So the promised update, although a bit late:
Warning, this is a long post. If you just want the most interesting bits, skip to the new additions. Otherwise: grab a coffee
.
The 3D-printed shock pistons are still going strong. After my last comment on them I overfilled my shock and one broke. After that I thickened it just a little bit more and refined the design some. They haven't broken since. Which is 4 months according to the post date. I heavily procrastinated on posting them though. I will put them online soon.
The 3D-printed hinge pin holder case I posted earlier is also still on:
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Under there is actually still the broken hinge pin holder because I was waiting for the Swiss steel drive cups to get in stock and with that order the hinge pin holder I wanted. In that time I took it out a couple times and surprisingly the 3D-printed bracket held up. When the drive cups didn't come in stock in the time frame they promised (I e-mailed the shop I was planning to order from), I decided to buy them from Corally directly. But Corally didn't have the hinge pin holder in stock and I couldn't find a place that had both. So in the end I am still running on a partially broken hinge pin holder with a 3D-printed bracket, also for about 4 months now. Some way it hasn't broken again
. I will add the hinge pin holder to my next part order though.
I also installed swiss steel drive cups for the center and front diff:
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The back and input cups are still OK. Thanks
@Horatio for helping me with the shimming, I got everything shimmed pretty well now. The center diff still has a little bit of play. That is coming from the drive cups being able to move inside the diff. I rebuild the diff dry with the out-drives shimmed, it needed five (I believe) in total, but that made it bind up. So now I am running three or four total, it isn't binding but has some excess play. The front diff needed one extra shim behind the spur. Weirdly my car came shimmed pretty well from the factory: two behind the spur, one on the other side. Before the gears were worn in, this was probably optimal. But from most of you guys I hear they come badly shimmed. I got my car from a influencer who got it from Corally to review, so I wonder if it got cherry-picked
. Wouldn't be so great from Corally
.
My wooden wing washer is still holding up surprisingly. I am debating sanding it to make it look nicer, but this look also has something to it. The first iteration of the wing holder broke a couple months back as I posted. After that I iterated the design and then purposefully printed it weak (mostly hollow), so I could see what was the weak point. I addressed that in the design and reprinted in TPU:
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I also added compatibility with the stock screw length. It hasn't broken yet, but the wing did rip out once. However I am using M3 screws, because previously that is what I had on hand. Soon I will change it to M4 screws and add a slot for a washer. I'm pretty sure that will solve the ripping out issue. Currently the first iteration is on my maker world, but when I add the washer slot to the M4 I will post the current (and probably final) design.
I know lots of people also break the big part attached to the shock tower instead of the little holders. To me that never happened. Probably because the TPU holders flex and absorb impact. I have had a couple really bad tail-landings. So my design might fix some of your problems, but there are also some improved designs for the big wing mount online which are probably worth a try as well.
New additions
Now for a new creation, as I mentioned in an earlier post, my body broke at the rear body posts. This is probably due to the roof being pressed in on roof landings and causing lots of stress on the body. That stress combined with the pretty sharp corners in the rear of the Punisher body lead to cracks pretty quickly. To avoid this, I would recommend getting the foam for the center brace, called: "Center roll cage foam"(C-00180-834). If you do lots of jumping or traction roll frequently, I think it would be a good investment for saving your body.
However, I didn't get that in time so my body is pretty messed up. But I don't want to throw it away yet, so I created a support that fits around the body posts and stops the body from pressing in:
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Even if your body isn't cracked yet, I think it might be worth printing one just to make it's live even easier. Currently my version only has one arm attaching to the chassis braces, but that was for prototyping purposes. When this one breaks, and I expect that is soon, I will print a 2-armed version. I am also planning 3D-printing that center brace foam piece in TPU, the same flexible material I used for the wing mounts. For this part I would use print settings that make it less stiff though.
I also created a custom fan mount, that should improve air circulation inside the body:
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It was mostly an experiment to see how much a change in airflow could improve cooling. So I tried to keep the air flowing in the same direction as it naturally moves through the car. And at the same time direct as much air along as much surface of the motor.
To my surprise there were really noticeable cooling improvements! I tested it out at a new bash spot I just found:
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That day it was about 25C I think and normally I would've expected the motor to get really hot, too hot for my liking. I usually bash at the local pump track or the small field in front of my house, which is way less intense then these grass hills. However, that same bash my fan also died. I think this new fan mount contributed to that. The fan is catching way more debris in this position then when it sits flush to the motor. But this could've be prevented in the first place with adequate protection like a full chassis shroud or a little offset and tighter mesh cover. I have lots of improvements in mind for a redesign, which hopefully will utilize this improved airflow, without the drawback of being harsh on the fans.
The last thing I tried are some 3D-printed shock protectors:
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They work well, as in they keep debris and dirt out of the shock. But durability wise they aren't up to the task. At least not yet. I have gone through about 5-10 revisions already. First improving the fit and then strengthening the design. I started with plain "sleeves". Then I added the quarter twist. These versions were printed upright, but they broke to quickly. I revised the print orientation which made them a great deal stronger. If your interested here is a short explanation of why that is:
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Anyway, the last two versions were printed on the side, like this:
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They lasted me awhile, until I drove into a bush:
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Currently they could be used on-road, but as soon as something like a branch hits the protector it snaps. I used PETG for these, ideally I would use TPU or Nylon. However my printer isn't capable of nylon and the TPU I currently have is not stiff enough. If I would use my current TPU I would need to make them way to big to make them stiff enough. I do want this to work though, as they were really nice when they lasted. I am going to revise the design yet again, and maybe I will have to pull the trigger on some stiff TPU. That stuff is pretty expensive though, basically the stiffer you go, the harder it gets to manufacture.
Okay, last thing. When it gets winter here I will probably start to work on removing slop, as my steering got really sloppy over summer. What are some things you guys did to improve it? I will be servicing my hubs, and tightening and possibly shimming my pillow balls. I also really like the work
@Nelson.81 is doing with the HPI servo saver springs. If that works out I might try it as well. Otherwise I might have to find some Dutch locals who are also in need, so we can get the Lee Spring minimum order count. What are some other areas worth checking for slop?
. I might look for a pack of fans as you said. I also have a 3dprinter fan laying around but that is 24v so won't spin fast on the 7.4v but might work temporarily. I am going to up the voltage on my 
. Definitely gonna do it now.
