Grasshopper 2 Ultra G Evo Black Edition

[ThunderDragonCy 8430]

Following on from m'colleagues help and encouragement, here is this winters project, a further evolution of my Ultra buggies. This one is going to be the most modern yet, whilst still based on a Grasshopper 2 tub. 

First things first, I have a Grasshopper 2 Black Edition on its way. I just love this shell, and I love orange so this works well. Comes with CVAs too which is excellent. 

The initial idea is a 4 gear transmission using a TD4/TA06 diff, TD4 layshaft, and a couple of TRF201 27t idlers inside my own design gearcase. I already did something similar on my old FF03. Why 4 gear? Because I always wanted to do one. 

Arms I think will be off the latest Schumacher Cougar. Tamiya just don't have good arms. The Td2/4 fronts make a regular shock tower nigh on impossible. The gullwing design Schumacher arms should allow me to keep the tub shock towers for more "its just a grasshopper" looks. 

These will need some front c hubs and rear uprights designing and 3d printing. Also need to figure out a shock tower. 

Front will be a version of my ultra Hornet design with said Schumacher arms which will hopefully give better geometry than the DT03 ones on Ultra Hornet. 

Steering will be some kind of linkage. Maybe same as my other Ultras, maybe new. 

I bought some bits last year for another project that stalled, so I currently have in stock:

70mm universals

DT03 turnbuckle set

DN01 steering posts

Xv01 alloy steering set

Bevels and seals of a TA06 gear diff

Top force suspension shafts

Hi torque servo saver

TRF open adjusters

F103 / Grasshopper reinforced knuckles

1060 esc

Spare Rx

Orange JC Racing astute style 2wd wheels

So, IN THEORY this needs a couple of carbon bits (trans plate, shock tower, steering mounting), some transmission internals, a few bearings, some arms, 3D printed bits, tyres and motor and I am away. 

IN THEORY

Transmission is going to be the priciest bit, so I am going on the blag here and now: Does any with a TD2 or 4 they have upgraded to slipper and gear diffs want to sell me the stock layshaft and ball diff? Thanks. 

As for the car? Yes it's rehashing some old ground, but I absolutely LOVE these buggies, and I think with modern suspension and the black body this will look really low and cool. 

 

[BuggyDad 6022]

1 hour ago, ThunderDragonCy said:

Following on from m'colleagues help and encouragement, here is this winters project, a further evolution of my Ultra buggies. This one is going to be the most modern yet, whilst still based on a Grasshopper 2 tub. 

First things first, I have a Grasshopper 2 Black Edition on its way. I just love this shell, and I love orange so this works well. Comes with CVAs too which is excellent. 

The initial idea is a 4 gear transmission using a TD4/TA06 diff, TD4 layshaft, and a couple of TRF201 27t idlers inside my own design gearcase. I already did something similar on my old FF03. Why 4 gear? Because I always wanted to do one. 

Arms I think will be off the latest Schumacher Cougar. Tamiya just don't have good arms. The Td2/4 fronts make a regular shock tower nigh on impossible. The gullwing design Schumacher arms should allow me to keep the tub shock towers for more "its just a grasshopper" looks. 

These will need some front c hubs and rear uprights designing and 3d printing. Also need to figure out a shock tower. 

Front will be a version of my ultra Hornet design with said Schumacher arms which will hopefully give better geometry than the DT03 ones on Ultra Hornet. 

Steering will be some kind of linkage. Maybe same as my other Ultras, maybe new. 

I bought some bits last year for another project that stalled, so I currently have in stock:

70mm universals

DT03 turnbuckle set

DN01 steering posts

Xv01 alloy steering set

Bevels and seals of a TA06 gear diff

Top force suspension shafts

Hi torque servo saver

TRF open adjusters

F103 / Grasshopper reinforced knuckles

1060 esc

Spare Rx

Orange JC Racing astute style 2wd wheels

So, IN THEORY this needs a couple of carbon bits (trans plate, shock tower, steering mounting), some transmission internals, a few bearings, some arms, 3D printed bits, tyres and motor and I am away. 

IN THEORY

Transmission is going to be the priciest bit, so I am going on the blag here and now: Does any with a TD2 or 4 they have upgraded to slipper and gear diffs want to sell me the stock layshaft and ball diff? Thanks. 

As for the car? Yes it's rehashing some old ground, but I absolutely LOVE these buggies, and I think with modern suspension and the black body this will look really low and cool. 

 

Sounds ace. Look forward to seeing where you take it. 

Do I have it right that XV-01 and BBX share a lot of these gearbox internals (they share idlers and diff certainly)? I have the leftovers from fitting slippers to two BBX gearboxes, if that's any use. And I think one or maybe two idlers because I bought the XV-01 gear set for the second BBX gearbox, that gear set is the part number in the BBX manual but it's not all used. 

