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Juhunio

The lock-down hop-up Dark Impact

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Having cut my 40-something year old teeth on Bigwig and Boomerang re-res last year, I decided it was time to try something a bit more complicated and 'modern'. I went for a DF03 Dark Impact, and bought the kit last August and spent the following months reading up on previous builds, known weak spots and tracking down the necessary (and some totally unnecessary!!) Hop Ups.

Having finally sorted out a hardened steel main gear for the slipper shaft, and suddenly having a lot of extra spare time, I decided to get going. The full list of hop-ups I managed to track down is:

  • Square RC SDI-27R Hardened Steel Rear Differential Joint
  • Tamiya 53925 Slipper Clutch with RW Racing Hardened Steel Main Gear Pinion
  • 3mm Ceramic Silicon Nitride Differential Bearing Balls
  • Tamiya 53922 05 Module Pinion Gears (23T / 25T)
  • Tamiya 53923 05 Module Pinion Gears (27T / 29T)
  • 4x 850zz Ball Raced Bearings 
  • Tamiya 53931 Centre One Way Set
  • Tamiya 53953 Front One Way Set
  • Tamiya 53924 Heat Sink Bar Set
  • Tamiya 53948 Aluminium One-Piece Propeller Cup Joint (x2)
  • 3 Racing DF03-05/LB Aluminium Propeller Shaft
  • Square TC SDI-3 Graphite Front Damper Tower
  • 3 Racing DF03-06/WO Rear Damper Tower
  • Xtra Speed XS-OM27001 Front Damper Set
  • Xtra Speed XS-OM227002 Rear Damper Set
  • 3 Racing DF03-22/LB Rear Suspension Stiffener
  • Square RC SDI-17 Steering Crank 
  • Tamiya 53941 Aluminium Steering Turnbuckle
  • Tamiya 53940 Hard Turnbuckle Set
  • Tamiya 51000 Hi-torque servo saver
  • Tamiya 54121 Aluminium horn for hi- torque servo saver
  • Tamiya 53791 Universal Shafts (x2)
  • Yeah Racing DF03-006BU Aluminium Front Knuckle Arm
  • Square RC SDI-36 Aluminium Front C-Hub
  • Square Racing SDI-42 Rear Hub
  • T-Bone Racing 56004 DF03 Front Bumper
  • T-Bone Racing 56002 DF03 Rear Bumper
  • Tamiya 53949 Aluminium Battery Stopper Pin
  • Yeah Racing DF03-021BU Aluminium Battery Holder
  • Tamiya 53984 Buggy Rear Wing
  • Tamiya 53569 Aluminium Clamp Wheel Hub
  • Tamiya 53161 Anodized 4mm Lock Nuts (Gold)
  • Core RC CR062 Small Body Clips (Gold)
  • Hobbywing Quicrun 10BL120 ESC
  • Hobbywing Quicrun 3650 Sensored Motor 8.5T

Lots of new things to learn with this build...changing gears on shafts (already done!), soldering, building and breaking in ball diffs. Going to take my time and try and avoid too many hiccups. 

IMG_4744.jpeg

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Day 1, and straight into the rear ball diff! I used the Square RC hardened diff joints and the Ceramic Silicon Nitride Differential Bearing Balls with a healthy daubing of the kit Ball Diff Grease. The trickiest part was getting the diff screw (MA7) to bite into the lock nut, but got there in the end. I tightened it up as much as I could, so there is virtually no slip at all. That seems to be what the instructions say?

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I then broke it in (as advised on someone else's build thread) using my battery drill, gently securing one of the diff joints in the drill chuck and then running it at low-medium speed. One minute holding the opposite cup, one holding the differential gear. It seemed to run really smoothly. Then took the sponges out and retightened the diff screw. Done! And hopefully, done right!

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Then tucked it into the gearbox and added the diff cover. That cover is a lovely little bit of design I think, looking at the manual it looks like it enables you to access the diff without taking the whole back end apart? I love those little "ahhh, nice!" moments in a build

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Day two and onto the rest of the gearbox, putting in place the slipper shaft with the hardened steel pinion gear. Thanks due to Neil at RW Racing for getting a batch of those gears made after a few months of pestering! And thanks to @Wooders28 for the advice and info on how to swap the old soft aluminium gear out for the hardened steel option

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This step also calls for the first of the one piece Prop Cup Joints. I managed to put the wrong Bevel Gear on this before finally working out why it wouldn't fit inside the gearbox!

