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Grasshopper 2 Ultra G - Independent Suspension All Round

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And the shell was dry when i got home from work so i got the stickers on. I give you Grasshopper 2 Ultra G

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This is set 2 of the Grasshopper2 Junior Dress Up decals i got adapted for 1/10 with MCI Racing. When for neon green on the "wings" bit kept the red for that semi-trad grasshopper look. If i had know i was going to do matching blue wishbones, and quite how noen the wheels are i think i woukd have gone blue instead of red and neon yellow instead of green. That said, i really like how it looks, and i love how tightly the shell fits the tub.

What do you think?

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A bit more fiddling. The Rising Fighter gearbox mount reduced the rear clearance and gave alightly weird rear down stance. I redrilled the gearbox mounting holes further down the slots so the bottom of the geatbox would be about the sane height as the bottom of the tub. This did mean the motor fouled the top of the mount, so more sawing and material removal.

It's a bit hard to see, but there is sloped edge to clear the motor now

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All this sawed off plastic does leave the geafbox mounting feeling a little flimsy, although it feels solid enough once bolted up. I think i am going to make a little top and bottom plate out of 1mm styrene and plastic cement them on.

Bought some more Rising Fighter D parts to replace the gearbox mounts on the kids RF that i stole for this and noticed that the sprue also contains the front shock tower reinforcements from the RF.

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The front towers on the GH2 are very thin, but the RF body also feature a large opened out moulding around the tower which the GH2 does not. Intrigued i whipped off the front suspension for a trial fit, and they go straight on!

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Result! As they don't have the moulding in the body to support them like the RF i doubt they are quite as effective as they could be, but they certainly make the tower feel stiffer which has to be a good thing!

Given that i have now pillaged Rising Fighter or common RF/GH2 parts i have to say that if you are considering building something like this, a used Rising Fighter might well be the better starting point. If you aren't obsessed with neon wheels like me, the RF comes with modern hex rear wheels and 2.2 fronts which would go straight on the Thundershot gearbox and all these better/reinforced parts. Given that the body is basically Hornet shaped you could maybe build an Ultra Hornet to go with my Grasshopper2 Ultra G? 

As you can see from the top picture its a little muddy because i got to run it yesterday. It is SUCH a fun little car. It is running 7.2 NiMH battery, TBLE-0S ESC and a Speed Passion 13.5R MMM 3300kv brushless motor with the largest 17t pinion. It is light so goes pretty well, and i can't believe how quickly i got the handling somewhere near good. Those vintage rib/spike fronts are great tyres. Shame they are hard to get now. Replaced the rear oval blocks with Schumacher CAT block blue with an insert and its great on grass. I guess although a bit of a mash up, it is fundamentally quite a good layout: rear mid motor drivetrain, forward longitudinal battery, so all the heavy bits are in a good place.

Not quite finished yet. Had a few quid spare on pay day so ordered the decal colours i think will work better and a revised front wishbone mount specifically for this application. 

To be continued.....

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My new dedicated wishbone mount arrived today. Its 17mm wider per side. The track width at the front was 205mm. About the same as the regukar GH2 as it happens. The rear is 255mm.

Although it actually handled really nicely the massive mismatch in front and rear track was bugging me. It looked weird. New part should make the front track around 240mm which should even up the looks nicely. As my 3D skills have progressed a little as well this new mount has 10 deg kick up built in too.

Original part

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New one

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I haven't got enough M3 threaded rod to make correct length steering arms so that is on order. Also had to move to the longer shock eyelet for 70mm eye to eye length to get the shocks to give decent ride height and to get the shock collar to clear the wishbone.

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Track evened out. Still narrower than the rear which i wanted for that vintage look

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Didn't go together quite as easily as the original install so i hope i haven't rukned the handling chasing a look! I guess i will find out next week once the new steering rod arrives. 

As an aside, i now have a grasshopper/gh2/hornet/rising fighter wishbone conversion part spare. If you want to upgrade your front suspension if you have one of these buggies then PM me for details.

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Got the M3 threaded rod and my new stickers today. Car is back up and running and full fluoro. Also added a section chassis brace.

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Wider front stance. Still a little narrower than the rear.

