Jump to content
kontemax

Runner Boomerang refurbishment

Recommended Posts

Amazing creativity and craftmanship Massimo!

I'll for sure copy the gearbox mod, thx! :-)

  • Like 1

Share this post


Link to post
Share on other sites

It's a simple modification that needs only a squared mini file and 1 mm of plastic filed away.

This will increase the torque at the wheels and the model acceleration. This allows hotter motors with more rotations per minute.

You run on technical tracks with short straight lines. This modification is for your Hot Shot.

Keep in mind to use only steel pinion gears.

Max

Share this post


Link to post
Share on other sites

Finally I discovered what kind of material is this:

Boomer_031.jpg

Tufnol.

It is a cotton reinforced bakelite.

Max

  • Like 1

Share this post


Link to post
Share on other sites

My faster motor is a 6 x 2 turns that I rewinded and balanced by my hands. It made something more than 68.000 rpm eheheheh! Never used on a model.

Max

Is prohibited by international laws.

Share this post


Link to post
Share on other sites

Ahahah! I didn't read the quoted line.

Yes, that motor is furious and when it ran on the bench I was scared that something could explode...

I don't own an esc that can manage that powerdrain.

Max

Max?! It was a joke concerning motor turns :rolleyes:

Share this post


Link to post
Share on other sites

This model is still under refurbishment.

I need to find a good used vintage front gearbox to continue the job and a good used chassis.

Max

Share this post


Link to post
Share on other sites

I have quite a few spares for this model, did you just need the gearbox halves or a complete unit? if you have a list of all you need I will take pictures for you :)

20150805_121125800x450.jpg

  • Like 1

Share this post


Link to post
Share on other sites

Hey there Chevelle, where on the planet do you live?? I have a HotShot to rebuild(big surprise) and I was already seeing that one half of my front gearbox is cracked rather big time.

Share this post


Link to post
Share on other sites

Hey there Chevelle, where on the planet do you live?? I have a HotShot to rebuild(big surprise) and I was already seeing that one half of my front gearbox is cracked rather big time.

Hey mate, I'm located in Melbourne Australia :) Which side do you need :blink:

Share this post


Link to post
Share on other sites

Hi, many water is flowed under the bridges and inside my home (maybe somebody knows) and now it's time to relive this thread again.
Finally I got the spare parts for the front gearbox that is totally broken.
They come from the Australia (thanks Chevelle) that is in the opposite side of the planet respect of the Italy.
Anyway the parts are vintage and not re released and are used, as requested, but are in perfect shape.
Now I will disassemble the front end of the car to replace them.

Boomer_099.jpg

But I must complete the rear end before.

Max

  • Like 1

Share this post


Link to post
Share on other sites

Ok,

time to come back over this project.

After the replacement of the rear gearbox now it's turn of the rear arms.

The lower rear arms are prone to breakage so I made years ago an alloy version to solve the problem forever.

Here you can see them assembled to the gearbox.

Boomer_083.jpg

I decided to eliminate the screws and replace them with some homemade steel suspension shafts. They are not nice like the Tamiya's ones but they work. I perfectly know that the aluminum arms could break the rear gearbox so I also made a Carbon Fiber brace between them.

Boomer_084.jpg

I could replace the upper rear arms with some adjustable turnbuckles as many people do but I decided to keep the original configuration. The positive camber of the Boomerang rear end has been eliminated with the aluminum lower arms that are a couple of millimeters longer than the original plastic arms. This will decrease the oversteering of the model.

Boomer_086.jpg

Another tip to save the upper arms. They always break in the suspension stoppers. This is a lack of design. I decided to eliminate the contact between the stoppers reducing the stoppers height on the gearbox. Now are the dampers that decide the end of the suspension movement. With this little modification I save the arms and I increase the rear ground clearance.

Boomer_087.jpg

As I said this model mounts the super rare vintage universal joints from Hobbyco Japan.

Boomer_088.jpg

I would like to use modern CDVs but this is impossible at the moment due the ball differential bigger outdrives. I'm planning to realize some new differential outdrives compatible with the modern CVDs but not at the moment.

Diff_project.jpg

I replaced the triangles with 12 mm exagonal wheel mounts.

Boomer_089.jpg

That's all for the moment.

Max

  • Like 2

Share this post


Link to post
Share on other sites

Thank you very much mates!

Well, let's go on.

Here you can see another little modification. These UJs are a little bit constrained inside the suspension and they touch inside the differential drive cups when the suspension is fully compressed. So I decided to to move the inner ball bearing position more outward to gain a couple of millimeters needed to leave the UJs to run free.

Boomer_090.jpg

You can see that the inner ball bearing is deeper than the original rear hub.

Boomer_091.jpg

The result is that the wheel axle has a little bit of movement. I will add an outer spacer.

Boomer_092.jpg

With this modifications the Boomerang rear end is different from the original, it is wider and the camber is negative, finally.

Boomer_093.jpg

Boomer_094.jpg

Next step is the propeller shaft.

The original 1 mm thick steel wire propeller shaft is a solution that I don't accept. Too much torsion, power loss, noise and vibrations.

My solution has been to create a Top Force style propeller shaft with a 3 mm thick steel wire and modified propeller joints. I also added two silicon tubes to reduce ulteriorly the noise and the vibrations. Now the part is perfect.

But I made this work before the Hot Shot re release so now there's a new choice, the HS dogbone style propeller shaft.

Boomer_095.jpg

Yes I perfectly know that the second choice is nicer than mine but the dogbone shaft touches somewhere into the chassis and it needs some work to fit properly. I will decide in the next future.

Boomer_096.jpg

That's all for today.

Max

  • Like 5

Share this post


Link to post
Share on other sites

Last step to complete the rear end: the dampers.

I was thinking to change the oil into the dampers but I will use the model again in march when the local track will re open again for the summer season so no reasons to make this job now.

Anyway the dampers are Duratrax with carbon nitride coated shafts and and teflon piston plates. They are silky smooth and don't leak oil so I only washed them.

Boomer_097.jpg

A little tip to get a smoother movement is to work the ends of the springs. I used original Tamiya Springs because they are the correct stifness for this model.

Boomer_098.jpg

Now it's time for the front end.

Max

  • Like 1

Share this post


Link to post
Share on other sites

Wow great work Max! Next step on mine is to get the slop out between the rack and steering servo. I have a bit of brass that I'll work into shims.

Share this post


Link to post
Share on other sites

In the next days you will see what I did with the steering rack.

I believe you will be surprised about it.

Max

  • Like 2

Share this post


Link to post
Share on other sites

In the next days you will see what I did with the steering rack.

I believe you will be surprised about it.

Max

Ooh I'm looking forward to it :)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...