Jump to content
Sign in to follow this  
Nikko85

RadioShack Jeep Renegade Jurassic Park Conversion

Recommended Posts

I know not strictly a Tamiya, but I always think it's worth sharing builds like this, as these Tandy/Radio Shacks are available quite readily but there's not always much information available. Once again this is a truck made by Taiyo, under license from Tandy. Whereas trucks like the RadioShack Off Roader 4x4 have plenty of build videos and information about hobby grade conversion, information for this one is a little thin on the ground.

It's 2WD, three speed and fully digital proportional. It's around 340 mm long (including tires) with a 181 mm wheelbase, which makes it around 1:13 scale. Oddly enough it was sold as 1:10, but that's just not true. With a 181 mm wheelbase the body would also fit nicely on a GF01 with a flipped rear arm, or a MF01x with a 185 mm wheelbase (give or take a few mm) and the long wheel arches at the front give more flexibility for a range of wheelbases. Tires are lovely, soft rubber and 75 mm diameter. I think with a pinch they would work on an M Chassis Wheel.

I have been after a toy grade Jeep for a while, so this was a nice score. The Jeep part will be important for part 2.

a7FvGj1.jpg

Overall the car has hardly been touched, an although the electronics are a touch temperamental, it's just amazing everything works at all after so many years.  Usually when something of this age arrives the electronics are gone, making it easy to rip them all out and start again. This time I decided to convert it into a modern runner using hobby grade gear but I'll not make any permanent mods so I can back to the original spec if needed. This means no extra holes, removal of any plastics, or gluing to the chassis.

First step, body off. Reminds me of a CC01.

nwBu1Qp.jpg?1

I took numerous photos of the original electronics so I can replace if needed. Really is pristine.

First real job was replacing the servo. I've often found this the hardest part of conversions (especially if you want to be able to go back to the original without serious mods to the chassis) so it's where I start to know if the conversion will even be possible. Thankfully Radio Shack used their own servos that were the same basic dimensions as regular RC servos:

tkXKyYP.jpg

 I found a step screw with a 3 mm spacer that meshed perfectly with the original steering rack. The end of the step screw is the nub that slots into the servo saver: with these old cars you really need to run a servo saver, otherwise something in the steering mechanism can easily pop.

The servo slots right in, with a small piece of double sided foam tape that the back to stop it moving backwards.

My first plan was to use the original transmitter. Using an old Acoms Rx with the right crystal I was able to get the throttle working with a Mtroniks Viper ESC as well as a steering servo (even going the right way). However the steering servo had an issue, when plugged in it was fine, but if I were to ever turn off the Tx (or the Tx were to go out of range or lose power) before powering down the the car the servo would flip 180 degrees. This would rip the servo out of the steering mechanism, causing real damage. I tried a few servo, some of which didn't move much after power loss but were in other cars or had other issues, so I'll keep looking. Oddly enough I think the really cheap Amazon ones might be my best bet. If I can keep the old transmitter on crystal tech it would be pretty cool.

So, that's where we are now.

Next steps are:

  • Solder in new wires for the power. I want to keep the choice of the 4 x C cell batteries, whilst also allowing for a smaller 7.2 volt pack for more speed and weight reduction. 
  • Connect all the new electronics
  • Work out a way I can get a three position micro servo to change gears (I think I can if I hack my GT3C) as that would be amazing. Might be too much work? 

For the body, I am going to add doors and a Jurassic park livery, but let's do the electronics first.

 

 

  • Like 2

Share this post


Link to post
Share on other sites

A little more work on the servo. The step screw was very slightly under the size needed for the steering mechanism, so I used some wire heat-shrink sleeves to expand the diameter a little. This gives a much snugger fit with much less play, leading to more accurate steering.

QFdBbzw.jpg

With this done I was able to focus on the electronics.

I am using a Mtroniks ESC for this. The ESC attaches via a Tamiya plug to the positive and negative terminals of the original battery holders, meaning I can use 4 C cells for original power. From the terminals I also wired in a Tamiya connector, which means I can use a 6 x AA pack instead, for 50% more power. The Mtroniks ESC is great in this role, as it’s designed for 4 cells, so there is no shut off at lower voltages.

The motor is a rather odd a Mabuchi 365 micro, which is larger than a 370, but smaller than a 380. From what I can gather the main use of this motor is in hairdryers, and in fact this motor looks identical to those still sold by Mabuchi today, 35 years later, so it’s good to know I’ve got options for a spare. I guess being a hairdryer motor it should be quite good at high temperatures?

As I mentioned to car came in great condition, but both the knuckles have stress fractures, and one was so cracked when the car arrived the wheel had come off. As I don’t want to be worrying about wheels popping off I starting learning how to 3D print to make a new knuckle.

I work at Imperial college, so we have a few nice bits of tech – including an ABS 3D printer. A play with the software (very basic) lead me to this design

EeOoiIP.png

 which with a bit of tweaking led me to these:

rTVffGm.jpg

bdBvMIv.jpg

 

Which worked perfectly. I hope to print in black, white or red once I find the ABS stock and can learn how to add new spools. The axle is a push fit into the knuckle, it might be I need a tab of glue to keep it secure, but it's a tight fit.…

At 7.2 volts there is more than enough speed (in fact too much as it will roll over) so I may trial a 5 x AA battery pack instead. Steering could be tighter, but there’s nothing I can really do for that as the whole mechanism bottles out. With zero suspension you don't want too tight steering as it means roll overs are too easy - for anything but driving indoors the turning circle is fine (or technical crawling, but that won't happen!)

The low gear is pretty low, which is great for rougher surfaces. It accelerates quite slowly on high gear, which makes it much more realistic. A servo that could move up the gears would be amazing – that would need a new radio gear which would cost more than the car. Of course it’s nothing like as competent as my MF01x on a trail, but it has a real old school charm that makes driving it really fun. Slow, scale speed and looks with enough speed on fast gear to make it a little exciting. 

Now I've been looking for a Jeep for a reason, and what you are all waiting for, to make a Jeep from Jurassic Park.

Now it’s not quite the right model (Renegade vs Wrangler) nor quite the right year – but it’s close enough. The headlights are the wrong shape for example but I can get over that.

So the plan is:

  • Fabricate a door and add on to the car. A working door with hinge would be cool, but I’ll probably just glue on. Could 3D print one, or use plasticard. If 3D printed I might be able to add a wing mirror (somewhat iconic in the film)
  • Add metal wire and  a hook over the fake winch to make slightly more realistic fake winch (also a little iconic, no dilophosaurus here please..)
  • Paint the light grey parts
  • Add some JP stickers (eBay sell a few in 1/16 size, which should work well…)
  • Add Edgarmon as a driver

And that should be it. I may yet decide to put the body on an MF01x to make a really nice small scale 4x4 with a low turn motor, but I'm quite enjoying this design to be honest.

 

 

  • Like 2

Share this post


Link to post
Share on other sites

Excellent!

Very cool that you’ve dipped your toe in the world of 3D design and produced something so usable straight away!

Also, chuffed that your getting to build the JP keep. I  know it’s been on your project list for some time!

 

  • Like 1

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
Sign in to follow this  

×
×
  • Create New...