IMG_4751.thumb.jpeg.5b76d82f56a28983948f3c0141808462.jpeg

And then on to building up and inserting the slipper shaft. Again, I initially put the wrong sized bearing on the shaft end, and again took me a while to work out why it wouldn't fit into the gearbox

Ultimately, I hadn't set my workstation up properly, there was too much other stuff in the way so I couldn't get the instructions onto my work mat to use the visual aids that Tamiya provide to help you identify the right parts. I had just tried to crack on without getting everything in order, and made two mistakes as a result. It's a lesson, to always get yourself properly prep'd before ploughing on! All sorted now though...

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And then on with the gearbox plate and slipper clutch, and that lovely moment when you turn the main gear shaft and the outdrives and prop cup all spin freely and smoothly!

IMG_4755.thumb.jpeg.81f2747c67f12566c84c50762cc32f2d.jpeg

I tightened the slipper to the 'normal position' shown in the instructions but it's ready to get properly broken in when the build is finished. I'll be using this video as my guide, unless anyone has any better examples? 

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Day 3 and today's school subject was soldering! Pretty sure I've only tried this once before when I was maybe 8 years old building a Tandy's crystal radio kit, with pretty disastrous results. So I watched a few videos and gave it a go, using Etronix 12AWG wires, bullet connectors and heat shrink wrap

This is my first attempt. I was happy enough that I hadn't set fire to the garage, or melted the motor, but while the bullet connectors went on easily enough (and tidied up with a bit of trimming) there was clearly too much solder at the motor connections. It looked messy, and the solder blocks would make contact with each other when the wires moved.

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So, time to take a breath and use the iron to melt the solder down and strip away the excess, take a bit more time and get a cleaner result

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For a first go, I'm pretty happy with that! The heat shrink wrap worked a charm too, and the motor attached comfortably to the gear box. This was another pleasing moment in the build, the way the motor attaches on the DF03 is so much easier and less fiddly than the Bigwig / Boomerang method, and the pinion slid on easily. Then added the heat sink bars (would have loved to find the silver ones rather than the blue, but they're impossible these days) before finishing it off with the gearbox cover and body mount.

IMG_4788.jpeg.9655bea4da4b2749fb77183f4d43bcb6.jpeg

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2 hours ago, Juhunio said:

Day two and onto the rest of the gearbox, putting in place the slipper shaft with the hardened steel pinion gear. Thanks due to Neil at RW Racing for getting a batch of those gears made after a few months of pestering! And thanks to @Wooders28 for the advice and info on how to swap the old soft aluminium gear out for the hardened steel option

IMG_4750.thumb.jpeg.c8757491d56b7ef76ed8a50eda066dc4.jpeg

This step also calls for the first of the one piece Prop Cup Joints. I managed to put the wrong Bevel Gear on this before finally working out why it wouldn't fit inside the gearbox!

IMG_4751.thumb.jpeg.5b76d82f56a28983948f3c0141808462.jpeg

And then on to building up and inserting the slipper shaft. Again, I initially put the wrong sized bearing on the shaft end, and again took me a while to work out why it wouldn't fit into the gearbox

Ultimately, I hadn't set my workstation up properly, there was too much other stuff in the way so I couldn't get the instructions onto my work mat to use the visual aids that Tamiya provide to help you identify the right parts. I had just tried to crack on without getting everything in order, and made two mistakes as a result. It's a lesson, to always get yourself properly prep'd before ploughing on! All sorted now though...

IMG_4752.thumb.jpeg.98c3223fc7b789e2ac3a9ff82f43f948.jpeg

And then on with the gearbox plate and slipper clutch, and that lovely moment when you turn the main gear shaft and the outdrives and prop cup all spin freely and smoothly!

IMG_4755.thumb.jpeg.81f2747c67f12566c84c50762cc32f2d.jpeg

I tightened the slipper to the 'normal position' shown in the instructions but it's ready to get properly broken in when the build is finished. I'll be using this video as my guide, unless anyone has any better examples? 

Nice to see a DF03 build going on. I went nuts on body shells for this chassis. There's a pretty good selection out there.

Do you happen to have any spare steel pinions or a link to the ones you got? Also, how straight forward was it changing it?

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I love seeing hopped up kits. The effort of planning which parts to install, how beautiful they'd turn out and perform. Hope to see more and the final result. I'm actually considering the DF-03 as my next project (if not the Super Astute or Egress).

