My little mods on the ZX5 FS

[shannow95]

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 .




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).


The nose after a few bodyshell assembly snaped and was a burden anyway so I cut it off and screw it !


I've setted the chassis on my CNC milling machine to give more clearance for the ESC :


Same with the batteries , they were too wide to fit touched it 1mm will a mill ...


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 .


Just showing them doing their job properly : ( nice fit )


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.


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

[Alex H]

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.

[RogerM]

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.

[shannow95]

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 .

[ace028]

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.

[Col]

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

[RogerM]

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

[ace028]

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.

[shannow95]

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 .

[RogerM]

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.

[shannow95]

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

[RogerM]

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.

[shannow95]

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):


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 :


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)






To assemble the weight to the chassis you have to remove the top plate , the shaft , and the middle spacer (plastic H shape ).


fitted nicely the shaft doesn't touch anything
(the silver mark was done earlier when I first assembled the car a few weeks ago) .


Last shot showing how it seats and clear eveything :



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 ?

[discostu]

now that is pretty trick.

[GRIFF55]

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

[jhammond]

Someone's obviously pretty nifty at machining then!

Top stuff.

[RogerM]

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!

[njc11]

Nice work!!

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

[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 ?

[discostu]

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