A Prime Dynahead

[OldSchoolRC1 1090]

A while back, I tried to turn my Konghead into a trail runner/light crawler. 

It did ok, but the lack of ground clearance and tallish gearing, even with an outrunner motor, left me somewhat wanting. It looked fantastic, but just didn't perform the way I envisioned. So I tore it back down, put the stock wheels back on, opened up the diffs, dropped in a 3300kv brushless and ripped around the backyard a few times. Very fun chassis. 

I've had my eye on the Dynahead for a while - the portals would solve both of my problems...but it was quite expensive stateside. A recent significant drop in price overcame my hesitations and I decided to order one. To keep life simple, I used my existing built Kong chassis and just built the portals. Relocked the diffs and bolted them on. So many bearings bushings, and gears.... everything fits perfectly as expected with a Tamiya kit and they spin super smooth and quiet. I'm not sure how Tamiya manages that since this truck has by my count a stunning 54 gears/mating surfaces (!!) Eventually I'll build the Dyna chassis (with about a pound of bearings) and rebuild the Kong as it was such a fun and unique runner. But for now, it's trail time!  

View under the hood. I used dual servos for 4WS, rear channel is set to run independently on the ch3 switch of my GT3B radio so I can swing the rear tires as needed. I redid the rear linkage slightly as mine tended to bind up in one direction - the servo would easily overextend the bellcrank and it would lock up. I fashioned an 10mm extension for the bellcrank and a more direct link and now it swings perfectly. For electronics, I used a crawler grade WP1080 and a Holmes 5 slot Crawlmaster which with its lower RPM and super smooth control is perfect for this chassis. 

Decided to go with the Dynahead body, though I ditched the factory scheme and went with something a little more "Prime" inspired. I think it came out great! A bit plain I guess, thinking about something to break up the blue a bit. I used some 1.9 beadlocks and a few sets of Gmade Sawback tires which fit the body perfectly and are decently grippy.   Front wheels have just a few grams of weight inside to balance out the chassis. 

And a few flex shots. Not a ton, but more than enough for this chassis. I'm using the Mini CVA's and a few sets of option CC01 barrel springs so I have a few springs rates to play with. It feels great on the bench - suspension is somewhat soft and supple, but not too much so. 

Of course, the week I finished this up, we received about 10 inches of snow. so a true trail test will have to wait a bit I'm afraid. 

[Mad Ax 10825]

Nice rig, love the paint scheme  

If you put the original balloon tyres on it might ride over the snow quite well  

[Busdriver 6525]

Even the body looks ok in that scheme 

[tamiya_1971 690]

Dangit.  That looks great. Now I wish I would have ordered one from Tower at 25% off.  

[OldSchoolRC1 1090]

Mad Ax, I think you are onto something....with the locked diffs, it should go very well! Has to melt a little, I don't think it's going to churn through 10in...

 

[JennyMo 3625]

I saw the title, considered what the paint-job would be, and you didn't disappoint - inspired!

It's funny, I've been increasingly considering building a 6x6 of some sort myself recently... and thought G6-01 chassis might be a simple way to go (copious bearing requirement not withstanding!), particularly with the rear steer option too...

OldschoolRC1 - can you tell me what size tyres you've got fitted and/or the distance between the rear two axles to know how large diameter tyres are able to be fitted without them rubbing on each other?

Love what you've done with this!

Jenny x

[OldSchoolRC1 1090]

@JennyMo Thank you! I would say the same for your builds - always top notch! I have been playing Snowrunner quite a bit lately and it has warmed me up to experimenting with 6x6 builds. In addition to my TRX6 (which has absolutely stunned me with its capability) I have a rather "Bullish" project on deck as well. 

To answer your question, the rear axles are spaced 125mm apart. They will fit standard crawler 4.19's no problem, which is what is on currently and seemed to look the best to my eyes. I initially built with Proline Grunt tires (4.4") and while they clear ok, they looked cartoonishly big to my eyes and rubbed the body more than I was willing to trim. 

If you are not using 4WS, you could mount 4.75 crawler tires, but there is very little wiggle room...my 4.75 Hyrax's fit with a scant 2-3mm between tires. Since there's a lot of variation between tire manufacturers, I'd be very hesitant about pulling the trigger on 6 tires without testing first.  With 4WS though, 4.4 is about as big as you can go - the scrub radius of the rear knuckles will push the tires into each other. 

I hope that helps! Would love to see you give a 6x6 a go! It's quite a treat watching all 6 tires undulating over the terrain. 