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28 minutes ago, Nicadraus said:

I love seeing hopped up kits. The effort of planning which parts to install, how beautiful they'd turn out and perform. Hope to see more and the final result. I'm actually considering the DF-03 as my next project (if not the Super Astute or Egress).

Always (still do) want an egress. The only problem is that I wouldn't want to get it scratched or dirty. The nice thing with the df03 is that you have the option to make it look just pretty and bling or a good looking functional kit

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If some of the parts were from ebay in the last three months im now fairly sure it was you who outbid me :ph34r:

Youre putting them to much better use than me though - looking forward to folowing this!

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13 hours ago, Superluminal said:

If some of the parts were from ebay in the last three months im now fairly sure it was you who outbid me :ph34r:

Youre putting them to much better use than me though - looking forward to folowing this!

Hmmm...I think the last parts I bought off eBay for this were before Christmas; the T-Bone front and rear bumpers and YR Battery Tray. Are they the ones??

TBH, I would have preferred the silver battery tray (and the silver heat sink bars) but pretty much all DF03 3rd party hop ups are virtually impossible to find now (as you probably know!), so I'll live with the blue. I ended up selling quite a few bits of blue bling (gearbox plate, lower arms, wing mount, body mounts, gear covers etc) as I decided to reign it back to things that actually add strength or rigidity or longevity rather than just looking nice 

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13 hours ago, Nicadraus said:

I love seeing hopped up kits. The effort of planning which parts to install, how beautiful they'd turn out and perform. Hope to see more and the final result. I'm actually considering the DF-03 as my next project (if not the Super Astute or Egress).

Oh, the reading up on other people's builds and experience of using the cars and finding / fixing their faults, then foraging and hunting for the parts, is a HUGE part of this hobby that I love! 

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13 hours ago, mman2005 said:

Nice to see a DF03 build going on. I went nuts on body shells for this chassis. There's a pretty good selection out there.

Do you happen to have any spare steel pinions or a link to the ones you got? Also, how straight forward was it changing it?

Interesting on the body shells. Didn't realise there are options for the buggy? Any links or suggestions?

I got the pinions from RW Racing. They're not a standard stock item so I had to email Neil with the spec and then wait for him to make and harden a batch. The spec is:

  • 0.6m
  • 18T
  • 5mm bore
  • 12mm teeth width

I got them about 4 weeks ago, so he may still have some if you drop him a line? If that fails I do have a spare one that I would be happy to sell to you if you want it

Once you have the part, changing the pinion on the slipper / main gear shaft is actually really straightforward if you have a bench vice. I followed @Wooders28 tutorial and added my own images and commentary there too. 

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25 minutes ago, Juhunio said:

Interesting on the body shells. Didn't realise there are options for the buggy? Any links or suggestions?

I got the pinions from RW Racing. They're not a standard stock item so I had to email Neil with the spec and then wait for him to make and harden a batch. The spec is:

  • 0.6m
  • 18T
  • 5mm bore
  • 12mm teeth width

I got them about 4 weeks ago, so he may still have some if you drop him a line? If that fails I do have a spare one that I would be happy to sell to you if you want it

Once you have the part, changing the pinion on the slipper / main gear shaft is actually really straightforward if you have a bench vice. I followed @Wooders28 tutorial and added my own images and commentary there too. 

Thank you! Will drop Neil a line and see if he has some left. Fingers crossed. 

Bodies that fit straight onto the DF03 chassis are 

Tamita Keen Hawk - Not likely to find

Avante Mk2 - https://www.ebay.co.uk/itm/293503391697

Team Azarashi - https://www.dms-racing.com/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=1796&virtuemart_category_id=69 (can fit without the front splitter/spoiler)

Dark Impact

The tamiya buggy wing as well looks good imo.

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28 minutes ago, mman2005 said:

Avante Mk2 - https://www.ebay.co.uk/itm/293503391697

The tamiya buggy wing as well looks good imo.

The Avante is a lovely looking thing. As are those gold dampers B). I like the fact it has a driver too

Yes, I've got a buggy wing for it, looking forward to seeing how it looks!

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2 hours ago, Problemchild said:

How are you soldering your motor wires?

JJ

Badly, as it turns out. I was happy with the female connectors on the ESC leads, but the motor lead connections to the motor weren't great.

