Grasshopper 2 Ultra G Evo Black Edition

[BuggyDad 5904]

Really looking forward to seeing this come to fruition. I think it'll be in a different league with that gearbox work at the back.

I blimmin love this concept of taking these basic buggies to their limits. The sleeper thing, I guess, plus the need for creative thinking to make it happen given the constraints. I'll take on another myself some time and have begun mulling over options. 

The 25+5° arrangement on my DT-03 is I suspect a big part of why it takes the rough stuff nicely, ditto BBX. Hey, you could design pill inserts into your c-hubs to allow 0° and +5° castor options, or be welcome to some of mine - the printer sent me about 20 of the inserts, for reasons unknown. The concept works well so far. They're just located with a grub screw beneath, which could equally locate the shaft now I think of it. 

Are you using a stock CVA short with the smallest eyelet to minimise compressed eye-to-eye length and spacing it internally to limit maximum extension? 

[ThunderDragonCy 8380]

@BuggyDad I am excited too. This one should be a pretty good sleeper with the black shell.

Thanks for the offer on the pills. Fire over the CAD and i will see if i can make them work. I haven't done anything adjustable before. C hubs are so cheap once designed i might just do some 5 deg ones as well.

Short shock will be a bit of a mashup hence waiting. Short shock body, i have a trf501 front rod which is 40.5mm vs 47 for the regular short cva. Short eyelet, but that might not fit the schumacher arm so i have some trf501 eyelets and fittings coming too. Don't know the dims of those. The other thing as an option is the 41.5 rods from the df03 set.

[BuggyDad 5904]

18 hours ago, ThunderDragonCy said:

@BuggyDad I am excited too. This one should be a pretty good sleeper with the black shell.

Thanks for the offer on the pills. Fire over the CAD and i will see if i can make them work. I haven't done anything adjustable before. C hubs are so cheap once designed i might just do some 5 deg ones as well.

Short shock will be a bit of a mashup hence waiting. Short shock body, i have a trf501 front rod which is 40.5mm vs 47 for the regular short cva. Short eyelet, but that might not fit the schumacher arm so i have some trf501 eyelets and fittings coming too. Don't know the dims of those. The other thing as an option is the 41.5 rods from the df03 set.

Will do. They're not very exciting, just give the option without much compromise. I'll PM you, might be a day or two. 

[ThunderDragonCy 8380]

Plaza Japan shipment arrived. YES!

Key thing was dry assembling the front shock with the TRF501 front shaft to see what the actual dimensions are

All measured up it's 60,7mm at full compression, and pretty much bang on 82mm at full extension. That's a little over 21mm stroke, so it will be perfect. 

I got the TRF501X damper retainer set because I knew I would need to modify any ball end for the shock for the Schumacher arm because the opening is very narrow. These plastic parts are narrower than the metal ball shoulder things for CVA, and being plastic are easier to file down to fit. In the end I just needed some sandpaper. It got cleaned up after the above photo!

So, I have finalised all the printed and carbon parts and emailed off my orders. Exciting!

[ThunderDragonCy 8380]

Built the front shocks tonight, including drilling the TRF 11mm pistons. Despite the dimples as drill guides the holes end up in different places on different pistons. I figured it would be ok as i used the same 1.5mm drill, but the pair of front shocks have noticeably different damping feel. Might have to go back to stock ones. Anyone got any advice on drilling pistons?

[BuggyDad 5904]

6 hours ago, ThunderDragonCy said:

Built the front shocks tonight, including drilling the TRF 11mm pistons. Despite the dimples as drill guides the holes end up in different places on different pistons. I figured it would be ok as i used the same 1.5mm drill, but the pair of front shocks have noticeably different damping feel. Might have to go back to stock ones. Anyone got any advice on drilling pistons?

What drill you got? Mine's just a hand chuck thing, like a mini screwdriver with a rotating top, works nicely - that's from Schumacher (Core RC), £10 for the drill and bits

https://www.racing-cars.com/1-10th-touring/mi7/piston-drilling-kit-1-1-1-8mm-8-bits-cr233 

The first one I did by hand with that was a little wonky. The second I held the drill horizontal in front of me, left to right, with the Piston against a vertical piece of wood. This way I could allow the piston to rotate periodically to check I was drilling true, which I found to get me pretty straight holes. They started reliably in the dimples both times though.

