Throwing tracks
 

Hi,
I have secondhand Heng Long tank and it work ok most of the time; however, it has a habit of throwing one of the tracks.
By throwing I mean the track jumps so that the rear sprocket is no longer between the track tongues that should be either side of the sprocket.


What should I look for to repair the fault?

I'll try to help. Best if we knew what model of tank. Always give the make and model of your tank for inquiries. Rear sprocketed tank makes us think KV, M26, etc....or you have your tank terms confused. Could be a Tiger? Check to make sure there is nothing stuck in the wheels, sprockets or idler. Is the track too long/slack?. What are you driving it on(grass, dirt, floor)? Stay away from small gravel/rock & wood chips. Is your "Sprocket" ( I'm betting it is an idler by your description) loose, broken or misaligned. It is not adjustable so make sure all the wheels are aligned and running true. Flip it over and use a ruler to check it w/o the tracks on. Make sure the gearboxes are tight too and not wobbling. Also look for loose bent track pins or bad/bent links. Hope this helps. Bob

Hello Truebuild,

Can you give us a little more information?
Which HL tank do you have?
Are you running metal Sprockets and Idlers - Suspension?
Metal or Plastic Tracks?
What Conditions cause the track to come off, turning, running straight, rough ground or smooth?

Photos might help as well...

Regards,

-gus

Rear drive tanks are very prone to throwing tracks. Things you can do to improve the the situation , increase the tension on the springs in the corners (the rear wheels on either side most inportantly) by clocking them. Make sure your tracks are properly tensioned. Bobs advice is good, misaligned wheels are your enemies.

if your tanks a front drive some idler tension adjusters will help, if your tracks are too loose they become more prone to skipping.

Based on the description, I think @Truebuild meant idler wheel at the back.

Throwing tracks
 

Sorry to all for expecting you all to be mind readers :(

The tank looks like a Tiger 1 (what you guys call an S/S?) all plastic tracks and wheels with no modifications.
The drive sprockets are at the front.
The track always moves off the back left (idler) wheel towards the outside so that the inside track tong guide falls inside the rear idler wheel.

After you guys comments I have measured the track slack at the 4th (5th wheel if you include the drive sprocket wheel) sprung wheel back from the front and the left track (the one that jumps) is 25mm slack and the right track is 22mm slack.

Can the sprung wheels be adjusted or do I need new springs to increase the tension on the tracks.

I have this exact same problem. With the same tank. You would have one or both problems, too many tracks or too much play in the idler wheels. Watch the rear idlers on the tank while driving it, see if it is turning and not simply having the tracks dragged across it. If your rear idler isn't turning much, that tells you some things, that probably have too many tracks and can remove one or two or, your idler screw is too tight. Even if the idler wheel is turning of course you could still have too many tracks.

First start by removing one or two tracks to make the whole assembly shorter. On the Tiger 1 you can remove 1 track at a time until you can't remove anymore, (on my King Tiger tracks you have to remove minimum of two, or none, because of the way they are made). I think i wound up removing 2 each side (From 97 tracks to 95 or something like that). And this helped keep the tracks in place a lot longer but did not fix the problem completely.

With mine part of the problem is too much play in the idler wheels. There's no way to eliminate all of the slop but often you can reduce it. If you can find bearings that fit inside of it, or metal wheels with them at the internet parts shops, that might work.

I fitted metal suspension arms because the plastic arms would allow the wheels flex outwards. Also "upgradE" susp arm springs that are stiffer and this helped some. But until I get the play out of the rear idler wheels I am going to have the problem still. trying to fix this issue it is very easy to find yourself throwing money at the problem. If the cheap ways of fixing the track throwing issue don't help, a decision has to be made on how much does this problem bother you and how much into the hobby are you, and what you can afford-sometimes after all the low cost mods have been done, simply slowing down on turns is enough!

Hopefully after trying all the low or no cost options that will keep the tracks from going out of place, that and just slow down on turns. If none of those things work, the only one left is to either buy the Taigen lower hull, (which has all the things i just mentioned already fitted, has adjustable idlers and metal susp arms with stiff springs. Also the Taigen hull has metal reinforcement so the hull is stiffer and won't flex much, and is just better in every way then the hull that comes with the tank) for about a $100, or get the Henntec idle wheel tensioner, for about $70. If you finally have to choose one or the other, I'd choose to just upgrade the whole hull instead of the Henntec. Since the Henntec adresses part of the problem whereas going to the Taigen hull might be a more comprehensive solution.

