Grasshopper 2 Ultra G Evo Black Edition

[ThunderDragonCy 8404]

Some street running to see how things stand. The new springs and balanced, lower ride height felt a bit more planted. Still a bit wayward under power oit of turns, but very stable doing slaloms down the street. Decided to try raising the roll centre even further at the rear by flipping the camber link mount.

Bit extreme, but it definitely made the car seem more stable in turns, but still the rear let go quite easily on exiting tight turns on power. Unfortunately this change made it more snappy and likely to spin. Previously it would do similar, but more slowly and i could catch it and it would turn into a bit of a tankslapper, but could be contained. This now spins very quickly. So, not the solution, but interesting.

I think i need to print a camber link mount to replace the carbon plate which gives me some height options around the middle of where the current plate it mounted.

Tried the mid position for my shorty lipo and it didn't help  the handling, but did push the rear down more than the front by a fair bit

 

I think i need to put the rear back to where it was on camber links and go and run on astro somewhere. 

 

 

 

 

[Wheel_Nut 381]

Did you try to revert the rear camber link position to original and use rear-most battery position?

[ThunderDragonCy 8404]

On 8/3/2024 at 11:10 PM, Wheel_Nut said:

Did you try to revert the rear camber link position to original and use rear-most battery position?

I didn't, but i don't think it made a hugh difference 

[ThunderDragonCy 8404]

Got half a day to myself on Wednesday morning so i am going yo get myself down to the track to give this a bit of a run on astro. Buggy wheels back on, and flipped the camber link mount back the right way up. Also set both ends with lowest roll centres possible. Then i had a bit of a brain wave, got my anti roll bar bag of spares out and fashioned this

I used longer screws through the suspension block/trans case/camber link and put two sets of ARB tabs spare from touring cars to mount the bar. It's one of the bars i made for my FF01 and it just needed a slight tweak to the bends. Installed ends and dropper links and we have an anti roll bar to try.

Let's see.....

 

[Grumpy pants 5511]

Let us know how Wednesday goes 👍

[ThunderDragonCy 8404]

Ran at the club track. Definitely better! Less looping on throttle, and much more planted. Front was riding a little low so i added another thick preload clip and it seemed pretty good. Might have to get some slightly stiffer fronts. At 2.8lb they are the softest Core RC fronts.

 

Damping seemed good and for first time i enjoyed driving. Didn't make any changes as i just wanted to like my car!

I did also run Ultra Hornet, and it was an interesting comparison. It definitely has more traction and more planted rear end. Doesn't matter where you are on exiting a corner you can just plant the throttle and it goes. It's just a bit more confidence inspiring, but Ultra G EVO is definitely getting there. Although Ultra Hornet definitely seems bouncy and under damped now. Need to try some heavier oil in the dampers.

There is a little running video of Ultra Hornet over on that thread.

 

 

 

[ThunderDragonCy 8404]

Additional: Ultra Hornet is way faster. That Reedy Rage Type R motor i picked up on ebay for that buggy is savage! Wish i could find another for decent price

[ThunderDragonCy 8404]

Additional additional: Had a couple of hours this afternoon and didn't want to waste it scrolling on my phone so i had a look at a 3 gear trans for this. I wonder if part of why Ultra Hornet is good is the 3 gear df01 trans, which spins the motor the other way to the 4 gear on Ultra G EVO. 

I had a look and couldn't make a 3 gear work using the existing motor plate or other parts sharing, so i took some inspo from some of the really current race stuff and saw if a 5 gear would work. First look is that it just about fits. Something to keep in my pocket if i can't sort the handling any other way

[guggles 295]

Had to pop in here and say I havent read all the pages of this thread, but I definitely am going to spend some time and enjoy all the posts of this build. 

Good call on being productive, always is more fulfilling than the media entertainment. What is the roll bar made of? 

 

[ThunderDragonCy 8404]

1 hour ago, guggles said:

Had to pop in here and say I havent read all the pages of this thread, but I definitely am going to spend some time and enjoy all the posts of this build. 

Good call on being productive, always is more fulfilling than the media entertainment. What is the roll bar made of? 

 

Thanks. Roll bar is just 1.8mm piano wire off ebay bent with pliers. I print out a 1:1 shape from CAD and keep bending and checking against that until it's pretty even

[ThunderDragonCy 8404]

After last week I figured some stiffer front springs would needed. At 2.8lb/in, i had to add a thick preload spacer to get the ride height i wanted. Those spacers are 5mm thick, which just under 0.2", so 0.2 x 2.8 = 0.56lb of load applied with that clip. I went ahead and ordered some 3.4lb/in core rc green medium length springs. 