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Full fluoro and blue to match the wheels and wishbones

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Tamiya, take note. Your next model is right here... :) 

 

Thunder, do you need an agent?

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1 hour ago, ALEXKYRIAK said:

Tamiya, take note. Your next model is right here... :) 

 

Thunder, do you need an agent?

Haha. You are too kind.

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It looks magnificent, and drives just as well, from reports ;) Excellent work!

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Quick run at the local park in the sunshine. Still fun so I haven't ruined it! 

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Stance is just nice now. Doesn't look weird when driving away from me. Just what i wanted. Bit of setup work to do (i think i need thicker oil in the rear dampers) and might try and tie the gearbox to the chassis from the third - currently unused - gearbox mounting. It rocks very slightly with the current setup.

So glad a got this done after being so lukewarm on it for a while. 

Anyone interested in a part list? It's a bit isoteric and involves a lot of ball connectors!

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Since going wide on the front i ran the buggy a couple more times but wasn't happy with the handling. There was much more understeer than the original narrow front track. Played around a bit with shock length and mounting position to get some decent ground clearance and shock angle. Ended up with 64mm shock length run on the 3rd hole in the wishbone using the blue Thunder Dragon shock spacer to keep the collar clear of the wishbone. Handling still wasn't quite there but whilst the shocks were off i noticed the damping was still quite slow despite putting 10wt oil in them. They have the solid pistons from the cheap DT03 set. Yesterday some new shafts arrived (50601) and i replaced the solid shafts with the new ones and some spare 2 hole pistons from a 50519 kit. Also noticed the black, dry o rings. Replaced with some used but ok red rings from the spares box. Rebuilt with 10wt oil. Muuuuuuuuch better! And much better handling! Managed to drive 1 handed long enough to get some video 

 

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Couple of updates. Firstly Ultra G has needed some surgery as the rod end attachment simply wasn't stable enough. I am much better at designing than making as you can probably tell, but these plates made from 5mm styrene are solid.

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Secondly a few weeks ago I ran at a track for the first time and so did Ultra G! My regular grass set up of the original Super Gripper rib spikes front and CAT Block blue proved woeful on astro! Massive understeer and oversteer. Luckily i had some other tyres and some 2.2" Minipin yellow fitted lovely on the 2.1" front wheels, and blue compound blocks were switched to yellows from my DT03 buggy wheels. Much better! Had to go softer again on the rear to get the grip balanced but after that it was great. Really fun and quite fast. Fundamentally it's quite a good layout: mid-motor with longitudinal battery. Looked pretty cool out there I thought.

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Best quote was from another guy at the event: " badword that Grasshopper moves! I remember them being rubbish back in the day!" Ha! Had to bring Ultra G in and come clean.

Final couple of things today. Firstly gone to turnbuckles rear because the rear grip is a bit low and there is absolutely no camber on the stock Thunder Shot layout. Turnbuckles are random cheap rcmart purchase when i bought something else. I think they are for a GT12 but this suspension needs short arms. Few degrees of camber has definitely improved the rear end

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And finally! The front if the 'hopper2 tub is very obviously flexible between the front if the battery box and the steering mounting. Wondering about beefing this up (mainly for strength, I am under no illusions about massively improving stiffness and precision!) I came across @Pintopower with some plates to reinforce the Hornet tub. As you can see above I am useless at making things so on a whim I drew them in CAD and sent the drawing to Fibre Lyte. Under a tenner for 2mm precision cut carbon fibre?!!! Yes please!!! 

Had to (ironically) cut a little bit of the ribs away from the tub (the Hornet must't have these) but they are in place with styrene cement. Should keep the front end from falling off, but I am still wondering about a strut brace from the servo mounts to the battery box.

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This is fantastic stuff. Goes to show what can be done even with something as basic as a GH2. A thought occurred to me when reading through the thread, namely would the lower chassis gearbox mounts from the GH1 fit the slots in the GH2 chassis? I know you have had a lot of trouble getting this area to be stiff enough and in the right position in relation to the tub, mainly because you have had to butcher the various slider mounts to fit the Thunder Dragon gearbox in solidly. The thing is the GH1 mountings do hot have sliders – they are just pivots which allow the whole axle to move up and down as a single unit, without any independent movement for each side at all. I understand you might still need to get the gearbox to sit further away from the tub to get the stance right, but it might be easier to do this by sliding the mountings further down the slots in the tub and then screwing them in place, rather than drilling holes in sliders which are supposed to allow movement.

