Hobao GPX4 Pro
02-20-2007, 06:40 AM
#481
Originally Posted by vc05hdt
John Tan; I still run Hyper 12 motor and the second one ain't bad. Patto is right with quality though. I have only played with nitro cars for about 3 years and my pro car with Novarossi motor is a dream. The .15 Kyosho motor with my FW05T+ was a welcome relief after burning first Hyper 12. Fires up on first pull of pull starter.
I set up my RTR car with factory settings and put 30k oil in both front and rear diffs. On power/off power/on power during turn the back end lost a little traction and i couldnt drive to full potential. Does anyone have improvement on factory settings? Also I drilled out piston to 1.5mm rear shock and added 1.5mm to make front 2 hole piston with 30 weight oil and made steering worse (back end no grip). Should I go back to stock and add more toe in for rear, currently -1 degrees. Also running 37 shore all round.
I set up my RTR car with factory settings and put 30k oil in both front and rear diffs. On power/off power/on power during turn the back end lost a little traction and i couldnt drive to full potential. Does anyone have improvement on factory settings? Also I drilled out piston to 1.5mm rear shock and added 1.5mm to make front 2 hole piston with 30 weight oil and made steering worse (back end no grip). Should I go back to stock and add more toe in for rear, currently -1 degrees. Also running 37 shore all round.
02-20-2007, 06:44 AM
#482
Originally Posted by shocker360
On the subject of diff oils, using a front diff, you would be better served using a heavier oil up front than the rear. But, rather using a heavier oil, try using 10K oil in rear, keeping 30K up front?!
is there any gear ratio need to be care of?
Thanks.
02-20-2007, 06:52 AM
#483
Originally Posted by vc05hdt
Another trip to the hobby shop for 10k diff oil. Shocker, what do you think if put 50k in front and leave 30k in rear diff? No time to test as ultimatum with wife race once a month only. Also does the thicker diff oil makes the diff behave like a solid diff/spool?
Can anyone roughly explain it simple and clear cut?Thanks...
02-20-2007, 06:22 PM
#484
Originally Posted by JOHN TAN
Hi Shocker, thanks for sum up relate issue on diff oil...totally blur on that...do u have any idea is it ok for me to put 30k in front diff and never put any oil at rear diff?
is there any gear ratio need to be care of?
Thanks.
is there any gear ratio need to be care of?
Thanks.
The GPX4 uses sealed differentials, which uses fluid, a big plus. Some, like the HPI RS4 3, that has a non sealed diff, uses grease. All metal gearing within a diff must have a form of lubrication, otherwise, your gears will strip & burn up from metal to metal friction.
The advantage of sealed diffs are the fluids, as it's heated from friction, flow better through the gears as it's thrown around inside the housing, making it better to tune. Grease, on the other hand, as it's heated, won't flow back through the gearing as well as fluid. The silicone fluid is measured in weight of viscosity, like 10K or 30k, for example. When tuning your differentials, Thicker fluid (30K) will decrease your turning capability, but increase forward traction, while thinner fluid (10K), will increase turning, but lessen forward traction. Even though heavier fluid decreases turning capability, when used in the rear diff, with lighter fluid up front, the heavier fluid will cause the rear diff to lock up. Thus, causing the rear of the car to spin out. Where the increased traction of the heavier fluid up front gives you great forward traction and control of the car when decreasing speed. Thus, less brake when approaching turns and increased traction when accelerating out of the turn. I hope this helps and sorry for the long winded explanation.
Regards
02-20-2007, 06:42 PM
#485
Originally Posted by JOHN TAN
Thanks...actually currently i have a offer on REX/Nova 5 port at $310 vs OS 5 port $300...which one is more worth? not sure is it modified engine on both brand...
I attend races that are under rules and mandates, from organizations such as ROAR, RC Pro Series, and IFMAR. The class I race in, 1/10 .12 Fuel Sedan, doesn't allow me to run any engine with more than 3 ports. Before you decide to buy a 5 port engine, if you race under rules, see if they allow engines with more than 3 ports. Because both engines use 5 ports, I've never ran them. They both are great choices. So I can't give you much advise, but, I would get the engine that has the best part support.
02-21-2007, 06:50 AM
#486
Originally Posted by shocker360
Hi John,
The GPX4 uses sealed differentials, which uses fluid, a big plus. Some, like the HPI RS4 3, that has a non sealed diff, uses grease. All metal gearing within a diff must have a form of lubrication, otherwise, your gears will strip & burn up from metal to metal friction.
The advantage of sealed diffs are the fluids, as it's heated from friction, flow better through the gears as it's thrown around inside the housing, making it better to tune. Grease, on the other hand, as it's heated, won't flow back through the gearing as well as fluid. The silicone fluid is measured in weight of viscosity, like 10K or 30k, for example. When tuning your differentials, Thicker fluid (30K) will decrease your turning capability, but increase forward traction, while thinner fluid (10K), will increase turning, but lessen forward traction. Even though heavier fluid decreases turning capability, when used in the rear diff, with lighter fluid up front, the heavier fluid will cause the rear diff to lock up. Thus, causing the rear of the car to spin out. Where the increased traction of the heavier fluid up front gives you great forward traction and control of the car when decreasing speed. Thus, less brake when approaching turns and increased traction when accelerating out of the turn. I hope this helps and sorry for the long winded explanation.
Regards
The GPX4 uses sealed differentials, which uses fluid, a big plus. Some, like the HPI RS4 3, that has a non sealed diff, uses grease. All metal gearing within a diff must have a form of lubrication, otherwise, your gears will strip & burn up from metal to metal friction.
