Grasshopper 2 Ultra G Evo Black Edition

[ThunderDragonCy 8380]

Got back from my walk and got the turnbuckles out. Thought i was short of some correct length screws, but even though they are JIS, the dt03 turnbuckle set had a bunch of screws the right size, so i cracked on....

Note (badly) painted driver figure in foreground.

Dt03 turnbuckles were perfect for camber links, but the long steering turnbuckles were replaced with 42mm ones for the steering arms. 

Steering needed a bit of tuning left to right on the Tx because of the angle on the steering arm makes it slightly uneven. Steering link is just cut M3 threaded rod.

All the effort on the CAD, plus my increased ability to be able to check suspension movement on the model worked out great. Universals fitted perfectly, nothing catches and no weird suspension behaviour is obvious. Very, very chuffed. 

Wheels are JC Astute style i had spare. They are fine, but colour is quite weak. Can see me getting some Fox ones like i have on Ultra Hornet.

Tried tapping the motor plate again for the spur cover, but didn't work.

I didn't find the laser cutting had slightly undersized the holes, so i opened them out with a 2.5mm drill. My new tapping handle is frustratingly crap, but the tap itself did feel better in the bigger holes. Fingers crossed i can sort these when back at the workshop at work.

So, finally, the big reveal......

I'll take better photos tomorrow in the daylight, but it looks so cool!

Springs needed playing with. Rear was about right with the CVA 50520 rear spring. Front had 50520 soft for top force front, but as its quite short it had about 10mm of preload which sat the front right up. Had a quick check of the trusty tamiya spring chart a fellow member measured years ago and saw trf201 fronts were around 2.4lb. I realised i had just bought that rate in Core RC big bore for the rear of the Hotshot2. I swapped these on and it seems good. With a shorty battery it's about 23mm ride height. 

Just need a bit of soldering tomorrow and hopefully i can get it running.

[BuggyDad 5904]

That looks great. The stance looks really purposeful and stable. 

[Wheel_Nut 376]

Looks awesome.  The overall layout of suspension and transmission really suits the Grasshopper body.   CAD modelling seems to have paid off, as it all seems to fit.   Can we see the underside of the chassis?

How long is the wheelbase now?

[ThunderDragonCy 8380]

24 minutes ago, Wheel_Nut said:

Looks awesome.  The overall layout of suspension and transmission really suits the Grasshopper body.   CAD modelling seems to have paid off, as it all seems to fit.   Can we see the underside of the chassis?

How long is the wheelbase now?

I'll take some better photos later. There is sunshine here today and no water falling from the sky [confused face] 

[ThunderDragonCy 8380]

Photos!

Wheelbase is about 277mm with front suspension at ride height. I did some danger soldering with the motor in place to get it all connected up, but it worked and its run briefly in the street under its own power.

Chuffed!

[wtcc5 5758]

I am not into these chassis, but what you have done here is amazing 

[Andreas W 2510]

Happy to see that the maiden run went nice and good. This one also looks the business. Looking forward to vids from the next Junkies meet. 

[ruebiracer 1181]

I knew it would be good, but the result is crazier, cooler and meaner than I could imganine! Your experiences with Ultra G and your other models pais off for the ultimate evolution Hopper! Stance, color´s and wheels are spot on! Never been a Grasshopper fan performancewise, (Started with a Brat and independent rear suspension), but this is the Grasshopper I´d use on a track!

Marvellous job @ThunderDragonCy, enjoy driving it in!

[Wheel_Nut 376]

This is beautiful and looks like an extremely functional design.   I also like the stock items such as the front bumper and grey CVA damper bodies from the kit. .

[ThunderDragonCy 8380]

23 minutes ago, ruebiracer said:

I knew it would be good, but the result is crazier, cooler and meaner than I could imganine! Your experiences with Ultra G and your other models pais off for the ultimate evolution Hopper! Stance, color´s and wheels are spot on! Never been a Grasshopper fan performancewise, (Started with a Brat and independent rear suspension), but this is the Grasshopper I´d use on a track!

Marvellous job @ThunderDragonCy, enjoy driving it in!

I am same. I love the look of the swing axle buggies, but hate the way they drive. That's what the original Ultra G was all about.

11 minutes ago, Wheel_Nut said:

This is beautiful and looks like an extremely functional design.   I also like the stock items such as the front bumper and grey CVA damper bodies from the kit. .

The bumper is SO important to the look. And i wanted to use the CVAs to give it a bit of a sleeper look. Glad you spotted it.

