OFNA 1/8 Buggys v1.0

[CTRallyRacer2]

Does anyone have a links to websites that cater to the 1:8th scale scene (on and off-road)?

Ok... It seems like the consensus is... the kit springs on the MBX RTR stink! Well, I have to agree... I installed everthing on my car... and the springs are soft... I push down the car and it's way too easy to do so. I could only imagine the bottom chassis after a few 6" jumps, never mind 2-3' air jumps that will be the norm for this buggy. So, what should I do... pistons and springs I assume, but which piston and spings? Should I stick with Ofna parts? I know shock oil depends on track (so do springs for that matter, just looking for a bashing setup)...

[Vmax911]

With stock pistons I was running 80 wt oil. I took Lost Racer's advice and got the Ofna O-ring pistons, but that was over the winter so I haven't tried them out yet (hopefully later today).

I also hear that the Mugen stock (black) springs are a good alternative, and only $6 a pair.

[Vmax911]

Also, both Ace hobbies nad Nitrohouse have had all the buggy parts I've ever needed.

Ace Hobbies (http://www.ace-hobbies.com/)
Nitrohouse (http://www.nitrohouse.com/)

[Draxx]

CTRallyRacer2, unsure about how the rtr mbx is equipped, but the MBX r2 has the front pillow balls, but not a rear pillow ball suspenion(does any buggy?). I suspect they are the same buggy...

[Vmax911]

Interesting... both my MBX R2's came with front and rear pivot ball setups.

[Lost Racer1]

I believe the R2 has front and Rear Pillowballs..Where the Ultra MBX just has them in he front.

Get the O-ring pistons..Big difference!!!

[CTRallyRacer2]

I have to order the pistons.. but for now, I'm going to run 80wt...

[Lost Racer1]

Once you get them you'll be able to use a MUCH lighter oil...

[CTRallyRacer2]

Along with the pistons.. should I also get the stock Mugen springs... or use Ofna springs?

[Vmax911]

I'm sure that either the Mugen, Ofna red, or Ofna yellow would be a big improvement over the stock silver ones. If your just going to bash around and do big jumps and stuff, I'd probably go with the Ofna Red.

I tried to go out to the track this morning. There's still snow! :mad:

But I had a little fun anyway!

[Draxx]

I stand corrected, my R2 does have pillow balls
front and rear.

[Lost Racer1]

nice pic Vmax. I miss my worlds II..:D

[maximumspeed]

if any of you guys/girls have a hyper7 i would like to know what you like/dislike about the car because im seriously thinking about getting one.i would greatly apresheat it.



by the way look its my hundredth thread:D

[Draxx]

Speaking of springs... I stuck Kyosho whites on the front and it made a big difference. What shock piston set are you guys referring to??

[Vmax911]

Lost Racer-

Now that you've had your H7 for a while, how do the two (WII & H7) compare?

[CTRallyRacer2]

Okay... I have a P4 engine in my MBX right now... I've heat cycled 3 tanks already, but I was watching the top where I have the glow plug, and there is an air leak. I have fuel bubbling out of the glow plug and dancing on top of the heatsink head. What should I do? Should I order a replacement head? Is there anything I can do with the current one? I'm all ears (and wallet is pretty darn slim right now)...

Hmmm... actually, I was looking at the manual... and the head bottom replacement is only $10.50... I guess that's all I need... I'm going to order that along with a head shim... and a new set of plugs. Should I stick with the A5 plug? And now that I've run 3 tanks through... should I run another tank easily or am I ok, to get it ready for racing (playing)?

So.. no 1:8th scale websites?

[Draxx]

I am using mc8 plugs in my p4..but I would stick to what you are using if it is working. I know
this may be a dumb question, but....you said you had a leak around the plug. Was it tightened down good with the copper plug washer? Is this a new engine??

Actually, I am having alittle tuning quandry myself. I too have the P4 and have run numerous
tanks for breakthrough. I have starting leaning the top end out slightly. I notice that if I give it a brief squeeze of full throttle, rpms and speed are great, but when I release from WOT, the rpms take a long time to drop to idle.It seems to stay in a high throttle condition for a number of seconds. Iam not
very experienced at tuning(2nd nitro,first .21).
Any suggestions?

[CTRallyRacer2]

The plug was definately tightened down with the brass washer. I think I stripped the bottom head adapter. I have part number and all... I just need to locate and order. As far as engine tuning goes... check this out...

RC Car Action - Super Engine Tuning Guide (http://www.rcnitro.com/articles/super_tune.asp)

[Draxx]

Bummer..hope the new button head does it.