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Here you go. Parts B10 and B11. Notice the complete lack of up-and-down movement allowed, meaning that when one rear wheel hits a bump, both rear wheels move. Not ideal from a purely handling perspective, but ideal as a bottom mounting if you are trying to eliminate gearbox  movement altogether. It is almost impossible to find images of these mountings in situ on Google, by the way, as everyone is always either showing how to replace them or doesn't want them seen, presumably because they're so embarrassed about them.

 

Grasshopper Gearbox Mounts.jpg

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@Yalson Thanks. Never had a grasshopper so I didn't know that. Might see if the b parts sprue is cheap and give them a look. They would be perfect if it put the gearbox bottom mount in the right place.

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They should hopefully be pretty cheap as the GH1 is available as a re-re, presumably still with the original gearbox mounts.

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I have been running Ultra G quite a bit recently, and it's making me smile a lot. I have a Core RC Lipo which fits and even just on 3300kv and the tamiya ESC it flies! I got a 17t dt02/3 steel pinion recently as the aluminium one had got pretty noisy. 

I ran it at Robin Hood Raceway at a track day in July and it was just brilliant to drive. Fast enough, great, easy handling and just fun seeing this bunch of 30 year old design parts moving so well on a modern astro track. Compared to some of the puzzling I had to do on my other cars it was nice just to switch on Ultra G and drive. I am running Schumacher Mini Spike yellow 2" rears and Mini Pin yellow 2.2" on the fronts. 

Moving onto today's fun, as it's driving so nicely obviously I had to fiddle with it! I had a couple of things I wanted to get from Shapeways, so I piggybacked a set of the 3 deg toe in rear uprights which I have already developed on my Thunder Dragon.

Before with ReRe uprights 

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And with a bit of toe in

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A bit of a punt was some 15 deg caster front c hubs to try and calm the the steering down a bit and improve the fit with the wishbone. I knocked up a first go on the CAD and ordered. Only a few quid so worth a go. Fit went nicely enough.

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Ultra G has always had a bit of bump steer but it was worse after fitting these. I had a play about and re-positioned the front camber link mount more parallel with the wishbone. This involved cutting the servo mounts that mount the ball screw in half, mounting vertical with a single screw to the front mount. Added some superglue to help strengthen it. Before and after....

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From above

All back together and cambers reset now. Hopefully give it a run tomorrow.

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After a few false starts due to the weather being very changeable (is there anything more disheartening in this hobby than having to put a full charged Lipo onto discharge/storage having had it ready to go for 2 days?) I finally got to run Ultra G with the modifications this afternoon. At first, very disappointing! Really soft turn in, weird lack or steering lock turning right, loads of understeer. Gotta love ruining a perfectly good buggy! Anyway, some puzzling and I got it running nicely. The shifting of the upper camber links to cure the bump steer radically changed the roll centre and camber gain of the front end. So I rotated the mounts down to about halfway between the original spot and the one I started with. There was just a sniff of bump steer, but nothing too bad and much more camber gain. Another quick run and this is much improved! Nice turn in and lots of grip. Not sure it I like it more than the original setup, but it was fun playing with it. Here's the new front end arrangement

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Rear end was planted and just lovely, as it has been. Can't really tell much difference with the new uprights, but they look nice!

