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CVA damper vs Aeration Damper relative performance

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The White TRF style pistons are a significant upgrade for black CVA V2 dampers, but you can only really get pistons for the mini and super mini, the CVA Short has a 11mm bore but Tamiya only makes the white TRF style pistons in 10mm and 12mm not 11mm required by CVA short (so rear shocks on DT02/03 DF01/2/3 etc etc) (reference my Buggy damper thread click linked text) 

of course Mini and Super mini used on almost all Tamiya M chassis and 1/10 touring rally cars use these so it’s a possible upgrade. 

The issue is the cost, while a set of 4 will only set you back about $5usd, these are something you’ll get standard with a set of TRF alloy dampers that will come with a stiff alloy body, proper nylon shaft guides which reduce friction and coated piston shafts which further reduce friction, in some cases more slippery seals too. So do you spend 10-15% of the cost of proper shocks on your plastic CVA’s? 

I guess it depends on context and what your doing. For my G6-01 it made sense as I could buy 3 pairs of CVA mini and a couple of packets of pistons and get good performance vs cost for that application, as it made less sense to buy 2 sets of 4 alloy shocks when I needed 6 not 8... 

the thing with any of us hardcore Tamiya collectors we often have bought many pairs of TRF dampers which often come with a full spare set of the pistons (different holes etc) so over time we accumulate these pistons so it’s a nice free upgrade in that case for kits we don’t intend to go alloy shocks. 

 

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Well, 10% of price means i don't need to spend another 90% for fancy shocks :D

I need four dampers of CVA mini size for my rally car. Tamiya makes set of 4 cva mini, but no such set of TRF dampers. I'd need two pairs of front buggy dampers, which would be too expensive.

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Someone at rctech forums tested piston hole sizes and other modifications in quite some depth. Their results summary is here: https://drive.google.com/file/d/0B-9Xopgk6BDNeDk0ZFBXMzI4SE0/view?pli=1

Basically, their results prove that a solid piston with straight holes produces an entirely linear damping force, so changing the quantity or diameter of holes in the piston achieves exactly the same effect; a linear increase or decrease in damping. Making the holes bigger has the same net effect as adding more holes. Personally I'd prefer using a piston with at least 3 holes, that way it's somewhat balanced and doesn't rock on the shaft as it moves in and out - probably doesn't make any difference in reality but the engineer in me is happier when something is theoretically better on paper haha.
I believe installing a piston which is smaller and therefore leaves a gap between it and the bore, achieves exactly the same effect as having more holes or larger holes - it's still linear.

The only time they observed any deviation from linear is when they used actual valving via flexible seals. The only time they observed inequality between compression and rebound damping is when the holes in the piston were heavily chamfered/tapered.

So in conclusion: science says that a CVA can perform identically to a TRF damper since they are both linear dampers, just need to pick the right oil and/or piston hole configuration.

Oh, and don't listen to anyone's advice on suspension if you're making a bashing rig. Just try different configurations and see what works for where and how you bash. The best way is to change 1 thing at a time, and make big changes - like doubling or halving the weight of the oil and see how that affects it's handling. The worst that can happen is that it sucks and you undo that change - OK the worst that can actually happen is that the car crashes, catches fire and is a total loss but let's not go there :lol:. My on road touring car basher has 1500cst oil in the front dampers and 3000cst in the rears, which are tiny 1:16 scale buggy dampers with tiny holes in a tiny piston. It takes about 2 seconds to fully rebound after bottoming and if you drop the car from 1ft the suspension won't bottom out. The suspension config is ludicrous compared to how you'd set up a touring car for racing but it works great for how I drive it. Heavy damping in the front and very heavy damping in the rear was the only thing that stopped it driving on its nose or flipping every time it hit a sharp bump at warp speed like a stone, or a stick or a 1" change between pavement surfaces.
 

