Grasshopper 2 Ultra G - Independent Suspension All Round

[ThunderDragonCy 8592]

Been in tidying up the Shapeways store as someone on here want's to build an Ultra Hornet (v excited about this). I've added the side plates as 3D printed parts and grouped all the Grasshopper 2 / Super Hornet / Rising Fighter Thundershot Transmission Swap parts into one place:

CTE RC by cy_turner - Shapeways Shops

[ThunderDragonCy 8592]

Oops! 

Broke this trying to do the jump on the club track. I am so bad at jumping buggies! Replaced it with a ratty spare I had, but if any of you reading this has the narrow Thundershot / Dragon tower spare from a Terra Scorcher, Fire Dragon or Saint Dragon Rere, I would happily buy a nice new one. 

Also found the rear very bouncy and bottoming out a lot on the club track, compared to Robin Hood Raceway where I normally run. Decided to do an oil change on the rear dampers whilst it was apart, and boy was that overdue! Horrible dirty oil, dampers not completely full. Cleaned and refilled with nice new core rc 400cst.

Also found a lot of the looseness in the front end was worn bores on the DT02/3 knuckles. Got some aluminium Jazzrider ones to improve things. They needed a little filing on the c hubs, but fit perfectly otherwise.

 

Also, the inner ball position is same as stock, but there is an outer position which would sweep the steering arms back. Any idea what this would do to the steering or handling? 

 

 

[Tamiyastef 2860]

3 hours ago, ThunderDragonCy said:

Any idea what this would do to the steering or handling? 

It would make the distance the servo has to move to get the wheels at the same steering angle larger. So it will make the steering slower but more precise. If, at the standard position, the steering isn't maxed out; it would make the steering angle bigger also.

[ThunderDragonCy 8592]

Track day! 

Had some fun running Ultra G on the big outdoor astro track. Nice layout, technical, but no big jumps. Nice! Ultra G was running nicely, but was grip rolling a bit and snatching the outer front tyres on some corners. Tweaked the steering on the Tx a little am improved it, but it never got quite as settled as Ultra Hornet. You can definitely feel those flexy Thundershot arms now I have a direct comparison. 

Still love this thing, but got a little voice saying I should put some stiffer arms on to keep up with Ultra Hornet. Not sure. 

 

[ThunderDragonCy 8592]

One of the fellas got some nice action shots in the barn

 

 

 

 

[Kol__ 3895]

Awesome mate, great to see this one still out and attacking the track! So you reckon stiffer arms will solve the handling issues?

[ThunderDragonCy 8592]

Track day! Indoor astro today as it was too wet outside. 

Ultra G was first thing I ran this morning, and it felt a bit out of sorts. Drove a bunch of my other stuff all day and came back to it right at the end and it ran amazing! Loved it. Lapped and lapped. Maybe I got my eye in? Lovely to give it a run. 

[ThunderDragonCy 8592]

Ultra G at the track. It was brilliant. Nothing further ;-) 

 

[Kol__ 3895]

Awesome mate, I do love that thing! Great to hear it's still tearing up the track!!!🏎️🏎️🏎️

[ThunderDragonCy 8592]

Not the best pic, but Ultra G was brilliant. Outdoor track was dry and running well and i did laps and laps. Marvellous!

[gazyang 2]

I purchased a parts chassis and another Hornet to do this exact same thing 3 years ago. I just randomly searched custom Hornet suspension yesterday and came across this thread!

I'm glad you did it and have made the parts available now as it saves me the trouble of designing them myself 👍although Shapeways prices are starting to get beyond ridiculous with their mark up these days. 

Oh and when I say another Hornet it's because I own two Vintage ( one I've had since 1984 ), one rere, a Super Hornet, a Supreme, no.3 Jun Watanabe, a Black Metallic and a Comical 🤷‍♂️ 🤣

[ThunderDragonCy 8592]

6 hours ago, gazyang said:

I purchased a parts chassis and another Hornet to do this exact same thing 3 years ago. I just randomly searched custom Hornet suspension yesterday and came across this thread!

I'm glad you did it and have made the parts available now as it saves me the trouble of designing them myself 👍although Shapeways prices are starting to get beyond ridiculous with their mark up these days. 