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New look for Ultra G today. What unwanted with the previous set was the neon yellow to match the wheels, but it never did quite match. Now the body is a bit scuffed up I thought I would ditch the yellow and go for neon orange instead. Love that colour. Came out pretty nice I think

Grasshopper2 Ultra G gets a new look. Neon Orange instead of green and blue instead of red on the Dress Up Decal Option 2 set from MCI RacingGrasshopper2 Ultra G gets a new look. Neon Orange instead of green and blue instead of red on the Dress Up Decal Option 2 set from MCI Racing

Grasshopper2 Ultra G gets a new look. Neon Orange instead of green and blue instead of red on the Dress Up Decal Option 2 set from MCI Racing

 

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Thanks dude! It's such a fun car to drive. I had a very specific thing in mind for this in terms of pursuing the Super G wheels. You could save a load of cash and effort by simply running modern Tamiya 2wd wheels like from a DT02 or DT03. 12mm hex rear and bearing front with 2.2" tyres. The Pargu converters for the rear wheels cost more than a set of modern wheels! I would recommend the DT02 turnbuckle set to get easily all the parts required for upper arms and steering, although I used m3 threaded rod for some parts because I had rod ends spare.

At the moment the only front end conversion in my Shapeways store is the one which uses DT02/3 front arms. If I am honest this work better than the one I have here with the blue Thunder chassis wishbones but I wanted matching arms. (I have the DT03 arm conversion on my Rising Fighter). The bobbins for extending the gearbox lower mounting into the Rising Fighter transmission mounting aren't up yet, and neither are the 15 deg castor front c hubs. That said i think possibly the handling is better with the stock DT02/3 c hubs. The Thunder chassis 3 deg toe in rear uprights are on the store but the kit rear uprights work fine too.

Give me a couple of days to get a chance to upload the models and I'll get them on sale. 

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On 10/5/2018 at 9:50 AM, PoormanRC said:

This is shockingly BRILLIANT!!! B):)  Do you happen to have these bits that you designed for this, in a Shapeways Store?? Would you have a link? This is a fantastic idea, and definitely worth trying!

~ Carmine

OK, here's some parts in my Shapeways store:

Front suspension conversion for the Thundershot wishbones - http://shpws.me/QLkw

The bobbins for mounting the gearbox to the Rising Fighter transmission mounts (you need 2) - http://shpws.me/QLky

I have redesigned the direct fit front uprights with better clearance and less caster than the ones I have fitted recently. You need 1 of each (or just get DT02/3 items) - http://shpws.me/QLkD http://shpws.me/QLkG

If you want to go whole hog then the Thundershot/Dragon 3 deg rear uprights are these: http://shpws.me/QLjE http://shpws.me/QLjx

As I mentioned above, I'd highly recommend getting the DT02 turnbuckle set as you'll get all the bits you need for upper arms and steering arms. 

Would be great to see another one. As I mentioned earlier in the thread, I think the Rising Figher is probably a better basis for this project if you're not hopelessly attracted to the Grasshopper 2 Super G like I am!

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@PoormanRC Sounds like a great plan. You have all the parts you need straight off the bat. I French guy in here @sellig did exactly what you are planning to do. Took a bit more creativity to mount the rear end but he did it. Here's the thread. You need to have a look at the YouTube video towards the bottom

 

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1 hour ago, PoormanRC said:

I'm glad someone else has done this!! B) I'll definitely take a look.

EDIT: I tried to look.... Couldn't see a single picture!! :huh::( Yet another victim of Photobucket......

If you Google Grasshopper ii evo 2 there are a couple of cached photos. Looks like he made his own flat plate shock mount and used some flattened rods to attach the bottom mounts to the tub. DM Sellig on here and see if he can 're host the photos on Flickr or something.

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Got a couple of new parts on Ultra G this week. Improved front suspension mounting which is a little narrower than the previous version gives better kinematics and standard 2wd buggy track width. Also fitted an improved version of the front upright with better fit and only 5 deg caster to improve steering.

Ran Ultra G at the track at the Tamiya Junkies track day yesterday. Was a pleasure as usual. This is such a great little buggy!

Tamiya Junkies Robin Hood Raceway meet 20th octoberTamiya Junkies Robin Hood Raceway meet 20th octoberTamiya Junkies Robin Hood Raceway meet 20th octoberTamiya Junkies Robin Hood Raceway meet 20th octoberTamiya Junkies Robin Hood Raceway meet 20th october

 

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On 10/23/2018 at 2:48 PM, Pablo68 said:

Great work on this buggy. Some very interesting ideas there.

Thanks. The 3D printed parts for the conversion are in my Shapeways store if you are interested. Search CTE RC.

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