I got some constructive advice about how to improve it, so took it all apart and started again. In doing so, I discovered that the solder-point connectors on the Quicrun motor were removable, with a male bullet connector underneath them  :rolleyes: So I don't need that extra bit of motor wire with a male connector at all, it's already got a built-in method of enabling easy motor changes. If there was a 'face palm' emoji, I would be using it! 

So I just slid the female connectors I'd attached to the ESC leads straight onto the motor. Job done.

Every day's a schoolday!

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Before the re-soldering...

Today I got to work on the rear shock tower and suspension. This meant cracking out the 3 Racing Graphite rear damper tower...

IMG_4789.jpeg.29850b2422506224c282ba976363052e.jpeg

...the Tamiya Universal Shafts...

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...the Square RC rear hubs and the Tamiya Aluminium Turnbuckles. Another little lesson learned here, based on me not understanding the concept of a turnbuckle. When screwing the adjusters onto each end, I could get one end to go on no problem, but I just couldn't get the adjuster on the 'other' end to bite, no matter what I tried. I was starting to get pretty frustrated, when my wife came in and asked how I was getting on. I showed her what was stumping me, and she had a go. Within 20 seconds she said "you have to screw it the wrong way". Sure enough, the adjuster on each end screws on in opposite directions. Which makes perfect sense, when you realise that the purpose is to be able to lengthen or shorten the shaft from a central bolt when fixed in place, rather than removing it and changing the adjusters. Thank God for female logic!

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Turnbuckles attached and rear bumper in place, all attached to the chassis...

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And then finally on with the 3 Racing rear suspension stiffener, to complete the back end

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It's been ages since I built a DF03. Loving the hop-ups - I wish I still had mine instead of my 2nd-hand DF02 which spends its' days in bits with the occasional run!

Looks like you used quite a lot of grease on the gears, sometimes this can be more of a hindrance than an advantage. Gears only need a really light coating of grease, everything else will act like a sludge, some of it will end up splattered inside the gearbox whilst the rest will add friction to the gears wanting to turn...

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1 hour ago, ChrisRx718 said:

It's been ages since I built a DF03. Loving the hop-ups - I wish I still had mine instead of my 2nd-hand DF02 which spends its' days in bits with the occasional run!

Looks like you used quite a lot of grease on the gears, sometimes this can be more of a hindrance than an advantage. Gears only need a really light coating of grease, everything else will act like a sludge, some of it will end up splattered inside the gearbox whilst the rest will add friction to the gears wanting to turn...

Thanks, I did wipe some of the excess off before I put the gearbox top on so hopefully it'll be ok!

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That’s a serious amount of hop ups! I bought a used one a few months back and have just rebuilt most of it. Waiting for the last parts to arrive and a new body shell and decals. 

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Awesome! Love this chassis, I have the the Avante and an RA version, both loaded with plenty of goodies. It's like a modernized TA chassis. 

You've got quite a collection of hop up there, watching with interest. 

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20 hours ago, Juhunio said:

Oh, the reading up on other people's builds and experience of using the cars and finding / fixing their faults, then foraging and hunting for the parts, is a HUGE part of this hobby that I love! 

You bet. The research and the challenge of trial and error. It's more costly but that's one of the fun part of this hobby. I have purchased parts that I thought they were ok but had to alter/modify them or sometimes replace them with something better and the later goes to storage. So much for the money spent on those. But sometimes they also come in handy for other kits with a little modification to fit them.

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Bit of work on the front end today, and a final Hop Up find on eBay that's going to necessitate a pause in the build....

The front diff again built with 3mm Ceramic Silicon Nitride Differential Bearing Balls and plenty of the kit supplied diff grease, then again broken in for a couple of minutes with the drill.

IMG_4805.jpeg.35897ad9f5618910a1beb64e3b522383.jpeg

Again, it took AGES and serious pressure on the diff spring to get the lock nut down far enough for the diff screw to bite and thread. Has anyone found an easier method for this step?

Then into the front gearbox with the second one piece propellor cup joint and bevel gear. I greased the gears well, span them with my fingers a few times then wiped off the excess grease

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And on with the top of the gearbox

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The next hop up out of the box was the Square RC steering crank. I replaced the kit-supplied bushings with some metal shield bearings, so the car is ball raced back to front

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Adding the swing shaft protectors to the 3 Racing prop shaft

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Then in with the prop shaft and on with the front gearbox

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The front end feels sturdy and looks great, the steering crank runs really smoothly and feels more direct and robust than what I've been used to in previous Bigwig / Boomerang builds

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