ZX5 Conversion kit

[Crim3Wav3]

Hey Jimmy,

I used the kit battery post screwed in to the rear top deck as shown in the instructions from KMC. Then i drilled out one of the extra wing-stay washers (the little black washers) and put that down the post a little ways....i will be needing a new body from the holes I put into my old one.....

[jimmy]

Thats how Ive got my old shell mounted at the moment, but with a new hole and body pin thru to support the shell.

[niggs98]

Originally Posted by jimmy

Cheers mate

did those extra ones come in the kit ? should i have a look on the discarded parts trees on my floor ?

no they come in the bumper kit. i have a spare pair i can give ya at the national this weekend if ya need some

[jimmy]

It does look to hold the shell on well, I'll just mention it I think in mi review (with those photos from southport) and stick to what I have, but thanks anyway mate.

[boomerang]

Howdy

i bought that kmc kit, and drove it. after about 30 driven pacs the carbon chassis was so weak, like you were holding an old sprint 2 hpi touring car with gfk chassis in your hands. i dont drive it anymore, cause it handels awful like this.

next thing, do you guys also feel, that the kmc kit is harder to drive when you slide with the rear end? but it has a bit more strait on traction, your opinions?

greetings from switzerland

Maurice

[Crim3Wav3]

I do not see this happening to the chassis itself....after looking at the car for awhile and trying to decipher how this could happen, i come to realize one huge problem with the design.

Each top plate screws to the center aluminum bulkhead and spans to the rear bulkhead and front bulkhead where two screws are also used....included in the conversion kit are two aluminum spacers that raise the mounting position up to that of the center slipper bulkhead. The rear and front screws, however, are screwing into the plastic camber plate that sits on the diff halves. While this is the stock location of the standard top plate mounting scews one significant difference is present. On the stock top plate, the design is such that it notches into the mounting location whereas the KMC top plate creates a 5mm moment arm centered at the thin section of the camber plate mounting location.....

This all means that as you drive the car, the area where the rear and front top plate mounting screws thread into the camber plate will become weak as the car flexes (and cant flex the chassis before those areas give-way)....

This being said, I believe that I will be designing and machining the correct spacer for this design...one which will notch into the rear and front top diff halves.....

If you look at the KMC chassis in the original pics, you can see that they were running the car with an aluminum front tower mount and this camber brace all machined into one unit.....this would definitely make a difference in the amount of stress this moment arm produces.

food for thought....and I dont think your chassis is failing....check this area of the car and let us know if I am onto something here.

I do have the chassis by the way and have held onto it and tried to bend it while all put together....the top plate diff mounting screws flex WAY before the lower chassis plate.

[boomerang]

Howdy

yes you are absolutly right, when the kit is new everythings has the flex on those points you described.
i think you are right too, when you said that there are missing notches on the kmc brace witch makes the level for the topdecks on the gearbox, that was my first opinion too. i think other braces would help definitliy.

when i started to drive the car with the kmc kit, it was enough stiff, even for an kardan driven car ( i think everbody who has driven an tc3/tc4 knows what i mean, when you look at the poor performance of other kardan cars like yoks and pro4)

but after driving you will discover that the car will start to flex more and more. when i take only the single top deck in my hands, i can flex that thing like rubber, i does not feel like you are flexing carbon. you can flex that thing about 45 degrees without breaking...

not such a big amount of flex i discoverd on the lower deck on the battery location, you can flex it without problems about 15 degrees

i know this sounds crazy. i was thinking i am nuts or something like that, but knowing that i was an race engineer in an car hillclimbing team for a few years working with lots of carbon i would say this explains why this kit has such a good price.

the problem could be solved with good quality carbon...and with your modifications the car would be ultra stiff.

anyway, but do you think too, that the higher center of gravitiy in the front of the car makes the cornering speed lower? i felt like that.

greetings from switzerland

Maurice

[Crim3Wav3]

I have yet to put more than 10 packs on the car, and so far everything flexes the same as it was when it was installed.

