ozzie boy

hey i found this old thread

n20ob4matt

recently bought an ofna nitro ob4 and i have ran into a few problems:

1) i have already broken the front bumper, it seems the plastinc is a little hard so im trying to figure out a way to soften the next one

2) the car seems to spin out at the end of the turns i think the problem might be the rear diff which feels real notchy at one piont in the rotation

im thinking about up grading to the ball diff in the rear but im not sure what the difference is between gear and ball diffs. I mean what the difference in performance and which one is better for what. Any suggestions or ideas would be helpful thanx.

to try to fix the spin out before i had noticed the diff problem i thought it might just be suspention so i put ofna yellow springs is the front(hard) and the stock black ones( they seem to be softer than the ofna blue to bad ofna dosn't have more spring info like hpi does) in the rear. This seemed to help alittle but it still spins at the end of a turn. Other than the springs everything else is the recomended settings that came with the car. Thanx for any help!

ozzie boy

the reason wy u keep spining out in corners is because your front wheels get more grip that the rear and causes it to swing out
what u need to have is mor3 grip down the back and less in he front, because it better to have the front slide a bit than the rear
so to fix the problem all u need to do is get softer rear tires

more grip down back=good
more grip down front =bad

n20ob4matt

i have tried that. The front has less grip than the back because i changed out the springs. Softer in the front will make more wieght transfer to the front so more pressure and thus more grip is sddsd to the front. The opposit happens if tou put stiffer springs in the front. I have also tried puting softer tiers in the rear.
This helps to some extent but i can hardly turn. I know the ob4 has for potential than this b/c my stock rtr hpi rs4 could handle better. I have a feeling its somthing with the diff b/c it feels real notchy at one piont in the rotation.This could cause it to spin out if one wheel locks or is slowed by this notchyness.

im thinking about up grading to the ball diff in the rear but im not sure what the difference is between gear and ball diffs. I mean what the difference in performance and which one is better for what. (is a ball diff smoother?)

ozzie boy

take you diff apart and get all the lube off
look for ANY signs of wear, if you do go to your LHS and get a new bit


yes ball diffs are better.
they give yuo better diff action

but it has a few downsides

1 its a bit trickey to get it set up
2 theres quiet a few little balls to loose
3it will get dift and grime in there and need a rebuild
4 andif too loose it will wear the rings out and wont work as efectivly

mugenman

your diffs are the problem ball diffs are good but you need to know how to set them up and are a lot of maintinence..
stick with the gear diffs but you need to use diff oil not grease
try 100000 in front and 30000 in the rear. you will notice the difference i raced a ob4 for 12months and won the club champ.
so stick with it when setup right thay are quick

Foger Rox

Yup Look at the diffs. Last year I had 100k in the front, 50k in the rear. That was real nice. End if the year I got the f/1 way, Weeeeeee ha! This year I will try 100k in the rear, which will be as close to a solid rear as I can get without going
to the ball diff (yuk).
Also the Ob4 springs are just fine, with 50 or 60 wt. The Ob4 likes to be driven throttle on in the corners, brake only at the end of the main straight.

This is important: If you go throttle off in a turn: the rear likes to come out on you.
It needs a steady throttle finger.

n20ob4matt

the ob4 doesn't come with grease its like a clear fluid and its really thick. Does anyone know the stock fluid wieght? (before i go out possibly buy the same stuff)

I took the diff appart and there is some wear on some of the teeth. Why is it worn? I was thinking the whole diff might be tweeked.Does this mean I have to replace the whole diff or just the gear.

Also I was reading car action (its old, like when the nob4 first came out) and they said to stack to diffgaskits insdead of one to stop it from leaking . Is this a good idea?

thanx,
matt

Foger Rox

That thick oil is for the diffs. I remember that RccA article, nah. Use permatex hi temp silicon gasket in a tube. Copper
colored. Get it at an auto parts store. The diff gears are available separatly.

ozzie boy

my ob4 need help

my 2 speed isnt engaging

how many turns should i have the 2speed set at to engage.
its not engaging when i want it to. iv tryed heaps of times to get it workin but it dosent want to

how many turns out should i have it set at?

Foger Rox

Do you have the lever type or the Clutch type? Is it a RTR?

ozzie boy

its the pro kit

i got it 2nd hand
yes its got a clutch type 2 speed

serpent 973

if any one would like to purchase a huge racing package with the ob4 please e-mail me. Picture below.

ozzie boy

how much do you want for it all?

serpent 973

I'm really looking at 550 but I want to at 525 shipped. E-mail me at [email protected] we can work some thing out if your interested.

Heres an upclose at the car itself.