I was just looking for the magazine with that article..thanks.

[CTRallyRacer2]

Ok... I need a mail order house, that I can user their website to order (without having to phone in an order) and just use a credit card... so, who carries Ofna stuff... Tower doesn't have the button head plate... HELP!

[Draxx]

Try Ace-hobbies. Just click on your motor for parts. They are good guys to deal with.

http://www.ace-hobbies.com/PartsPricing/index.html

[eman88]

Draxx- sounds like your engine is too lean on the low end or top end or both

[nitro lover]

I finally got my MBX R2 together and running this weakend. I didn't have to shim the diffs different than the stock setup. I didn't check the shock piston nuts yet though. I am running a hyper 21 with the 14 tooth spur gear and clutch from my pirate 10 monster. After many rollovers and a few small jumps, I am happy to have not broken anything! I am going to put the flywheel, clutch. and spur gear that came with the kit on tomorrow. I am also going to check the shock nuts. After seeing my buddies O.S. .12 CVX come to life after being put away a year and a half ago with zero maintenance ever done to it, and it screamed like it was brand new, I have decided to go with an O.S. RZ V01B. The hyper does very well, even with the taller gearing, so I can only imagine how the RZ will do with lower gearing. Anyone running this engine? How much top end will be lost with the one tooth smaller spur gear on the hyper setup?

[Draxx]

Eman88, thanks. After re-reading the Super Tuning Article, that was my guess too. I will richen
the low speed alittle to start. That is my best guess.

[Lost Racer1]

Vmaxx-

No comparison..The H7 out does the W2 in racing condition. The W2 parts are more fragile thatn the H7 and the W2 is a much lighter buggy in weight. When you put a torqy engine in the W2 the engine basically controls the handling of the buggy..With the H7, its different. The buggy keeps those torqy engines tamed so you can stay on a straight course and not bounce around.

You have to drive one to understand..I had my W2 for a year and a half before I upgraded. The H7 is very different.

[Vmax911]

Cool, one of these days I'll have to get one. Why don't you send yours to me so I can have a chance to drive it? :D

[CTRallyRacer2]

How does the H7 or H9.5 compare to the other premier buggies out there (Mugen or Kyosho)?

[AEAddict]

Maybe this'll help you decide??

http://www.radiocontrolzone.com/forums/showthread.php?s=&threadid=77102

:D

[Crashtastic]

Can anyone recommend a good beginner engine (pull or not) for a Hyper 7? I have experience will small block stuff but this will be my first .21. Also, I have a Ofna universal starter box with two 550 motors, is this capable of starting a sport level .21? Thanks for the help!

[WHITESTER1]

OS .21 RG an affordable engine, with the OS reliability. Not too much power but enough to make you happy. .21 engines are easier to tune, because they are larger and not as sensitive to weather conditions like a .12 would be. OS carbs are simple and hold tunes. So I say go with the OS .21 RG I think my LHS sells them for just over $100.

[Crashtastic]

The RG is definately in the runnning, I have always had good luck with OS, anyone think the ofna universal box will turn one?? I'm using two 6 cell nicad packs and low-resistance wires/connectors.

[Jamesh7p]

I have the same starter box and it starts my RZ-V01B with no problem. I also use a 12v gel cell to power it. So 14.4 volts from 2 stick packs should be even better.

[Crashtastic]

That's what I wanted to hear!

That sure does open up alot more choices...

[spowell940]

I have a Ultra MBX RTR that came with a pullstart. I have a 12V starter that I used on my airplane and I got the black rubber wheel for it so I could use it to start the car. Two issues:

1) The black wheel doesn't fit very tight and sometimes just spins on the aluminum starter wheel. Any suggestions on what to use to glue it to the starter.

2) Do I need to modify the chassis (something I don't really want to do) or get a new flywheel in order for the starter to work? I've tried and the starter wheel doesn't quite fit up into the slot to spin the flywheel. I guess I could grind down the wheel a bit to make it go further up into the slot.

Any suggestions?

[CTRallyRacer2]

You most likely need to convert the motor to a non-pullstart motor. This would mean changing the flywheel and removing the Pull Starter and replacing with a back plate. Should improve spool up from what I hear (if you remove the Pull Starter).

[Lost Racer1]

Just change the fly wheel. Pullstart motors usually use smaller flywheels or taller engine mounts. In your case see if you can get a larger flywheel. I've started my P4 pullstart on my starter box a number of times. Maybe compare your engine to someone elses if possible for you to and verify the height from the chassis and the flywheel.