[Wheel_Nut 382]

Great idea. We always needed a Grasshopper 2 Ultra G Evo.  I was hoping Tamiya would create a Super Hornet Evolution.  I look forward to watching your build.

[ThunderDragonCy 8430]

7 hours ago, BuggyDad said:

Sounds ace. Look forward to seeing where you take it. 

Do I have it right that XV-01 and BBX share a lot of these gearbox internals (they share idlers and diff certainly)? I have the leftovers from fitting slippers to two BBX gearboxes, if that's any use. And I think one or maybe two idlers because I bought the XV-01 gear set for the second BBX gearbox, that gear set is the part number in the BBX manual but it's not all used. 

Thanks. Just had a look and the BBX/XV01 layshaft is shorter and quite different to the TRF201/TD4 style version. Although I am sure it could be made to work I think I will hang out for the TD4 one. The longer layshaft allows me to put the motor more central in the car which in turns fits the motor and mounting bits between the rear trans mount. The XV01 idlers are 33t so a bit big. I have found Associated do a set of 48dp 26t idlers from their B6D which will be good. Will only be a tweak from thd Tamiya 27t idlers and they come as a set without the ball diff gear like the tamiya stuff. 

[ThunderDragonCy 8430]

6 hours ago, Wheel_Nut said:

Great idea. We always needed a Grasshopper 2 Ultra G Evo.  I was hoping Tamiya would create a Super Hornet Evolution.  I look forward to watching your build.

My Ultra Hornet is already kind of that. Search the Buolds forum for it. But you could fit a Hornet or Rising Fighter (painted like a Super Hornet like I did) to this idea. 

[BuggyDad 6022]

11 minutes ago, ThunderDragonCy said:

Thanks. Just had a look and the BBX/XV01 layshaft is shorter and quite different to the TRF201/TD4 style version. Although I am sure it could be made to work I think I will hang out for the TD4 one. The longer layshaft allows me to put the motor more central in the car which in turns fits the motor and mounting bits between the rear trans mount. The XV01 idlers are 33t so a bit big. I have found Associated do a set of 48dp 26t idlers from their B6D which will be good. Will only be a tweak from thd Tamiya 27t idlers and they come as a set without the ball diff gear like the tamiya stuff. 

Gotcha. It seems like a lot of people don't like the ball diff and go straight for gear diffs instead and since so many kits come with this one it's a fair assumption there should be some unwanted ones about. Unless they're burning them out before replacing. Maybe worth mentioning the in vogue BBX in the title of your wanted ad, for the diff?

[toyolien 5933]

@ThunderDragonCy Looking forward to this project 👌

I maybe have some bits from my TD2 which I'm not using. Let me look tonight.

[ThunderDragonCy 8430]

Spent a bit of time after work throwing some CAD around. With minor modifications the 4 gear I designed for my full buggy project drops in nicely

I got some measurements for pin locations on the Schumacher arms and done a rough model. Looks like they should work, but there is no point doing any more on shock tower or other geometry until I have the arms in hand to do a proper model. I ordered LD3 arms today. This layout gives similar wheelbase to Ultra G at around 268, which is fine. 

Currently I am using some touring car adjustable mounts for arms which I have one in spares. Again, waiting for Schumacher arms to finish off, so will leave in position for now. 

Luckily the uprights I designed for the other buggy work pretty much perfectly with tamiya 70mm universals. 

Other thing I looked at was an evolution of my linkage steering as I have an xv01 steering set. First look. Needs some more thought and work

 

 

 

[toyolien 5933]

Just had a look and unfortunately I don't have one. I seem to remember someone else on here asking for TD4 transmission spares for a project, and I sent him what I had, which must have included the layshaft... sorry.

[ThunderDragonCy 8430]

The Schumacher arms arrived yesterday whilst I was at work. Grabbed a coffee this morning and modelled up the outline properly. They sit really nicely, but a couple of not-Tamiya things have been found in that the hinge pins are different sizes. The inner hinge pins front and rear are 3.2mm, so I can't use tamiya suspension blocks, and the outer hinge pin is 2.5mm. Luckily the Schumacher pins are fairly cheap, but the alloy suspension blocks is probably 35 quids worth which is a bit annoying when I have tamiya ones here. 

At the front the outer hinge isn't a pin at all. The outer front arms are 4.5mm diameter and you insert top hat bushes into them and the screw m3 screws into the c hub from both sides. Interesting idea, and seeing as I plan to do my own c hub, I can adopt that. 

 

[ruebiracer 1181]

Oh, this will be a so cool project! Will follow it for sure, @ThunderDragonCy!!

[jonboy1 3537]

looks like a great plan forming here - can't wait to see more!!

