TrueBlue

DT-03 CVA Dampers

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Not too long ago, I finished building a Tamiya Aqroshot which included the DT-03 CVA damper set. I followed the instructions to build the dampers 100%. Once the build was done, I noticed that the front dampers were fine and could push the chassis back up, but the rear dampers are very stiff and are unable to lift the chassis without me lifting it up myself.

All the parts were used, nothing was left over. I filled the dampers with oil to the top and cleaned any overspill, I remove the air bubbles as I went. It's like the spring itself has no resistance (right word?) when compressed.

Does anyone have any idea why just the rear dampers are doing this? Is it normal and has anyone experienced this before with this damper set? Any help would be awesome.. I wanted to drive this tomorrow!

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I thought that the Aqroshot rear springs were a bit weak too tbh. The back does squat down under power when driving which is normal for a 2WD.

Disconnect the dampers from the lower suspension arm and make sure that the suspension travels smooth and no binding or tight spots in the arm movement. If both sides are nice and free then reconnect the dampers and use all three spring collars provided with the kit.

If you want harder springs for this truck, then get yourself a DF03 (that's delta foxtrot, not a typo) setting spring set. The one with 3 spring sets, silver, gold and black in colour. Sorry, no link but the part number is 53927, best of luck !

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I just got the Aqroshot myself and noticed the same exact issue. I did add all 3 collars which helped a little. Someone told me to try TRF 54028 dampers but I really can't justify spending $65 on just shocks for a $120 kit. I did add a bunch of other hop ups though. I also purchased 2 different motors supershot GT and the super stock RZ which I haven't tried yet.

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The DT-02 hop up springs give n additional choice to hardness.

I run the softer red ones and they hold up fine on my DT-03.

Are you running big NiHI packs?

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The DT-02 hop up springs give n additional choice to hardness.

I run the softer red ones and they hold up fine on my DT-03.

Are you running big NiHI packs?

Same here but I am using the blue springs

6FD453E4-3963-4B02-A3F1-3265CB0532F5_zps

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its even cheaper to buy the medium or hard oil sets, this is what I do on my dt02 / dt03's

the soft oil is slightly too soft for the rears if not using lipo

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A setup like this will have been done by Tamiya on purpose. The soft rear springs make the buggy understeer more, which is easier for less experienced drivers to handle. While adding ride height spacers above the springs will raise the buggy up a little, it does nothing to make the rear end stiffer (no matter what the Tamiya manual states). If you increase the rear spring rate, be prepared for a change the handling characteristics of your car (less understeer / more oversteer). Not that it's necessarily a bad thing.

The overly stiff dampers holding your buggy down could be caused by any of the following factors.

- A very thick damper fluid (this will have been chosen on purpose by the setup team)

- A very imprecise plastic damper with lots of friction between parts (only expensive dampers will solve this)

- Pistons that weren't trimmed properly and are scrapping along the cylinder wall

- Imprecise fit & excess friction in the suspension components

Keep in mind that while the buggy is running, there is a lot of vibration in the drivetrain and suspension. This effectively helps keep damper and suspension friction in check. Your buggy will not get stuck in the same lowered position like it does sitting static on a table.

Lets me also mention that the above examples help illustrate that there is a reason TRF cars are so much better and so much more expensive. The smooth & precise action of the chassis & suspension can be worth every penny.

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I kinda sorted it out, but it's not great. The instructions say to slide a small tube onto the piston rod, which I have no idea what it does. So what I did was move the tube below that disc the spring presses against, therefore making the spring a little stiffer. It's not the best fix, but it kinda works and it now pushes itself back up. My description might not make much sense, hopefully the pictures do. I may opt for some better springs in the future though.

wkU4t7H.jpg

EVV2kZR.jpg

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According to the instructions I'm looking at, the shorter ones do go on the rear, and the longer ones go on the front. According to the instructions.

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According to the instructions I'm looking at, the shorter ones do go on the rear, and the longer ones go on the front. According to the instructions.

You are correct. I use the longer ones though

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Those spacers don't make the springs stiffer. They simply raise the ride height.

