Working on heng long, 1/16 RC Abrams

[keilau]

I just got emails from Derek Mares at MotionRC. He said that all their current stock of Heng Long Abrams are V2 torsion bar version. Just disregard their product description.

I am still waiting for motionRC to change their product description to state explicitly that their HL Abrams has torsion bar suspension. Better yet, to show the pictures of the new battery compartment and the torsion bar interior.

Below are some pictures at AliExpress.

[keilau]

Finally, toucanhobby.com is listing the torsion bar version Heng Long Abrams. It includes an interior picture showing the torsion bars.

https://www.toucanhobby.com/products/th17788-usqc-dzn1?variant=43529935126778

I also added a pair of Heng Xin steel gearbox. Shipping is US$40 for just under US$230 total. I already have the Tamiya hybrid tracks, 390 motors and metal sprocket and idler wheel.

I am a firm believer in the torsion bar suspensiion. Of the small collection of 8 tanks, this new Abrams, the HL/Torro Leopard2A6, the HL Merkava and the Tongde M60A1 are torsion bar suspension. The 12-20 pounds total weight and torsion bar suspension prevent the tank to jump off the ground and run more realistically on rough terrain.

The earlier era medium tanks, Tiger 1, Sherman, T34-85 and Pershing weight 7-8 pounds with metal tracks. They run fine with coil spring suspension, but not as well as the heavier modern tanks. The opinion is personal, and my experience is limited to the 8 tanks I have.

[keilau]

I added a set of Mato metal road wheels for weight and the ball bearing. The added weight should make the Abrams less bouncy on rough terrain.

https://www.toucanhobby.com/products/mt-mt198-dzn1?variant=42912846872826

[Rubicon99]

I added a set of Mato metal road wheels for weight and the ball bearing. The added weight should make the Abrams less bouncy on rough terrain.
https://www.toucanhobby.com/products...42912846872826

Metal wheels add overall weight but have no impact on "bouncing". They are "unsprung" weight. What you need is "sprung" weigh which is weight that pushes down on the suspension springs. Wheels don't push down on the suspension springs.

[keilau]

deleted.

[keilau]

Metal wheels add overall weight but have no impact on "bouncing". They are "unsprung" weight. What you need is "sprung" weigh which is weight that pushes down on the suspension springs. Wheels don't push down on the suspension springs.

A battle tank and the mini RC toy copy are very complex dynamic systems. Granted, the road wheel in a coil spring RC toy is less rigidly coupled to the chassis than in a torsion bar tank, but they are not dynamically isolated from each other. The comment is based on my mechanical engineering training and observations. No, I have not tried to setup a dynamic simulation of a RC toy tank and am not planning to.

My observation is based on the metal upgrade of the Heng Long T-34/85 which has metal road wheel and metal track now. The last part of my build journal is below:
https://www.hobbysquawk.com/forum/rc...ion#post414994

[Rubicon99]

A battle tank and the mini RC toy copy are very complex dynamic systems. Granted, the road wheel in a coil spring RC toy is less rigidly coupled to the chassis than in a torsion bar tank, but they are not dynamically isolated from each other. The comment is based on my mechanical engineering training and observations. No, I have not tried to setup a dynamic simulation of a RC toy tank and am not planning to.

My observation is based on the metal upgrade of the Heng Long T-34/85 which has metal road wheel and metal track now. The last part of my build journal is below:
https://www.hobbysquawk.com/forum/rc...ion#post414994

You are overthinking the issue. It's simple road wheels do not effect sprung weight they only effect the gross weight of the tank on the ground. The two are not the same. This is automotive 101 stuff not rocket science.

The torsion bars push against sprung weight only not gross weight. I know that's to simple for you but sometimes it is just simple. But you do you as it's your money and time to experiment with. I have been down that money and time rabbit hole fat to many times myself and just trying to help others not end up with far lesser results then they expect.

[keilau]

You are overthinking the issue. It's simple road wheels do not effect sprung weight they only effect the gross weight of the tank on the ground. The two are not the same. This is automotive 101 stuff not rocket science.

The torsion bars push against sprung weight only not gross weight. I know that's to simple for you but sometimes it is just simple. But you do you as it's your money and time to experiment with. I have been down that money and time rabbit hole fat to many times myself and just trying to help others not end up with far lesser results then they expect.

We should agree to disagree.

The road wheel goes up and down on rough road. It is the total tank gross weight affect how bouncy it is.

[Rubicon99]

We should agree to disagree.

The road wheel goes up and down on rough road. It is the total tank gross weight affect how bouncy it is.

I have been down this road enough times to know what I am talking about. I understand where your confusion is, I thought the same thing years ago, it is something you have to just experiment with and learn on your own. We can disagree that's how best to learn, it a friendly pointed discussion not an argument.

[SoCalBobS]

Is there one other factor? Heavy wheels carry more inertia, which may cause them not to bounce as readily, and the suspension not compress as much, resulting in a smoother ride? Just thinking out loud.

[keilau]

Is there one other factor? Heavy wheels carry more inertia, which may cause them not to bounce as readily, and the suspension not compress as much, resulting in a smoother ride? Just thinking out loud.

Good point. Entirely possible. When multiply by the suspension arm, the difference in inertia is even greater.

When I worked on the T-34/85 metal upgrade, I have to add 2 pounds of dry weight in addition to the metal track. The plastic T-34/85 was very light weight to begin with. After the metal road wheel upgrade, I removed 17 ounces of the dry weight.