I fitted them this morning after measuring ride height before and after and the 3.4lb without preload the extra preload clips sat lower! I added medium (2.5mm) clips and it sits about right. This is the tricky thing with measuring ride heights. It's hard to get the measuring consistent even if you do the 'drop the car' thing before measuring. Should be better with the stiffer springs though, based on driving last week with the soft ones.

[toyolien 5933]

4 minutes ago, ThunderDragonCy said:

After last week I figured some stiffer front springs would needed. At 2.8lb/in, i had to add a thick preload spacer to get the ride height i wanted. Those spacers are 5mm thick, which just under 0.2", so 0.2 x 2.8 = 0.56lb of load applied with that clip. I went ahead and ordered some 3.4lb/in core rc green medium length springs. 

I fitted them this morning after measuring ride height before and after and the 3.4lb without preload the extra preload clips sat lower! I added medium (2.5mm) clips and it sits about right. This is the tricky thing with measuring ride heights. It's hard to get the measuring consistent even if you do the 'drop the car' thing before measuring. Should be better with the stiffer springs though, based on driving last week with the soft ones.

Are you at Junkies meet this weekend? Looking forward to seeing your cars in the flesh👍

[ThunderDragonCy 8404]

Just now, toyolien said:

Are you at Junkies meet this weekend? Looking forward to seeing your cars in the flesh👍

Unfortunately not. Working this Saturday. The last few Junkies have fallen on my working weekends which is a bit frustrating. Shame to miss you.

[toyolien 5933]

2 hours ago, ThunderDragonCy said:

Unfortunately not. Working this Saturday. The last few Junkies have fallen on my working weekends which is a bit frustrating. Shame to miss you.

Not to worry. I'm hoping to make the September one also.

[ThunderDragonCy 8404]

Finally going to make it to a Tamiya Junkies meet next saturday, so doing a final bit of tweaking on this.

For a while i have suspected that the front might be part if the problem. I tried to measure the geometry off photod of the schumacher car i used the arms off. As the lower arms are banana shaped it's hard to get an instinctive feel for where the camber link is in relatioon to actual line of the lower arm, but i always suspected it was quite parallel giving a very high roll centre, which rolls very easily.

I needed some 3d printed parts for work a while back so i piggybacked some revised front uprights (shown left with ball installed). They are 3mm talker than the originals to lower the front roll centre and hopefully control the roll of the whole car better. That's the theory....

I also noticed quite a bit of slop in the pivots on the originals so i dug out ny shima and did a proper job of installing the new ones nice and tight.

 Not a lot different to look at, but hopefully better. We'll find out next Saturday. After the first run at Junkies back in spring ended so quickly and ignominiously with a suspension mount failure, i am hoping to get a few laps of the big track in this time.

 

 

[Wheel_Nut 381]

It seems the new front uprights make the links less parallel to the arms?  It should allow a *higher* roll centre and increase the stiffness in roll.  I agree with the theory.   I’m not sure about the wording.

[CRC505 232]

Your work is great!！！ I think this is more interesting than Tamiya’s Hornet evo!

[ThunderDragonCy 8404]

Ran today, and finally i think i am getting somewhere!

Only ran indoors on flat, high grip astro but it was great. Fast, neutral handling, easy to drive.

Be interesting to get it outside on the big astro at some point. That track was too wet today. Glad it's finally coming good though. 

[ThunderDragonCy 8404]

Did LOTS of running with Ultra G EVO today on the big outdoor astro, in gloriously dry, grippy conditions.

Was first car i ran this morning. The grip took some getting used to, needing the steering turning down a bit on the Tx. I even grip rolled once. Was really planted though, which given where i was a few months back is definitely good. 

Ended up being last car too, to run through my last pack. As it was a bit on the nose earlier, i moved the shorty to the more rearward position, which is about central in the battery box rather than slammed all the way forward against the steering tub. I also added thin preload spacers to the front shocks to lift the front a touch too. THIS was it. I don't know if it was the changes or me having got my eye in, but it flew. So planted, so fast being and to power through some of the turns. Really great. Very clinical and sort of what you would expect from something with so much race bits on it, but really satisfying to try and go fast. 

To the point where i need to try some bigger pinions. The Superstock motor is lovely, but it wasn't that warm even after a long run, and it's markedly slower than Ultra Hornet with it's Reedy Rage Type R motor.