My little mods on the ZX5 FS

[Neil Skull]

Originally Posted by shannow95

Thank you I will consider making them yes

I've just come back from the session and unfortunaly for polished floor the weight wasn't improving it at all .I think it will be great on something with more grip because here it sort of balanced like a pendulum in each corner like draging something heavy behing that was pulling the rear in the outside of the corner . Anyway I got it quickly off , less sudden back loss but still a little lack off control . So I took off the other modification that I did wich is the 23t spur got back to 25t and although the motor was hot it really was more sweet as a feeling . More controlable .

One thing that burdens me a little is that the car still lost a bit the rear in corners as if the car was trying to pivot from the front suspension . Could it be the 1°deg toe out that I have on the front ? Sort of understeered in entry corner and oversteered comming out (sort off because it's so slipery that it's hard to really feel whats going on while trying to control the drifting ).

By the way I broke the steel piston axle on the front suspension at the end

PS: Just remembered another thing about the front toe out is that I think I didn't notice this problem last time because last time I had a lot of play on the pivot/swing arm servo (wasn't very tight at all) . The front wheels really shook a lot lol It could have compensated my setup by itself then . What do you think ?

One thing that burdens me a little is that the car still lost a bit the rear in corners as if the car was trying to pivot from the front suspension . Could it be the 1°deg toe out that I have on the front ? Sort of understeered in entry corner and oversteered comming out (sort off because it's so slipery that it's hard to really feel whats going on while trying to control the drifting ).

try a front one way!!

[RogerM]

Exactly what I was going to say Neil!!!
The one-way will help in two ways
1) remove braking effort from front tires so they only have to deal with cornering forces with their limited grip.
2) allow the front of the car to pull the rear around thus keeping it in check.
It will require you to take slightly different lines and braking points but over all the car should be lapping faster when you get used to it!

If you post a FULL set up and tell me as well as you can how the car behaves I'll do my best to help you dial this in.
As I say I've not run on your sort of surface for many years and never with an FS but the car is so reactive to geometry tweeks I'm sure we can get there!
I'm still certain that the FS will beat all on the slippy stuff as it's so neutral and well balanced.

Will do my best to get back to you ASAP but going to be a busy week at work & a big race this weekend so if it takes a few days please accept my appologies.

[shannow95]

Thank you ,

I've tried to follow most your recommendations at the moment the car is setup like this :

-no camber front and rear suspension .
-3° toe in rear suspension 1°toe out front suspension .
- dark yellow spring all around
- 30wt 3A piston front and 25wt 3A piston rear
- no sway bar
- Front shocks = in on tower, mid on wishbone
- Rear shocks = in on tower, in on wishbone
- tyre mini spike yellow
- 7° caster angle
- 23/25 pinion on 10.5t x12 LRP brushless
- ESC : The GT 2.0 SP has 0% drag brake force / DRRS start mode 4 ( I hate below 4 because there's a sudden incontrolable burst of power a short moment after the start not progressive at all) / brake force 75% and then eveything set to 1 .
- ride height is set so that the shaft/wishbones are set horinzontal with the batterys and eveything on it .

Basicaly when you turn in you start to loose traction (not willing to turn sharply it goes straight on a bit more than idealy) , i have to touch the brakes hard and then at this stage i'm 1/2 through the bend and there's like a sudden grip from the front the rear suddlenly slide sideway . A lot of trying to get control back when i'm coming out of the corner : left , right left , right oscillation about twice before getting a steady straight line .
The chief club tried it and said that it was understering going in and overstering coming out .

May try to make a drawing to show it if I can

[shannow95]

thats the car position according to its progression in the corner :
(sorry i'm very bad at this and went really fast to do it)

[dagfather]

Sorry.. Can't really help you with this. But I came across a great article at RCtech.

Here's some of the key info:
"Steering turnbuckle inner ball ends: Shave those puppies down till you can see the balls. If you run the grey ones, you really have to dremel those down until it almost turns into a eye instead of a cup. I found that even after trimming mine, at full lock, the inside one was still catching. I shaved it down much further and upped my EPA and got crazy amounts of low speed steering. If your car is hurting for low speed steering, check here FIRST. Pop the upper chassis plate off and turn full lock and see if you're binding on the outdrive of the front tranny. I have also found that setting your EPAs so it flexes the servo saver a bit really helps hold that inner wheel at its most extreme angle. Increase your epa until you have reasonable resistance when trying to straighten your inner wheel -- i.e. don't let it be floppy by setting your EPAs just off of binding, you will lose steering."


