My little mods on the ZX5 FS
 

Hi there,

I'm starting a new topic to show some pics of my new ZX5 FS .
I've changed some (very) little details on it already but more are to come later on . It's no big engineering but anyway I wanted to share .

http://img691.imageshack.us/img691/1...rwithshell.jpg

http://img51.imageshack.us/img51/534...thoutshell.jpg
I've setted her up like RogerM advised me too :)

The general arrangement :
note that I've use conventionnal car bullet conectors for fast switch between 6.5t and 10.5t motor , works fine doesn't heat at all (yet) . Also the battery holders are inverted it is deliberate (see a few pics below).
http://img684.imageshack.us/img684/9...utshelltop.jpg

The nose after a few bodyshell assembly snaped and was a burden anyway so I cut it off and screw it !
http://img51.imageshack.us/img51/636/nosesk.jpg

I've setted the chassis on my CNC milling machine to give more clearance for the ESC :
http://img51.imageshack.us/img51/3896/escclearance.jpg

Same with the batteries , they were too wide to fit :( touched it 1mm will a mill ...
http://img697.imageshack.us/img697/9...tclearance.jpg

The original pole were the correct height but they only gave 2 in the kit :/ so I've made my own one in brass to give a bit more weight to the lipos .
http://img696.imageshack.us/img696/93/polesg.jpg

Just showing them doing their job properly : ( nice fit )
http://img130.imageshack.us/img130/453/polesinplace.jpg

The rear poles have been offsetted to the outside because the clips are too close at this height to the radio plate .
So I inverted the left and right battery holder and drilled the chassis on the same offset but mirrored according to the holders.
http://img697.imageshack.us/img697/8...leposition.jpg

More mods will come as thing break down probably lol or if I get fed up with some parts .

Very nice! I am like you. Also like to improve exciting cars for the better.
Tip for you. You can use team Durango rubber boots on the Lazer if you first take some shrinkwrap around the outdrives. Then simply place the boots on the driveshafts and slide onto the outdrives. Did this yesterday with my RB5 and it works great. Now the diffscrew and dogbone end of the driveshaft are protected from dirt and the lube stays fresh.

Looking good there. I think you will find that you need a bit more weight in there for LiPo (car seems to need to be at NiMh weight to work ... not supprising as it was designed around the weight distribution with 4200NiMh cells).
I know most people have added around 180g to the car when running LiPo!

I use the same speedo you have there but rotated 90deg. Keep a close eye on the car Lucar style connectors, might well be ok but if not might cause an expensive ESC failure. You seem like a sensible chap (certainly can machine well, good work there!) so I hope I'm not sounding too insulting stating that about the connectors.

2 other little tips

1) put M3x3 (or x5) grub screws in the unused camber link holes on the hubs, just helps reduce flex in the hub and thus helps prevent the used hole going oval and failing.

2) Make up some form of stand-off for the ball stud connected to the servo horn to get the link between the horn and the bellcranks as straight as possible. This really helps the car feel balanced as you move through the range of lock left and right. The car was designed around low profile servos (I think it gives a guide stand off size in the manual but can't remember exactly)

Hope you have lots of fun with the car, just ask if you need help with set-up etc. I'm more than happy to help, especially as the base set-up I gave you was a bit of an estimate.

Thank you very much :)

I will do what you advised me to do thanks .

No problem I am a very young teacher in mechanics . I work with kids (17-20years old) in a workshop all day with many CNC and conventional lathes and milling machines . So I am no electrician , electricwise I usualy try and see lol . For the connector I took the biggest I could find they are 5mm diameter I've test the car for a good 10 minutes they didn't get warm or anything and they are very stiff to separate , but I will be carreful next monday where they'll be fully tested for 2hours .

thank you again .

Nice mods! I wish I had a teacher to teach me machining!

Do you think you can make more of those battery strap posts, but with the top flat and slightly shorter to accept the B44 battery thumb screw set screws so you can use the thumb screws? I would be willing to pay for them, LMK.