[ThunderDragonCy 8430]

Some to-ing and fro-ing with the front end. Been scaling and copying off the LD3 pics, and the geometry fairly closely mimics this, just with a mini CVA shock. Couldn't make it work with the tub shock tower so this will get a carbon tower. Linkage steering looks good with minimal camber changer and bumpsteer. My only quandry now is the F103/Grasshopper knuckle. It's a bit limiting in terms of steering thow, and I've had to scallop out the c hub quite a lot to get some good steering lock. I'm only really using it because I have the F103 ones in stock, but looking at Ultra Hornet I think the DT03 ones are a better bet. More on that later in the week.....

[BuggyDad 6022]

1 hour ago, ThunderDragonCy said:

Some to-ing and fro-ing with the front end. Been scaling and copying off the LD3 pics, and the geometry fairly closely mimics this, just with a mini CVA shock. Couldn't make it work with the tub shock tower so this will get a carbon tower. Linkage steering looks good with minimal camber changer and bumpsteer. My only quandry now is the F103/Grasshopper knuckle. It's a bit limiting in terms of steering thow, and I've had to scallop out the c hub quite a lot to get some good steering lock. I'm only really using it because I have the F103 ones in stock, but looking at Ultra Hornet I think the DT03 ones are a better bet. More on that later in the week.....

On my Funky Falcon I switched to F10X from the dead straight DT-03 knuckles for Ackermann - they're quite different to each other in that regard. Just a point to note their differences. On that geometry I needed the angled F knuckles. 

Interested to know what angle of inside wheel steering throw you reckon is adequate/good when designing? I was unsure on this. I think I got 42°, which looks ok just eyeballing it, but I don't have any numbers from good cars to compare it against (maybe I should just get a protractor out!). 

[ThunderDragonCy 8430]

9 hours ago, BuggyDad said:

On my Funky Falcon I switched to F10X from the dead straight DT-03 knuckles for Ackermann - they're quite different to each other in that regard. Just a point to note their differences. On that geometry I needed the angled F knuckles. 

Interested to know what angle of inside wheel steering throw you reckon is adequate/good when designing? I was unsure on this. I think I got 42°, which looks ok just eyeballing it, but I don't have any numbers from good cars to compare it against (maybe I should just get a protractor out!). 

I still haven't been able to work out or understand what Ackerman is and why I should care! All I noticed was that on Ultra G the front wheels can turn a massive amount with no mechanical hindrance (although I haven't check the actual amount powered up). 

Everything I have seen on other buggies uses a cranked axle though. I trued finding TRF201 C parts, but these are rocking horse poo at these days. 

Maybe I need to redesign the c hub to bodily swing forward out of the way to maintain structure rather than the large scallop I put in last night. 

[BuggyDad 6022]

31 minutes ago, ThunderDragonCy said:

I still haven't been able to work out or understand what Ackerman is and why I should care! 

I reckon ya do, it's one of those things you already know and take for granted, it's just some fella called Ackermann went and stuck his name on it making it sound complicated. 😉

Ackermann is just the inside wheel turning by a greater angle than the outside wheel because it's turning around a tighter radius. Ackermann off neutral either way is dragging a tyre a little, some tuning effect which I don't really understand. For my use I just reckoned that it needed not to be miles out of neutral - I'm not seeking perfection, but designing from scratch I found a danger I'd really **** it up (like on one Falcon version I had wheels pretty much dead parallel = zero Ackermann). And it can be quite sensitive to small(ish) changes in dimensions. My simplistic view of this is two main variables to play with:

1. Fore/aft piston of bridge/tie rod joints - with forward facing cranks as you have, if your bridge and tie rods make a straight line at steering centre, that's the longest they can be, they'll make a less straight line at full lock, shortening them and so taking the wheels out of parallel (adding some Ackermann). Hence bridges with multiple holes to adjust Ackerman. 

2. Knuckle arms. Parallel like DT-03 and it moves like a parallelogram = no addition to Ackermann. Swept in like most others = added Ackermann. 

Oh and there is a 3 I suppose - direct mount to servo saver a la DT-03 - Rotating saver reduces total width through the steering travel. 

Hey I wondered also whether your axle needed to to be set so low with respect to the arm/c-hub pivot. Maybe a small height change could afford you more clearance in the C-hub (or space to add a bit of meat to it)? 

[BuggyDad 6022]

Digging out my Falcon pics. No Ackermann (maybe even a bit negative):

The tie rods and bridge make almost a straight line at full lock, so that's at its longest in this position. 

Changed bridge to add some Ackermann:

Fair bit of angle through the tie rods there.

[jonboy1 3537]

great explanation there @BuggyDad 

[ThunderDragonCy 8430]

All this talk of Ackerman got me thinking so I put together a mirror image of the parts and modelled a complete front end then checked.

