Snoop Dawg

Hello folks. I need to have a fast rc car without putting a dent in my pocket. I currently have an OFNA GPX4 but i already adjusted the suspension setup to suit track and i also put in a tuned JLR engine. However there are guys here running Mugen and Kyosho and are going way faster than i am. My idea is to take the RTR as close to the other guys' cars as possible. Are there any specific upgrades I can do that will make a major difference? Gears, etc.. I think my 2nd ger is currently 47T. If I upgrade this to a 43T will the car be significantly faster? As I have been only into the actual taking part in the sport for 2 months, any help will be greatly appreciated.

three50zx

iTrader: (2)

http://www.rctech.net/forum/nitro-ro...-gpx4-pro.html

There is a lot of tips and tricks.

Kyo83

iTrader: (3)

Let me get this out the way and please don't be mad.....but what kind of driving skills do you have?

If you can't drive worth a darn, then it won't matter what you do to the car. The other guys will still be faster than you just because they ae better drivers, they are more consistant, and their cars are better than yours in (terms of settup).

Now on the other hand, if you happen to be one of Gods gifts to RC racing and possess the skills of a seasoned veteran after only two months of driving/racing, then here are some general suggestions.

Increasing, not decreasing your spur gears, will give your car more top end speed. Decreasing will give more acceleration. You need to find the right balance for your track. Too much of one and not enough of the other will make for a bad set up.

If you are still running the stock, pull-start engine, it needs to go. if you can't afford a new engine right now, then at least take the pull-started off. this will reduce weight and drag on the engine's shaft which will give you more power.

Also read the Tunning bible guide. A finely tunned engine can make a world of difference.

Finnally, what body are you running. Some of the sedan bodies may not look as cool as the more realist looking HPI or Kyosho bodie, but they have better aero-dynamics than them. see what some of the fasters guys are using and get yourself one...if you can't beat 'em, join 'em.....hold true here.

That should be enough to pull you closer, but keep this in mind.......a RTR car in the capable hands of a good driver will never beat a racing kit car driven by the same driver.

nitrodude

iTrader: (8)

If you have been racing for only 2 months, its not the car or motor, its the driver. It takes years of practice and expirience to get faster, just keep practicing and racing and little by little you will go faster.

Riketsu

iTrader: (34)

Complete opposite. Bigger spur gears will give you more acceleration, smaller spur gears will give you more top end.

Bigger pinion, will give you more top end, Smaller pinion will give you more acceleration.

Please note that "pinion" refers to the clutch bell while "spur" refers to the transmission.

Kyo83

iTrader: (3)

Thanks for the correction on my brain fart, there Riketsu...that's what happens when you pull an all-nighter, go to sleep for 2 and a half hours and then wake up and try to act like a know it all....lol

Snoop Dawg

I basically want to make the car as fast as the Mugen and Kyosho setups by transforming it instead of buying a chasis. So far i have got advice on changing from the standard 1.0 spurs and pinions to the 0.8 and possibly reduce slightly both the 1st and 2nd gear ratios. The track here has only 1 straight which is about 80m long and all the rest of it is tight cornering until you meet the straight again. I need to perfect a balance between acceleration for the tight part of the track but not be too slow on the straight. Any help and suggestions in terms of gearing and any other transformations that can be made to put me closer to the Mugen and Kyosho setups would be appreciated. The standard 1.0 gearing for 1st right now is 0.34 and for 2nd is 0.46.

three50zx

iTrader: (2)

Snoop,
On the GPX-4 gearing is not even half the battle. I ran that car for 3 yrs. Here are the changes that I made.

1. You have to loosen the belts front and rear, especially the front.
2. Shim all the uprights because of too much play.
3. I put 2 x 1.1mm holes in the front shock pistons
4. I then put 50wt shock oil in all four shocks.
5. Front springs Hobao Light Blue springs.
6. Rear springs Hobao Yellow springs.
7. Front and rear diff 80k frt - 20k rear

As for Gearing. You can use the 2speed shoes and all the 2 speed gears from Mugen if that's easier for you to get. I ran on short tracks mostly.

.8 Spurs 60/54 Pinion 20/26 - Small track
.8 Spurs 59/54 Pinion 20/26 or 21/27 - Small to Medium track
.8 Spurs 59/53 Pinion 21/27 - Medium track
.8 Spurs 58/53 Pinion 21/27 - Medium to Large track

Try different combinations to see which one works for you. In this game it's trial and error, in hopes to, trial and accuracy.

Keep in mind races are won on good corner speed. Everyone for the most part can go fast in a straight line it's the turns that make you a winner.

Good luck

nitrodude

iTrader: (8)

You cant say I want my X-brand car to handle like Z-brand car, you need to set your car up to handle in a way that’s going to let YOU drive it as fast as possible. Do you like and under steering car? or an over steering car? or a well balance car? What tendencies are going to let you drive it faster? One of my best buddies is a Serpent team driver, so I always copy his setups, but I always change them to add a little more steering, I like a car that’s on the edge of getting loose.

And like I said before, if you have only been racing for 2 months, its not the car or the setup, you just need to stick to something drivable, little by little, as you gain experience, you will ask the car to do different things and you will have to change the setup to accommodate your new experience. The way it happened to me, as I got a little faster I was always looking for more steering.

Snoop Dawg

I currently have yellow(medium) springs to the front and blue(soft) springs to the rear. The car is driving nicely on the straight but it has quite a bit of understeer in the corners. I have to come off early and hug the corners to get around. Would anyone suggest putting blue(soft) springs to the front?

nitrodude

iTrader: (8)

Without knowing the car I would go to harder springs on the rear, if its pushing you need more weight transfer towards the front when hitting the brakes. If it still pushes, go to a softer front spring.

You have to get the setup ok with the shocks and springs and then fine tune it with the other adjustments.

NeoRC

Its easy Upgrade to GPX4 Pro Evo

HarKonnenD

iTrader: (23)

Neo is right. By the time you upgrade a stock GPX4 you would have spent enough $$ to buy a new car. I learned that when I bought the stock HPI R40. It won't handle like a Mugen however I tuned the car to drive it as fast as I possibly could. Still a stock Mugen was a night and day difference between a car with some moderate upgrades.

aturbotony

SALE IT!!!!!! BUY A USED MUGEN MTX 4R ON EBAY OR SOMETHING. THEN WHAT YOU DO IS GO GET THE FAST GUYS GOOD LUCK

NeoRC

The upgrade costs 90 Euro / 122 $ in Germany .....

The CG of GPX4 Pro = 26mm
Mugen/Kyosho/Xray CG 29-31mm

Mugen is too heavy on the exhaust side

I have to show not enough Posts to post pictures ....