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ThunderDragonCy

Grasshopper 2 Ultra G - Independent Suspension All Round

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21 hours ago, ThunderDragonCy said:

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. 

Ultra G DT03 Trans V2

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. 

If you're printing a new gear case anyway, you could go for different uprights to bring the arms out and down with no practical effect on geometry? Uprights pretty small on the bill from the printers, taking away this constraint and giving you control over toe. 

I'm not a fan of the boss for the suspension mount being between the arm pivot points - outside is so much stronger. On Blitzer and DT-03 which have inside bosses I have had success with making braces out of sheet CF to tie the left and right pivots to each other, fore and aft of the arms.

So whether bosses inside or out, you could also design for braces - you could have small bosses just to locate the pivots with slots outside to take a brace, or in the case if the rear screw on to the back of the gear case. Give me the dims and I can CNC small sheet parts for you no trouble. 

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12 hours ago, Kol__ said:

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!

Thanks. Credit must go to the fellas over on the Buggy Damper Thread who came up with all these mods. 

I hope I am close to this being good. Whilst I like tinkering, Ultra G is like my safe place that always seems to be brilliant, so I am worried about making it worse. It has been consistently on these springs for years, so they should stay. I will tweak the oil if the balance needs changing. 

I know what you mean about it getting pricey. I managed to last a long time on DF03 and TRF501 springs I bought cheaply years ago tagged onto PJ orders years ago, but recently I have been buying Core RC big bore springs. They are tapered at the bottom but big bore at the top so they fit all CVA2 shocks, and they are fairly cheap to buy as pairs, or they do a big set for decent money too. Worth a look.

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53 minutes ago, BuggyDad said:

If you're printing a new gear case anyway, you could go for different uprights to bring the arms out and down with no practical effect on geometry? Uprights pretty small on the bill from the printers, taking away this constraint and giving you control over toe. 

I'm not a fan of the boss for the suspension mount being between the arm pivot points - outside is so much stronger. On Blitzer and DT-03 which have inside bosses I have had success with making braces out of sheet CF to tie the left and right pivots to each other, fore and aft of the arms.

So whether bosses inside or out, you could also design for braces - you could have small bosses just to locate the pivots with slots outside to take a brace, or in the case if the rear screw on to the back of the gear case. Give me the dims and I can CNC small sheet parts for you no trouble. 

All good points. Ultra G and my Thunder Dragon already have printed 3 deg toe uprights and as you say, if I am thinking in terms of offering a cheap conversion kit they are probably cheaper than the parts tree which has all the front knuckles and c hubs on it too, but would be unused here. 

I could possibly "do a TD4" and have front ball joint indents in the gear case, then use the TD4 adjustable rear mount. Then the new rear knuckles wouldn't have to be handed because the adjustment would be at the inner pivots. Or a couple of carbon sheet parts by your good self and keep the e clip pivots. Hmmmmm.....

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53 minutes ago, ThunderDragonCy said:

All good points. Ultra G and my Thunder Dragon already have printed 3 deg toe uprights and as you say, if I am thinking in terms of offering a cheap conversion kit they are probably cheaper than the parts tree which has all the front knuckles and c hubs on it too, but would be unused here. 

I could possibly "do a TD4" and have front ball joint indents in the gear case, then use the TD4 adjustable rear mount. Then the new rear knuckles wouldn't have to be handed because the adjustment would be at the inner pivots. Or a couple of carbon sheet parts by your good self and keep the e clip pivots. Hmmmmm.....

That's a good point. Maybe another development of the idea could be that the section with ball joint indents be one piece spanning both sides, so the case is more one main section with a cover, than two broadly equal halves. A bit tougher again in what I assume is the most stressed element, and made possible because that area is not interrupted by gears. The adjustable mount is nice, I used the same one on Mohawk.

Reminds me - a simple way, of course, is to use similar aluminium mounts front and rear - it ties the sides, strengthens the gear case, but it'd blow the budget I guess. 

By the way, little parts like the braces I've made are really the easiest things to run off the CNC router - I have strips of scrap material they can be cut out of and they're just vertical cuts and holes. Piece of cake. And thickness hardly matters - I think even 2mm GRP would make a strong enough part. 

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