Twin Det. stability :overall width vs tire profile

[Saito2]

I'm piecing back together my Twin Detonator as an alternative to the Stampede from the evil Traxxas corporation. The setup of 8.4v powering twin HPI 15t Firebolts makes the truck squirrely to say the least. I have several tire options. First, I'm using 10mm wheel wideners to increase overall width for stability. I can run HPI 2.2 Mud Thrashers (tallest tire) on stock 2.2 rims, Proline Masher 2000s  on stock 2.2 rims or Traxxas 2.8 Talons on 4wd Stampede rims (shortest tire). The Stampede rims don't have the offset the stock 2.2 rims do so the truck becomes narrower.

So which will be better for stability, a wider width with tall squishy tire sidewalls or a narrower width with lower profile, tighter sidewalls (and a slightly reduced overall vehicle height as well)?  Thoughts?

 

   

[kwkenuf]

Don't use the Talons.  Period.  Nobody that buys a Traxxas with them on is impressed with them.  Bad traction and balloon easily.  I have two Stampedes (I know...  the the **** was I thinking...) that wear Pro-Line Trenchers on one and Badlands on the other.  If I was going to get Monster truck tires for something right now,  I would be all over the Badlands MX28.  HTH

edit:  Dang it...  you made me research the Twin Detonator.  Now I want one...

[Saito2]

Ok, so using a better tire (i.e.not Talons), which is more important for stability, a wider truck or a narrower one with bigger wheels and lower profile tires? 

The Wild Dagger/Twin Detonator series of trucks is highly configurable. It was awesome but unwieldy with the big HPI Wheely King Mud Thrasher tires. On pavement its almost un-driveable, twitchy and skittish at full tilt. I was wondering if lower profile tires would help keep it under control. Unfortunately,  the Traxxas 2.8 wheels lack the offset (and thus width) of the stock 2.2 wheels.  

[Juggular]

Saito, does your build include longer shocks?  I still have short (on-road) shocks on my Wild Dagger.  I'm eyeing on aftermarket shock towers.  Your question made me wonder what longer shocks would do to stability.  

 

 

[Nobbi1977]

The shock towers and longer shocks help stability loads. The extra travel and sag mean it can lean a lot more before flipping over

[Prescient]

You want the 135mm x 70mm chevrons like I have on this. I have run out of sets to sell now though sorry.

These are the biggest volume 2.2s I have found. They come with foams.

eBay or Hobbyking sell them. Typically £25 for 4. In my experience they out perform the more expensive competition.

They come on rims which have the wrong offset but fit perfectly on Tamiya 2.2s.

https://hobbyking.com/en_us/hobbyking-r-tm-1-10-crawler-monster-truck-135mm-wheel-tire-silver-rim-2pcs.html?___store=en_us

[kwkenuf]

I think the quality of traction the tires provides is the most important factor.  In theory a shorter sidewall profile (Talons) should be more stable and predictable. But that’s assuming equal traction.  Put some car tires on it for a fun test!

You can do a lot of help through suspension tuning also.  Spring rates and shocks can do wonders to keep any tire planted to the terrain.

[kwkenuf]

I think a narrower truck.  At a certain point center of gravity height becomes an issue as the truck can start to traction roll.  Stampedes are right on the edge in stock form.  Doing a wide-mod helps, but lowering the CofG is even better.  But doing the wide-mod doesn’t really change the driving dynamics enough to notice.  Neither did using my 2.8 Trenchers vs 2.2 Badlands.  The Badlands are actually taller overall and not as wide as the Trenchers, but the driving dynamics are remarkably similar.

This is probably what I should have posted first...

[Prescient]

18 minutes ago, kwkenuf said:

I think the quality of traction the tires provides is the most important factor.  In theory a shorter sidewall profile (Talons) should be more stable and predictable. But that’s assuming equal traction.  Put some car tires on it for a fun test!

You can do a lot of help through suspension tuning also.  Spring rates and shocks can do wonders to keep any tire planted to the terrain.

It's almost irrelevant on the WT/WR01 though as even with all the shock tower and tuned suspension options, the chassis design hits it's limit at 25-30mph and any speeds after that are survived through luck. 15-20mph off road is enough for these. You can do straight-line speed runs on a good road or smooth grass surface and hit 50mph+ 

Traxxas equiv do 30mph out the box and are as comfortable at 50-60mph+ in the lipo variants.

