Used Challenger Strip and Rebuild.

[zooma]

The set of new springs arrived nice and quickly from HAYA, so I will have another go at getting the suspension settings that I would prefer to have.

The springs that have come look a little more sturdy and less shiny than those on the tank (from memory) so I will take the "troublesome" (L3) spring off first and see how firm it feels compared with these replacements.

Fitting and removing these springs is not a job that I enjoy at all, so I will be pleased to get it done and "out of the way".

[zooma]

Cardboard template with alloy side rail.

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After much thought about using or not using chassis reinforcement, I decided that I would like to make something to stiffen the chassis after seeing just how wobbly it was when I took everything out to clean it and check it over.

I still like the idea of making a wooden inner construction, but I need a little more time to sort this out, so I decided to make a frame from angle alloy (as so many others have already done before me), and I just happen to have some strips of 20mm x 20mm angle alloy left over from when I used to make 1/16 scale Wedico model trucks where this material was used to make various custom length chassis.

I took some serial packet cardboard and made a replica of the angle alloy and used it to make a template for the holes that need to be drilled to make space for the mounting posts that will be covered by these angle alloy ladder sides. A felt tip pen was rubbed over these body mounts, and then the card was aligned with the front of the hull side and pushed over it to make an imprint to determine the position of these mounts so I could accurately drill some holes for them to push through. The hole was the cut out with a paper punch.

The length of the side rail was decided at 13.5" long (143mm) and two were cut to length from the angle alloy and marked left and right to make it easy to orientate any hole positions that may follow later.

The card template was used to mark the holes needed to clear the body mounting posts and drilled. The side frames drop nicely over these clearance holes so I just need to file away some of the plastic moulded webbing between the inner hull sides and the body mounting posts to allow it to "sit" nicely into the hull......although the alloy axles for the return rollers look like they will also slightly foul the bottom line of the angle alloy, so I will need to check for this (after I have made the opening in the moulding webs to allow the frame to sit down into the hull fully) and cut some scallops to clear them if needed.

[zooma]

Once the angle alloy is cut to length and small adjustments are made to it and the moulded hull to allow it to "sit" nicely, it becomes obvious that the hull sides are not at 90 degrees to it's flat tops - but the angle alloy has a 90 degree angle that cannot be easily adjusted to match the angle of the hull sides.

The angle alloy needs to fit flat on the top of the hull and inserts (tongues) of the cross pieces need to be made to touch, but not push the side rails outwards.

When cutting the two alloy cross pieces, I had to experiment with the shape of the "tongue" part that fits down in-between the side rails. Once the angle had been determined to allow the top for the angle alloy to sit flat on the top of the hull without distorting the hulls original moulded shape it was copied to make a pair of them.

The fit of these cross pieces was checked by allowing them to "drop fit" between the side rails without pushing the moulded hull outwards. Once this was achieved the tops of them were bent to make a "tab" on each end to fit flat on top of the side rails.

A final check of the finished pair of cross pieces was to fit each of them at the front, and then the back of the hull. This was repeated with each cross piece facing in the opposite direction to prove that they were a mirror image and made no difference where they were to be fitted or which way they faced.

The centre of each tab was marked and drilled to take a 4mm button head stainless screw to be fitted with the head on the underside to give as much clearance with the tracks as possible.

[zooma]

Minor adjustments were made to the angle of the top "tabs" to make sure that they sat perfectly flat against the top surface of the two side rails after selecting the best place to fit them.

Meter rat had already told me that he used 4mm stainless screws to fix his chassis reinforcement frames and as his has been a very successful installation, I also chose to use 4mm stainless steel screws, washers and 4mm Nyloc nuts to secure them.

The closest size of stainless steel screw that I had in my workshop were 15mm cap-heads, so I used 4 of them to fix the two long side rails and the two cross members to the chassis tub using a stainless steel 4mm washer on the underside to help spread the load and another on top of the alloy rails - mainly just to look nice, but also to stop the Nyloc nuts digging in to the comparatively soft angle alloy.

The 4 cap-head screws were tightened firmly but not over-tightened as I did not want to stress the moulded plastic chassis.

With the alloy frame installation completed, I tried to twist the chassis tub and found that the very floppy moulded tub was a LOT less easy to twist and was much more rigid, but it still possible to "twist" it very slightly.

I have some concerns about moving all of the previous chassis twisting strains onto just four 4mm mounting screws on each corner of the alloy frame and I am considering spreading the load more evenly by either gluing the long frame side members down onto the flat top of the chassis (this would make it harder to remove the frame if it was ever needed to be removed) or to add an additional pair of 4mm fixing screws along each side of the leg rails.

Another cross member was also made, but it would have to repositioned very close to the front of the gearboxes to clear the turret turning motor or fouling the gun elevation unit or getting in the way of the movement of the wires as the turret was being turned, so this idea had been dropped (for now) and this cross brace could be used on another frame in the future.

The cap head screws may well clear the tracks but I would like to improve the clearance by changing them for some "Button Headed" stainless steel screws (as originally intended) and the lower profile "dome" shaped heads would be much more likely to encourage the tracks to slide over them if they should ever come into contact with each other.

Since I need to order some stainless steel 4mm Button Head screws, I will buy some that are 12mm long so they end flush with the head of the Nyloc nuts to look a little neater.