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5 hours ago, nbTMM said:

The only time they observed any deviation from linear is when they used actual valving via flexible seals. The only time they observed inequality between compression and rebound damping is when the holes in the piston were heavily chamfered/tapered.

So in conclusion: science says that a CVA can perform identically to a TRF damper since they are both linear dampers, just need to pick the right oil and/or piston hole configuration.

Did you read summary at end? They didn't test high velocity when dampers "pack" - if I recall corectly, packing is when flow changes from laminar (linear damping force) to turbulent (exponential damping). They aknowledge different performance during high-speed compression, but they tested C:R ratio during normal (linear) damping. Hole size should have effect on exponential damping.

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16 hours ago, Honza said:

Well, 10% of price means i don't need to spend another 90% for fancy shocks :D

I need four dampers of CVA mini size for my rally car. Tamiya makes set of 4 cva mini, but no such set of TRF dampers. I'd need two pairs of front buggy dampers, which would be too expensive.

Both CC01 and GF01 damper kits come in roughly the same length as CVA mini (they are a few mm longer and with more travel, so ideal for rally) 

both these shock sets include TRF style pistons and nylon shaft guides. For all intensive purposes both sets are near identical, color excepted. 

They are the best bolt on for XV01 Long Damper set. They are also ideal on most  touring chassis being used for rally. (TA01/2/3, TB01/2, TL01, TT02S, XV01LD etc.)

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5 hours ago, Honza said:

Did you read summary at end? They didn't test high velocity when dampers "pack" - if I recall corectly, packing is when flow changes from laminar (linear damping force) to turbulent (exponential damping). They aknowledge different performance during high-speed compression, but they tested C:R ratio during normal (linear) damping. Hole size should have effect on exponential damping.

They way I read that was that it was more a disclaimer that as measurements were only taken up to about 200mm/s, they could only speculate about what would happen at say 500mm/s. Logic would have it that if it's perfectly linear from 0 to 200, it would be unexpected that it would deviate far from linear at 500mm/s as that would then be quite a non-linear behaviour overall. Like all good scientists, measuring is knowing so I'd happily be proven wrong about that point :)

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6 hours ago, nbTMM said:

Logic would have it that if it's perfectly linear from 0 to 200, it would be unexpected that it would deviate far from linear at 500mm/s as that would then be quite a non-linear behaviour overall.

Well, fluids acts non-linear overall. It can be expected that there will be point where turbulence occurs and drag increases significiantly. They didn't reach speed needed to show that behaviour, because test was about different thing.

CVAs have large hole area, which needs high viscosity oil to achieve atleast some damping effect. And high viscosity fluid keeps laminar flow for longer. TRF piston should, at least in theory, requie lower viscosity oil for same damping effect, which should develop turbulent flow sooner, which is also aided by higher speed of fluid caused by smaller area of holes.

And that's what I need, because when I set damping force to keep car from bottoming out on jump, it's too stiff for small bumps.

EDIT: this pdf confirms what I thought. Interesting pages are 15 and 22, where is shown non linearity caused by high speed and low viscosity respectively.

https://drive.google.com/file/d/0B-9Xopgk6BDNeTBRMEVkcnFDZ28/view

8 hours ago, Juls1 said:

Both CC01 and GF01 damper kits come in roughly the same length as CVA mini

Thanks for tip, CC01 dampers look good and affordable. Are plastic parts (nylon guides) replacable by TRF ones?

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3 hours ago, Honza said:

Thanks for tip, CC01 dampers look good and affordable. Are plastic parts (nylon guides) replacable by TRF ones?

The GF01 damper is identical to CC01, just in blue. 

The parts in the GF/CC01 Damper kits in terms of nylon pistons/rod guides are the same as used in many of the TRF dampers, at least they where the same as in my 42102 anyway. I see no reason why these wouldn't be viable replacements.

