DT-02 understeer

[mike_o]

I got bitten by the plane FPV bug last year and my Tamiyas have been collecting dust. Then, by chance, I purchased a HobbyKing / Turnigy 2WD SCT kit a few weeks ago:

As far as I understand it's a Kyosho clone, and the kit seemed of decent quality for the price. I tried it out this weekend and was surprised how neutral the steering is compared to my Tamiya DT-02s.

I am well aware that other forum members here have mentioned the dogged understeer of the DT-02, but until I got a direct comparison, I didn't bother too much about it. Now, however, I wonder what can be done to make the DT-02 more neutral. Any suggestions?

Thanks

[taliesin]

There's not a lot to be done. Softer springs and oil in the front shocks, plus use tires with some spikes or aggressive tread up front. That's about it I'm afraid.

[MAD RACER]

Just raise the rear ride height a little which places more weight up the front.

Lower the front ride height a little which places more weight up the front.

Add a rear sway bar which helps with on power steering. ( thin bar for off road)

Different front tyres as taliesin said.

The DT02 is a very good chassis and can be tuned to be ok with chassis balance & tires.

Oh I have a Turnigy sct as well & yes very good value & is indeed a Kyosho clone.

[mike_o]

taliesin, MAD RACER,

thanks for your inputs. I will try fiddling with springs, tyres and front/rear ride height.

But how about the camber angle? My DT-02s are of the dual plastic wishbone sort, but replacing the upper one with an adjustable one, couldn't be that difficult, and I think that this is stock configuration on some of the expensive DT-02 version...

[DCLXVI]

It is, my Desert Gator came with threaded rods (not real turnbuckles though)

[super gripper]

The DT02 chassis is a great fun car as we all know. It is however light on its front end and the rock hard tyre compounds that Tamiya always put in their basic kits does not help the understeer issue.

As people have suggested all that is needed is a good balance of both tyre compounds and oil weights (if you have oil dampers)

Oil weights.

A basic starting point on any 2wd car whether it is a top of the line racer or just a fun buggy is always 40 weight and 2 hole piston in the front and 30 weight oil and a 2 hole piston in the rear (kit springs)

this will give you a basic balance.

Tires > the sharp ribbed front tyres now in many of the DT02 kits are great on the beach but useless practically anywhere else.

there high grip tyres from Schumacher will give you great bite on grass and astro turf, mud too I suppose.

http://www.modelsport.co.uk/schumacher-cut-stagger-low-profile-yellow-pr-/rc-car-products/369048

make sure you use a foam insert too, having the wrong one even if it is the right tyre is just as bad.

this one for the cut staggard tyre

http://www.modelsport.co.uk/schumacher-front-2wd-slim-foam-tyre-insert-med-1pr-/rc-car-products/32129

so easy peasy really.

• all you need is the right tyre and insert
• the right oil/spring combo
• and you could add a little weight up front too.

I use one of my heavier servo's > that helps.

If you are wearing out your rear tyres or they are no good for what surface you run, just shout and I can point you in the right direction

[30YrsL8r]

My son and daughter (who, up until yesterday, had never driven an RC car) have both commented on the poor turning of his DT-02 (stock kit Violet Racer) on grass and how much better my DT-01 is (has SLICKS on the front).

I wondered if using a LiPo (which I do in both, to be fair) might mean that it's not as forward heavy as the designers planned. It's also MUCH faster (acceleration and top speed) in a straight line than my whiney DT-01, so it has the power to lift the front wheels (but the motor gets much hotter than mine for some reason).

I'll have to try to tune his car based on this thread.

EDIT: Might try swapping the front wheels over.

[super gripper]

The DT02 chassis does have a motor cooling issue. There a few heat sink options available from a lot of manufacturers.

I decided to experiment with a couple of gearboxes.

this first one looks drastic but the integrity of the gearbox is not compromised

or a little less material removed with holes drilled for airflow

[super gripper]

You could always try using a 540 motor with a cooling fan built in. It is a guaranteed 27 turn too so it is safe to use on the Tamiya esc's.

http://shop.huntersystems.co.uk/hs3--the-hunter-fan-motor-tm-461-p.asp

[Percymon]

Putting the front shocks in the most laid down position (inner hole on top of shock tower, outer hole on wishbone) will also help steering turn in, but as pointed out earlier the Tamiya rib tyres are very hard and not much use on anything other than sand or soft dry dirt.

[30YrsL8r]

Whilst on the subject of this DT-02; I had to take the rubber tubes out of the kit shocks because the pogo was such a tight fit that they took a couple of seconds to return to their start position after you pressed them in. Now they bounce around like crazy. How do I get a happy medium?

[super gripper]

Whilst on the subject of this DT-02; I had to take the rubber tubes out of the kit shocks because the pogo was such a tight fit that they took a couple of seconds to return to their start position after you pressed them in. Now they bounce around like crazy. How do I get a happy medium?

pogo sticks, don't yeah just love em

there should have been some grease for them in the kit, playing around with the amount of grease you use should get a happy medium.

saying that you cannot beat investing in some oil dampers, improves the cars handling ten fold.

I don't want to exaggerate but oil dampers make the DT02 a million times better

[Champ85]

Whilst on the subject of this DT-02; I had to take the rubber tubes out of the kit shocks because the pogo was such a tight fit that they took a couple of seconds to return to their start position after you pressed them in. Now they bounce around like crazy. How do I get a happy medium?