[ruebiracer 1181]

1 minute ago, ThunderDragonCy said:

I am same. I love the look of the swing axle buggies, but hate the way they drive. That's what the original Ultra G was all about.

The bumper is SO important to the look. And i wanted to use the CVAs to give it a bit of a sleeper look. Glad you spotted it.

And especially these sleeper dampers with TRF internals is so ccol, I also like doing this on CVA´s.

[toyolien 5908]

Such a well thought out, and brilliantly executed buggy. It's absolutely marvellous. I really like how you haven't lost any of the character of the buggy. I really wish I had the skills to design and 3d print my own parts. You should start a business doing stuff like this to vintage Tamiyas.... (or maybe it would then become a chore rather than fun). Either way, I'm super impressed.

[ThunderDragonCy 8380]

@toyolien Thank you. That means a lot. I do wonder about getting some kits printed and on sale sometimes, but it would need manuals and probably get asked about it in my spare time, which leans towards chore. Maybe one day, when work is less bothersome.

[ThunderDragonCy 8380]

Gave it a proper run in the street on road tyres and a couple of things became apparent: Firstly, the diff doesn't seem stiff enough. Maybe i am too used to ball diffs, but the diff action is very free. It has 3000 in it right now and my next option "in stock" is 10,000. Certainly needs a blob of stiffer stuff i think.

Secondly, and nore concerningly, it seems the loose bores in the gearcase print aren't ok. There was definitely clicking. A little under power, and a lot on the brakes. I think i need a new gearcase from a supplier i know and trust. I can add an extra clamp bolt in though.

Finally, didn't seem that fast. I was relly excited about running a Superstock. I suspect its gearing, as i gave my RR03 Rally car a spin after and that's running quite tall gearing on a Torque Tuned and it was whizzing about. Might need to see what 48dp pinions i have of a sensible size.

[Wheel_Nut 376]

What spur gear sizes are available for your transmission?   The BBX seems to have short gearing, but I don't know about the TD2.

[BuggyDad 5904]

10 hours ago, ThunderDragonCy said:

Gave it a proper run in the street on road tyres and a couple of things became apparent: Firstly, the diff doesn't seem stiff enough. Maybe i am too used to ball diffs, but the diff action is very free. It has 3000 in it right now and my next option "in stock" is 10,000. Certainly needs a blob of stiffer stuff i think.

Secondly, and nore concerningly, it seems the loose bores in the gearcase print aren't ok. There was definitely clicking. A little under power, and a lot on the brakes. I think i need a new gearcase from a supplier i know and trust. I can add an extra clamp bolt in though.

Finally, didn't seem that fast. I was relly excited about running a Superstock. I suspect its gearing, as i gave my RR03 Rally car a spin after and that's running quite tall gearing on a Torque Tuned and it was whizzing about. Might need to see what 48dp pinions i have of a sensible size.

Loose bores is a shame. I guess really quite loose to cause a tooth skip? I wonder sometimes on 3d printing, with the surface imperfections and whatnot that are inherent in the method, whether we might be better either to undersize and then drill/ream to accurate size or to design in pressing something else into a bore for the critical face, like a spacer (accu seem to make them with fairly tight tolerances so perhaps their nylon ones might do, and they have a huge range of sizes) or a bit of brass sleeve? 

I'm a loosely related matter I am thinking with my home printing being somewhat weaker than good commercial stuff, I may design in some external clamping or sleeving to some parts, like rear uprights might get an M12 (or more likely bigger) shim/washer on the outside to wrap around the part, and some other parts getting sandwiched between bits of CF sheet like licorice allsorts. 

Basically, I think 3d printing is amazing for complex and irregular shapes, but it can need a hand for either points of critical accuracy or with something stronger to wrap around it if the part is prone to a split. 

[ThunderDragonCy 8380]

@BuggyDad In this case - given my successful transmission builds from both Shapeways and 3D Print UK - i think its simply the vendor and their process. As well as being loose, the bores were noticeably tapered as well. I agree that under sizing and reaming might be good, but as the case is in two halves, hand reaming opens up the possibility of misalignment, which is an issue when dealing with 10ths of a millimetre.

I need some prints for work this month, so i think a new gearcase with better clamping will be on the cards. 

[ThunderDragonCy 8380]

5 hours ago, Wheel_Nut said:

What spur gear sizes are available for your transmission?   The BBX seems to have short gearing, but I don't know about the TD2.