Oh and when I say another Hornet it's because I own two Vintage ( one I've had since 1984 ), one rere, a Super Hornet, a Supreme, no.3 Jun Watanabe, a Black Metallic and a Comical 🤷‍♂️ 🤣

Wonderful! Looking forward to seeing your build. Drop me a DM if you want some stl files. Shapeways is getting ridiculous, i agree.

[ThunderDragonCy 8592]

After a frustrating morning breaking things (including Ultra G EVO) and chasing setup, i emptied what remained of my last battery of the day in Ultra G

Was absolutely magic. Not quite as precise qnd on point as Ultra Hornet, but still quick and fun, and with the brushless it lasted aaaaaaggggessss. The battery wasn't full when i put it in and i must run for 25+ mins before the lipo alarm cutoff. Wonderful. Love this thing.

[ThunderDragonCy 8592]

Usual story: Ultra G was brilliant. No tweaks, no notes, just ace. Never change old friend!

[ThunderDragonCy 8592]

I ran this today after fighting the TD4 a bit, fiddling with it's dampers etc, and having found Ultra G EVO a bit edgy early on because of the grip. Aaaaaaaand Ultra G was just great. It just has a balance of speed and grip and handling that's just so easy to drive. It's not super fast, but moves well, and there is just a warmth to the way it drives which is so nice. And still enjoyable despite my other Ultra buggies definitely being faster, more precise, but just a bit more clinical. Given it is just a bag of old vintage design bits held together with a few ideas and dreams, it's so good! 

 

[ThunderDragonCy 8592]

After Ultra Hornet was so good on the damp outdoor track, I got Ultra G out with high hopes, but it wasn't to be.

Seems the ball diff in Ultra Hornet was the big thing today, as Ultra G was constantly looping out on the lightest of throttle applications. Got plenty of laps inside, which was great. High grip surfaces seem to completely negate the open diff, but I still got wondering how if there was something to be done.

On the drive home a vague idea formed based on Hornet EVO. Replace the thundershot gearcase with something 3D printed that still mounted the thundershot arms and bits, remained mid motor, but use DT03 0.8mod internals so there would be a ball diff open. Keep the thundershot metal motor mount with lots of pinion options. It might even be cheaper than using the Thundershot trans in full, as you need to buy a lot of Thundershot parts trees and gear bags and not use lots of parts. Might be a nice little upgrade project for the first time in 5 years for dear old Ultra G.

 

[BuggyDad 6368]

12 hours ago, ThunderDragonCy said:

Replace the thundershot gearcase with something 3D printed that still mounted the thundershot arms and bits, remained mid motor, but use DT03 0.8mod internals so there would be a ball diff open.

Hey, if you're using DT-03 internals and designing a new gear case, you could easily go for the @ruebiracer Xtra Speed gear diff insert, as used here (but he's also put one in a DT-03 with a bit more work to the gear case):

 

 

[ThunderDragonCy 8592]

@BuggyDad Interesting. Given it uses the same internal bevels as the others, do you think that xtraspeed widget would fit in a Thundershot diff? It's quite large and wide in the body. It's only the crown gear that's narrow and offset to fit around the rest of the transmission

[BuggyDad 6368]

44 minutes ago, ThunderDragonCy said:

@BuggyDad Interesting. Given it uses the same internal bevels as the others, do you think that xtraspeed widget would fit in a Thundershot diff? It's quite large and wide in the body. It's only the crown gear that's narrow and offset to fit around the rest of the transmission

My guess is the TS diff and the space it fits in will be a bit narrow but it's a good thought - I should be able to offer it up to check today. 

[BuggyDad 6368]

With the TS diff the toothed gear is the cover rather than the deeper half of the casing, and that cover is deep with its spoked structure, so it's not very space efficient and we're quite a few mm short of space. Have you ever tried 3d printing gears @ThunderDragonCy? A bespoke toothed cover might screw on to the Xtra Speed case. 

[ThunderDragonCy 8592]

4 minutes ago, BuggyDad said:

With the TS diff the toothed gear is the cover rather than the deeper half of the casing, and that cover is deep with its spoked structure, so it's not very space efficient and we're quite a few mm short of space. Have you ever tried 3d printing gears @ThunderDragonCy? A bespoke toothed cover might screw on to the Xtra Speed case. 

Thanks for checking. That's frustrating. Tried printing gears once years aho, but it wasn't very successful. I need to follow up my plan to send the DT02 ball diff gear to RW Racing to get them to make me a narrow 47t version. The rest of the DT02 ball diff fits the thundershot trans.

