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Tamiya DT-03 - Tamiya speed challenge


Derka

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Finally reveived my motor to get this project started. 

 

This primarily for the Tamiya Club Official Speed Challenge thingy on their forum. 

 

Bought a DT03, fitted all the electronics and gave it a brief run today on the drive. Managed 34mph on a half flat 2s Lipo and not much room to get up to speed but was mainly to setup the steering trim etc. 

 

Pretty pleased, fingers crossed for a full run asap

 

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So... Finally got the stock DT03 out for it's maiden speed run.

 

Similar issues to @Oh How Original with his HB... Wheelies and lots of them and then the aftermath of several tumbles, cartwheels and lots of sliding.

 

Touch wood, the car is fine considering it has been cart-wheeled and flipped a lot at speeds around 40-50mph. The nice metallic green wing and body certainly show some useage now! 😂😤.

 

That leads me onto something I was totally not expecting... Range issues.

 

I'm using a Sanwa MT-S with a genuine Sanwa receiver, a RX-481WP. Not cheap gear by any means so it baffled me as it's not something ive ever experienced and I've raced at large out door and indoor events with hundreds of fellow racers and never had a glitch or range issue. I'm not expecting miles of range but I was totally losing signal at 75-100m MAX metres outside in the open with nothing around. I had to get within 5m of it again to re-gain control. Fail safes were set but still very inconvenient. 

 

I wondered if it was the Tamiya factory metallic green bodyshell? Could the metallic finish interfere with range? It also has like a aluminium mirror effect on the inside. With shell off things were better, but I didn't want to push my luck, especially crashing with no body due to signal loss. Any feedback guys?

 

Apart from those issues, I am pleased to say I hit 52mph, then 56mph and then pushing my luck I just hit 58mph! Very pleased for a basic, box stock DT03. I now need to add weight to the nose, maybe in the form of fishermen's tungsten putty? I also have a small front wing to add and may remove the rear wing. To eek out a bit more. 

 

I think in regards to the range issues, I may buy a Sanwa receiver with an antenna to see if that helps or maybe a clear lexan shell?

 

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Lots of people have issues with range with Sanwa stuff, check some other guys speed runs on YouTube and Tamiyaclub.

They are super super fast response times, but don't seem brilliant for range.

If you think it's body related, only way to find out is put a hole in the shell and poke the antenna through it and test it.

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My Sanwa receiver are the antenna-less ones like the RX-482 (https://www.modelsport.co.uk/sanwa-rx-482-telemetry-ssl-receiver/rc-car-products/404646) and a WP one currently in the DT03 https://www.modelsport.co.uk/sanwa-rx-481wp-receiver/rc-car-products/439936

 

I think what I will do is put the Arrma radio gear into the DT03 and not poke the aerial out (just to see if it's the shell) as if I poke the aerial out first, that negates the shell and I can buy Sanwa ones with an antenna.

 

I'll have a Google on the range issues. Disappointed to be honest. I appreciate they're antenna less but less than 100m range seems off, even for that design. Expensive receivers too. 

 

Maybe time to change to Futaba? Are they better?

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I have seen that radio suggested a few times. I'm doing some more research before either buy a Sanwa receiver with a proper wire antenna or may take the opportunity to change my main radio gear from Sanwa to Futaba.

 

Got some bits for the DT-03 today, wasn't expecting them to come so quickly from RC Jaz in just 3 days!

 

A nice carbon front shock tower and universal rear shafts.

 

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Popped the DT03 onto the scales to compare the weight balance once my ballast putty arrives. Hopefully it will be enough to keep the front end down.

 

Also fitted a small front wing and reduced the angle of the rear wing. 

 

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  • 2 weeks later...

Not weighed it yet after adding nose weight.

 

Hitting a wall at 62-64mph and I can't change gearing as it's fixed, 17 or 19t pinion. 

 

I'm thinking of adding some timing to the motor to see if that can bump it up a few mph as I'd like 70mph out of it but it's such a handful trying to keep tracking straight. With the Tamiya slop it wanders so much. Turned the steering dual rate down to 40-50% to try and stop it, added -30 expo to slow the steering just off centre. 

 

Adding some front toe in but didn't make a huge difference. Maybe front toe out will help? 

 

Would a thicker diff fluid be better?

 

Vid of 62mph

 

 

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I changed the front to 1 degree toe in. I'll try a degree out and see how it runs. 

 

The LRP motor as stock is -10 degrees of timing. I've just changed it to 0 degrees so hopefully that will give me the few extra mph. 

 

On the tyres, possibly. The current ones are 78mm diameter. They are really soft and baloon a lot. I wouldn't recommend them for speed runs. I'd be tempted to try something else. Not sure if there is a belted option off the shelf option

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  • 3 months later...

Out of interest, are you using the kit wheels? All the photos and video are showing as removed/unavailable so cannot tell from what you've posted so far.

 

If you are, it might be worth changing to these: https://www.jcracingproducts.co.uk/tamiya/astute . I would link to Modelsport but I think this is the only place that sells them and cannot find anything similar on the MS website.

 

They are a modern replacement for the Astute wheels,  but looking at the manual (https://www.tamiyaclub.com/modalpic.asp?img=astute_manual_20.jpg) should fit a DT-03  (I think the 850 bearing is for spacing on the Astute; the bearings that fit inside the wheels are 1150 like on the DT-03) and will apparently allow you to fit 2.2 tyres without needing to use a bearing to hex adaptor for the front. The stock wheels are a bit smaller than 2.2 and that might affect your tyre profile and switching to slightly larger wheels might also help with top speed. Hopefully it'll give you more options and a better fit. I haven't tried them myself but plan to buy them for my DT-03 after I get paid later in the week. If you're intersted and still attempting this speed run I can let you know what they turn out like for me.

 

Also can vouch for the Dumborc, I have one and it's great. Mine lacks the gyro though as I couldnt get ahold of that reciever at the time. I know the name is probably meant as 'Dumbo RC' but I prefer to read it as 'Dumb Orc' and make tastless LoTR jokes instead.

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