[spowell940]

I'd like to avoid taking off the pull start cause I like the flexibility of starting it somewhere other than in the pits. Is replacing the flywheel a big deal or does it have any other side affects on the whole setup of the car.

[Lost Racer1]

You may have to adjust your idle a little but thats it.

[CTRallyRacer2]

Well, after running three tanks through my P4... I decided to test her out. I took her to my local park and started her up. Running really rich... I ran a little to warm up the engine. She was idling high, so I adjusted the idle... and then leaned her out 1/4 turn. She was pretty rippin fast! I still need to adjust the carb and all... and all of this out of a 1.7hp Ofna P4 engine... whoohoo!
Then, a turn for the worse happened... I was making a few passes, and the engine died and the car stopped. I walked over and pulled out my junky Ofna "C" cell igniter, and went to fire it up again... except the pull starter wouldn't budge... Assuming the worst... I packed it up... tossed it in the trunk and fired up the Kyosho Megaforce (that is one tough truck... slow, but tough)!
After I ran a tank and a half through the truck... I tossed that back into the truck and then tried the pullstarter on the P4... It still was stuck. I gave it a good lookover... and found a small pepple stuck between the flywheel and the chassis... YES!!! So, I dug it out, and then tried the pull starter again... it spins! Grabbed the igniter... and off she went, I had her humming in a few tugs of the pull starter. I ran through another half tank and then left to the hobby shop to pickup a receiver pack. 1:8th scale buggies are fast! And this is my first...

[CTRallyRacer2]

Ok... so how do I adjust my front brake? The front brake seems to slide around on the brake post... so much so, that it slightly applies front brakes when I give the car full throttle. Any suggestions? Also, how do I lock the little arm that slides into the brake post... where the servo brake rod goes through? I've used a dubro bolt on the top unit (rear brakes), but I'm not able to do the same for the lower unit (front brakes)... unless the screw could go all the way through the shaft to the front brake arm... I dunno. I'm kinda ticked about this RTR thing. I didn't want to dissasemble the entire car... but now I have to, so I can make sure everything is properly threadlocked... don't they apply this stuff while assembling the car?

[Draxx]

Sounds like I am about at about the same stage you are... getting the engine tuned and making some minor adjustments.
As far as the brakes go, it should have some of the small locking collars on the rod that runs from the servo to the brake arm.I adjusted the brakes by loosening the set screw on the collar and sliding it in towards the brakes so it take less servo throw to apply the brakes. I also
placed a small(1/4 inck) piece of fuel tubing
on the brake rod between the collar and the
brake arm.

As far as the brake staying applied, I am considering placing small springs on the screws that hold the brake pads(the steel pads) so they
seperate fully when no brake is applied. I have seen this on some buggies. I hope this answers what you were asking.

[CTRallyRacer2]

I've actually done the same with the locking collars and fuel tubing. The problem is the actual brake lever that rests inside of the brake cam. I can't seem to get that to stay put. I'm thinking of using some of the spare Dubro collars that I have... and placing it on the outside of the brake lever... that should work. I have also nicked the bottom engine bolts pretty good... need to find the #s for the replacement bolts to go into the engine... why they didn't include those to begin with is beyond me!

[Vmax911]

I've put some small springs between the brake pads like Draxx said. In fact, if you upgrade to the stainless steel brakes the kit comes with the springs. If not, just open up an old ball point pen (the 'clicking' kind) and cut up the spring in there. It helps to keep the locking collar stay centered in the brake cam hole. I think that is the problem that CTRally is having.

[CTRallyRacer2]

Cool idea... I'm going to do the spring thing... and I might as well use my dubro idea as well. Thanks for the help... now I have to search this thread for the engine bolt screws...

[Lost Racer1]

The brake cam should have a set screw that fits in the top. Thats what holds your lever in place. I'm sorry I don't remember the size. But I do remember I had to use a 1.5mm allen driver to adjust it. So it is pretty small. But that should take care of your problem. Unfrotunately they never loctite rtr vehicles at the factory. So it is up to the consumer to take care of this. This is a long time problem, but it does give you a chance to figure out your vehicle for future repairs. I can understand not wanting to tear down your buggy, hence buying the rtr. But so you know what you vehicle contains, it is necessary. It makes it easier in the long run:D

[CTRallyRacer2]

Ok... would someone be so kind as to tell me what the part number is for the engine screws and cone washers... so I can get rid of these brakes that are under my car now (the huge bolts that are sticking out from the underside of the chassis for the engine mounts).

[Vmax911]

Ofna # 10111

[CTRallyRacer2]

Thanks VMax... just got back from ordering them!