There is a bit of Ackerman. Best I can measure there is about 10 deg difference in wheel angle at full steering. 

I think we have the basis of something that might work....

[BuggyDad 6022]

2 hours ago, ThunderDragonCy said:

All this talk of Ackerman got me thinking so I put together a mirror image of the parts and modelled a complete front end then checked.

There is a bit of Ackerman. Best I can measure there is about 10 deg difference in wheel angle at full steering. 

I think we have the basis of something that might work....

This with F104 knuckles? Hard to tell whether that's as much as neutral (or whatever it's called) Ackermann but there's certainly some. DT-03 knuckles would reduce that 10°, not sure by how much. Other knuckles might be available to increase it. Moving steering posts a few mm back would increase it, if they're movable? Another thing that would increase it is taking the cranks slightly out of parallel, so the bridge takes on a slight angle as you steer (I tried this with Falcon also, following advice here, in fact I suspect that's my second pick up there ^). 

There'll be a calc linking angle of each wheel with wheelbase and track, but I've just gone for finger in the air and then rolling the car along and eyeballing it. 

Is it easy in your CAD to move one part and see the resulting movement in connected parts? Although I'm sure this'll be possible in Fusion 360, it's above my pay grade. I should maybe look into that as one of my next things to learn. 

[ThunderDragonCy 8430]

@BuggyDad That is with the F103 knuckles. They aren't very long and the arms are quite a way forward of the steering posts because I am a bit hemmed in by grafting a 25deg kick up onto a GH2 tub. 

I can move pivots around to try different things. As you say, it's hard to know what is good and what isn't. Might try measuring my TD4. It's the only vaguely modern, mostly stock chassis I own. Thanks for the suggestion of non-parallel cranks. Given that the steering servo is way back on the right of the chassis, having the master steering crank angled a little in that direction wouldn't be a bad thing. 

[BuggyDad 6022]

Another question if I may - why the cranks in that configuration, so close together? If you could space them wider (swap them?) I think that'd reduce the forces on the bridge and any play, but also the geometric effect of any out-of-parallel-ness you introduce? 

[ThunderDragonCy 8430]

10 minutes ago, BuggyDad said:

Another question if I may - why the cranks in that configuration, so close together? If you could space them wider (swap them?) I think that'd reduce the forces on the bridge and any play, but also the geometric effect of any out-of-parallel-ness you introduce? 

They are in that arrangement to fit in the car. No other position works

[ThunderDragonCy 8430]

Some more work and more hand waving.....

I've come to the conclusion that the Tamiya suspension blocks won't work. I managed to pick up some older generation Schumacher ones off ebay for a tenner, so they have bene modelled up and laid into the model. I've ordered the LD3 suspension pivot shafts now as well, as it's all getting quite tight on packaging. Had to move the idlers inside the 4 gear around to clear the split blocks on the Schumacher parts. Still quite a bit to do on this now as they have moved everything around a few mm and made the track a bit too wide. 

On the front, I think I have got something that will work quite nicely, but my wanting to use the kit CVA shocks to keep the vaguely stock look is potentially limiting. I've setup the suspension tower so the wheels are at the same height as the tub at full compression so with a bit of tyre squish the tub will bottom out before the shock. However, the short 15mm stroke of the CVA means at maximum extension the ground clearance is only 28mm, and at around 23mm ride height, the shock has barely compressed 2mm, so it will make setup a bit tricky. According some learned colleagues on here, the Schumacher shocks have 22mm stroke. So decision time! Either I get some posher shocks (I can get some Buggy Aeration dampers from PJ for decent money) with more stroke, but lose the wolf-in-sheeps-clothing vibe, or I get some short shock bodies and rods in grey to match the kit and run them on the front with a taller tower. Thinking short eyelet, a few spacers inside to get the matching 22mm stroke of the Schumacher shocks. I am even considering the grey Super Astute bodies, as they are CVA1 so would be able to use the 10mm pistons and softer short front CVA springs of the kit shocks whilst still getting more stroke. 

Thoughts? 

[BuggyDad 6022]

Could the CVAs be modified to increase the stroke a little? I have some longer shafts to try in the minis on my Falcon. That also hasn't enough droop, even though its ride height is not very high. I recall, but not with absolute certainty, that with my old DT-03 shocks it had more front droop. Well, it certainly did on the back and I have pulled the old parts together to try in the coming days. I know the bodies are longer but the DF-03 fronts have 42mm shafts vs 34mm in my Minis, so I wonder whether a bit of modifying potential is there. 

Could another option be to move the top mount points inboard on a 3d printed or CF tower, increasing leverage rate and therefore wheel travel for a given shock stroke? Or something I may do on the Falcon is 3d print arms with a more inboard mount point, to achieve the same effect, while at the same time reducing the jelly wobble of Blitzer arms.