It's worth remembering the CVA dampers DO NOT have any rod guides, there isn't room, they just run through the seals and expect the piston inside the body to grind it's way up and down to keep everything inline. The entry and exit holes in the CVA dampers act slightly as rod guides, but the bottom caps wear quickly and then they rely on the piston in the body to be supported by the plastic body of the damper. 

Juls 

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On 7/5/2019 at 8:58 AM, Juls1 said:

The White TRF style pistons are a significant upgrade for black CVA V2 dampers, but you can only really get pistons for the mini and super mini, the CVA Short has a 11mm bore but Tamiya only makes the white TRF style pistons in 10mm and 12mm not 11mm required by CVA short (so rear shocks on DT02/03 DF01/2/3 etc etc) (reference my Buggy damper thread click linked text) 

of course Mini and Super mini used on almost all Tamiya M chassis and 1/10 touring rally cars use these so it’s a possible upgrade. 

The issue is the cost, while a set of 4 will only set you back about $5usd, these are something you’ll get standard with a set of TRF alloy dampers that will come with a stiff alloy body, proper nylon shaft guides which reduce friction and coated piston shafts which further reduce friction, in some cases more slippery seals too. So do you spend 10-15% of the cost of proper shocks on your plastic CVA’s? 

I guess it depends on context and what your doing. For my G6-01 it made sense as I could buy 3 pairs of CVA mini and a couple of packets of pistons and get good performance vs cost for that application, as it made less sense to buy 2 sets of 4 alloy shocks when I needed 6 not 8... 

the thing with any of us hardcore Tamiya collectors we often have bought many pairs of TRF dampers which often come with a full spare set of the pistons (different holes etc) so over time we accumulate these pistons so it’s a nice free upgrade in that case for kits we don’t intend to go alloy shocks. 

 

I did a little searching around and kyosho make an 11mm piston.  I think it would work.

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3 hours ago, danimaldaisy said:

I did a little searching around and kyosho make an 11mm piston.  I think it would work.

Since this post I found the hi cap mini dampers (front buggy) pistons fit, they are not white resin, but the plastic is stiffer and tighter fitting than the stock CVA short piston and does improve performance. But yes the kyosho piston may work if it has the right hole in the middle. 

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16 hours ago, Juls1 said:

Since this post I found the hi cap mini dampers (front buggy) pistons fit, they are not white resin, but the plastic is stiffer and tighter fitting than the stock CVA short piston and does improve performance. But yes the kyosho piston may work if it has the right hole in the middle. 

I think I will hold out for those.  I know they are not available or hard to get.  I'm hoping the Y parts will be re-released with the egress re-release. I will probably order 5 or more sets. I plan to use these in a future TD2 build.  Then again Tamiya may just go with one of their modern dampers.  We will see I guess.  

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19 hours ago, danimaldaisy said:

I think I will hold out for those.  I know they are not available or hard to get.  I'm hoping the Y parts will be re-released with the egress re-release. I will probably order 5 or more sets. I plan to use these in a future TD2 build.  Then again Tamiya may just go with one of their modern dampers.  We will see I guess.  

It’s unlikely that the 53075 will be re released, however every set of dampers out there will have spare unused pistons so maybe you can find someone willing to part with their spare pistons. 
 

i used up my spares on my CC02. 

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On 10/25/2022 at 9:42 PM, Juls1 said:

Since this post I found the hi cap mini dampers (front buggy) pistons fit, they are not white resin, but the plastic is stiffer and tighter fitting than the stock CVA short piston and does improve performance. But yes the kyosho piston may work if it has the right hole in the middle. 

#42332 TRF BIG BORE DAMPER PISTONS for the SS big bore shocks.  Set of 4 piston blanks.  While Short CVA pistons are ~10.7-10.8mm diameter, These are 10.95.  They are blanks and require drilling your own holes.  They provide starter divots on the surface for 2,3, or 4 holes.  I have a pair of these in one of my CVA short sets currently, so I know they fit. 

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