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LongRat

Full Option Ultimate Grasshopper

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Here's my take on what an unlimited Grasshopper should be, if it wasn't built down to a price and complexity budget for beginners as the standard car is.  I've always wanted to build a Grasshopper that actually reflects the car on the box art.

It is a long travel, trailing arm buggy, with a 6061 billet aluminium chassis as the core of the vehicle.  Buckle up ;)

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Going to make some tweaks after quite a hard bashing session, pretty happy for the first iteration though.  Going to up the front travel and increase ground clearance all round.

 

IMG_20210403_194316069.jpg

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Just seen this. Absolutely great looking Grasshopper, if you still can call it a Grasshopper. Seems to be way beyond of it. Cool car. 👍😎

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22 minutes ago, Superluminal said:

Wasnt expecting that!

How are the rear wheels attached to the arms?

A drive dog that is compatible with my alloy wheels and some standard Tamiya rims.

This area is part of what I am planning to change, to a portal style setup to get more ground clearance and reduce driveshaft angle.

IMG_20210403_214721994.jpg

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Brilliant stuff! Feel free to document everything you do in the workshop with a metric ton of pictures :) 

Incidentally, is there a list somewhere of the stuff you’ve got for sale, as the full option website might not be entirely up to date in this respect? 

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Thank you, I'm going to update the web site soon with more project details but I tend to keep the parts for sale on Facebook, and sometimes eBay. Currently working on some custom one-off commissions but always happy to help with requests where I can.

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Ah, thanks -then I’ll have a look there. Also did a search on here and found quite a few, which I obviously should’ve done before complaining about your website, sorry about that. 

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Absolutely WOW!!!! 😲  Jaw Dropper! 

Is ANY of that adaptable to a stock GH Tub? I understand the total custom made aspect of this.... But maybe some of it could be adapted to the Stock Tub (albeit with heavy modifications)?? 😉

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Cheers Carmine.  The remaining standard Tamiya parts left on this are all DT-02, originally this project was intended to be a long travel variant of that platform.  To make it work properly it's going to end up being almost devoid of DT-02 items as well.  There is nothing on here which has any compatibility with anything on a standard Grasshopper, aside from the wheels.

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With my previous tested set up, I couldn't get the rear droop I wanted without putting an uncomfortable angle on the drive shafts.  I decided to make a portal hub set-up, to drop the rear axle line while keeping the diff high for clearance, and minimising the driveshaft angle. The portal housing is tiny so it fits inside the wheel with just enough clearance.  Those gears are less than 10mm diameter, it's all a bit tight in there.  So far, it's working out well.

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Brilliant!  I am in awe of the abilities of so many people on this forum, especially when it comes to custom made stuff like this. I am also quite envious of the time, equipment and knowledge required and that I don't have myself!

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Portal hubs are complete and on the car.  Got the stance, clearance and look I was going for.  Just waiting for a program card to reverse my motor and set up the ESC and she'll be off for a test!

IMG_20210620_151526908.jpg

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Amazing stuff, we’ll done and I’m looking at with a very jealous eye 😉
 

The Brushless ZTW set up in my Blitzer ran backwards as well. 50% forward/ 100% reverse. So I looked up on YouTube and you can swap two of the motor wires over to get it to run the right way.

Obviously having gone to do much time and effort with your GH a Program card is better but at least you would be able to go for a quick spin until it arrives 😁

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7 hours ago, Re-Bugged said:

So I looked up on YouTube and you can swap two of the motor wires over to get it to run the right way.

 

This only works for sensorless motors by the way. If it's sensored, the sensor won't pick up the signal properly and it won't work. There are ways to reverse some cables in the sensor, but you are better off just reversing it through the programming.

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You actually can reverse a sensor motor this way but only one particular wire combination works. With sensorless you can swap any two. I need to change boost settings and the direction and this requires the program card with the ESC I'm using.

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In my tyre trawling I managed to find a 1/14 scale tractor truck tyre that I thought was a closer match to a real desert tyre used by these buggies.  I have bought a whole load of tyres to check the look and feel, but this is the best so far, so it warranted a wheel to mount it.

I'm very happy with the way it looks, I it would be just perfect if I could find a high profile rear tyre with maybe 5mm more diameter and I would be 100% happy.  But good for now.

IMG_20220122_215912952.jpg

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On 6/27/2022 at 1:57 AM, tilstad1 said:

Amazing! How is the handling, and how do you like it when running it?

Thanks, actually I have been constantly modding and tinkering with this for many months.  Not a lot of running, but when I have it has been on very beaten up ground and I've also done a few laps of an Astroturf buggy track.

The result?  In its form shown above in the thread, for me it handles kind of too well.  It corners flat and smoothly, and doesn't have as much of the heave and roll of a real buggy.  In some ways it is too close to a racing RC buggy.  The latest round of mods are aiming to change that.  I'm almost done with the new wheels so I can run the 1:14 big rig tyres all round.  That will raise the CG and increase clearance, and reduce grip I expect.  I couldn't keep the portal gears together without ripping them apart (even moved to hardened steel gears but they just can't handle the torque at that size).  So new parts for the rear end will be needed and a scratch built gearbox to drop the outdrives without compromising ground clearance.  I'm in no hurry, this is my favourite side of the hobby.

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That is an excellent build!

Drop outdrives->will you be putting something similar-to-but-more-robust-than the portals you tried on the sides of that gearbox to do it?

More heave/roll, progressive springs that are softer to start off?

With the initial design of the rear swings i think you could fit bolt on portals on the inside of the arms to avoid a custom gearbox, if you are happy with the current one, should have space for larger and wider gears:

o0hiwk3.png

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On 6/29/2022 at 9:21 PM, Ziddan said:

That is an excellent build!

Drop outdrives->will you be putting something similar-to-but-more-robust-than the portals you tried on the sides of that gearbox to do it?

More heave/roll, progressive springs that are softer to start off?

With the initial design of the rear swings i think you could fit bolt on portals on the inside of the arms to avoid a custom gearbox, if you are happy with the current one, should have space for larger and wider gears:

o0hiwk3.png

Outboard portals are basically what I had before.  The size is constrained by having to fit inside the wheel hollow itself.  If the portal unit is pulled out of the wheel too allow for bigger gears, the drive shaft would be effectively shortened and the angle increased even more.

My intention is to make a whole new gearbox for this car, which has drop-down gears like a portal attached to the diff outdrives, bringing the inboard axle line much lower

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