"I've been going back and fourth on front sway for a while -- our track owner has been giving me grief on that for weeks! If I ran the shocks middle top and middle bottom, the car was good, but really needed the sway in the high speed corners or it would roll a lot on hard corners. If I moved the shocks out on the bottom, and in on the top (like what Tebo runs), the progressiveness lets the front be soft for good steering, yet firm up under hard cornering and the sway is not needed at all (which also contributes to low speed steering) but the car was way too unforgiving on jumps because of the reduced droop in the front. Tebo had the answer, which made me feel like a tard for not thinking of -- he runs the fronts with the shock eye unscrewed about 4 turns out. Whala -- front end is perfect. I also went back to the factory yellow springs in the front (what Tebo was running) -- I was running oranges, and they worked well, but the yellows are stiffer and I didn't notice any decrease in low speed steering, so perhaps more high speed stability can be had with the yellows over the oranges -- should prevent more roll at speed."

"A note on the shock eyes -- the manual shows you lengths from the eye to shock base. If you screw the eyes in all the way, you will be shorter than you're supposed to be. Measure with a set of calipers to be right on. Tebo said that he thought he was running the rears screwed all the way in. In the end, I was running with them at the length the manual specified (I think that was around 3 turns out from bottom on the eye, not sure). I tried them screwed all the way in and at manual length and to be honest -- there wasn't a difference I could tell in the rear like the front. I left them at manual length in the mounting positions the manual called for."

"I'd like to note that I'm now running 2mm of limiting in the rear shocks on my fs (two 1 mm limiters on each side) with the shock eyes screwed all the way into the shafts. This has made a dramatic difference on our small indoor track with its long smooth sweeper corners and ultra tacky conditions. Without the limiting the car would traction roll easily and I really had to take it slow in the sweepers whenever the track became really sticky."


Just thought perhaps some of you were also new to some of this intel...

[discostu]

it sounds like your tires don not generate side bite what you have discribed is acatly what mini spikes do on our track FORCC which is why we do not use them i betting your car is quicker than the rest when it is straight and has forward traction.

stu

[shannow95]

Indeed but all the others are using mini pin (got them and tried them as well it's quite worse ) I may consider buying a set of full spike but unfortunaly if I need to wear them for 3 weeks with a 2h/week trainning that may take 1-2years

[discostu]

yeah but you could always take the edge of them in a smooth carpark and think of the money you would save whilst the guys with the pins on are using them up in what 4 meets (guessing) yours will be good for at least three months.

how comes you only have 2h of racing a week.

stu

did you watch the link

[butch]

thats the car position according to its progression in the corner :
(sorry i'm very bad at this and went really fast to do it)

Hi to help u with this problem, would need to know what camber links u are running front and rear, and wheelbase, but some of it could be when u get on the gas, if u get on it to early then it will not help you,
Thanks Simon

[shannow95]

Camber links are all stock manual position I haven't modified them . The basewheel is stock as well .
For the gas I don't think it's the issue because although I'm no good driver the chief who tried it as well is very good and had the same motions problem .

Unfortunaly we don't have a proper track it's an indoor gymnasium that we rent 2h/week . That's why I'm really relying a lot on your experience to gain knowledge fast because I simply don't have enough on track time to self test randomly .If I had full week end racings I would literaly buy anything I could find for it and just test every setup , tyre , weight etc ... but in these 2h 20min are alocated for assembling the road rails and plus 10min installing my self . Basicaly over the 1h30 left I can barely make a quick modification and then it's over ... see you next week ... by that time I totaly lost the last feeling I had to judge the behaviour of the car . On top of it it's gymnasium floor so can't even test anything on a bit of road , grass in the garden ... It is a shame that I don't have a track closer than that .

yes I saw it it's nice they seem to have a good grip .