[JennyMo 3625]

18 hours ago, OldSchoolRC1 said:

@JennyMo Thank you! I would say the same for your builds - always top notch! I have been playing Snowrunner quite a bit lately and it has warmed me up to experimenting with 6x6 builds. In addition to my TRX6 (which has absolutely stunned me with its capability) I have a rather "Bullish" project on deck as well. 

To answer your question, the rear axles are spaced 125mm apart. They will fit standard crawler 4.19's no problem, which is what is on currently and seemed to look the best to my eyes. I initially built with Proline Grunt tires (4.4") and while they clear ok, they looked cartoonishly big to my eyes and rubbed the body more than I was willing to trim. 

If you are not using 4WS, you could mount 4.75 crawler tires, but there is very little wiggle room...my 4.75 Hyrax's fit with a scant 2-3mm between tires. Since there's a lot of variation between tire manufacturers, I'd be very hesitant about pulling the trigger on 6 tires without testing first.  With 4WS though, 4.4 is about as big as you can go - the scrub radius of the rear knuckles will push the tires into each other. 

I hope that helps! Would love to see you give a 6x6 a go! It's quite a treat watching all 6 tires undulating over the terrain. 

That's just what I needed to know, thank you!

I did wonder (looking at a stock G6-01 chassis) where there would be much more room than the Tamiya sized tyres, and while I have been considering to build something more scale looking - including leaf springs etc. which would suit more modest size tyres anyway, I can't help but think it would be fun to build more of a basher and 'fun runner' on a 6x6 platform - much as the G6-01 was conceived for of course - so in that regard perhaps I'll stick with the stock Wild Willy/Pumpkin size Tamiya tyres on that chassis platform?

I do like what you're putting together on that TRX6 chassis though - especially since I already have a set of six 2.2 wheels and tyres that sort of size too (approx 130mm diameter), which is what has started me down this road!

Looking forward to seeing the Bullhead Beast when it's finished!

Jenny x

[Busdriver 6525]

my Dynamog runs on standard CC01 rims and 4.3 inch/110 mm tyres. Personally I think it’s just about right. Admittedly this is a Dynahead so has greater ground clearance due to portal axles. 4WS works perfectly without binding. @JennyMo my only comment to you would be if you go down the G6-01 route the chassis is not very conducive to scratch building. It is basically a brick lying on its side with six axles poking out the sides. Everything sits on top of the chassis. If yo go for hard bodywork it does make it top heavy. I keep meaning to rebuild the rear deck of mine in plasticard rather than MDF and brass!!! Can’t do much about the Loops cab which is just a gorgeous hunk of heavy plastic.. with your building skills you would be better extending a twin rail chassis and fitting a second rear axle, or reversed front axle to get 4WS. That way you would get a better spacing between the front and rear pair of wheels IMHO😊

[JennyMo 3625]

3 hours ago, Busdriver said:

 @JennyMo my only comment to you would be if you go down the G6-01 route the chassis is not very conducive to scratch building. It is basically a brick lying on its side with six axles poking out the sides. Everything sits on top of the chassis. If yo go for hard bodywork it does make it top heavy. I keep meaning to rebuild the rear deck of mine in plasticard rather than MDF and brass!!! Can’t do much about the Loops cab which is just a gorgeous hunk of heavy plastic.. with your building skills you would be better extending a twin rail chassis and fitting a second rear axle, or reversed front axle to get 4WS. That way you would get a better spacing between the front and rear pair of wheels IMHO😊

Hee hee - yes, funny you suggested that... I've already been noodling around for some extended RC4WD/SCX10 style rails with that idea in mind - not least as it would offer a lot more versatility to space the axles as required; and as you suggested, using a second front axle on the rear to give 4WS would certainly be an option too!

Of course I've still got in the back of my mind that suggestion from year's ago on the STUMPkamper thread, and creating a 6x6 that could pivot around the middle axle so that it would effectively wheelie on it's rear four wheels... might be time to dust that crazy idea off again?!

Jx

[Dakratfink 1022]

I love my G6-01 king yellow for bashing , now I want a Dyna for crawling.

dang you and your interesting builds 

[burakol 463]

Now I can't really wait to build my Dynahead... its been collecting dust for the past 4 months... Great build BTW.

