CVA damper vs Aeration Damper relative performance

[ThunderDragonCy 7877]

Since I got back into the hobby I have been running (quite happily) CVA dampers. Few choice upgrades here and there (Nice piston rods, red o rings etc) but generally just CVAs. Although I play with oils and handling and all that I am not a racer so never saw the point of getting some fancier kit. What I have read is a lot of blogs and setup guides saying "oh use three hole dampers, anything less will be rubbish" and "lightest damping possible". I have to say this has left some of my setups a bit bouncy, but I figured I am taking advice from experienced guys. Well, only if the frame of reference is right......

Recently I picked up a DB01R which has aeration dampers. Today I drilled the caps to make them full aeration and rebuilt them. 2 hole TRF pistons. And here is the thing: The high performance TRF shocks are waaaaaay slower damper than CVAs. I compared the rear Aeration shock to the CVA on my Thunder Dragon. Aeration had 2 hole pistons and 350cst/30wt oil. It is visibly and noticeably slower damper than the CVA with 2 hole piston and 500cst/40wt oil. 

So, do we all need to be rebuilding our CVA shocks with the 1 hole pistons to get TRF style damping performance? 

[TwistedxSlayer 1290]

I guess it would all depend on how fast you want damping action really. But now you've mentioned it I'm curious to see how my Levant dampers have come from the factory

[nowinaminute 2815]

Hmm I guess it depends on your usage scenario but as far as I can tell, if you have such weak damping that the vehicle becomes springy then it kind of defeats the object of having damping.

I know if you want to go over rougher terrain that less damping is preferable but even then with an MT or what have you, I still have enough damping that when you drop it, it squats and rebounds in a composed manner instead of it bouncing back off the ground again.

I'm not an expert but I try to set my off road vehicles up so they sag a little at rest and so that if I lift an individual wheel, it gets a good amount through it's travel before the vehicle lifts up with it. I then use either oil thickness, or number of holes or a combination of both to get the "cat landing on its feet" effect when I drop the vehicle.

Not scientific in the slightest but for me, it seems to be a half decent place for an all rounder. 2 years ago, when I first got back it RC, I would often buy dampers that weren't benefiting the vehicle at all and be oblivious to it. And I would buy Chinese ones and think they weren't much good because they had too much or too little damping when I put Tamiya 400CST oil in them having no idea they could need anything from 100 to 5000 or more to work properly with the piston discs in there.

I'm still not an expert by any means but that's my basic starting point, set the car up so that if you drop it, you get that kind of thud noise and you can see it sink and then rise again in a controlled manner VS bouncing back up again.

I know some of that was probably off topic but I do think that going too soft is kind of self defeating after a certain extent. And by comparison, it's surpising how slow the damping can seem but the vehicle still seems to cope quite well with reacting to terrain quickly in actual use. I have a Traxxas X-Maxx and the shocks feel like they have treacle in them but they seem very supple when in use, the weight of the vehicle and spring strength both play a role there.

By all means experiement with the 1 hole damper or thicker oil in the CVA, both things should give the same effect to a degree.

[TwistedxSlayer 1290]

Tuning suspension is a fine art. As we all very know. It's never something I've given much thought to on my RC cars. On my 1:1 car I spent months researching the best spring and shock combos for the look I wanted and funds I had. But with my rc cars I'm like yeah they will do the trick. Lol. Need to pay more attention to my rc suspension setups.

[speedy_w_beans 4272]

You'll never get TRF-level performance from CVA dampers for a number of reasons:

- CVA pistons don't seal against the damper bodies as well.

- CVA piston holes are way too large to transition between linear damping and nonlinear damping like the TRFs do.  Landing jumps effectively while still handling smaller bumps requires both types of damping.  The CVAs never provide "pack".

CVAs are better than spring holders, but TRFs definitely provide an advantage with the way they are designed.

[Juls1 1661]

Typically speaking RC racers will run there dampers quite slow purely for stability, the thing to remember compared to a full size car you don’t have to sit in your RC car, so tuning for comfort is irrelevant. 

Most of tamiyas bashers are setup far too fast from factory and as a result are quite unstable. You have bought a race vehicle and discovered that the race setting if far from what than your run of the mill vehicles. This is normal and personally I setup most of my chassis this way to improve overall handling. The number of holes in the piston isn’t really relevant, it’s the size of the hole. For CVA I almost always run single hole piston, sometimes with heavier oil than stock too depending on situation. The damper should show obvious compression damping to handle jump landings and slow enough rebound to stop the springs from unsettling the car after large impacts.

i generally run soft enough springs to have 25-40% sag on my off road vehicles, the damper needs to be able to control the motion and absorb the impact. The spring is not there to absorb the impact as it just stores the impact then releases it. It’s the dampers job to deal with the initial impact and the stored energy of the spring.

the downside of cva damper is the body can swell under high pressure situations leading to bypass. But for most applications can still be setup just fine.