I went to the website where KMC gets their carbon from (KCI), and they have a couple different grades. Obviously, the quasi-isotropic sheets would be the best grade, however, KMC does not specify which the car is made from...this website does also offer lower grade carbon that is in the traditional 90, 90, 90 degree pattern (verses quasiisotropic, which is 90, 45, 0, 90, 45, 0 degree lay)

I would suspect that, based upon what you are describing, the laminated layers are separating at each layer....which seems almost impossible without noticable damage to the edges of the plate....

Anyway, i will be on SolidWorks tonight to design the part (upper deck bulkhead spacer) and will be fabricating it this week at work.

Have you contacted KMC yet Boomerang? Im sure they would love to see what is happeing with their chassis...and I would be pissed if it happened to mine....I would more or less demand a new one if no foul play is obvious...

Boomerang, did you notice any diff gear damage as an issue with the kit? It seems with the flexing at the diff cases that the diff gear would get chewed quickly....

[boomerang]

evening...

i took one of my upperdecks an used a sandpaper to determine if its 90-90 or quasi isotropic...i would say its 90-90. i just remeberd that when i was building my 4wd prototype a few months ago, i had 90-90 carbon too. and after loads of packs it was the same problem, it was soft like GFK. and i m sure that this was 90-90 because they only sell that one. and you can t see any damage with the human eye, i mean i cant see any damage...

i do not have contacted kmc, because if i will ride that layout again, i will produce some chassis with the carbon from www.swiss-composite.ch , they have quasi isotropic one, which i already used in an touring car prototype. there it works fine.

but thats the thing, i have two cars, with specific setups to both layouts, same tires same engine etc. and the car with the original layout is faster most of the time. its got usually more grip. but it has less strait on traction. when you are faster in the corner especially out of it, you don t need so much rear traction, maybe thats why its faster?
to be sure about the test, i gave both cars to a friend of mine without telling him wich car it is.

about the diff gear damage, yes the kmc car needs more diffs. definitly, i cant say how much more but it is more.
your modification could help with that. at the momemt im trying to do the brace around the diff cage with carbon, if it helps, i will tell you.

by the way, the last testride with the kmc was on this track in germany:

www.mac-inzell.de

probably it was to hard for the kmc kit. not to say that the original was faster on this track than the worn out kmc.
there was only one track i know where the kmc was faster: in koppl, a very slippery track with slow lots of 180 turns.

just saw your braces for the damper stay. good thing, how can i get them to switzerland?

greetings from at the moment rainy switzerland

Maurice

[jarkkom]

Thanks for great information Maurice. The BJ4WE layout is very tempting tho'. Kyosho even had one or more prototypes with similar layout so there must be a reason why the actual kit is like it is.

[kentech]

Here's a Japanese body made for the conversion.

More here: http://www.team-azarashi.com

[notlawnomis]

Like the shell, not sure on the wing though!!

[paulc]

same he like the shell shame about the wing though i suppose it's different !!

[omen1975]

Hi guys,

Im an off-road ZX-5 racer here in Australia, I use and test KM/RC products and have yet to have any problems with what yas have mentioned, I will keep a close eye out on them problems and let yas know if I come across them.

I notice that someone has made a body to fit the chassis, I personally use the standard body with a BJ4 undertray and find the undertray lifts the body 5-8mm and it clears the motor ok, also I found the undertray handy when it comes to holding the body in the car with a small strip of velcro down the sides of body and tray, its a quick and simple way of removing the body. I also have extended my brushless novak ESC switch and mounted it on the inside on the back of my carbon works shock tower hole, it allows easy switching on and off of the car with out removing the body, also I placed the ESC fan next to the ESC. (will post more pics if anyone is interested).

Anyway keep up the good information and if you need any info or have any questions to do with any ZX-5 KM/RC products let me know as I have a close relationship with them.

P.S. they have a new Shock tower mount out now that might fix a problems you mentioned with flexing.

Take it easy guys and good luck racing

Damien

[Squintz Palladoris]

Hey Damien, Who's shock towers are those?

Thanks,
Brad

[omen1975]

G'day Brad, They are Carbon works shock towers, try (A Main Hobbies) for them, hope this helps.

Damien