[butch]

I've tried to follow most your recommendations at the moment the car is setup like this :

-no camber front and rear suspension .
-3° toe in rear suspension 1°toe out front suspension .
- dark yellow spring all around
- 30wt 3A piston front and 25wt 3A piston rear
- no sway bar
- Front shocks = in on tower, mid on wishbone
- Rear shocks = in on tower, in on wishbone
- tyre mini spike yellow
- 7° caster angle

the few changes that i would make is to run -2deg camber all round, this will give more corner grip, all round, ( never run less then -1deg)

move rear shock out on bottom, this will give you more rear corner grip,

and try short wheelbase, this will give car abit more turn it and more rear grip coming out of the corner,

[RogerM]

In addition to what Butch says above make sure that you are running the longest possible camber links all round.

Front 2mm shim under inner ball stud, 2mm shim under both rear ball studs.

After that it try moving the upper end of the shocks to the inner most hole on the towers. Run the cells in the rear most possition too.

Still think a one-way might be worth a try to remove some of the corner entry understeer.

See if you can get hold of an editable set-up sheet (think there is one on PetitRC) and fill that in and post that up, will give us a better idea of the over all setup.

I can only think that the tires aren't working well as the only time I've ever had any form of true understeer on the FS it was because I'd fitted the wrong compound of tire to the car by mistake.

Its unfortunate that we don't run on similar surfaces but as I say we'll do our best to help, might just take a couple of itterations to get there.

[shannow95]

Right I'll get a set of full spike yellow with green inserts and a one way diff (seems weird that it doesn't come complete you have to buy 3 different parts) . I'm scared of the one way diff because when braking it'll be a 2wd ... and I don't have a nice remembrance off 2wd on that surface ...

[discostu]

i personly wouldnt run a one way just a very tight front diff almost a spool but with a little give it will react in a very simular way to a one way but feel stable under breaking.

[discostu]

also try a full rear insert in the front tiers it will fill the tire out more than a front insert in the front tires and make the car more consitant though the corner as the tire holds its shape better so to confirm yellow full spike with green rear inserts front and rear. and doing this if you dont like the feel you can always trim the inserts that are in the front to suit you.

stu

[RogerM]

The near-locked diff will promote the understeer into a corner but may help on the way out.
Personally I struggle more with the entry into the corners than the drive out but different things will suit different driving styles.

What tires are the fastest guys using ... those will be the right ones

[discostu]

yeah but it will take the aggresivness out of the front of the car the problem that was discribed was the car would snatch going in and coming out looking at the clever picture a tight front diff will smooth the problem out and make it easier.

and yes use the tires that the quick guys are using but he has probably done that

[Fabs]

I would most definately start by running stiffer springs all round, or at the very least up front, try fluo yellow up front.

It might seem strange but it will give you more turn into the corner, trust me. Also stiffer front oil, try 40 or even 45.

Also, change your shock tops ! On the plastic set of shock parts, there are 2 different shock tops, the one the manual tells you to use is the short one, but I'm advising everyone with an FS to try using the long ones. This will give more front droop and will most definately help your car in all areas. Basically now I run nearly as much front droop than rear, so much that when I go to full lock and suspension fully extended, the steering knuckles rub a tiny bit on the wishbones.

At the rear I run fully screwed shock ends, normal shock top, and 2mm limiters inside the shocks.

[shannow95]

I bought the one way to give it a shot and the full spike tyres .

The lack of time that I have racing to the club is ennoying me a lot unfortunaly . I really like to fiddle with things etc but with 2h/week (club doesn't run on holidays) there's no way of learning how to set the car . And even so to me 2h/week is not enought to play with it everything is rushed ... I don't like being rushed .
I have found that the gymnasium at our school has a sort of painted floor with a slight rippled like surface . To my shoes rubber it slides about the same at my club I might try to set her there or at least try to figure by myself what does what .

There's a 1/10 1/12 on road club that run not so far from home I'll probably go to see what's going on there for curiosity . They are at least opened the whole sunday which is nice for fiddling training chatting etc ... I doubt the zx5 will be welcomed .

(merci Fabien il me semble que tu es français non ? J'ai regardé de nombreux set up à toi pour la rb5 à darmatin mais on m'a prevenu au club que le sol du gymnase a dammartin était chauffé car sinon on a la même surface au club.)

[ace028]

Good luck with everything, I hope you can find out a suitable setup, your car looks amazing. I have never ran onroad cars, but I think it may be fun. Same boat here with the track locations, I have to drive a hour to my track so it makes it difficult.