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Those spacers don't make the springs stiffer. They simply raise the ride height.

Keeps the back end from dragging though.

Just a thought, the rears have a story of black coating on the shaft. I always polish this off, did you?

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I did not polish off the coating of black, no. I was wondering why one pair was silver and one was black.

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I did not polish off the coating of black, no. I was wondering why one pair was silver and one was black.

I have no idea why one is black but the coating seems to cause stiction

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I have no idea why one is black but the coating seems to cause stiction

You speaking about that?

DT-03_00025_zpsrmfrztlb.jpg

I've polished in my DT03 these parts- It is not a coating. I think it's a failure to finishing of the parties. Polishing paste and drill

DT-03_00027_zpsnoyzlwmw.jpg

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You speaking about that?

DT-03_00025_zpsrmfrztlb.jpg

I've polished in my DT03 these parts- It is not a coating. I think it's a failure to finishing of the parties. Polishing paste and drill

DT-03_00027_zpsnoyzlwmw.jpg

That's it. I used a bit of scotchbrit and autosol to polish them up

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OMGoodness, those rods are heinous! Polishing them is definitely a worthwhile task. Though I'm wondering if they are even made of stainless steel, and won't rust. :\

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I found that the CVAs on my DT03 leaked after a few runs. I put it down to the hard black O-ring seals. I stripped and cleaned them and put softer red seals on and they don't leak anymore.

The rear end still seems a tad soft on kit springs, but the use of lightweight gear shafts and a ball diff shaved a few grams off the rear end. The gear diff in the kit is so heavy compared to the ball diff upgrade.

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When I built an Acroshot I also polished up the pistons for the rear dampers. What ever the reason or purpose of that black coating on the shafts is, the effect is that the pistons don't work as smoothly as I'd like. Here's a link to the step in my build thread where I built up the dampers. I have a DT-02 spring hop-up and I did try the hard springs on the rear before I settled on sticking with the stock springs.

The plastic tubes placed on the shaft have various effects depending on where you place them.

  • Inside the shock body and it will reduce the overall length of your shock
  • On the piston between the shock body and the spring cup will limit the compression stroke. This can extend the life of your shock if you are bottoming out the shock before the chassis slaps the ground.
  • On the piston below the shock cap. This will generate spring pre-load compression, and will be exactly like adding clips to the shock body. The downside to this method is that you can't adjust the pre-load as easily as you can with clips.

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When I built an Acroshot I also polished up the pistons for the rear dampers. What ever the reason or purpose of that black coating on the shafts is, the effect is that the pistons don't work as smoothly as I'd like. Here's a link to the step in my build thread where I built up the dampers. I have a DT-02 spring hop-up and I did try the hard springs on the rear before I settled on sticking with the stock springs.

The plastic tubes placed on the shaft have various effects depending on where you place them.

  • Inside the shock body and it will reduce the overall length of your shock
  • On the piston between the shock body and the spring cup will limit the compression stroke. This can extend the life of your shock if you are bottoming out the shock before the chassis slaps the ground.
  • On the piston below the shock cap. This will generate spring pre-load compression, and will be exactly like adding clips to the shock body. The downside to this method is that you can't adjust the pre-load as easily as you can with clips.

Any reason why you went back to the stock springs? I was thinking of buying them for the rear shocks. The front seem to be fine, but the rear are suspect.

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Any reason why you went back to the stock springs? I was thinking of buying them for the rear shocks. The front seem to be fine, but the rear are suspect.

Once the rig was built the stock springs seemed to be the best balance. I guess you could say I tuned the shocks using damper oil rather than springs. There is a dark art to suspension tuning that I freely admit I am not yet even a sorcerers apprentice. My limited knowledge is that spring rate determines shock rebound. Too strong of a spring and the rig will hop right back up, too weak and it'll be lazy. Damper oil effects the "character" of the shock. Too light of an oil and the rig will feel skittish, too thick and the rig will feel sluggish.

I hope that makes sense and that I'm right. :/

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