Ryanater

I have an Ofna ultra GTP with the force .28. My problem is that the thing is just undrivable. I realize that a lot of it is because of my driving skill but it still should be better than this.

It feels like the steering is really inaacurate and slow. It also won't turn very sharp at all when it is moving at a decent speed (I'm not talking about sliding out, it just won't trun the wheels.) I also noticed that right when I replace my receiver batteries the problem gets better for 1-2 tanks of gas.

Right now I am running the stock servos which I am not sure if they are standard or High Torque, and the receiver is being powered by 4 AA batteries.

My question is would it help my problem if I went to a 6v battery pack? I don't understand why it would though because isn't running 4 AA batteries 6 volts? (1.5v x 4)

Or should I buy a high torque servo? (if It doesn't already have one.)

If I but one or both of these things am I going to notive a big improvement?

shannow

Well I do not own that car but my first guess is the batteries (the stock servos are probably crap too but it's more expensive to change) , I have to check my science on the batteries .

Alkaline is crap . It's got the amps the volt BUT it does not have no where near the discharge rate of a rechargeable nimh batteries

My first and cheapest suggestion is you go and buy 4 nice 2-3 amps Nimh batteries (so 4.8v 'cause 1.2x4)

Edit : I tried making more sense in my sentences (i'm french)

Yeah I'm 98% sure the batteries is your solution

Also alkaline voltage goes down as the amps goes out whereas nimh keeps it's voltage untill nearly the end.

Ryanater

Sorry if i'm a total idiot but I do have some rechargable nimh batteries. They are only 1.2V so I didn't use them. They are 200Mah, what does this mean? It's miliamp/hour right? You said to run a 2-3 amp battery, how does that convert to mah? Should I run those?

shannow

200mah is not possible for AA it's too low I don't think it exists If you have found 200Mah on it it's probably it's recharging rate (usualy given for 10hours ) if so your batterie is probably 2000Mah (2 Amps) .

Mah is milliamps (1Amp = 1000Mah)

Yes these should be much much better (but do charge them just before running because there do discharge even not being used)

Ryanater

Sorry I meant 2000mah. Thought I het the 0 key one more time.

So The higher mah the more powerful the batter?

Would I see a big improvement over those if I used a 6 volt receiver battery with 300mah or would I have to get better servos to notice.

Thanks for the help!

authorjim1

I guess I have to agree with the others. Even though the voltage is the same with the alkalines they won't allow the heavy current draw which will drop their available voltage to the servos. Also all those Ofna off road cars could use quicker stronger servos, your hobby shop can help with that.

One other thing though, if you don't have enough toe out in the front and toe in in the back it will make a car seem lazy making the turns, understeer. Camber also. Set it to the manuals suggestion. I know you said that it's not sliding out but slick tires and bad steering geometry will make it all seem worse. If you have switched to foam tires with alot of grip then you will really need the stronger servos and the NiMH battery.


Let us know know how you make out.



Jim

Ryanater

Your really supposed to run toe-out??? I'm running about 1 degree of Toe-in. I couldn't find a setup sheet anywhere so i just set it up lie a normal car.

camber is about -1.5 degrees all the way around. Out of the box it was all out-of-wack.

wminmi

My Feedback: (26)

http://www.ofna.com

Right side of the page, about 1/3 way down, click on "instruction sheets" I think it's called, and it will let you download the complete instruction manual for your car.

I'm currently converting an LX one over to on-road using GTP parts. Will have to do the toe-in & camber myself yet....

Hope this helps some.

authorjim1

Sorry about the long, long delay. I have not received updates on this thread.

Anyway if you are still having trouble let me know. Describe it best you can.

These cars definitely need high power servos at least 120 oz-in or more (I use 190 oz-in.) on the steering and NIMH receiver batteries 1600 mah or more.

This car runs decent with stock tires but GRP gandini MO1 A or MO1 E are great on this car.

for most situations, rear toe in about 1.5 to 2 degrees, front toe out about 1 degree, rear camber about 1 degree(for non racing), front camber flat.
If this works good leave it. If not let me know we can talk about ride height, softer springs in the rear and stiffening up the front. Changes in diff fluid etc.

One last thing, about front toe. If it turns poorly off power increase toe out. If the car is too loose exiting a corner you must decrease toe out, that's why I compromised with the one degree front toe out. It will also help you stay straight down the straight away, at a slight cost of speed.

Jim

oneofakindtrini

If its too high its gonna handle like a bus.

authorjim1

You are absolutely right, I didn't want to throw out too much at once. I set the rear ride height about as low as it will go with minimum to no scraping, how about you?

Jim

Mufasa_719

4 AAs is 4.8volts a "hump pack" is 6 volts. So more power is faster and stronger servos. Somthing you would want to upgrade right away.

pontiac6000le88

thanks for the toe in / out theory. how do u guys measure the toe in degree? u must have those alignment setup thing to get that degree? I ask because i always use a ruler and measure the wheels. But this only works when i setup the toe to zero ( both tires parallel to each other).

rc18junky

i would not think it was battery related if the AA are new. but if there almost dead well i think it could be that easy. if not that what i would do is lower the car and tweak the suspension trying stiffer and softer setting and try different tiers. as for the servo i thinking it might be high power but not high SPEED so a upgrade would be good to help handling. and just for kicks look and see if there is any binding in the steering linkages or WORN out servo saver