GoldenApe

DF03 rear shock tower - ideas

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Hi - I'm a newbie here so apologies if I'm getting this wrong. I have a Dark Impact (DF-03) for general fun and running around in the park. As I'm discovering to my cost it seems rather fragile - 20 years ago I had a Hot Shot that rarely broke, the DI seems to spend most of it's time waiting for me to fix something. The main culprit is the rear shock tower. I cracked the plastic one that came with the kit and so tried an aluminium one that bent after a flip - while straightening it I cracked that too. I can see that some people have tried carbon/graphite towers which I guess might be a bit tougher. But here's the problem I can find anyone that still sells them - the 3racing ones are out of stock all over and look like they will never be back. 

 

Does anyone know where I can get one from (perhaps a tower that's comparable from a different body) or should I just give and go back to the plastic. I'm only running a brushed sports tuned with NiMH by the way, so it's not like I'm going crazy...

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No idea about buying one, but if you are in any way capable with 2D CAD drawing you can measure and draw out a carbon tower and email the dxf file to Fibre Lyte and they will make you a carbon tower. If you get one 4mm thick its going to be pretty strong. 

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Ah interesting idea I hadn't thought of that - thanks. Looking at the examples of carbon towers for the df03 online, they all seem to be split into an upper and lower part which connect to an aluminium boss, which then connects to the chassis. Any idea why? My CAD skills might run to a single carbon tower but the aluminium boss would be pushing it!

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Where abouts is the plastic original one breaking? Could this area be reinforced or braced in some way?

I spent ages looking for carbon ones but gave up. I even found some on ebay quite recently but they were missing the aluminium mounting blocks which meant they were pretty useless sadly.

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Both the plastic and aluminium break/bend at the weak point where the 'arm' of the tower meets the body. It might be possible to run turnbuckles from the top arms of the tower to the bottom arms. Would look a bit ugly but worth a shot.

I also saw what looked like a DF03 carbon tower on eBay without the aluminium mounting boss. I even contacted the guy to see if he knew where to the get the boss from but he didn't. Based on the conversation above I'm wondering if I could get an aluminium boss CNCed up and use that.

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Just had a look at the manual online, and unless i am missing something a 1 piece carbon plate that is the sane shape as the plastic one will just mount up with the four screws into the gearbox. No idea why aluminium bosses and 2 piece designs come into it. 

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Mines in the loft in parts bags at the moment but im sure the top and bottom arms dont sit in the same plane where they bolt up to the gearbox which is acheivable on a moulded plastic part but recall the aluminium mounting block was to provide this offset. Or i might be talking #!@×¥% as its quite a long time since I looked at it assembled.

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Superluminal: I think you're right, the towers aren't quite in the same plane. Thinking about it, the reason the aluminium arms bend is because the point where the top arms 'kink' forward the metal also tappers down - so it's a real weak spot. 

I think what I'll do is this: Order up another set of plastic arms for the time being but in the interim I'll try to model up a 3D boss and arms. A few iterations on the 3D printer should get them sorted. Will then be able to get an metal boss and carbon arms made up (or go for broke and get the whole thing in titanium!)

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If you have the skills (a very particular set of skills) and can 3d model the part for 3d printing i think this is the best idea as you can then strengthen it in the weak spots or make the hole thing a big solid plastic plate at the back with the mounting holes for the dampers rather than the spindly arms. I would avoid titanium or aluminium again - if they are too robust and you crash too hard again the shock mount will survive but likely break the gearbox cover or chassis.

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In case you're interested this is the broken aluminium tower. It's not a great design, the arm snaps at the point where it joins the body - also clear that the lower arms and upper arms are offset by nearly 10mm. Time to put those Liam Neeson style skills to good use ...

IMG_4746.jpg.92099b4227b18248431ecf6950b2367a.jpg

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12 hours ago, GoldenApe said:

The main culprit is the rear shock tower. I cracked the plastic one that came with the kit and so tried an aluminium one that bent after a flip - while straightening it I cracked that too.

That's one of the only parts I don't think I've broken on mine, even manage to shear driveshafts! 😳 Guess I've just been lucky.

 

12 hours ago, GoldenApe said:

 I can see that some people have tried carbon/graphite towers which I guess might be a bit tougher. But here's the problem I can find anyone that still sells them

A couple of people are making them, a guy on Facebook has a great reputation, and done a set for my Mid, (not next day delivery, as he does them in his spare time).

A closed DF03 group (so you'll need to send a join request, and see if you get accepted) on Facebook:- 

https://m.facebook.com/groups/307822689796939?group_view_referrer=profile_browser

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7 minutes ago, GoldenApe said:

In case you're interested this is the broken aluminium tower. It's not a great design, the arm snaps at the point where it joins the body - also clear that the lower arms and upper arms are offset by nearly 10mm. Time to put those Liam Neeson style skills to good use ...

IMG_4746.jpg.92099b4227b18248431ecf6950b2367a.jpg

I think the carbon ones a 2 piece, maybe if you cut the other side off, fit a carbon lower section , and put longer screws through?

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Ah yes, good idea. I might be able to use the remains of the aluminium tower as a boss to attach the top half of the carbon one. I'll give all these things a go and report back!

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I see the offset now. Its quite a lot though. If you did a flat plate in carbon would the shocks be able to mount on the shocks on the rear of the plate instead of the front? Another idea to avoid aluminium would be overlapping carbon plates. One lower one foe the camber links the extends upwards plast the gearbox with 4 more holes in it, then mount an upper shock tower to that to get some of the offset back. You could even draw up a carbon plate to sandwich between to the two in order to get the correct offset of the tower. A 2 or 3mm thick spacer plate will only be a dew quid. Maybe use the wing mount screws as one of the sets of fixings to avoid too many screws in there. 

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I use the Yeah aluminum rear tower and the 3Racing one ( carbon fibre with an aluminum bridge ) With both towers I use a turnbuckle mountet between the tower and the 3Racing gearbox support.

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OK wow that looks really different to what I have. Do you think the turnbuckle is helping there? For me the weak point is where the upper arms of the tower join the body - I was thinking of trying to have a turnbuckle on either side running vertically from the bottom to the top arms.

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The turnbuckle is there to prevent the gearbox to break. When the tower is strong enough the plastic were the tower is mounted to the gearbox is the next weak place.

I use the same turnbuckle on a car with 3Racing carbon and alloy tower for the same reason.

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