Have you tried running your battery straps upside down?
Gives a better fit with the single strap on the SP.

Be careful with shell clearence (especially the front posts) if you try to use thumb screws. I've never understood why people think they are an advantage to be honest, the good old R clip has never let me down and is easy enough to instal remove ;)

I bought mine second hand and it has the original ones modified to use thumb screws and works very well, I haven't noticed rubbing or anything unusual. Its just they didn't really do the best job on the mod as far as looks.

Hi there,

Me too I never liked the B44s thumb screws (in fact it would have been easier to do thumb screw than the one I did ) . Too much time undoing them and even tightening them hard on the b44 .
I had the batteries come off while running several times ... Much prefer the R clip ones :) .


Right today was the first time I tried her on the track ... and it simply was brilliant !! Incredible , really amazing ! I just love it :) On top of it a mate just got a brand new Durango with a 6.5t and even though I have far less experience in driving than him I just overtook him so easily !

After a while one of the big experienced drivers tried the durango he said it felt kinda special ... then we tchated a bit and he said "I've been looking at your kyosho it's pretty obvious it has a proper set up " so I proposed him to try my car ... First corner and he was like "Wow !" "that's impressive!" he had the same remark as me "it is so easy to place it in the corners" "it just goes where ever you want it to go" a lot lot of smiling and he gave it back to me and said "20/20 it's fantastic !". A lot of people wondered by saying "is that realy just a 10.5t motor ? it's really shifting ! "
Then another mate was disapointed with his new mini spikes yellow on his B44 they were brand new ... so I said that I had too brand new mini spikes yellow , the very same as his and conditions ... So he had a go at the kyosho too . Same remarks "it's just got so much grip and control I can't believe you use the same tyres ! the car feels so easy . "
Basicaly everybody was after the set up of it :) and the experienced guy said that kind off set up can go direct in a shampion ship race for indoor gymnasium .
Really many thanks RogerM it's an incredible car . It just blows the b44 away .

Now a little problem but no big deal . The 10.5t motor felt too hot I think ... It's a 25/78 ratio should I go 24/78 (or less probably 22-23 spur ) ? It wasn't too hot to touch but felt very hot after a complete 1/2h running non stop . With a 4200Mah lipo pack it did 26minutes non stop with a very technical track .

By the way I had remarks on the connector as well . The mates saying that they were worried about power loss ... well after a 30minutes non stop really driving it hard (for me lol) the motor was as I said really hot , the wires just under warm and the batteries warm .... well these connectors felt the same if not colder than the wires . So logicaly if it isn't warm at all I don't think they're a problem no ? I couldn't feel any heat from them .
But I don't know I'm not very experienced in electonics .

Again thank you so much for these superb advices :)

ps: the SP 2.0gt ESC barely felt warm as well .

No problem mate, always happy to help if I can!

I'm shocked the car went so well as the set-up was purely an estimation based on experience with the car, I've never run on your type of surface. So glad you happy with it.

Electronics wise I'd say leave it alone as to be "warm" after nearly 30mins driving I think is more than acceptable.

Keep us posted and if there is anything I can suggets to improve the car please ask away.

Thanks again ,

The motor really was almost to hot to touch though . And the room temperature was cold (some guys had their coats on ) . I have made some quick and aproximative maths and they suggest a 21 or even a 19t pinion . What I had forgotten was 2 facts on the ZX5 ... The first one is that I'm used to the B44 84t spur whereas the ZX is a 78t spur so a slight higher gearing ... the second is that I had chosen the 25t pinion for the RB5 which as a 2.6:1 final drive ratio and not 2.5:1 like the ZX5 .
Anyway I've just ,as I write , switched on the car on off ground and full throttled it (makes a certain whole sound on the diffs etc) and I've mounted a 21t pinion the sound is exactly the same . That's a very aproximative guess but really the top speed seems the same . And of course I have much more acceleration on my carpet lol .