[zooma]

The turret was checked to see if it could turn freely with the "turret turning motor assembly" clearing the extra cross brace if it was fitted in front of the gearbox position - and it did - so I have fitted it and also added an extra pair of 4mm screws between this extra brace and the front brace.

With four 4mm screws now securing the long chassis rail on each side (8 in total), and the additional third cross brace added, the chassis now has ZERO flex or twist even when applying a fair bit of muscle to each end of the chassis, so hopefully this will help to stop the tracks being thrown off when being driven over very rough terrain.

The front cross brace was also turned through 180 degrees (to face the other way) and that has allowed the speaker box to be moved forwards (underneath it) by almost 20mm to maximise the available space for the Clark TK24CH board and the LiPo battery pack inside the tank.

Once the 12mm x 4mm stainless Button Head screws arrive I think it will look quite tidy, and with 8 fixing points now holding this frame to the moulded plastic chassis I have doubled the number of screws that can help to "spread the load" across it a little better than the original 4 would have been able to do.

I have enjoyed making this chassis brace along similar lines to the one that Meter rat made and fitted to his Heng Long Challenger 2, and I hope that it will perform as well as his has done.

If this chassis reinforcement works well, I will make another one (slightly modified) to fit my Challenger 2 "Rat Catcher" project that I am slowly working on in the background, but first I want to get this used Challenger 2 fully "sorted" and back in action again.

[zooma]

The suspension has now been set up with P1 and P6 adjusted to HARD, and P2 - P5 adjusted to SOFT. This will be a starting set-up to see how it works.

With seven years of use by its previous owner, and no idea if this was the first owner, this is a very old chassis and it does not have the same simple type of screw operated track tension adjuster as the more recent and current Challenger 2 models have.

I have not taken the front return wheels off yet, but it looks like the track adjusters may be the early original non-adjustable types that are only dummies?

When I get the tracks re-fitted I can check to see if any adjustment is needed, but the tracks certainly looked like they were a little loose when I acquired it so if the chassis has been "sagging" under the weight of the metal running gear and tracks, the metal chassis reinforcement may help to tighten it up a little?

The stainless cap-head screws will be replaced with button head screws when they arrive to give better clearance for the tracks.

[Pavel]

This "realism" will be covered by side panels.......
And sagging tracks are the way to them jumping off.
This is not a real tank and it requires tensioned tracks......
You are so carried away by "strengthening" the body, as if you are preparing for truck trial......

[zooma]

The body has been lifted to show how slack the track tension was that this tank had been successfully running with.

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This "realism" will be covered by side panels.......
And sagging tracks are the way to them jumping off.
This is not a real tank and it requires tensioned tracks......
You are so carried away by "strengthening" the body, as if you are preparing for truck trial......

Hello Pavel,

You have expressed your views about not being in favour of strengthening the chassis previously, and if you don't run a LONG CHASSIS tank over extreme (often muddy) rocky terrain with climbs and drops etc there may be no need to do it.

Having said that, there are a lot of owners of the modern LONG CHASSIS Heng Long models such as the CHALLENGER 2, ABRAMS and LEOPARD 2A6 that have not found it possible to run them with heavy metal tracks (and running gear) without throwing a track - even on less demanding terrain than that mentioned above, and they have solved this problem by stopping the chassis flex.

1/16 scale r/c tanks that have a shorter wheelbase (such as the Russian T70 and T90 and most WW2 tanks) may not suffer from throwing metal tracks (to the same degree) - because the shorter chassis do not FLEX as much as the three longer chassis Modern Tanks referred to above.

Maybe you don't have any experience of running any of the three long chassis modern tanks mentioned above over rough undulating ground after they are made very heavy by the addition of all metal running gear and metal tracks etc - a situation often further complicated by the need to use extra power to drag these "over-heavy" tanks across extreme (often muddy) terrain that most owners would not want to risk damaging their models on.

The heavy LONG CHASSIS of the Heng Long Challenger 2 Modern Tank pictured above has been run "as seen" in the picture above for the last 7 years!

It has heavy metal tracks and all metal running gear and powerful RED motors, and yet it has been run both with this SLACK track tension and no chassis reinforcement !

I have seen video of it being run fast over a loose surface ground to prove this - but I have no idea how it would perform over the sort of terrain that it will be subjected to in the future.

This tank both defeats your argument about the tank needing "tensioned tracks" and (to a degree) my reason for wanting to reinforce the chassis, so it just goes to prove that neither argument can apply to all tanks.

I have no plans to run this Challenger 2 with such a loose track tension over the terrain that I have in mind, and I have reinforced the chassis because I want to drive it without having to worry about it throwing a track when being driven through mud and when climbing up and down severe terrain that I know would defeat it without some form of chassis reinforcement.

Have a nice weekend,

Bob.

[Pavel]

I have a Challenger 2 and a Leopard and now a Merkava. and ALL of them have iron tuning.
I have been modeling for many years and we ride in a club on difficult tracks.
I am very sorry that I cannot give you a link to YouTube.
On the contrary, we dress tanks like the Tiger in iron....
As trite as it may sound, it is the short-wheelbase ones that lose their tracks.
I am not trying to convince you otherwise, I like your work.

[Meter rat]

I am enjoying this build a lot. Your chassis brace is overkill even by my standards. A link will definitely need to be taken out of the tracks.