However next time I'll do them in my bench drill, to get them absolutely straight.

[ThunderDragonCy 8380]

3 hours ago, BuggyDad said:

What drill you got? Mine's just a hand chuck thing, like a mini screwdriver with a rotating top, works nicely - that's from Schumacher (Core RC), £10 for the drill and bits

https://www.racing-cars.com/1-10th-touring/mi7/piston-drilling-kit-1-1-1-8mm-8-bits-cr233 

The first one I did by hand with that was a little wonky. The second I held the drill horizontal in front of me, left to right, with the Piston against a vertical piece of wood. This way I could allow the piston to rotate periodically to check I was drilling true, which I found to get me pretty straight holes. They started reliably in the dimples both times though.

However next time I'll do them in my bench drill, to get them absolutely straight.

Thanks for the run down. I don't have a suitable bench drill. The one at work is a monster!

I just gave a regular hand drill with a teeny 1.5 bit. I think the speed and having to do it free hand and the flexy little bit all conspired against me.

I have bought the 4 hole pre drilled pistons of the same size (53728 if you interested) and a pin vise (that hand drill you have). Once i have worked out how big the holes are in the stock piston i will try and open them out a little to make them suitable for a buggy. When i was doing the maths on hole area for these, even 4 x 1mm holes is a smaller area than 2 x 1.5mm, which is about where it needs to be i think. 

[BuggyDad 5904]

9 hours ago, ThunderDragonCy said:

Thanks for the run down. I don't have a suitable bench drill. The one at work is a monster!

I just gave a regular hand drill with a teeny 1.5 bit. I think the speed and having to do it free hand and the flexy little bit all conspired against me.

I have bought the 4 hole pre drilled pistons of the same size (53728 if you interested) and a pin vise (that hand drill you have). Once i have worked out how big the holes are in the stock piston i will try and open them out a little to make them suitable for a buggy. When i was doing the maths on hole area for these, even 4 x 1mm holes is a smaller area than 2 x 1.5mm, which is about where it needs to be i think. 

Yeah I think with these teeny drill bits, with either a normal hand drill or any handheld power drill it would be very easy to snap a bit or cut out of straight, hence the pin vise type thing. It's not like you need any significant drilling torque. But counterintuitively I find my bench drill can be used really delicately, because it can only move in one dimension and the lever to drop it can be nicely finger touch sensitive. Oh and I've left mine set to a minimum speed anyway, which seems to suit all my RC applications for it so far. 

And as you say, small diameter changes have a big effect (squared relationship) so I think perhaps a set of bits in small increments is a near necessity anyway. When I bought the above set it was really the result of looking for just some bits. 

[ThunderDragonCy 8380]

Couple of little design/sourcing updates this morning. Unfortunately Ken at Cobra sold his CNC machine during Covid so I don't have any options for getting the motor plate in aluminium. I am working with a laser cutter with work, so I updated the part to 1.6mm stainless steel instead of 3mm aluminium this morning. Still a few grams heavier than aluminium, but won't corrode and will conduct heat well. I updated the spur cover to be 2mm thicker to compensate and Midlands 3D have updated that at no cost as they hadn't started making my order yet.

 

[ThunderDragonCy 8380]

Got the 4 hole ssbb pistons. 1mm holes according to the pin vise bit set i have now bought. Little bit of maths suggest opening out two of the four holes in each piston to 1.2mm will get me close to what I was aiming for with drilling the blanks. Unfortunately my set doesn't have a 1.1mm or I would have done all four that size

 

[ThunderDragonCy 8380]

Pin vise for the win! Drilled through the holes onto my mouse mat and they came put great. 4 consistently damped shocks built. Boom!

Used the lightest cva 50520 springs which are supposed to be for df01 front as a starter for 10. They have always been too soft on anything else at the rear.

On the rear I put the softest df03 spring set springs that just came off my hotshots. Damping still seems quite strong, so we will have to see how first runs go. Started with 400 oil all round. I have some 300, but it will be drills in the pistons if it needs to go lighter than that.

Built them with the rod guides and clear o rings as suggested on the buggy damper thread, and they do feel very smooth.