Drop into a RC racetrack where they run 1/10 ep buggy’s on clay and go around the track and bounce all the cars suspension you’ll probably find they are even slower than your factory Db01r setting.

cheers

Juls

[Juggular 4964]

Everybody does it differently.  

I prefer softer settings.  I want my RC car to bottom out when it lands from 3 feet up.  Many Tamiya bashers are set too stiff.  You can see TXT-2 bouncing on tires, because springs just don't give.  (But TXT-2 is fine because that's how monster trucks roll)  But other cars bouncing on tires makes them look like a 20 dollar Radio Shack RC toy.  

Over the years, Matteo (of the Youtube fame) got softer settings too.  Before I bought Bigwig, I saw his on youtube.  I liked how fast and smooth the shocks were soaking up the mini-dunes.  I asked, and he replied "4 big holes."  It doesn't bounce with 4 holes for Bigwig.  But obviously, for you, if the shock bounces, that's too much.  

Here is a video of "Nordic RC" guy setting up his Thundershot.  The rear is too stiff, and the front is too soft, so he fixes both.  As Juls1 said, don't get hung up on the number of holes.  It's what the shocks do that's important.  2 small holes with softer oil might work just like 3 medium holes with harder oil.  Like Juls1, you can set it up to improve handling by making them a tad stiffer, especially if the track is gently rolling and there isn't a lot of obstacles.  

Tires should stick like a spitball when landing.  No bounce, no squishing the tires too much either.  If you make them rock-hard, you will end up with more air time.  While flying from one little rock to another, the tires will have less chance to steer, and less chance to push the car forward.  Steering and accelerating work best if the tires are on the ground.  So the shocks should prevent the wheels from bouncing up.  But if shocks prevent the springs from giving in, that could be just as bad as bottoming out at every chance.  So find a good middle ground that suits you and the terrain you'll run it on.  

 

[TwistedxSlayer 1290]

I've generally been using stiffer springs on my off road vehicles to keep ground clearance to avoid that sag. I'm starting to feel like a complete idiot with my setups.

[ThunderDragonCy 7877]

Thanks for sharing your experience guys. Feels like I am on the right track with going slower. I don't often run at a track so big impacts aren't a massive issue, but in struggling to get my Thunder Dragon to handle I have ended up with really quite soft rear springs to give a lower ride height and to back off the steering. Even with 500cst oil in the 2 hole CVA dampers result in a very 'active ride. Driving away from me across grass I can see it moving a lot and probably bottoming out a lot too. I measured some spare TRF pistons I got with the DB01R but annoyingly whilst they fit in the front CVA the rears are 1mm bigger so they won't work. Currently scraping together all the 1 hole pistons I can find!

[Juggular 4964]

13 hours ago, TwistedxSlayer said:

I've generally been using stiffer springs on my off road vehicles to keep ground clearance to avoid that sag. I'm starting to feel like a complete idiot with my setups.

Oh no, you shouldn't feel that way.  Andy of "Andy's Hobby Headquarters" on Youtube said a great thing.  "It's a hobby. You should enjoy it. Don't take it too seriously."  He simply laughed off the criticism of him being a mediocre modeler.  I thought that was an awesome attitude.  Just take the info you want to use, and enjoy. 

In this hobby, you are the boss.  

 

[TwistedxSlayer 1290]

18 minutes ago, Juggular said:

Oh no, you shouldn't feel that way.  Andy of "Andy's Hobby Headquarters" on Youtube said a great thing.  "It's a hobby. You should enjoy it. Don't take it too seriously."  He simply laughed off the criticism of him being a mediocre modeler.  I thought that was an awesome attitude.  Just take the info you want to use, and enjoy. 

In this hobby, you are the boss.  

 

I kinda have to feel that way just a tiny little bit. Mainly due to having an Advanced Apprenticeship and an Technical Diploma in Mechanical Engineering which I spent 8 weeks studying suspension entailing components and setups. I honestly have no excuse for my own poor judgment of RC suspension. Lol. As I said, I spent months researching the suspension for my 1:1 car to ensure it was perfect. I've kinda overlooked the settings on all of my RCs. And go e for trying to maintain ground clearance as oppose to handling. Once I'm back off my holiday I'm going to re setup my RCs. Think the TB01 rally car is a good place to start as I know the setup may be a little too stiff.

 

[Jason1145 3986]

If I get my rigs landing like Nordic RC got his TShot at 3:28 in the video I’ll call it a day... just as described.. enough absorbtion from a drop to squat and raise back up without the tyres leaving the ground is what I would like best for general use.