All the Associated ones fit. The Tamiya spur is 77t or 79t. You can get 69, 72 and 75 Associated ones. I have a 69 in my RR03 i think. 

It's the standard Tamiya internal gearing of 2.6. Can't remember which, but i only had a 23t pinion in spares which makes the FDR around 8.7. I have some other pinions, but they are all in the 30s for touring cars. 

[BuggyDad 5904]

15 minutes ago, ThunderDragonCy said:

@BuggyDad In this case - given my successful transmission builds from both Shapeways and 3D Print UK - i think its simply the vendor and their process. As well as being loose, the bores were noticeably tapered as well. I agree that under sizing and reaming might be good, but as the case is in two halves, hand reaming opens up the possibility of misalignment, which is an issue when dealing with 10ths of a millimetre.

I need some prints for work this month, so i think a new gearcase with better clamping will be on the cards. 

Fair point. I think we should feed back to the vendor. See what they say and give them a chance to check their process. Maybe they'd reprint the offending parts to confirm/check critical dimensions themselves. I have a feeling they're all using the same printers, in which case it'd presumably be settings rather than something fundamental.

[ThunderDragonCy 8380]

@BuggyDad You are probably right, but i have enough supplier tolerance wrangling in my day job without importing it into hobby. For the same of 25 quid i will just buy a new one from 3D print uk I think.

[BuggyDad 5904]

42 minutes ago, ThunderDragonCy said:

@BuggyDad You are probably right, but i have enough supplier tolerance wrangling in my day job without importing it into hobby. For the same of 25 quid i will just buy a new one from 3D print uk I think.

That's cool. I can just write them a note asking them to look into the issue, not seeking a reprint or owt, just wanting them to sort their quality out so they're an option in the future, and to make them aware of the issue for their own purposes. Mind if I refer to your part also? I think that way they might have a bit more to go at (I can't remember for certain where I had the issue, but also your bigger [5mm?] bores might be a lot easier to see the problem on, especially with the tapering). 

[ThunderDragonCy 8380]

20 minutes ago, BuggyDad said:

That's cool. I can just write them a note asking them to look into the issue, not seeking a reprint or owt, just wanting them to sort their quality out so they're an option in the future, and to make them aware of the issue for their own purposes. Mind if I refer to your part also? I think that way they might have a bit more to go at (I can't remember for certain where I had the issue, but also your bigger [5mm?] bores might be a lot easier to see the problem on, especially with the tapering). 

Sure thing. Thanks.

[ThunderDragonCy 8380]

Figured out the clicking in the gearbox, and it's not just loose bores. I made a mistake. The shaft centres are based on the tamiya 27t idler gears. I ended up using associated 26t idlers because they come as a separate pair. I never adjusted the bore centres to suit, so everything is about 0.3mm too far apart. Not enough to prevent the gears meshing, but enough with the loose bores to cause the teeth to skip and click under braking, and sometimes acceleration. I needed some 3D prints for work, so i have very carefully recalcuated the bores and ordered a new case from a known supplier. I also added and extra clamp screw boss above the diff. Hopefully this will be here in time for tamiya junkies track day at the end of the month.

[BuggyDad 5904]

1 hour ago, ThunderDragonCy said:

Figured out the clicking in the gearbox, and it's not just loose bores. I made a mistake. The shaft centres are based on the tamiya 27t idler gears. I ended up using associated 26t idlers because they come as a separate pair. I never adjusted the bore centres to suit, so everything is about 0.3mm too far apart. Not enough to prevent the gears meshing, but enough with the loose bores to cause the teeth to skip and click under braking, and sometimes acceleration. I needed some 3D prints for work, so i have very carefully recalcuated the bores and ordered a new case from a known supplier. I also added and extra clamp screw boss above the diff. Hopefully this will be here in time for tamiya junkies track day at the end of the month.

So do you reckon the bores were still baggy/tapered? Will be interested to know if you can see a difference in the bores and holes if you pop a caliper on the new print and old side by side. I hadn't got round to contacting the supplier yet anyway. 

[ThunderDragonCy 8380]

6 minutes ago, BuggyDad said:

So do you reckon the bores were still baggy/tapered? Will be interested to know if you can see a difference in the bores and holes if you pop a caliper on the new print and old side by side. I hadn't got round to contacting the supplier yet anyway. 

I will definitely check, but the taper on the bores is for definite. You can roll them around off axis when the shafts are all the way in