[ThunderDragonCy 8380]

Wanted to do something more on the build today, so I did the shell!

The shell comes moulded black so I just went to decals straight on. They look like they should have been die cut but they weren't. Was a packed sheet so was tricky to get them all cut. They are great decals though. The brown bits are actually metallic gold, the orange looks great and sponsor decals are good too. Really pleased with it. Will probably shoot some automotive clear over the top at some point.

[ThunderDragonCy 8380]

Got another half an hour to tinker so had a go at the motor. My first Superstock. Picked up this by used on ebay for about 60% of new prices. Really excited to run one of these.

Buuuuut of course I couldn't leave it alone. After seeing a big increase in runtime and reduction in heat in my Reedy motor when I put bearings in, I wanted to do the same with this one

Got a pair of motor bearings for rcbearings.co.uk. Watched one of the many YouTube videos and got it done. Pretty easy. Pushed the bushes out and bearings in with a small screwdriver. Better.

[toyolien 5908]

29 minutes ago, ThunderDragonCy said:

Got a pair of motor bearings for rcbearings.co.uk. Watched one of the many YouTube videos and got it done. Pretty easy. Pushed the bushes out and bearings in with a small screwdriver. Better.

What size bearings did you buy? I need to do this to the BZ I my Wild One I think.

[ThunderDragonCy 8380]

1 hour ago, toyolien said:

What size bearings did you buy? I need to do this to the BZ I my Wild One I think.

I think the exact size is 2rrzz, but rcbearings.co.uk have them listed as Tamiya Superstock bearings. 

You will have no trouble doing it. Flick the bush springs off and retract them, unscrew the screws and pull the end cap off. Just make sure you collect the spacers from each end and put them back in the right order.

https://www.rcbearings.co.uk/index.php?route=product/product&path=162_69_111&product_id=2079

Edited February 25 by ThunderDragonCy
Added weblink

[ThunderDragonCy 8380]

And another little bit! Built the diff

TA06 gear diff with steel internals. I had the steel bits in the spares box, so just bought the case and outdrive kit. The seals in that are just the black ones which isn't great, but they got a got dousing of Green Slim so hopefully they will be OK. 3000cst oil. Doesn't create the stiffest diff action, but I have this oil because it's what I used in the diffs I built for my TRF buggies and the rear of the TA06 I briefly had. Should be OK.

[toyolien 5908]

22 minutes ago, ThunderDragonCy said:

I think the exact size is 2rrzz, but rcbearings.co.uk have them listed as Tamiya Superstock bearings. 

You will have no trouble doing it. Flick the bush springs off and retract them, unscrew the screws and pull the end cap off. Just make sure you collect the spacers from each end and put them back in the right order.

https://www.rcbearings.co.uk/index.php?route=product/product&path=162_69_111&product_id=2079

Marvellous, thanks. Just ordered a few.

[ThunderDragonCy 8380]

Bit of a bump in the road this week. My guy wo I was going to get to make me a custom motor plate has sold his CNC machine. I don't want to get a carbon plate because of the heat, so I redesigned it as a thinner stainless steel piece to keep the weight down and adjusted the spur cover to suit. Unfortunately the cost of laser cutting is quite high, I expect due to covering the setup cost of doing the job for just 1 off. Annoyingly I was casting about for other options last night and laid a TRF201 motor plate into the transmission model and it's almost exactly right for the spur gear and motor position, but all the holes for mounting it to the transmission are wrong. I checked out how much it would be to order more transmission casings (as they are already in production) and once I totted everything up it's the same price as getting an expensive one off motor plate made. Live and learn. And I guess we learn that one should try and use stock motor plates where possible!!!

[ThunderDragonCy 8380]

Been quiet waiting for parts to arrive, but i think everything is here, so i made a start. First issue: They dyed one side but not the other. Rather than stop at the first hurdle i cracked on. Will shoot some black on it at some point

Rear deck and arm blocks installed. The rear arm block bolts to the trans case eventually

Didn't asemble the transmission as i need to saw up a gear shaft to get them correct length and i didn't want to get into that. Moving to the front....

Bolted the reinforcing plate in place with the screw for the front body mount. Used the slot in the carbon part as a template to open up the steering aperture in the tub

DB01 steering posts on the mount plate

And installed with XV01 steering kit

Need some washers and shorter screws to complete this.

