Dark Impact build

[DI driver]

Thanks WC. Tapping would have been a good idea - I'll add that to my tools list. What sort of screws do you use to replace the cheese-soft Tamiya self tappers - is there a particular brand?

[WillyChang]

27 minutes ago, DI driver said:

Thanks WC. Tapping would have been a good idea - I'll add that to my tools list. What sort of screws do you use to replace the cheese-soft Tamiya self tappers - is there a particular brand?

My DF03 was built from start with blue Tamiya alloy screws but yeah they're overkill - the aluminium is soft & can strip if your hex driver is blunt.

Generally I just keep stock of M3 stainless steel button heads & countersunk flat heads in most of the common sizes eg 10mm, 8mm, 12mm, 16mm etc

the generic stuff found on fleaBay work fine  I can buy a pack of 100 for what I'd pay locally for 10pcs so yeah, stock up in advance (as mail takes like 2mths)

ditto generic bearings in 1150, 850, 1050, 1510...  

 

[DI driver]

Awesome - just ordered a job lot of stainless hex head M3 in 8 10 12 16mm. Thanks again!!

[ALEXKYRIAK]

30 minutes ago, WillyChang said:

My DF03 was built from start with blue Tamiya alloy screws but yeah they're overkill - the aluminium is soft & can strip if your hex driver is blunt.

Generally I just keep stock of M3 stainless steel button heads & countersunk flat heads in most of the common sizes eg 10mm, 8mm, 12mm, 16mm etc

the generic stuff found on fleaBay work fine  I can buy a pack of 100 for what I'd pay locally for 10pcs so yeah, stock up in advance (as mail takes like 2mths)

ditto generic bearings in 1150, 850, 1050, 1510...  

 

I’ve always wondered about the differences between these screws in terms of quality. Ie, the cheap 100-in-a-pack vs the local more expensive ones. The local ones seem to be made a bit better.  I have both types. 

Also, I think there are two schools of thought on using machine screws in the actual plastic itself, vs tappers. Some say the bigger spacing on the tapping screws bite a lot better and is easier to replace over time, as the groove cut into the plastic is bigger and more defined, guiding the replacement screw in without damaging the plastic. However I do use machine screws quite a lot. 

 

[DI driver]

It's going to be "Sand Viper" yellow - that was my second choice car and is still like one. I've not painted a car for 30 years ago might be interesting. Also decided to buy an £8 15t HPI motor - rude not to try at that price.

[DI driver]

Freshly reamed Associated B4 48dp slipper spur with 20t RW steel 48dp pinion. Fits perfectly and now I have a bunch of pinion choices. Could cut tamiya pads to fit but have B4 pads arriving tomorrow. 

[DI driver]

Can't get the 84t spur under the cover but the 81t does and will take an 18t pinion. Reaming needs to be gentle as very little material needs to be removed. 

[DI driver]

I have 81t, 78t and 75t spurs and 16t to 30t pinions. Bit more fiddling....

Longest gearing :75/28 FD 7.96 

Shortest gearing: 81/18 FD 13.37

Might get 75/29 and 81/17 but I haven't got 17 or 29 pinions.

There are smaller B4 spurs but they won't take a slipper pad. This range is achievable with Tamiya spurs but I couldn't find the smaller 0.5 module pinions. I want the option to run my 11x2 (which is off to ignify to be serviced) and I reckon I'll need some low gearing to avoid over heating.

This is a simple mod to allow the use of 48dp pinions provided you're using a slipper - B4 spurs won't key into the stock shaft. The plastic reams easily and evenly. Really pleased!!

Edit to add: without cover could have 85/16 FD 15.78.

Edited January 4, 2019 by DI driver
Use of 85t spur

[DI driver]

Added rear turnbuckles - used dry PTFE and graphite powder rather grease on ball joints and in an drive cups. Had spare foam so added a half piece to the outboard drive cups - positive pressure on dogbone at full droop. Used inner shock mounting point on tower and outer on bottom arm to (slightly) limit droop based on what I've read about dogbones popping out. The dampers sound very slightly bubbly so may have some air in there. Already thinking about hop up but also have some 1000cst oil to try in these - I read somewhere they are under damped with stock 900 oil. I used 1 hole pistons front and rear.

[WillyChang]

Keep the damp in light, you don't need much & they're long throw.

Think my shocks are filled with 25-30wt. 

[DI driver]

Photos of ride height. It is quite low - bottom arms horizontal at full droop. Damping seems reasonable with a drop test - doesn't bounce. Rear is relatively slow to rebound. Front end bottoms out and front end is sitting lower than rear. I've kept it low to try and limit loss of dog bones at full droop. Any comments? Bring front up to match rear height?

