DT-03 front suspension mod

[CptMookie 49]

I've been working on a racing DT-03 that I can take to my local carpet track. I have a goal to take this to the track and race it a bit. I have zero expectations because of my lack of skill, and the build limitations of Tamiya, but I think it's a fun project.

Anyways, this mod requires the front suspension of a Kyosho RB7, a set of spacers, and the metal front suspension arm mount. Pretty straightforward, and it allows for standard 12mm wheels to be used.

[BuggyDad 5334]

Interesting stuff. Looks really nice. It may well not be an issue but I'd be a bit concerned about the arm being spaced out from the mount like that, for its potential to bend the pivot. 

Those are really nice looking C hubs and uprights though. What was your reason for using the Kyosho arms over the stock ones?

Are the RB7 parts same as Dirtmaster? 

I would guess that your toughness issue with the DT-03 on the track might be the chassis nose. It's quite a common failure. I brace my shock tops back to the mid chassis with M3 rod. It looks a bit rough but is very effective. 

[RichieRich 771]

I like the modification. I hope it works out. The Dirtmaster is based on the RB5 so it does not have the gullwing front arms.

[CptMookie 49]

9 hours ago, BuggyDad said:

Interesting stuff. Looks really nice. It may well not be an issue but I'd be a bit concerned about the arm being spaced out from the mount like that, for its potential to bend the pivot. 

Those are really nice looking C hubs and uprights though. What was your reason for using the Kyosho arms over the stock ones?

Are the RB7 parts same as Dirtmaster? 

I would guess that your toughness issue with the DT-03 on the track might be the chassis nose. It's quite a common failure. I brace my shock tops back to the mid chassis with M3 rod. It looks a bit rough but is very effective. 

Thanks! The reason for this mod was driven mainly by the need for 12mm hex. Also to possibly lower the ride height while maintaining the shock stroke length. There is a slight angle to the arms that should (in theory) lower the ride height by a few mm.

I am also fortunate (maybe unfortunate?) enough to have an abundance of RB7 parts. I have a rolling chassis, and a second chassis that I bought as a parts car.

The added strength to the parts is a bonus.

I am also curious to the mounting position, and am wary of the offset fitting. I don't believe it will be an issue, but I might be wrong. From the feel to it though, it is really solid, but I haven't had any track time to test it.

[BuggyDad 5334]

4 hours ago, CptMookie said:

Thanks! The reason for this mod was driven mainly by the need for 12mm hex. Also to possibly lower the ride height while maintaining the shock stroke length. There is a slight angle to the arms that should (in theory) lower the ride height by a few mm.

I am also fortunate (maybe unfortunate?) enough to have an abundance of RB7 parts. I have a rolling chassis, and a second chassis that I bought as a parts car.

The added strength to the parts is a bonus.

I am also curious to the mounting position, and am wary of the offset fitting. I don't believe it will be an issue, but I might be wrong. From the feel to it though, it is really solid, but I haven't had any track time to test it.

I'll be interested to hear how you get on with tuning it for the track too, to get it cornering nicely. My efforts with mine have been gradually to improve it for loose rough surfaces and it has come on a long way but that has simultaneously probably also made it gradually worse for a track situation. 

On hex conversion parts, I started a thread a while ago. It was kind of originally from DT-03 but I widened it because mostly the same questions (and answers) apply to other Tamiya buggies too. Basically, it ended up that there are loads of different ways. Even though it probably won't help you because you've already got a good answer (and I am running similar Kyosho uprights to you on my BBX and may use them again on something else), I thought it might be worth a link, just in case of interest:

 

[CptMookie 49]

I considered making a new post, but decided against it. 
 

The build is complete! 
 

A few images and descriptions incoming.

The main goal of this build was to make a respectable Tamiya club racer. I don’t expect to win anything. I don’t expect to make it to the A main. All I want to do was to take a bad car and make it meh. 
 

So the obstacles in this challenge were: gearing options, suspension adjustability, ride height, rear motor weight bias. 

[CptMookie 49]

I’ve met the max total upload size. Hmmm

Nevermind. I think I figured it out. 

[CptMookie 49]

To address the rear weight bias I added a foam tire insert. Stuffed it to the back, and placed a shorty pack closer to the front. It’s not elegant, but hopefully it works. 

[CptMookie 49]

I also added tungsten weights found on Amazon. These weights were designed for box car racing. It added 39g to the front. Hopefully this helps the front bite into the track as it hits the hairpins.

[CptMookie 49]

I wanted to address the gearing options and this was a bit harder than the other mods. I took the existing spur, cut off the teeth around the spur, and also cut and filed off material so that the existing spur would sit flush with the new intended spur. I then had to use a reaming tool to widen the center hole in the new spur, drill the holes where the new spur needed and “ta-da” one spur for the price of two! 
 

Important note. The holes you drill into the existing spur need to be made while the new spur is seated onto the bearing. Otherwise your risk a wobbly spur gear. Currently the new setup is crisp and true. 
 

It is a 27/70. I don’t know the exact internal gearing but I don’t think it’s a 2.6. If it was, the FDR gearing would be 6.74. BUT I’m not sure. So if someone knows. Please let me know. Otherwise I’ll hunt the info down later. 
 

Also I used the out drives from a DT-02. By default it comes with smaller metal ones rather than the huge dog bone ones the DT-03 comes with. 

[manny 102]

Projects like this are always interesting to see.  I also hate the limited gearing on the DT02/03 especially since it was designed after the turn of the century.  I'll have to take inspiration from (copy) your solution.

[CptMookie 49]

4 hours ago, manny said:

Projects like this are always interesting to see.  I also hate the limited gearing on the DT02/03 especially since it was designed after the turn of the century.  I'll have to take inspiration from (copy) your solution.

Thanks! I took it on the track the other day and it did as well as I thought (which is good, but not great). The gearing still needs to be adjusted and I’m gonna try a smaller spur and a bigger pinion. 
 

Copy all you want! Let me know how it goes. 😁

[SlideWRX 883]

There is another spur gear that technically fits the DT-03, but it makes it hard to line up the pinion gear.

 

[alvinlwh 6893]

On 7/24/2024 at 6:56 AM, CptMookie said:

It is a 27/70. I don’t know the exact internal gearing but I don’t think it’s a 2.6.

Is the original spur 55T? I cannot remember... If yes, then the I is 2.873. If not, take this number 158 (SI) and divide it by the number of teeth on the original spur.

[CptMookie 49]

7 hours ago, alvinlwh said:

Is the original spur 55T? I cannot remember... If yes, then the I is 2.873. If not, take this number 158 (SI) and divide it by the number of teeth on the original spur.

Thanks a million. Yeah I have seen 2.6 on other builds, but never knew the dt-03 internal gearing. 

[Howards 588]

Looks fun. 
 

I wonder if the TD2 front end is a more straightforward swap albeit without the gull arms. I just swapped out a DN01 to TD2 fronts as the 201 arms are unobtanium now. Required a tiny bit of dremeling but otherwise slots in fine.