[Dakratfink 1022]

On 12/18/2020 at 7:25 PM, OldSchoolRC1 said:

have been playing Snowrunner quite a bit lately and it has warmed me up to experimenting with 6x6 builds

I’ve not tried Snowrunner yet, but been playing quite a bit of the older MudRunner. It is increasing my interest in crawling/ trail trucks. 1/24, 1/10 and 1:1 

[OldSchoolRC1 1090]

On 12/19/2020 at 2:45 PM, JennyMo said:

 I can't help but think it would be fun to build more of a basher and 'fun runner' on a 6x6 platform - much as the G6-01 was conceived for of course - so in that regard perhaps I'll stick with the stock Wild Willy/Pumpkin size Tamiya tyres on that chassis platform?

 

Sadly, the Konghead/WW/Lunchbox tires do not work on the Dynahead if you want to use 4WS.  The scrub radius of the portals and the wide offset of the rims push the tires into each other when turning. Works fine if you skip the rear steer however. Something to keep in mind. I'm sure that's why Tamiya includes the somewhat odd 2.2 wheels with the Dynahead kit. 

@Busdriver Your build looks great! I thought of an extended Tamiya Mog body as well for future builds. Looks fantastic with the portals. 

[Busdriver 6525]

Works pretty well. The body is heavy though so it tends to roll on side slopes if not careful 

[BJoe76 577]

I love the paint job on this build, you kinda have men wanting to get one of these now too........even with all the projects I have going too😅

[BigJag 46]

Lovely paint job. Takes the Dynahead to another level. We need more Transformers inspired RC vehicles. The Bullhead is crying out for a Prime theme.

[OldSchoolRC1 1090]

Trail report! The Prime Dynahead did very well on the trail. Surprisingly well, it's far more stable than I expected it to be (It looks tall, but most of the weight is down low) and pretty darn capable. The tires kind of let it down a bit, it was cold, wet and slick and they really struggled for grip on the rocks - even with 6 of them. But they did fine everywhere else..I'll give it a run in the dry before considering any changes. The gearing is spot on with the 18t pinion and Holmes Crawlmaster, I had excellent low speed control and plenty of wheelspeed if needed. 4WS was for sure the way to go, I have it set for 0, 50, and 100% so I could lock it out if needed...which wasn't often.  

It got quite a bit of attention out on the trail too, kids seemed to gravitate toward it. I must have answered 100 questions... Can really see the wet conditions in this pic - made for some challenges, but a good time in any case! 

Much more at home going down the trail, it was a blast watching the IFS work and the 4WS snaking around obstacles. 

Made it! Too bad the shot came out blurry.  

No real changes are needed imo, though might look into a tire change depending on how it does in drier conditions, and eventually I'll tear down the portals and add the tiny bearings. Very happy overall with the build and result!   

[Dakratfink 1022]

I really love seeing the independent suspension work on the Dynamic/KH chassis.  I’m sure solid axle has its advantages but the dyna with locked or semi locked diffs seems to do pretty well. 

[BJoe76 577]

2 hours ago, Dakratfink said:

I really love seeing the independent suspension work on the Dynamic/KH chassis.  I’m sure solid axle has its advantages but the dyna with locked or semi locked diffs seems to do pretty well. 

I’ve been noticing that with the Dynahead videos I’ve watched too, I’m curious how they would do fully locked like I’ve done with my Traxxas Telluride, between that and M3 compound Proline Trenches on Proline SC10 beadlocks, it goes almost anywhere I aim it!

[OldSchoolRC1 1090]

As a follow up on this build, I decided to take it to this years G6 event, along with 6 other trucks... this one was the smallest of the litter, with the narrowest track, widest turning circle, worst breakover angle, and I was not expecting big things per-se, I just thought it would be fun to run (As most Tamiyas are, no?)  Well, it WAS fun to run, and much to my surprise, I'd say it was my most capable truck I ran all weekend. This little guy went everywhere, and I mean everywhere. 

Before leaving, I swapped over to a set of 4.19 Hyrax tires with stock foams and was debating a bit of weight in the front wheels, though ultimately decided against it. Turns out I didn't need it at all, and the tires were a huge improvement. This truck climbed, sidehilled, and mudded it's way through all of the G6 courses. Never even flipped it once, it was incredibly stable and while the front bumper wasn't doing me any favors, as long as I attacked from an angle and got a front wheel on something, I got up and over it. 

Unfortunately, it was over 100 degrees and very high humidity, and many of my pics didn't make it... lens had fogged up from being in my pocket.

Resting after three and a half battery packs of wheeling. Job well done! 

[Grumpy pants 5541]

What’s a breakover angle? 

[OldSchoolRC1 1090]

This explains it far better than I ever could...in a nutshell, it's clearance under the chassis.

https://en.wikipedia.org/wiki/Breakover_angle