The Dark Impact

[DCM71]

Bender, apreciate where you are coming from, just think the setup will

be different on the DI due to it's cells and motor down the centre

setup.  Roll rates should be lower.

[bender]

Bender, apreciate where you are coming from, just think the setup will be different on the DI due to it's cells and motor down the centre setup.  Roll rates should be lower.

To a point, I agree with you, but often weight distribution plays a smaller role than you'd believe.

For example... the BJ4x4 runs B4 rear arms. I can bet that most drivers who race both cars run their shocks on the back in the same location on the arm- even though the lateral weight balance between the 2 cars would be nowhere near the same []

On a sort of related topic... this has just as much to do with springs as well as leverage rates... so does anyone know the spring rates of the 3 df-02 springs (red, yellow, blue)?

[blakeyx]

Jason on ebay now has the new 05 pinion 23,25 and 27,29 at about £3.50 a pair

[DCM71]

If they are the same quality as in the KIt, running a mod motor, might as well use butter or chocolate instead...

[James4ihl]

Just started the build and come across a hitch on page one - says I need Tamiya Instant Cement to glue part of the rear diff assembly. I don't have any because all the local suppliers are out, but it looks like its saying it's cyanoacrylate (superglue) - anyone know whether that stuff is just normal superglue, because I have some of that lying around, whereas I don't have any access to Tamiya Instant Cement and I'd like to know if I can use generic instant glue before I melt the plastic or anything nasty!

While we're on the subject, which is the preferred glue for sticking tyres to rims? Anything that allows a bond, but also allows you to get the tyres off in the future if you want to?

Ta

James

[DCM71]

Superglue will do, make sure you degrease both parts though, and only

use a little otherwise you will spend an age scraping off the overspill.

[James4ihl]

Thanks excellent!

James

[mp3ranger]

Battery Pack in my dark impact. I was running a sanyo 3300 battery .The 3300

pack run time was 15min the lipo run time 35min. It got so much more power that

all four tires balloon up on take off . More photos in my showroom

[James4ihl]

How much should one tighten the diffs? The instruction manual says, tight enough not to come apart, but not too tight. It's about 15 years since I've built one of these, so 'feel' is gone. Do I need to at least tighten through the plastic threadlock on the end of the nut, or just until it starts to feel too tight for the diff to turn easily and then back off a little?

James

[James4ihl]

Battery performance sounds good from that one!

Nice looking DI, which shocks are you using?

James

[DCM71]

They look like old Kyosho Option House shocks....

Diffs, before you build them, place the diff spring in a stout pair of

pliers and compress the spring once fully, this takes some of the

settling in of the diff out.  Tighten the diff till it wont come

apart, install in car, it is so easy to remove to adjust.  Once

you got your wheels on, remove the diff cover, hold one wheel and the

diff pulley and turn the other wheel, if it turns easily, you need to

tighten it a little (1/8th of a turn a go) and repeat till the wheel is

tight to turn (use common sense).

Once the car is fully built, before your first thrash, prop the car on

a stand, plug it all up, hold one wheel on an axle and throttle up, not

stab, but gentle to full throttle (take about 3 to for seconds in

total) and repeat for the other axle.  Check diffs are still set

by holding one axle set of wheels between your legs and one wheel in

one hand and try to turn the other, if all feels well on both ends, rip

up the tarmac.

Shocks, whilst building them.... please read.

Front shocks, piston setup is fine, shock length is incorrect if using

CVD's.  Use the longer rod end and move to the third hole out on

the wishbone.

rear Shocks, use either the same as the front, or the next hole up, do

not use what Tamiya tells you, it ends up like a pogo stick.  Rod

Ends, use the shorter one.

[James4ihl]

Thanks DC - excellent instructions, I particularly appreciate the shocks advice before getting to that part!

James

[terry.sc]

Any ordinary superglue can be used to stick the diff washers in place,

one or two small drops will do as the diff washers are keyed to the

diff outdrives.

To adjust the diff you need to test it for slip. Use something that

will fit in the slots of the diff outdrives, like two flat bladed

screwdrivers or a pair of allen keys. Hold the diff outdrives still and

try and turn the diff gear. If the diff gear moves tighten the diff a

bit more, until the diff gear does not slip when you try and turn it

with the diff outdrives held. The diff is now set correctly, you do not

need to tighten it up any further. The diff should not slip, but the

diff will still spin freely.

[mp3ranger]

T he shocks are from a Kyosho buggy

[James4ihl]

Thanks I've just done that. I actually had it a little overtight before, but only a turn or so.

Do those Kyosho shocks work well? Did you have to modify anything to fit them?

James

[mp3ranger]

The shocks work alsome . They bolt right up with no mod.

[Tamiya King]

"]

Good to see some new parts coming up for the DI. I really like the look of this rear damper mount...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=6055195092

 

I love those damper mounts, but really really hate the price! [] That is $65.00 USD before shipping for me. I think I will wait until the parts are mass produced by several companies so the price get more competitive too! []

[pUs]

 

In order for the DI to have a similar geometry to that of most other competition 4wds (such as XX4, BJ4x4, ZX5 Lazer etc) the shocks need to be mounted in the outer arm hole at the back, and the 2nd inner arm hole in the front.

