critterracing

well took her out and beat her for a few hours this morning. we set up a parking lot tracks every Saturday with road rail and pretty much just run till the battery dies. lots of banging and launching off the rails .

i love this new car. i also run a g4s and most of our guys run rrr's. everyone thought the car looked great for its 1st time out. it had a off throttle push that i didn't like but i think just changing tires will fix that.

when i built the 2-speed i sanded the shoes nice and smooth with some sand paper. i had to set the spring tension 1 full turn tighter then stock to get it to shift. once i did that it shifted perfect all day. the clutch is outstanding held its setting perfect all day behind a OS TZ18.

oh before i forget the fuel tank leaked out of the box at the seam. i fixed it up with my soldering iron.

tear down showed a right rear shock fully ripped apart. the threads pulled right off the plastic bottom piece. all the belts and pulley's looked brand new. the brakes were alittle weak at 1st but bedded in nicely.

for gear i run the tz18,stratus 2.1, twister 37 front and 35 rear, Futaba low profile 9550 servos and a Jr z-1 with spektrum. the stock serpent battery sucks so a lipo is going in Monday. the lipo in my radio, which was in my blade cp heli for a few flights, started the day at 11.8 volts. it also finished the day at 11.8 volts. truly amazing. a 2 cell thunder power 1320 will slide in under the fuel tank perfect. that will give me a full day of running for sure.

this car is a keeper. cant wait till next week.

later
Aldo

madbeats

Da big Pay back is today , after a crash two sundays ago the snake out to bite some b..... Ass punks.. Wish Me well U Guys...

ShermanSim

iTrader: (2)

Cute Radio bag

Acid

Hi Guys

I took the 720 for its first competition run and the car is good but had the follwoing problems.

1. The rear of the car is loose - allot of the 720 drivers experienced the same problem - track only has hairpin bends - everyone said the same thing, the back doesn't follow the front. But still the car was easier to drive then the 710.

2. The rear lower wishbone - with two pivot balls is very weak - if you toutch the rear side of the car against the track piping - it pushes the rear pivot balls further in - I started with 3 toe in at rear and the slightest toutch at the rear and I was running 3 toe out. I wanted to try thread tape over the pivot balls but i did not get a chance too.

But, just so that all of you know, the winner at the Soth African Nationals in Durban this weekend was a Serpent 720.

Really not sure why the back of this car is so loose.... any ideas? I figure its the diff oils - the standard 50000 F and 30000 R doesn't work on a hairpin track. Thinking more like 100000 in the front and 10000 or 20000 in the rear.

Acid

Qlone

That is odd. I find the rear of the 720 a lot more (maybe even a little *too*) stable than the 710. My 720 has a tendency to understeer more than I like and I lose some time in the corners now (though I'm still very slightly less slow with the '20).

What surface did you run the car on? Was it treated with some sort of traction compound?

deepfree_z

I have the same problem with you Qlone, I can't go in to the corners as I did with my 710 before. I'm using 40 front,40 rear gq's, I will try a softer front tire.

Acid

Yeah, the track was treated with a traction compound. Also, the track was re-surfaced 3 weeks before the race. Tyres, 37 front and 35 rear. the front grip was amazing, point the car and she goes in that direction. The back following the front was the problem. As soon as you come onto the power, coming out of the turn, just a little, and the back steps out of place. Allot of slide... The fun part was doing some drifting with the 720 on foams that was fun to see the car sideways... but not good for laptime

Also, what I was thinking to help keep the rear in place, is to use the lower hole on the back suspension arm for the shock mounting. Haven't tried this, will do and let you guys know how that works out.

I has the understeer that you were talking about - changed the front roll to higher roll center (lower position on car) and it was gone. But the rear was very hard to keep in place. Finding the balance between front and rear was hard but the car was allot easier to drive than the 710. Even with the back stepping out every now and again, it was easier to control than my 710.

Have any of you experienced the problem with the back arms, where the pivot balls move in if you toutch something?

Acid

B4

iTrader: (1)

Have you given any thought to your clutch setup. The 720 is geared lower than the 710.

Qlone

The tracks here are not treated with traction compound, so the comparison is not easy to make... I can come out of a corner full throttle without any issues with the rear. I drive on GRP tyres, 40sh both front and rear. I will try changing the roll center on the front side. More grip on the front side of course also requires a more solid rear end, so maybe sometime next week you'll see me here complaining about a loose rear end too .

I have changed the shocks to the lowest mounting hole on the shock towers. This makes suspension slightly more progressive and improves the driveability of the car quite a bit. I also put purple springs in the front (which improved the understeer problem quite a bit, but not completely), and red in the rear...

Haven't had any issues yet, and the car has taken a few hits by now. A friend's 710 hit mine a while ago on the rear right wheel, with his left rear wheel. His DRS arm was torn completely out of the bearing block, but my 720 was just as it was.

Acid

Yeah B4.. that was the first thing I changed..i first went with a small clutch gap 0.5 and a quick engagement, clutch tension was set to 1.4mm. Thinking that a quick engagement would give me the extra power coming out of the bends.

Then changed a late engagement.... clutch tension was up to 1.8mm. Still, same problem...

The car was allot better with the later engagement... easier to control... but still the rear was loose...

Acid

Acid

Hope not... you will find the balance... the car is good....that much i saw for myself...


When I go with the lowest mounting positions, the car is easier to drive, but I ended up with traction roll. I still think the main thing to change would be the diff oils.

Did he hit your 720 from the side or the rear... my only problem with the arm came from a side impact... arm did not break, but is pushed the pivot ball in... weird... as some of the Mugen drivers who choose the same driving line as me didn't have this problem...

If you choose this driving line and if you get it wrong then you rub your wheel against the side piping... some of them got it wrong too, braking too late but it did not push the pivot balls in on their wheel...

Acid

madbeats

Mate- check your End points on the steering from the radio try setting it too 50% that should do the trick.. ok

Edgar Millenium

I had the same problem this weekend.

Qlone

Traction roll has not been an issue yet. Then again, our track is not treated with traction compound and my tyres are a bit harder, so overall traction could be a bit less on my side.

I had to stop, so I was standing near the grass at the edge of the track. The other car took the curve a bit too tight and almost missed my car, just our rear wheels touched. The impact was quite hard, and I had really expected a broken arm on my car too.

Tracks here typically have grass on the side, so no pipes or other hard things to slam in to. I did however hit the brick 'wall' between the track and the pits a few times at moderate speed, which is a side impact but the car held its setting without problems.
Is your track width at the rear 200mm? In order to get it at 200mm the pivot balls are screwed into the arms quite far. If they are not in far enough I can imagine the construction to be a bit weaker...

Acid

No. I was running a rear track width of 204 due to the 3 degrees of toe in. So when measured, the the furthest points of the wheel measured 203/4mm. At the SA Nationals they allow up to 205mm, I think, due to the toe in effects.

Edgar, what happened to you?

Will be going out again this weekend to a new track, long, wide, fast sweepers with a few chicanes... will let you guys know what she handled like...

But, there is one thing I must say, after all is said and done, this car is definitely easier to drive and faster than my 710. There is allot in the car, you just need to find the right balance - as with any car.

In the A main finals, wow. The 720 was the only car that held its line throughout the entire race. The Mugen MTX4 was extremely good in the begining but lost its line after 10mins. The 720, from the start, faster and consistent No tyre change as the finals are 30mins long.

It was then that I realised my setup was not where it should have been...

Acid