Yup, I had the same problem with my Super Fighter GR. I ended up adding more grease to the shock shaft inside the rubber tubes even though I thought I put enough in when I built them. The second application has removed the "stickiness" and high friction that they had before and they are smooth, but with a little bit of resistance, unlike the zero resistance with no rubber tubes.

[taliesin]

Whilst on the subject of this DT-02; I had to take the rubber tubes out of the kit shocks because the pogo was such a tight fit that they took a couple of seconds to return to their start position after you pressed them in. Now they bounce around like crazy. How do I get a happy medium?

Here is the 3-step process to cure the under-performance issue caused by the stock pogo sticks:

1. Remove kit supplied pogo sticks

2. Throw them in nearest trash bin

3. Replace with oil dampers

Problem cured.

[bromvw]

Someone please correct me if I am wrong but aren't the DT -01 and blitzer steering arms essentially the same - ie the ball pins screw in place on top of the arm ? If that is the case one way to improve the bump steer is to flip the arms side to side so the pins are under the arm . I did exactly that on a Blitzer and it made a huge difference .

[TA-Mark]

Someone please correct me if I am wrong but aren't the DT -01 and blitzer steering arms essentially the same - ie the ball pins screw in place on top of the arm ? If that is the case one way to improve the bump steer is to flip the arms side to side so the pins are under the arm . I did exactly that on a Blitzer and it made a huge difference .

The mis-alignment in the DT01 steering is not vertical like it is on the Blitzer, hence cannot be solved by moving the mount point vertically (from above to the steering knuckle to below the steering knuckle). The mis-alignment is horizontal with the steering boss being positioned too far forward in the chassis. To align this correctly you need to cut the existing steering boss from the chassis (the moulded post), fabricate an alloy boss, and mount it further toward the rear in the chassis. This also requires a shorter link between the servo saver and the steering bellcrank. Effectively, this puts the steering arms more parallel to the arms (shown in the following picture in red).

I have done this, and double wishbone front suspension (using a modified Blitzer C-hub and Modified DT01 arm) to my Rabid Rabbit, and it has removed 99% of the bumpsteer. Now you only have to worry about the live axle rear end causing it to 'steer' when it hits a bump.

[bromvw]

The mis-alignment in the DT01 steering is not vertical like it is on the Blitzer, hence cannot be solved by moving the mount point vertically (from above to the steering knuckle to below the steering knuckle). The mis-alignment is horizontal with the steering boss being positioned too far forward in the chassis. To align this correctly you need to cut the existing steering boss from the chassis (the moulded post), fabricate an alloy boss, and mount it further toward the rear in the chassis. This also requires a shorter link between the servo saver and the steering bellcrank. Effectively, this puts the steering arms more parallel to the arms (shown in the following picture in red).

I have done this, and double wishbone front suspension (using a modified Blitzer C-hub and Modified DT01 arm) to my Rabid Rabbit, and it has removed 99% of the bumpsteer. Now you only have to worry about the live axle rear end causing it to 'steer' when it hits a bump.

Cheers Mark - now I see a image I understand . Good fix there Mate .

[GregM]

Aside from all the great suggestions of how to improve the steering, I don't think understeer is a fault of the DT-02 chassis itself, but much more a common design trait of RWD buggys.

Before investing money in oil dampers, tires and foam inserts, stabilizers (they aren't needed with most DT-02 cars), I would suggest at first:

- Adjust the track rods. Toe-in causes understeer, toe-out causes oversteer.

- Pack the friction dampers with a lot of grease. They will work suprisingly fine then.

- Adjust your driving style to a RWD car by slowing down in turns.

- Use weights only if you really need to (e.g. when using LiPo batterys). However I found the DT-02 to behave well with LiPo without adding weights.

The slice ribbed front tires of the Super Fighter G are ideal for dirt. You can't expect them to work great on tarmac though, where you need a larger contact patch.

[30YrsL8r]

I adjusted the steering extremes on the transmitter, greased the dampers all round, dialled in a bit more toe-in and replaced the front tyres with a cheap pair of Team Losi ones (£4 delivered off ebay, including foam inserts). I just took it around the back garden a few times and the DT-02 now drives like a whole new buggy. My son will be very pleased.

[taliesin]

Do you have a part # for those tires? Like the look of those a lot!

[Percymon]

My son will be very pleased.

I bet Dad is too at that price - £4 to transform the handling

[Percymon]

Do you have a part # for those tires? Like the look of those a lot!

http://www.ebay.co.uk/itm/GENUINE-TEAM-LOSI-A-7203-S-2-2-FRONT-2WD-R-C-BUGGY-DIAMOND-TYRES-w-INSERTS-/400292525644?pt=UK_ToysGames_RadioControlled_JN&hash=item5d334b364c

[30YrsL8r]

I bet Dad is too at that price - £4 to transform the handling

Yep

In case they ever run out on ebay, the part # is "A-7203 S" (don't know what the significance of them being the "silver" variant is).

2.2" tyres, though, rather than 2.16" but they seem fine and I don't suppose it's such a big deal on the front.

[Percymon]

silver will likely be the rubber compound - colours often used to identify hardness/grip

[mr crispy]

Those tyres look good, just ordered a set for myself.