[ThunderDragonCy 8592]

Spent an enjoyable hour or so last night pulling my dt03 trans apart, measuring it and modelling it. Did a super basic mid motor gearcase to use them and offered them up to my Ultra G model. It's not immediately a goer. I ideally wanted to reuse the mounting plates that pick up the Thundershot trans, but the issue I have run into is that the thundershot trans is unusually narrow, and the DT03 trans is unusually wide. Not a great basis for a swap!

I could keep at it using some new mount plates, but there are a couple of things about the DT03 trans which make it less than ideal, and they are to do with the stepped idler. Normally in a 3 gear trans the idler is one size/tooth count and doesn't contribute to the internal gear ratio at all. It simply changes the direction of rotation of the spur relative to the diff. On the DT03 the idler is 19t to the diff, and at the other end 23t to the spur shaft. This not only makes it unusually low geared (2.86 internal, so the motor mount needs capacity for quire lathe pinions to get gearing lower than 8FDR), the long, stepped shape means its impossible to slide it across the car to narrow the trans and improve packaging. 

I could swap if for a 19t pinion mounted to a shaft with bearings in the case, but then we are into more complexity when I was trying to make this easier and potentially cheaper than using a full thundershot trans. 

I will have another look without holding onto the common thundershot pickup points as its fun to work these things through, but it's not the easy win I thought it might be.

[ThunderDragonCy 8592]

Did a bit more on this DT03 internals idea this morning, but the more I try and the more I measure, the more I think it's not going to work or be worth it. 

Kinda fits, but motor pinion adjustment has to be vertical, and mounting points are tricky. The main issue I have discovered is that the Thundershot rear arm mounting is really narrow and high. The centre of the pivot is 11.5mm above the deck plane, and only 35mm wide across the centre of the pivots. This is the reasons why the Thundershot arms mount outside instead of a boss between the pivots like on more modern things. There isn't space for a boss on the inside! The DT03 trans arm mount is 43mm centres and 9mm above the deck, giving lots of room for a mounting boss. It's almost same as the Top Force/DF01 trans as it happens. 

I'm going to park this now. I think I need to send this modifed DT03 ball diff gear to RW Racing and see if they'll make me some 47t versions for the Thundershot trans. As for a cheaper, easier "Ultra" buggy build, I suspect Ultra Hornet with it's DF01 trans and DT03 arms front and rear is the one. Maybe I'll have a look at replacing the custom carbon rear deck on that with a 3D printed rear chassis section. 

[ThunderDragonCy 8592]

NYE plans pushed back a couple of hours due to the Indian takeaway bring busy. Who've thunk on NYE? 😆

Anyway, decided to give Ultra G long (long) overdue damper rebuild and upgrade

New o-rings, rod guides and nice pistons. Plus new oil. Because - especially in the case of the front dampers - EEEWWWWWWWWW. Like I said, LONG overdue. 

Decided to do this one semi-scientically and fitted an unmodified SSBB piston to a rear damper with new bits, and test the feel relative to the other one in original, 1 hole cva piston spec. Mainly because doing the maths doesn't seem to relate to performance in reality, and also because Ultra G generally runs really great and I don't want to ruin it!

Anyway, stock SSBB 4 x mm holesx piston definitely gave the new setup much more damping with 400 oil, and I wasn't sure that was good. Next step was opening out the holes to 1.2mm like on Ultra G EVO and this felt good so that's what I went with. 

On the front the oil was DISGUSTANG. I found some TRF 2 hole pistons with 1mm holes in. I knew from previous experience these would be too much, and I remember the Aeration dampers are 2 hole 1.4mm front. Decided to split the difference at 1.2mm and went for 400 oil again. Although the unmodified damper was very squelchy to compare to this felt about right in terms of damping so I went ahead and finished both in same spec with new o rings and rod guides too.

 

 

[Kol__ 3895]

Great work on the shocks mate! Are you happy with the set up now or will there be more tinkering?

I've been enjoying some shock tinkering recently, but it can be a but frustrating and expensive. I find I try what I think will work as a baseline and then keep tweaking from there until I get it feeling right, but sometimes extra bits are needed. For example I've just bought 3 more different weights of big bore spring sets to try and find the sweet spot for the rears, and then some different weight oil too!