Chevrons on the WT/WR get the most out of the chassis.

[kwkenuf]

 I would love to get a Twin Detonator together with my Stampedes and do a comparison.  

[Saito2]

I have both and they are quite different. Stampede uses stadium truck front suspension + rear drivetrain/suspension riding low but bridged by a narrow, high riding chassis section. Tack on some bigger tires and presto, a monster Rustler. This direct buggy/stadium truck DNA means the Stampede can tolerate higher speeds. However, like you said, that higher center of gravity puts them on edge in stock form.

The Twin Detonator by nature must be symmetrical to allow for the same drive system front and rear. As such, even in 2wd form (i.e. Blackfoot Xtreme, Bush Devil 2, etc) the chassis isn't optimized for speed like a Stampede. There is no front kick up in the front suspension because the front end has to be able to also be swung around and used as the back end as well.  

Another thing that may be contributing to the nervous handling is the scrub radius which is tremendous in these trucks with their stock wheel offset. Wheel wideners make this condition even worse. The whole front becomes darty on high grip surfaces. If anything, the rather hard stock tires tame this as they'll skid around rather than grip and pull. Of course traction off road then suffers with these. 

[Baddon]

On 28/01/2018 at 9:59 AM, Prescient said:

You want the 135mm x 70mm chevrons like I have on this. I have run out of sets to sell now though sorry.

These are the biggest volume 2.2s I have found. They come with foams.

eBay or Hobbyking sell them. Typically £25 for 4. In my experience they out perform the more expensive competition.

They come on rims which have the wrong offset but fit perfectly on Tamiya 2.2s.

https://hobbyking.com/en_us/hobbyking-r-tm-1-10-crawler-monster-truck-135mm-wheel-tire-silver-rim-2pcs.html?___store=en_us

That truck looks somewhat different now.....I put the shocks and towers on my one and the body went to another TC member and was changed to the photo below. All three of our trucks run on these tires. Great job.

 

They are a great job for stability when messing about. See the last photos. No idea how many times we hit the ramp, half on off etc and only one roll all session.

 

 

 

 

[Baddon]

With the long travel butter smooth shocks and longer aftermarket towers I find the rear is very soft, its squats notably under power and on full lock will un-weight the inner tire and spin it causing the truck to spin. It does this on my sons as well and its got the stock short pogo's. Mine is more derivable and less twitchy.

[wolfdogstinkus]

Put another axle on it

6x6

[Juggular]

4 hours ago, Saito2 said:

I have both and they are quite different. Stampede uses stadium truck front suspension + rear drivetrain/suspension riding low but bridged by a narrow, high riding chassis section. Tack on some bigger tires and presto, a monster Rustler. This direct buggy/stadium truck DNA means the Stampede can tolerate higher speeds. However, like you said, that higher center of gravity puts them on edge in stock form.

The Twin Detonator by nature must be symmetrical to allow for the same drive system front and rear. As such, even in 2wd form (i.e. Blackfoot Xtreme, Bush Devil 2, etc) the chassis isn't optimized for speed like a Stampede. There is no front kick up in the front suspension because the front end has to be able to also be swung around and used as the back end as well.  

Another thing that may be contributing to the nervous handling is the scrub radius which is tremendous in these trucks with their stock wheel offset. Wheel wideners make this condition even worse. The whole front becomes darty on high grip surfaces. If anything, the rather hard stock tires tame this as they'll skid around rather than grip and pull. Of course traction off road then suffers with these. 

Well explained.  No kick-up (caster?) and positive scrub radius... now I know why Wild Dagger has a robotic and unnatural feel to the handling.    

[Saito2]

49 minutes ago, Juggular said:

ow I know why Wild Dagger has a robotic and unnatural feel to the handling.    

Bingo! That's it! You put to words what bothers me about the Dagger series. With stock motors, "robotic" and 'unnatural" are prefect descriptors of how the the truck's handling bothers me so much. Turn the wheel, and the truck says "ok, i'll go over in this direction now". No grace, no verve, no personality. Bland. 

Now, with hotter motors, the chassis can come alive. Once you start overpowering the chassis limits a bit, it becomes a bit more exciting. You get back some of that unpredictable nature old Tamiya monsters have but with a bit more durability and stability. 

