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wtcc5

wtcc5's TT-02 race development and race reports

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13 hours ago, wtcc5 said:

The oil sweats slowly through the housing walls.

There's one method, which address this issue - remelting/annealing prints in salt or plaster makes even FDM prints airtight:

It might be good enough atleast for prototypes 

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On 3/8/2021 at 8:25 AM, wtcc5 said:

Another vision is to do a 4wd LeMans chassis for my Toyota Gazoo TS050; middle motor and very low.

This would be awesome!
 

What a thread, mind blown (about 4 pages back!)

 

 

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6 hours ago, Honza said:

There's one method, which address this issue - remelting/annealing prints in salt or plaster makes even FDM prints airtight:

It might be good enough atleast for prototypes 

Interesting method. I don’t think it will work with my very small housings, but a cool method nonetheless. Thanks for sharing!

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7 hours ago, ThunderDragonCy said:

@wtcc5 Can i ask what the advantages of the rotational damper and leaf springs are? Especially now the heave damper is not included?

Could you paint the inside or outside of the printed plastic damper body with clearcoat to seal it instead? 

I don’t think the rotationdamper has an advantage, it is just deep down in the car. The heave damper had to go to develop and understand the rotationdamper. Also I need to redesign it.

I thought of sealing it with color, but now it is too late. I should have done it before putting the oil in...

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I started to work a little on the rolldamper, but very fast lost the fun in doing so. There are so many challenges and the compromises I have to do also insult my sense of engineering as I want it to become perfect. So I let it be and switched to the KRv2.

bildschirmfoto2021-03bmkwj.png

 

I want to do a facelift/upgrade/further development with some design ideas from the KRv3/KRv2.5 and more; I want the swaybars to move lower, use parts of the TRF420 suspension and if possible reduce the parts count. I also added the Yokomo BD10 shocks to the cad file.

bildschirmfoto2021-03z6kcr.png

bildschirmfoto2021-03o5j36.png

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It was a good day in the office.

The front parts changed a lot. Overall complexity could be reduced. I am happy!

 

bildschirmfoto2021-03wgjzw.png

The idea to mount the top of the damper on an arm instead of a bridge (like Mugen does) was in my head for some weeks and today I tried to implement it. My design is destined for that. The arm for that just needs to be 9mm long and will be strengthened by the topplate and inner camber link. With a little more material added, I changed the mounting type of the camber link away from a nut, to a thread, which will make working on the car much easier.The topplate was optimized in geometry, too. No more shock tower needed :)

The lowered swaybar got mounted to the lower droop plate mount. Like that I save the use of extra screws and the mount will be tough. For a bar change, the assembly can be taken out upwards. The outer lower damper mount got another mount for the anti-roll-bar-mount on the arm, again saving saving screws and extra mounts like that.

With the droop screw now installed on the droop plate, the arms lost a lot of complexity and material. I optimized the shape for the TRF420 c-hub, made the struts thinner and made a little notch for the outer anti-roll-bar-mount. The best news here is, that I also made the arm 1mm longer, by taking away not needed material on the inner rings (around the Awesomatix arm mounts). This will make car even better outdoor and when touching curbs.

bildschirmfoto2021-037bjjw.png

Last, the droop plate had to be adapted to all the changes. I relocated the droop screw from below the rear arm strut to the front strut. This way it is better supported by the droopplate fastening screws and as the damper mount is on the front strut also, there will be no warp in the arm through the forces of the damper. The new shape also saves material towards the rear of the plate without losing strength. Disadvantageous is the width because of the layout. The plate got wider and I need to smooth the edges especially around the droop screw assembly.

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@wtcc5Love the way you deleted all the various parts and fixings. It's so satisfying optimising a design in this way. Do you think you might use some parts from the TA08 eventually? There are some quite close similarities to the KR in the new suspension. Also, did you find a TT02 diff that works? You complained that the Tamiya oil diff leaked. Would SpecR still be the best? 

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At this time I see no TA08 part that I could use here and benefit from. It seems to be a good plastic car, but pulling over parts to other chassis looks impossible.

I am still using the 3racing diff. It makes no problems and shows little wear up to now. I am not touching another TT02 geardiff until someone proves it is not leaking anymore or Tamiya solved the problem...

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And here I was, thinking I did some goofy stuff to TT-chassis'd cars. My hat's off to you, Sir. Wow. What a build! Wirklich wunderbar!

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@GooneyBird Thanks! I haven't thought too, that it will become what it is now...

 

I continued with the car and now feel like having made a larger step than originally expected. And that is why I want to give this child a new name. From now on I will call it KRv4.