The advantage of sealed diffs are the fluids, as it's heated from friction, flow better through the gears as it's thrown around inside the housing, making it better to tune. Grease, on the other hand, as it's heated, won't flow back through the gearing as well as fluid. The silicone fluid is measured in weight of viscosity, like 10K or 30k, for example. When tuning your differentials, Thicker fluid (30K) will decrease your turning capability, but increase forward traction, while thinner fluid (10K), will increase turning, but lessen forward traction. Even though heavier fluid decreases turning capability, when used in the rear diff, with lighter fluid up front, the heavier fluid will cause the rear diff to lock up. Thus, causing the rear of the car to spin out. Where the increased traction of the heavier fluid up front gives you great forward traction and control of the car when decreasing speed. Thus, less brake when approaching turns and increased traction when accelerating out of the turn. I hope this helps and sorry for the long winded explanation.
Regards
Thanks ( master of Hobao GPX4 Pro! ) for explain it so clear to me...Thanks a lot...really appreciate that.
02-21-2007, 06:52 AM
#487
Originally Posted by shocker360
Hey John,
I attend races that are under rules and mandates, from organizations such as ROAR, RC Pro Series, and IFMAR. The class I race in, 1/10 .12 Fuel Sedan, doesn't allow me to run any engine with more than 3 ports. Before you decide to buy a 5 port engine, if you race under rules, see if they allow engines with more than 3 ports. Because both engines use 5 ports, I've never ran them. They both are great choices. So I can't give you much advise, but, I would get the engine that has the best part support.
I attend races that are under rules and mandates, from organizations such as ROAR, RC Pro Series, and IFMAR. The class I race in, 1/10 .12 Fuel Sedan, doesn't allow me to run any engine with more than 3 ports. Before you decide to buy a 5 port engine, if you race under rules, see if they allow engines with more than 3 ports. Because both engines use 5 ports, I've never ran them. They both are great choices. So I can't give you much advise, but, I would get the engine that has the best part support.
02-23-2007, 06:18 AM
#488
Has anyone got set up sheet for this car? With successful settings on med/high bite track?
02-24-2007, 08:04 AM
#489
Originally Posted by shocker360
Hey John,
I can't speak of the Nova engine, for I never ran one. But those who run them and their track record, they are highly recommended. Because they are high end Italian engines, even the stock one's are going to be expensive. On the other hand, I do own and run the O.S. TZ 3 port(P) engine, and I can speak for these.
I run an EB Modified O.S. .12 TZ 3 port(P) engine, and I highly recommend one. It is user friendly, easy to tune, plenty of power & torque. This engine is tough and bullet proof! In fact, on the dynometer, it's power band is nearly linear to an electric motor! Check R/C Car's website on September 2005 product test article for proof. For the cost of an Italian stock engine, you can purchase an EB Mod, Murnan Mod, Zeppin Mod, or the new O.S. Speed Tuned TZ! Even a stock O.S. TZ can hang with any any high end stock engine!
Any choice of the above is fine.
Just my two cents
Regards
I can't speak of the Nova engine, for I never ran one. But those who run them and their track record, they are highly recommended. Because they are high end Italian engines, even the stock one's are going to be expensive. On the other hand, I do own and run the O.S. TZ 3 port(P) engine, and I can speak for these.
I run an EB Modified O.S. .12 TZ 3 port(P) engine, and I highly recommend one. It is user friendly, easy to tune, plenty of power & torque. This engine is tough and bullet proof! In fact, on the dynometer, it's power band is nearly linear to an electric motor! Check R/C Car's website on September 2005 product test article for proof. For the cost of an Italian stock engine, you can purchase an EB Mod, Murnan Mod, Zeppin Mod, or the new O.S. Speed Tuned TZ! Even a stock O.S. TZ can hang with any any high end stock engine!
Any choice of the above is fine.Just my two cents
Regards
Finally found someone to set my clutch correctly...now my car is much faster do not need high rpm to move the wheel...now my hyper engine can easily par with other engines...
Thanks for your guidance.
02-24-2007, 07:04 PM
#490
Just to share my GPX4 PRO...with RTR engine and servos...
02-24-2007, 07:06 PM
#491
another one with my fav tyres ...
...
02-25-2007, 05:15 AM
#492
John Tan, what pipe are you running with the Pro car? I can't make out model/part number. Is your pipe/manifold better lower rpm reponse? How about the pinions/spurs? I think mine is 0.8module 16/20pinion and and 60/56 spur. Very neat car.
02-25-2007, 10:42 AM
#494
Originally Posted by vc05hdt
John Tan, what pipe are you running with the Pro car? I can't make out model/part number. Is your pipe/manifold better lower rpm response? How about the pinions/spurs? I think mine is 0.8module 16/20pinion and and 60/56 spur. Very neat car.
A very nice car! I'm glad you were able to resolve the clutch issue. Definitely pick the brain of the racer who fixed your clutch. Hands on experience is the best way to learn new aspects of your car. I'm glad to read that your engine has improved for you. If you decide later to swap engines, at least by then, your comfort zone and experience driving the GPX4 Pro would make a transition to a faster engine no problem. Now, does your GPX4 Pro out perform your old Cen CT4 ?
Note to vc05: John's pipe is an Orion CRF exhaust, and these are tuned for high r.p.m. range.
Regards
02-25-2007, 11:59 AM
#495
Tech Regular
just as a warning, the front carbon fiber brace on the bumper has a tendency to crack during high impacts. So I use the plastic brace instead and place the carbon fiber on top. This also reduces the flex between the front bulkhead around the diff