I have the same problem with my pantiger since it use Tiger I hull. I'm 99% sure it's because too many tracks. I have not yet removed a link or two yet though. I thought about slow turns but it's hard to achieved it with Heng Long 2.4GHz. Neutral turn when turning helps a little bit though. I didn't test this extensively unfortunately. I have metal idler wheel & tracks. Too much play in the idler wheel is a possibility too. I did researched a little bit on how to fixed this. Track tensioner & metal bar to stop hull flexing always come up in my search.

@Marc780, do you have picture how to install the ball bearings in the idler wheels?

Throwing tracks
 

Having now stripped the tracks, suspension arms and wheels (suspension wheels between the idler wheel and the drive sprocket wheels) I believe the fault is the suspension.

One of my suspension tension springs was not located correctly causing it to bind and thus not move freely and some of the others where not a free moving as they should be.

The long arm of the suspension tension arm spring must have a slight outward bend to make sure that the spring arm is always located in the suspension arm. To much outward angle is just as bad as to little as too much causes the spring to bind.

If I can obtain just the springs and the cost of postage is not silly for such light items I will buy and fit new springs.

All the above assumes that the tracks are not to long.
Since an unmodified tank has plastic bearing surfaces to much track tension will wreck the plastic bearings and introduce even more slop.

My understanding is that the key to how the track system works is the suspension system.

If the whole plastic track system is worn-out and floppy nothing other than a complete new system is going to cure it!

Not having a new tank to compare with makes evaluating the track system impossible.

Thanks all for your help.

The two main things that effect track tension are suspension height and length. HLs (and upgraded clones) aren't engineered to exacting specifications and stock, one side will be longer so you'll always be chasing balance, if not to throw tracks at least for it to track straight. They only way around it is to install a adjustable idler, just like the real thing. One link, added or removed, will never be a fine enough tuning.

In terms of height, over time if any brand model sits on the suspension, it will eventually sag. It's usually not noticed because it is gradual and the results will be on both sides. The solution for that is to store it on a block to keep the suspension off the surface when not in use. I use two pieces of molding glued together, but a 4 x 4 or a brick works well too.

Kizwan, what a lot of people do is fit roller bearings sometimes called "cassette bearings".

http://i80.photobucket.com/albums/j1...psda56a394.jpg

I stacked three of these on each other, sorry i forget the size-they fit neatly inside the idler wheel, which is aftermarket, Mato or something and not the one that came with it. But there is still far too much play. The bearings i got from the hobby shop, they are for model cars. i think i need to make a bigger axle that fits more snugly inside the bearings, and fix the bearings inside the idler. I'm using threaded rod for the idler, they fit inside the bearings but not tightly enough. I could probably fix it permanently with JB weld or some such to take out the play. JB Weld is strong enough I could build up the axle with it and sand it down to size and it would work for a long time.
I'm waiting for a Henntec for my king tiger because the tracks too long but if i take out a link it would then be too short. Also I'm waiting for metal susp arms to arrive, going to fit them because the plastic road wheels bow outwards and sometimes the teeth don't go perfectly in their grooves, and so the tracks are chewing them up.

Throwing tracks
 

>They only way around it is to install a adjustable idler, just like the real thing.
Are these available for the heng long tiger 1 tank?
and if so at what cost approximately?

I've sourced some stronger springs to cure the sagging; I will supply a link if that is allowed.

Throwing tracks
 

It looks like some tanks can work with realistic slack tracks

http://www.rcuniverse.com/forum/atta...mentid=2045660This is a Tamiya picture.

In my case, the inner teeth tracks (Tiger I early tracks) keep hitting the idler wheels even when running in straight line. I figured I need to adjust the idler wheel a little bit (move outward). Do you know any batter way to achieve this?

Link to ETO's HennTec idler for HL Tiger 1. I just Henntec on a good number of my tanks and they work quite well.

http://www.etoarmour.com/product_det...roductID=HT011

Throwing tracks
 

This looks like how it should be done...
http://www.youtube.com/watch?v=BKtIYp-skiE
Floppy tracks with a shock absorber :)

This is the upgrade part for adjustable idler wheels in an HL Tiger

http://www.etoarmour.com/product_det...roductID=HT011

@Truebuild, I figured out why my tracks throws at the idle wheel. Not throws completely but instead of the tracks teeth are the either side of the idler wheel, the inner teeth go into the idler wheel groove when turning on grass or carpet or any rough surface. This is because the idler wheel is inward a little bit causing it to misaligned. It's not new issue actually & not all Tiger I chassis have this issue. Some people replaced the stock washer with sturdy & correct thickness washer to realigned the idler wheel. It seems track tensioner or adjustable idler wheel fixed the misaligned issue as well. There you go, you can choose cheap or expensive solutions. The key is to make sure the road wheels, sprocket and idler wheel are align.