Bouncing around again i installed the steering servo.

Glad to get started. Need to have a better run at it later in the week and be in the mood to saw and drill.

 

[ThunderDragonCy 8380]

Tiny bit further forward, but ultimately frustrating. Cut the shaft i had to make the idler shafts and assembled the slipper shaft

Unfortunately, new new tap set (lost the other one) doesn't grip the M3 tap despite it coming with one. So, i can't cut threads in my metal laser cut motor plate in order to bolt this together. Taking it to work tomorrow to sort it there.

Luckily the Tamiya thread forming tool (which wouldn't cut steel) does fit the tap tool so threading the plastic bits has been possible at least.

[ThunderDragonCy 8380]

Little more today, but it's still fighting me a bit. Got the steering done

Carbon mounting plate for the DB01 steering posts, through bokted to the reinforcing plate underneath. Onto which I mounted the xv01 steering kit. After faffing with various short screws for either end i used m3x16 screws all the way though the posts and then screwed nuts onto the top to retain the steering arms. The arms are supposed to be a little off centre like that as it provides a bit of ackerman to the steering. Apparently that's a good thing?!

Underside....

3D printed spacers sit above this piece, which has back to back 730 size flanged bearings with a 0.2mm tamiya shim between them. What all this means in practice is the those m3 x 25 screws pass all the way through everything and can be torqued up hard into the xv01 arms without crushing the bearings and the steering wiper is fully retained by the bearing flanges.

Finally did a bit on front arms. The Schumacher c hub attachment is excellent. Perfectly sized top hats sit in the holes in the arm, and you screw into the c hub from each side with an m3x10 screw. Really secure, no slop, simple to install. Very good.

Didn't get to install these because there is a lot of slop on the inner arms, but because they are 1/8" none of my 3mm tamiya spacers or shims fit. Ordered some 4mm ID shims to sort it.

In other news, i have mislaid my new front shock tower when tidying for a guest who stayed last night, which is deeply irritating.  Second thing was that i couldn't get any m3 taps to bite the stainless steel motor plate so that has required a change of plan. If i drill the holes out to 3mm i can squeeze a button head screw behind the slipper clutch plate, so can can bolt through from the spur side qnd put nuts on thd other end. But that means needing 5mm longer screws, so i have had to order those. Finally, i am fairly sure my wife has borrowed and lost my nice 3.05mm drill bit, which is also quite annoying. 

More soon, hopefully with less annoyance! 

 

[ThunderDragonCy 8380]

Little bit more after some shims arrived. Unleash the hacksaw!

Committed now!

Cutting the tub front towers off allowed me to complete fitting the front tower, and the shims (2 x 0.3mm per side) perfectly tightened up the front arms, so they could be installed too.

You can hopefully see from the second photo the 25 deg front kickup i managed to squeeze in.

Did a trial fit of the body and it looks like it will only need a small square cutting out of each side to clear the tower. Probably a little more for camber links. Too tired to be doing tricky stuff like that tonight, so here it stops again. 

I did get the m3x45 button head screws i need for transmission though, so when i am less eye bleedingly knackered i will drill the motor plate and try and make some progress on the rear over the long weekend. The next Tamiya Junkies track meet is a month away, so i am aiming for a maiden voyage there.

[Wheel_Nut 376]

The front end looks pretty awesome.  Especially the chassis brace and shock tower.   The 25 degree kickback looks like it fits perfectly.  I hope the suspension mounting is strong enough to absorb frontal impact.

Did you consider a front suspension brace like Kyosho use on the Dirtmaster?

[ThunderDragonCy 8380]

@Wheel_Nut Thanks! The Schumacher bits don't really lend themselves to a brace. I have also not had any trouble with this type of design on Ultra G or Ultra Hornet so it should be ok. It's a pretty chunky piece.

[ThunderDragonCy 8380]

Some progress!

Received my 3.05 drill bit and 3x45 button head screws and opened out the mounting holes on the motor plate to fit them. Nuts on the other side

Everything mounted up quite nicely

My first Superstock motor tucked in nicely

Got the c hubs and knuckles on the front. 

Parked it here as its not sideways raining for a change so i am going for a big walk.