It all has to do with roll axis, leverage rates, etc etc. For my way of thinking, duplicating the geometry of what is known as the best handling 4wd (Losi xx4) is the first step in having a consistant handling and competative car... I suppose it depends upon how serious you want to be.... for me it is easier if my base-line setup is close to that of a known top level 4wd.

Without being unpolite, you're not the only one who's looked at the XX4. It's probably the most balanced 4WD ever made and I raced it myself a couple of seasons. Just a beautifully thought out chassis.

However the weight distribution is nothing the same between these two cars. I can just say that it does cause the car to behave totally different to the XX4 and you're not going to be able to replicate the feel of a properly set up XX4 if you want to drive this car fast, I can assure you that. No matter how you try, the dynamics differ totally. This is a different beast, but I'm confident it could be just as fast.

And I don't want to brag, but I think I consider myself quite "serious" after having raced (raced as in competing, not bashing around) 1:10 buggys for 17 years.

[bender]

Actually the front to rear weight distribution is surprisingly close between the two buggies, it is only the lateral weight distribution that is different.

Regardless of this.. I just don't think the DI is so radical in it's design to require an entirely new approach to setup. I have already used one example with DCM but I'll use another....

The Losi 2 and 4wd's use the same rear suspension.... by your logic, you couldn't run the same oil, spring, shock position etc as the weight distribution is very different between the 2 cars, and yet most Losi drivers DO run virtually identical rear-end setups! Maybe 5w difference in oil or 1 spring rate different - very minor.

Again, it is the same with the BJ4 and the B4 - Same suspension, vastly different weight distribution, and yet the drivers run close to identical setups.

Let me ask you this, you know on the Losi rear arms there is a hole located very inboard on the arm - this is used for the roll bar ballstud. Would you set the car up for any condition with the shocks mounted in this hole?

Of course you wouldn't, and you wouldn't even need to explain it - you'd just know that it's wrong and not going to work.... and that's what I'm talking about with the DI - there are some mounting positions on the arms that are just wrong.

Take a look at any competition 4wd (or 2wd) from the last 10-15 years and look where the shocks are mounted on the arms - there is only about a maximum of 10% difference in the holes. This isn't just coincidence, regardless of what car it is, what the weight balance is etc, some things "just work" []

Of course, the one thing that is probably THE most important when setting up the car is the track surface - and most likely we are all racing on VERY different tracks.

Where do you race and what are the tracks like?

Here we have fairly low grip, often dusty, hard-packed dirt tracks. At big meetings, when there are lots of cars running, the track sometime develop the "blue-groove" like many tracks in the US.

[DCM71]

I think you are both indulging yourself, I myself been in this since

1988 so seen most, tried them etc etc...  All cars are different

yet all cars are very similar to, yes your shock positions are going to

be relatively the same on the rear it is the front that changes most,

which comes down to two things, weight bias up front and geometry.

Personaly I don't give a fig about shock positions on other cars as you

got to think away from that and work on it as a totaly seperate

entity.  We all know (or should do) that the kit setting is for

bashing/playing and not suitable for racing.  So rather than argue

the pro's and cons of this and that, let work on getting a baseline

setup on the car.

[bender]

All cars are different yet all cars are very similar to, yes your shock positions are going to be relatively the same on the rear

We all know (or should do) that the kit setting is for bashing/playing and not suitable for racing.

Err, wasn't that my point [8-)]

As you said, lets work on getting them sorted out[]

My first major meeting with mine is next week, but unfortunately there's a real danger I won't make it as I can't find any tyres [:@]

Not only do none of my local shops have any tyres, but very few shops OS have any either []

[GSM Storm]

Hi all

Raced the DI last night, went very well, had some radio interference in the races, in the end stood at the end of the drivers stand and worked ok in the final, got caught at the far end of the track on a tyre and lost time, worked my way back to 2nd, 1.3sec quicker than my Rising Storm with the same motor and gear ratio.

My GSM shock towers stood up very well and my RC10 shocks were set up very well, did not change the front all night, my 2nd set up set of rear shocks worked much betterthan my first setup. No problems with the DF-02 uni joints, track has a lot of ruts and rough in places and they did not give any problems.

If anyone wants RC10 shocks setups just email me.

PS. Bender

I have a new set of white DI rims with new Hole Shot tyres mounted if you want to buy them for next week end, if you still have my number, ring me.

Regards

Gary

 

 

[James4ihl]

I've tightened the diff as instructed, I'm feeling an uneveness when turning the shafts opposite ways, loose-tight-loose-tight type of thing. Its not severe but is there. Is this normal at this stage, does the diff need to bed-in, or does something need adjusting? Its still relatively easy to get back into because I haven't done the rest of the build...

James

[DCM71]

I would pull the diff back out and rebuild it, you NEED to check your

diff plates have been glued flat on the carriers me thinks.

[James4ihl]

I've taken it apart, the plates look dead flat to the eye. I can't really get them off to reset them as they're superglued on! Could anything else be causing this - did I over tighten and flatten the ball bearings (doesn't feel like it, its a bit too regular for that, which is why I agree wonky plates would be a better bet...)?

Can I get a spare diff yet in the UK, in the worst case scenario that it's faulty?

Cheers

James