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In the rear, I added the same principles as at the front. No shocktower, longer arms (2mm on each side), one mount for shock and sway bar, integration of the TRF420 rear hub. 

bildschirmfoto2021-030kkoo.png


Special are again the rear body posts. I wanted to implement them with less material and also needed a new concept now that the shocktower is gone. They stay curved and are now located directly above the outdrives.

bildschirmfoto2021-03nojfz.png


Back at the front axle, I had the idea to reduce the C-hub to a _-hub. I don't know if that will work, but I will try in the next days.

bildschirmfoto2021-03t3kll.png

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c678d83e-3e2a-48b3-8jdj82.jpeg

The _-hub idea was tested on the real car and while it would work it, has the disadvantage, that the caster angle would not be accurate anymore with just the lower mount. And that was the idea for the KRv2, to have an easier setup work by keeping the C-hub. So if I continue with this idea and have to check caster on the setup system with every camber change, than why not go full ballstud on the steering hub and remove the C-hub assembly? The answer lies in the arm length. Attaching the ballstud to the steering hub would mean, that it attaches to the arm closer to the chassis than the C-hub is with the outer pin (see picture in my last post). I guess that is why Awesomatix went the long arm route with the A800. And long arms really work well on my conversion, too.
So I am trying something, which will maybe a dead end:

bildschirmfoto2021-039bk01.png

To regain arm length, the steering arm axis will move closer to the hex. This reduces the offset to the wheel and will reduce the scrub angle. I am going a bit aggressive here. The steering feel should become very direct (not sure if it will harm the performance?). Worse is, that I changed the Ackerman angle too. The steering will be more smooth with the new angles. As this is all experimental and I don't want to waste more money than needed, I added another mounting point on the arm to use the TRF420 steering hub with proven Ackermann angles.

bildschirmfoto2021-03gyk7g.png

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These ideas further simplify the suspension. The hub is smaller and lighter. The steering arm moves to the top, allowing less shim use for the relocated Tamiya Hop Up steering system. For the lower hub attachment I use the same parts as for the arm mounts.

The rear was updated, too:

bildschirmfoto2021-036qkmt.png

 

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If keeping consistent caster angle is important, couldn't you make angled holes in the bottom platform of your first idea so that the caster was defined and fixed by the bottom block? Use the flanged tube and bolt arrangement from the Tamiya c hubs just on the bottom. You would need to adjust the top links carefully to avoid binding, but with the caster axis defined in at least one place it should be easier to get it the same left to right for consistent handling.

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That is what I did in the first picture, but what I meant is, that the slop in the bottom block is enough to have 4 degree different caster. I could match the right caster with the top links, but I lose the easy setup advantage. And then I could go full Awesomatix/MTC2 right away (and reduce parts, weight and complexity).

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Ah, understood. Without the top part of the c-hub the bottom on it's own isn't enough to located it accurately. Fair enough. I hope the long arm version works then!

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One area I have on my mind for a long time is the bumper assembly. After buying and tuning my childhood TA-02 chassis, I liked how Tamiya designed the tuning bumper (53145). The foam part is fully supported and the owner can cut his own piece and attach, simple and effective.

Right now, I use the standard Xray T4'15-'19 bumperbase and foam piece. The latter is just supported by the two bodyposts. Like that the foam can move easily until the bumperbase mounts try to stop it or it rips around the holes. That was never a problem (for me), it works with that design. Still the bumper topic always bothers me. It is the dispute between sheer performance and protection of the precious material. The little red guy on my shoulder says: "It is just dead weight you seldom need. Without it you are faster!" From the other side, the girl with the halo and the white dress warns: "Even though you may not need it everytime, it can save a good race result." :lol:

More than once I looked at the 1/10 pan cars and their piece of carbon plate that is the bumper and was tempted to follow that path for the KR. As you can see in the picture below, I settled for a compromise:

bildschirmfoto2021-03f9kfb.png

I reduced the foam volume and split it in three pieces. These are attached to plastic mounts, that fully support the foam cross section.These then will be secured by form locking and a little screw on the carbon plate. It has the body mounts and guides the forces of a strong impact into the chassis. It is mounted to the lower chassis protection piece.

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bildschirmfoto2021-034qkzp.png

bildschirmfoto2021-03uikqj.png

I kept the mounting position of the Xray bumper to have an alternative just in case.

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Some more thoughts regarding the weight, as it isn't easy to save a lot here:
My actual bumper unit weights in at 19g without the body height adjusters. The design shown above has approximately 15g (screws and body posts included). If I would use only a carbon plate I could get down to 11.8g...

bildschirmfoto2021-0360ki1.png

The bumper topic isn't an easy one. I am still not satisfied with my ideas. Having a lot of foam in front is not wrong, but you need to support it and need the body posts to be attached to something, too.

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@wtcc5 Could you pull the carbon plate back to the body posts, and double up the fixings for the outer bumper mounting parts with the body posts? Then the carbon part would be smaller, foam blocks could be thicker and you can get rid of two screws?

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