[keilau]

Finally, toucanhobby.com is listing the torsion bar version Heng Long Abrams. It includes an interior picture showing the torsion bars.

https://www.toucanhobby.com/products/th17788-usqc-dzn1?variant=43529935126778

I also added a pair of Heng Xin steel gearbox. Shipping is US$40 for just under US$230 total. I already have the Tamiya hybrid tracks, 390 motors and metal sprocket and idler wheel.

I am a firm believer in the torsion bar suspensiion. Of the small collection of 8 tanks, this new Abrams, the HL/Torro Leopard2A6, the HL Merkava and the Tongde M60A1 are torsion bar suspension. The 12-20 pounds total weight and torsion bar suspension prevent the tank to jump off the ground and run more realistically on rough terrain.

The earlier era medium tanks, Tiger 1, Sherman, T34-85 and Pershing weight 7-8 pounds with metal tracks. They run fine with coil spring suspension, but not as well as the heavier modern tanks. The opinion is personal, and my experience is limited to the 8 tanks I have.

I received the Abrams from Toucan Hobby through FedEx today. It arrived in good condition. It comes with the original Heng Long Abrams manual showing battery cover at the tank bottom.

I just noticed that Toucan offer the original plastic version for $24 less. The listing does not show the torsion bar picture.

While the HL tank box arrived in good physical condition, the Abrams inside came with a turret split open.

I am very concerned, not knowing if it is repairable. I do not want a turret with a twisted lower half.

I tried to take the Abrams apart for a closer inspection but could not. The Abrams' bottom has 7 screw holes. I could only remove the screw nearest to the rear. It is a typical M3 self tapping anodized black Philips screw. The other 6 screws holes looks silvery at the end. It may be a flat head with a slot. But a flat head driver did not extract anything. I need firsthand experience help.

[Meter Rat]

Are the screws for these not under covers on the top? As in the photograph used by Tankme?

[keilau]

Are the screws for these not under covers on the top? As in the photograph used by Tankme?

Meter Rat , Thank you for your reminder.

The M3 screw I removed is likely the smoke unit screw. I was too excited to think clearly when I received a broken RC tank. First time in 10 1/16 scale orders. I am not optimistic because the damage may be due to heat at long summer transit, not shaking or droping. I have written Toucan Hobby asking for advice, and a possible return.

When I get a new HL Abrams or repair this one, I will fill the 6 holes on the bottom. They are natural dirt traps.

[tank_me]

I have modified my Abrams turret by cutting the rear up angled portion off and attaching it to the top of the turret. That way the basket doesn't interfere with opening the turret as the basket mounting point span the top piece and the lower piece. After the modification the basket now only connects to the top half of the turret. The turret is also held together with magnets so whatever that damage is from shipping wouldn't be an issue.

[keilau]

I have modified my Abrams turret by cutting the rear up angled portion off and attaching it to the top of the turret. That way the basket doesn't interfere with opening the turret as the basket mounting point span the top piece and the lower piece. After the modification the basket now only connects to the top half of the turret. The turret is also held together with magnets so whatever that damage is from shipping wouldn't be an issue.

Thanks, _me

I have not been able to gain access to the upper/lower chassis holding screws yet. The cover pieces are very tight fit. I am very careful, not wanting to break any piece. I used very sharp edge, thick knife to pile the covers loose but to no avail.

[keilau]

Thanks, _me

I have not been able to gain access to the upper/lower chassis holding screws yet. The cover pieces are very tight fit. I am very careful, not wanting to break any piece. I used very sharp edge, thick knife to pile the covers loose but to no avail.

I finally have this figured out. The rear screw hole cover has 2 hinge looking tab which are actually latching tabs. Use a sharp object to pile under them gently and the cover pop out.

[keilau]

Working deliberately on the Heng Long torsion bar Abrams. I got the tank, Heng Xin gearbox and Mato sprocket, idler and road wheels from Toucan Hobby.

1. The Abrams is a big tank with lots of room for the gearbox. I have the High-low gearbox pair per Toucan recommendation, but I should have gotten the Mid low instead. The high gearbox is almost touching the upper chassis half and interfers with the on-off slider switch. I cut off some of the switch mounting plate to avoid interference. I put heat shrink tube over the switch terminals to prevent short.


2. The Mato idler and road wheel all have ball bearings and work very well with the HL suspension arms. Much, much tighter tolerance than the HL plastic parts. I like the rubber tire on the Mato wheels which I can remove for painting the metal part.

3. The Mato sprocket is another story. The tooth pitch and outside dimension match the HL plastic parts and work well with the HL plastic tracks. However, the Tamiya tracks (33.20mm wide) does not fit the Mato sprocket (33.14mm wide between outer plates). The tooth plates on the Mato sprocket is 0.5mm thicker than that of the HL plastic sprocket. The Tamiya track is 0.6mm wider than the HL tracks making it 0.06mm too wide for the Mato sprocket.

When I do some research and found that Mato market 2 type of sprockets for the Abrams, with and without middle track guide at about the same price. I wonder if the sprocket with track guide can be 0.1mm wider? I can buy either the track guide only or the sprocket with track guide. I did not do it yet. First, I don't know if the sprocket with track guide is wider. Second, the Mato Shop minimum shipping charge is $18.

I am trying to separate the 2 sprocket half and put a shim inbetween. So far, no succes separating the sprocket yet. Any suggestions?

[keilau]

I will pay whatever the Mato Shop want to charge me if the sprocket is wide enough for the Tamiya track. Anyone has any information?

[keilau]

I gave up on the Mato sprocket and ordered an unassembled Heng Long sprocket from BangGood. $18 shipped from China.

I like sprocket comes in 2 half making track installation much easier.