 

[GTodd]

Boy does that look good!!!!

What an important car for tamiya! I need one and a Durga!

[DI driver]

Is it just me or is there a bit of slop in the front axles? Both bearings in and wheel bolt tight.

[DI driver]

I ordered  more urethane bushes from Tony and added an extra half to each front outdrive and a half to each front drive cup. You'd think that would make it really tight at full compression but it's comfortable - very loose at full droop without and I may need to limit droop if they pop out.

Front damping with stock 900 cst oil and single hole piston seemed non existent so I refilled with 2000 cst and now it feels controlled when I drop it. Might be a bag of spanners to drive of course.

Cutting lexan is tricky. Looks a bit rough in places so I'm going to try sanding it. Also need to get some suitable masking tape as I've seen one today with clear windows and I think it looks great.

[DI driver]

Radio arrived today so electronics "in". Ran diffs in by locking one outdrive and running low throttle for 5 minutes each direction then tightening until rotating one wheel will turn the motor over (tight). Spinning a rear wheel I get half a turn of diff action and spinning a front I get 3/4. Sound ok?

Adjusted slipper (B4 81t spur and 21t pinion) by tightening until the  rear diff just started to bark (horrible sound) when the rear wheels were held still. Backed off a bit and then set up the slip by pushing it backwards on carpet and then full forward throttle. Happy with it so far. Diffs still feel smooth thank God. I wouldn't recommend my first method - tightening until required slip on a high grip surface probably more sensible. 

Might be under geared with this 21 turn brushed but wanted to start slower rather than quicker.

[DI driver]

Thought I'd ruined it this morning. I did some more diff break in at low throttle with one wheel locked and it made some strange noises. Also got the motor and esc very hot. Worryingly the rear diff was very stiff before the strange noise and now is merely firm - still less than 1 full rotation of I spin it by hand. I think I've probably over tightened the diffs - I've rounded the front diff screw hex head and the rear was bonkers stiff. Had a pang of buyers regret this morning - thought maybe I should have bought a simpler kit. At least if I've damaged the rear diff I can rebuild with the benefit of hindsight.

I'm really enjoying the clutch and I can see why they're recommended on ball diff cars - it's set to just under a metre slip on carpet but is nice and doughnuty on wet driveway.

Edited January 15, 2019 by DI driver
Used a mild but unnecessary naughty word

[Scipunk]

Following along!

There is one local to me for sale for $90 bucks, missing the battery door cover. Do you think they are asking to much? Not sure if it has the box or anything but i love the look of it. 

 

[DI driver]

Sounds like a good deal to me. I don't think I could throw the box away - it looks too pretty!!!

[DI driver]

Mostly done. Damaged a few of the decals when trying to fit them so a bit minimalist. My attempt at a 4WD Sand Viper. Took 2 cans of yellow to get coverage and I wish I hadn't taken the film off the wing before painting (manual said to remove it?). Driven it a bit today and noticed the rear wheels aren't exactly round so may look out for replacements. The slipper needed tightening after a while and currently running a cheap 17 turn motor with 81/20 spur/pinion. Didn't get hot but time will tell. Tends to understeer so I've increased negative camber to 4 degrees up front and reduced rear to 1 degree. Looking forward to giving a proper shakedown soon.

[Juls1]

If you want more ride height, the Tamiya alloy df03 damper set will increase it quite a bit. The front and rear are nearly cm longer. 

[Wooders28]

9 hours ago, DI driver said:

Tends to understeer

Softening up the front shocks and /or stiffen the rear will help get rid of understeer , there comes a point where more camber will be less grip.

Looking good👍

[Danno77]

I can’t believe how good the yellow is! Really works in my opinion with the di , I’m waiting on a call from lhs to say when mine is in very excited , been thinking of red with hot shot decals?? What you guys think

[DI driver]

1 hour ago, Wooders28 said:

Softening up the front shocks and /or stiffen the rear will help get rid of understeer , there comes a point where more camber will be less grip.

Looking good👍

Thanks. Yes, I may have over damped the front (and my driving is poor!!). 

[DI driver]

24 minutes ago, Danno77 said:

I can’t believe how good the yellow is! Really works in my opinion with the di , I’m waiting on a call from lhs to say when mine is in very excited , been thinking of red with hot shot decals?? What you guys think

I think red would be cool. I'm not keen on the Dark Impact box art decals (though if I'd not torn a few I would have fitted them). 

[Scipunk]

Really like the yellow, though does that make it a light impact now? Sorry terrible humor...lol.