I know LRP's motor need a lot of gearing doing . My X12 6.5t I had put on the B44 was boiling hot with a 19t pinion (17t equivalent ZX5) I had to drop it to 17t on the B44 to get a nice temperature (just warm) so that's as if I had 15t-16t pinion on the ZX5 (for a 6.5t motor) . What was nice when I tried this is that I had much better acceleration and more top speed all together :)
Also another thing that I remembered is that with the 19t pinion the car did 25min with a pack whereas the 17t did a nice 35min for more perfomance ! And that was with a much more powerful motor .

Something else to mention is that on the track we have a long straight (the whole gymnasium lenght) and my car was slightly slower than the other until the middle of that straight but it was reaching its top speed a about 3/4 of the straight ... I sometimes had to touch the brake before the max speed was reached .

I'll try to get a 23t pinion as well just to try (I'll have a complete set 17-19-21-23-25 which is nice to have to experiment with) .


One car question :

I've put the car on a scale and it weighs 1580 grams is it ok ?

thanks

My car weighs in at around 1700g .... many people have found that a bit of extra weight at the back of the car (to return weight distribution to where it would have been for the 4200NiMh cells it was designed for) really helps with balance.

Sorry for the late reply I've been a bit busy .

Yes I can make you polls for thumb screw if you want but I may have a lot of things to do as well :( .

Anyway I've been working on the chassis weight lately ...

Many ideas crossed my mind and I came up with this this week end :

A weight to be put between the batteries . (two holes were already there from stock):
http://img138.imageshack.us/img138/7762/solidwork.jpg

This is the CAD I did for me to not forget measures while machining it ...
with these dimensions (in mm) it went straight in . But some of them can still be optimised :
http://img138.imageshack.us/img138/3096/drawinga.jpg

I've made it this morning in brass . The CAD programs estimated its weight at 130 grams , when I've put it on a precision scale it was 126grams . (plus the 30grams from the battery poles in brass it makes the perfect weight to match the Ni-mh weight with my lipos)
http://img35.imageshack.us/img35/5949/partfronttop.jpg

http://img63.imageshack.us/img63/6450/toprear.jpg

http://img682.imageshack.us/img682/7581/bottompb.jpg

To assemble the weight to the chassis you have to remove the top plate , the shaft , and the middle spacer (plastic H shape ).
http://img682.imageshack.us/img682/192/positionned.jpg

fitted nicely the shaft doesn't touch anything
(the silver mark was done earlier when I first assembled the car a few weeks ago) .
http://img35.imageshack.us/img35/6043/topviewn.jpg

Last shot showing how it seats and clear eveything :
http://img20.imageshack.us/img20/6254/finalview.jpg


I'll test her tonight and see how it goes :) thanks

@ace028
You may want to change the thumb screws as well to something more beefy ? like M5 M6 ?

now that is pretty trick.

nice work there!! sure you'll sell a few of those

Someone's obviously pretty nifty at machining then!

Top stuff.

:thumbsup:

That I like!

I think you will need to think of a price for that and the posts, I can see you getting ots of requests for both items!

Nice work!! :thumbsup:

As Roger says.. i think you should make a few ;)

Thank you :) I will consider making them yes :thumbsup:

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 :blush:

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 ?

have you tried schu full spike tyres we race on dusty polished floor every week and we have plenty of grip her http://www.youtube.com/watch?v=SPgel...ature=relatede here is a link mine is the oange white and chequerd cat sx leading

the tyres need to be worn in it takes about three weeks of running and they must stay on the correct side as the wear in a certain way.

stu rand

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!!

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.

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 :(

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)
http://img710.imageshack.us/img710/9909/yft.jpg

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... :)

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

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 :(

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

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

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 .

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,

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.

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 ...

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.

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

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 ;)

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

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.

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.)

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.