My Rear Is Springy

[RallyDude]

Hey guys, I have a DF-03ra and my rear shocks are so bouncy. I am using a 1 hole piston with 25 weight and the medium preload clip with stock springs. Is there any way to eliminate this? I mainly run on dirt and gravel. I ordered a set of the TRF's but it's going to take a while for me to getem'. Thanks in advance

[matisse]

first off i'd try increasing the oil weight, maybe go up to 35wt, but keep it lower than the front as this can aid steering.

i generally like to use heavyer weight oils with more holes in the piston, but thats just me

secondly look at the springs, losing the tensioner will reduce the bounce back, but so will moving to a softer spring.

with any thing like this, it's worth doing one thing at a time to guage the results and then trying something new if needed.

given the quality of the kit shocks though, it'll probably be worth waiting until you get the upgrades, they really are much better.

also, are you running the car with the arms level when its on the ground? aim for this and your ride will be a lot smoother.

mat

[djmcnz]

Okay, if it's too 'bouncy' then the problem is that you have too much energy being exerted for the dampers (shocks minus springs) to absorb and disipate.

Eliminating tyre damping from the equation, this behaviour can only be because the oil/spring combination is wrong. Ultimatly the oil is too soft for the springs (or the springs are too hard for the oil). Now, exactly which to change and why is a bit of science and a bit of art. If you have spare setting springs and different weight oils then trial and error can be the fastest route to success.

Keep in mind that oil provides the damping, not the springs. Indeed springs only store and release energy whereas oil absorbs and dissipates energy. If your springs are releasing too much energy they will overwhelm your oil's ability to control/manage this through the damping effect. Also keep in mind that viscous damping is non-linear so adjusting the spring retainers or shock travel/droop will compleatly change the dynamics of a previous setup so I recommend avoiding this.

What you need to establish for your surface is the correct oil/spring combination. Simply matching oil/springs isn't good enough because you may end up with a setup that is either overall too soft or too hard for your surface. If the combination is too soft it will "reach capacity" too early and start releaseing energy at the wrong time, if the combination is too hard it will not be able to absorb sufficient energy (in a given timeframe) to allow the car to maintain traction.

Now that I've told you what you probably didn't want to know (but I feel all 1/10 engineers should know) how about the answer?

* Adding a hole to the piston will reduce damping - therefore avoid.

* Changing shock length/travel/pre-load will move you away from a safe nuteral (read: understandable) setup - avoid until you've fixed the problem.

* If you have spare oil, increase to 35wt and try again - keep going harder until you find the right weight for the springs

* If not and you have setting springs, soften them a bit - keep going softer until you find the right strength for the oil

Once you've found the correct combo you can then tune for a specific track/surface - as hard or as soft as necessary. When you understand the dynamics between oil and springs then you can change one without changing the other because you'll know what to expect. Until you do then it's best to stick with a matched oil/spring combo for any given surface.

Finally, remember that any change to the suspension will have an impact on the oil/spring combo, some more than other and some hardly noticable. Even low friction piston rods will make a (marginal) difference. Don't bother with these settings (including shock mount positions) until you understand the oil/spring relationship and more importantly what happens when you change one or the other.

[RallyDude]

Thanks for the breakdown guys. Yeah I kinda feel that my shock oil is too thin for the stock springs. The kit weight is around 800-900 and I went with my 25 Losi thinking I could get away with the one hole piston, but it just seems that the spring is to hard for what I'm using. I just figured someone has a good set up baseline to start off with. Cheers

[loaded]

"My Rear Is Springy"

This happens when you get older.

I am thinking of putting this in forum quotes of the week :-)

Paul.

[RallyDude]

"My Rear Is Springy"

This happens when you get older.

I am thinking of putting this in forum quotes of the week :-)

Paul.