[ThunderDragonCy 7877]

I switched the Thunder Dragon over to 1 hole pistons yesterday and it works great. Suspension just seems way more controlled. Last night I switched my DN01 to 1 hole rear and a spare pair of TRF pistons for the front. Certainly seems promising and the drop test is positive. Thanks for the advice and thoughts everyone.

[nowinaminute 2815]

On 8/18/2018 at 9:27 PM, Jason1145 said:

If I get my rigs landing like Nordic RC got his TShot at 3:28 in the video I’ll call it a day... just as described.. enough absorbtion from a drop to squat and raise back up without the tyres leaving the ground is what I would like best for general use.

Yup that's pretty much my starting point and usually the ending point too lol

[ThunderDragonCy 7877]

Gave the DN01 a quick run before work. It's handling soooo nice. Much more calm and seemingly more grip.

[Pata76 501]

5 hours ago, ThunderDragonCy said:

I switched the Thunder Dragon over to 1 hole pistons yesterday and it works great. Suspension just seems way more controlled. Last night I switched my DN01 to 1 hole rear and a spare pair of TRF pistons for the front. Certainly seems promising and the drop test is positive. Thanks for the advice and thoughts everyone.

How many holes in the TRF fronts?

[TwistedxSlayer 1290]

Daft question... But what height are you dropping from? Don't wanna drop a rally car with like 14mm of suspension travel from say 5ft.  Or say my Levant with a lot more travel from say 2ft and not actually achieve anything

[ThunderDragonCy 7877]

14 minutes ago, Pata76 said:

How many holes in the TRF fronts?

2 x 1.3mm holes. It's just the pistons, fitted to black CVA shocks.

[ThunderDragonCy 7877]

9 minutes ago, TwistedxSlayer said:

Daft question... But what height are you dropping from? Don't wanna drop a rally car with like 14mm of suspension travel from say 5ft.  Or say my Levant with a lot more travel from say 2ft and not actually achieve anything

Not daft at all. I am picking up one end of the buggy leaving the other end on the ground then drop. About 30cm maybe? 

[Jason1145 3986]

1 hour ago, ThunderDragonCy said:

Not daft at all. I am picking up one end of the buggy leaving the other end on the ground then drop. About 30cm maybe? 

Yep same as me, and for touring cars I’d only lift them about 10cm off the ground and test drop from there, any more and it gets painful.. I’d actually like to find/make some small ramps for these just to vary driving round on a flat surface a bit.... thinking ramps about 5cm high with a straight angled lift off area would be good ( no kicks)

[ThunderDragonCy 7877]

1 minute ago, Jason1145 said:

Yep same as me, and for touring cars I’d only lift them about 10cm off the ground and test drop from there, any more and it gets painful.. I’d actually like to find/make some small ramps for these just to vary driving round on a flat surface a bit.... thinking ramps about 5cm high with a straight angled lift off area would be good ( no kicks)

Don't have any on road but sounds sensible based on suspension travel.

[Honza 936]

On 8/18/2018 at 12:30 AM, speedy_w_beans said:

You'll never get TRF-level performance from CVA dampers for a number of reasons:

- CVA pistons don't seal against the damper bodies as well.

- CVA piston holes are way too large to transition between linear damping and nonlinear damping like the TRFs do.  Landing jumps effectively while still handling smaller bumps requires both types of damping.  The CVAs never provide "pack".

 CVAs are better than spring holders, but TRFs definitely provide an advantage with the way they are designed.

a little bump...

I measured CVA2 mini bodies and their pistons - while bodies have exactly 10mm in diameter, pistons are 0,3mm smaller. That's area of 4,6mm2, while holes in CVA dampers have 1,5mm2... no wonder they don't pack.

now to my question - would TRF pistons 53572 or 53573 fit better? it could be nice, cheap upgrade

[speedy_w_beans 4272]

I think I found the same thing as you; my measurements and change to TRF-style pistons are documented here:

In my case I had some spare pistons lying around and they fit very nicely in the on-road CVA bodies.  I haven't tried this with the taller off-road CVA bodies.

[Honza 936]

That's great info, thanks  Is difference between 3 hole TRF and one hole CVA noticeable?

[speedy_w_beans 4272]

Yes, the three-hole 1 mm pistons provided a little more damping than the one-hole 1.5 mm piston.  That might sound counterintuitive given the hole areas (about 50 pct more area for the three hole setup), but the TRF-type pistons sealed against the CVA bodies better and the 1 mm holes pack up sooner than the 1.5 mm hole.

Anyhow, I remember building them and thinking how they felt more damped in hand, and how the chassis showed good damping in a kitchen counter drop test.

I'd love to have a shock dyno someday to generate numbers.  I can measure spring constants pretty well, but I don't have a way to measure force vs. velocity.