[Juggular]

53 minutes ago, Saito2 said:

 Once you start overpowering the chassis limits a bit, it becomes a bit more exciting. You get back some of that unpredictable nature old Tamiya monsters have but with a bit more durability and stability. 

 

I wouldn't have guessed hotter motors could subdue the stiff attitude to some degree.  I always thought, "it has two 540 motors, that's twice the power of Blackfoot."  Your knowledge opens up the possibility of upgrading.  Another project!  Yes!  But I don't know how much Quicrun WP860 could take. 

I might have to get stock motors and advance the timings.  RPM matching could be tricky.  I should get a cheap RPM meter with a reflective tape.  Put diff putty in the diffs, stick a reflective tape on one wheel...see what I get on max throttle, and try to match it for the other end.  I suppose some RPM difference wouldn't make any real difference.  For me, though, fiddling to maximize the potential is the most fun part of RC.  If I cannot match it exactly, I want the motor in front to go faster.  If I remember correctly, the steering end has bigger turning radius and could use more rpm.  That's why racers use one-way bearings allow in the front, I think.    

On that note...  it just occurred to me if the rear motor happens to turn faster, it would be awkward or unstable.  huh...  I wonder if that could also cause the instability issues of WT-01 to some degree...  I hadn't thought of until you mentioned hotter motors, but that could contribute to the instability, couldn't it?  

 

[Saito2]

Well, with my longer Maxx shocks those big bouncy Wheely King tires and 0 timed HPI Firebolts, the truck tears all over the place. With all four tire pulling hard, its kinda neat. I run a Traxxas EVX2 for a speed controller set to run one 8.4v pack. I imagine motors with unmatched speed could exacerbate instability issues. You're right, the fiddling around for max performance is where the fun's at.

Now this thread got me thinking a little outside the box. If I settled on keeping the chassis 2wd, it would be interesting to develop a more optimized front suspension. Imagine a Dagger series truck with a better scrub radius, more front kick up (and caster) like an RC10. Since the chassis is technically mid motored, it would yield better balance than the tail heavy Stampede (which also has a higher COG). It would still be a truck chassis, but it just might beat the Stampede at its own game.

[whahooo]

How do you put in the 8.4v Battery?

 

I have a Wild Dagger with the Maxx Shocks, a QuicRun WP860 Dual Motor Speedcontroller and the Standard Silvercans.

I`m almot happy, but i would love to get a Little more Speed.

 

I have 2 Super Stock BZ Motors With 0 Timing, but at the Time i`ve tested the System, something went wrong. The Truck was very slow (4km/h or so), so i think the QuicRun WP860 isn`t the right Speedcontroller for those Super Stock Motors.

Maybe i should try the TEU-103BK wich i`m running in my Clod. (or maybe i should put the Motors in my Clod...)

 

Anyways, i like the Tyres shown in that Pictures a lot, so i will get them if they are available. (In the linked shop only backordering was possible)

[Prescient]

21 hours ago, Baddon said:

That truck looks somewhat different now.....I put the shocks and towers on my one and the body went to another TC member and was changed to the photo below. All three of our trucks run on these tires. Great job.

They are a great job for stability when messing about. See the last photos. No idea how many times we hit the ramp, half on off etc and only one roll all session.

Yes yes, baton handed over, glad your having fun still.

@Saito2the WT/WR chassis works better as 2wd and is much more cost effective. The independently driven dual axel set up does not perform close to a central box with drive shafts. 

Plus on dual motor, what you gain in the dual motor power is lost in additional weight; notably where you need a proper dual motor, dual ESC, dual battery setup to maximise the performance. This definitely effects agility and handling.

2WD with a 5000kv or higher motor and suitable ESC and 2s lipo is a great way to maximise performance on these.

[Prescient]

10 minutes ago, whahooo said:

How do you put in the 8.4v Battery?

 

 

You can widen out the battery bracket using aluminium flat bar, folded and cut to length. Battery needs to be long ways not hump pack

[whahooo]

Are These Tires the right ones?

 

 

https://www.ebay.de/itm/2pc-2-2-Truck-Badland-Monster-Big-foot-Tires-Fit-RC-4WD-Axial-RPM-2-2-Wheels/172941395513?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D49927%26meid%3Dc1bddc33ceb54d759735596b7a094907%26pid%3D100005%26rk%3D5%26rkt%3D5%26sd%3D182402319210%26itm%3D172941395513&_trksid=p2047675.c100005.m1851