you nose dive depends on if rear bottoms harder than the front. You can see at frames 5 and 6 ms the rear is bucked up from the ramp face.

The take-off and landing sequences are advanced in 1 ms increments.

Time 0
Jump 0.webp

+1 ms
jump 1.webp

+2 ms
jump 2.webp

+3 ms
jump 3.webp

+4 ms
jump 4.webp
 
Last edited:
Looks cool. I think your results are pretty standard for most all RC cars. If you make it stiff enough to stop hitting bottom, you'll probably make it too stiff and it'll handle turns and bumps poorly. Maybe some progressive rate springs?
 
Killer RC said:
Looks cool. I think your results are pretty standard for most all RC cars. If you make it stiff enough to stop hitting bottom, you'll probably make it too stiff and it'll handle turns and bumps poorly. Maybe some progressive rate springs?
Click to expand...

Yeah, standard stuff, but neat to look at and really shows the abuse these rc can really take. Maybe I'm staying the obvious for some, buy I'm looking at it from the perspective of trying to tame the dbxl nose diving tendencies.

Problem with the dbxl shocks is that it doesn't have many tuning options yet. They have dismal rebound and for some reason, Losi (or whoever) designed the shocks to use diff fluid. The only other springs are the stiffer DDM linear springs, which are hard to set for level-arm ride height, especially in the front.

I have contacted some manufacturers about improving the shocks. Hopefully they will have something soon. So far, the traditional "clone" manufacturers seem to be more responsive and showing some innovation in their product design.
 
Last edited:
Disp0sablehero321 said:
Man... Does the spare have foam in it or is it strictly for looks and empty?
Click to expand...

The spare is the stock dbxl wheel/tire/foam combo. Fully functional and mounted to shift center of gravity more to the rear. The rubber and foam are pretty soft to begin with. Nothing like the Hostile MXT and HPI foam that I was running in the pics.
 
Last edited:
One thing I forgot to mention is that the spur gear protrudes from the bottom of the chassis a few mm. Should I be concerned that it would be scraping dirt as it goes up a ramp?
 
Nice photos.
I would say if it really 'bottoms' on softer dirt there's no issue - might get some grit in the mesh from time to time.
If it bottoms regularly on a harder surface, then it would be worthwhile looking into FG-style covers or perhap a skid plate either side / front rear .. to take the knock before the gear does.
Al.
 
DBXL jump analysis

There is one other fix out there the people Makeing the jumps need to make the ramp longer so it's not such a transition to stright up and that will fix it to
But good luck with that one [emoji174]
Ps great job showing non-racers what's happening to there cars it's hard to see if your driving and most see it from watching other peoples cars hit jump
 
Last edited:
fwuzzy said:
Yeah, standard stuff, but neat to look at and really shows the abuse these rc can really take. Maybe I'm staying the obvious for some, buy I'm looking at it from the perspective of trying to tame the dbxl nose diving tendencies.

Problem with the dbxl shocks is that it doesn't have many tuning options yet. They have dismal rebound and for some reason, Losi (or whoever) designed the shocks to use diff fluid. The only other springs are the stiffer DDM linear springs, which are hard to set for level-arm ride height, especially in the front.

I have contacted some manufacturers about improving the shocks. Hopefully they will have something soon. So far, the traditional "clone" manufacturers seem to be more responsive and showing some innovation in their product design.
Click to expand...


I'm not a shock building pro, but I've been told that shocks aren't supposed to rebound.

See video
 
Last edited by a moderator:
Killer RC said:
I'm not a shock building pro, but I've been told that shocks aren't supposed to rebound.

See video
https://www.youtube.com/watch?v=eByiPy_VCts
Click to expand...

I don't think we are talking about the same thing or I am referring to it incorrectly. You are referring to the rebound when you compress an unsprung shock shaft and the rebound from the internal pressure in the shock.

I am referring to the rebound of the shocks when mounted on the dbxl with springs and the weight of the buggy. Try pushing down on the shocks on your dbxl. It can literally take 3-5 seconds for it to return to its default resting position.
 
DBXL jump analysis

It's two problems the biggest is the lack of different weights of shock fulid in small enough increments to adjust rebound
Number two no progressive springs
Yes I know losi uses flat rate springs but this is not a losi it's toy grade and most are happy with what comes on it
Yea right they don't know us
If losi has there way we will get 5 sets of springs to adjust with where one good set of progressive springs can do it
The cheapest and best fix would be new pistons with 25 small holes in it for shock oil use and one bigger spring so some one get on it the piston is easy I'm supprised there not out yet
 
It seems to me that the slow rebound you have is due to you using 5000w diff fulid. Try some 45w shock oil and it should rebound quicker. The diff oil is too thick. Its made to slow down the gears in the diff and that what its doing in your shocks.
 
I was surprised to hear that some of the drivers at my local track use as low as 20 wt in their 5ive shocks. The difference has to be the holes in the pistons. I run a 5000/7000 mixture in the dbxl shocks and it handles beautifully. Level on jumps, corners hard and soaks up rough stuff so much that my buggy is leading the race series in points so far. It's also consistently putting lap times in that are right with the better amatuer 5ive drivers. I have a set of 5ive shocks to try out but it really hasn't needed it.
 

Attachments

  • image.webp
    image.webp
    30.2 KB · Views: 40
Marky said:
I was surprised to hear that some of the drivers at my local track use as low as 20 wt in their 5ive shocks. The difference has to be the holes in the pistons. I run a 5000/7000 mixture in the dbxl shocks and it handles beautifully. Level on jumps, corners hard and soaks up rough stuff so much that my buggy is leading the race series in points so far. It's also consistently putting lap times in that are right with the better amatuer 5ive drivers. I have a set of 5ive shocks to try out but it really hasn't needed it.
Click to expand...

It would be interesting to hear back if you notice significant improvements with the 5T shocks installed, given that it seems that you already have your suspension setup dialed in. I've been contemplating on upgrading my shocks myself. I guess I'll wait on your report before I make the purchase.
 
I had a chance to run with the new shocks on Sunday. I had posted earlier that they were 5ive shocks. They are actually GTB shocks for the 5ive. Not sure if there's much difference other than the springs I got with them. I filled them with 50wt shock oil as I still wanted a good amount of damping to avoid the initial problems of the stock shocks with 3000cst oil (the nose dive/bucking characteristic) I think the 50 is a little heavy as the nose would bounce when landing rear wheels first. Not the desired way to land but it happens. The rear would get squirrelly from time to time when the buggy got light. Also probably due to heavy oil or stiff sway bar. Other than those points, they performed very well. I'm going to leave them in with about a 35-40 wt oil. I still think the stock shocks perform better but I paid around $200 for the set of GTB's so I wanna get them to work.
 
Back
Top