Pro 4 Still Competitive?
 

Hey

I have a HPI Pro 4 and am looking to get back into racing. Probably will run a 17.5/27T stock class and then move to 13.5 SS.

Do you think my Pro 4 will still be able to keep up with all the belt cars today? I know a lot has to do with the driver obviously, but all things being equal whats your opinion?

The real queation i guess is will buying a belt car give me an advantage over using my Pro 4. I cant afford a fancy new one but may buy a used 415 MSXX. Does anyone one think thats worth it?

Thanks,
Tom

I don't think it would be worth it to you to just go out and buy a new one. I race street weapons still and they are just as competitive now as they ever were in the stock class. Ya really gotta weigh your familiarity with the car and your driving style. I still prefer my old school touring car because it matches my style. I don't think anything would really be that much of a disadvantage in a stock class and I think when you go to move up, you should be just fine especially with the great equalizer.... the brushless, lipo setup. It seems to breathe new life into most older cars from what I hear. If you can still get parts, keep what ya got. Newer aint always better.

Great car, still very competitive. Especially in stock racing (shaft drive is very efficient). Make sure you get good equipment for it and when and if you upgrade car's you'll already be ahead of the curve.

The PRO4 is definately still a very competitive car in 17.5/27t and 13.5/19t. We still have a couple running at our club and they are right up there with the latest and greatest touring cars.

Some people feel that shaft drive cars are faster in a 17.5 class and with brushless motors torque steer really isn't a problem anymore. So I would stock with the Pro4.

Just found out i will be running 13.5...

Thanks. I wonder what makes torque steer not a problem with lipo?

Ive never run BL before so can anyone recommend a good gearing to start with for 99/100 tooth pinion (64 pitch) with a 13.5 motor.

I guess my best plan is to get my BL setup and lipos, start racing and then see where im at. Thanks!

Torque steer was mainly a problem with the armature of the brushed motor. With brushless that problem is greatly reduced.

Gearing is tough now with different timing options on ESCs. Most people start around 4.6 and go from there with a 13.5.

Thanks. Do you know what pinion size that matched up with? My gearing chart doesnt do to 4.6 (isnt made for BL).

Or an can anyone recommend a few pinion sizes to get that i can play with.

All help is very much appreciated, thanks!!

what do u have now ?

I have a pro4 now. I dont think its a special driver edition. I just havent raced in in maybe 2-3 years.

+1

ok,
i'm talking abouth pinion, spur ......... al my electric 1:10 are pro 4
what are u lookin to run
i was comprtitiv with 19 T brush & LIPO,if u whant to run BL u have to up-gear motor pinion and down gear the spur

I'm running a Pro 4 Myself in stock class and doing well. First day out for the season I took TQ and finished second in the main. Hoping for a first place finish this Sunday. :)

Torque steer isnt as big of an issue with the BL motors. Lipo wont make any difference. The reason is brushed motors have a lot of RPM. So the armature of the motor was spinning very fast and had a lot of inertia(lots of mass) while the driveshaft and transmissions were spinning slow with not nearly the same rotating mass. But now with BL motors the RPM's arent even close to what the brushed motors are. They're very very close to one another so torque steer isnt a problem. At least thats how I see it.

I love the pro4. And when its set up right its a tough car to beat. Just keep the bearings cleaned, the diffs and gears shimmed right, and you'll be set! I cant wait to get out there this sunday and beat some TC5's, Xrays, and other cars. :sneaky:

Actually I think its more the size of the rotating mass being about half the size that causes it to not be as big an issue. A brushed arm is a lot bigger then a brushless arm.

That would play a role too because it would have a larger rotational mass compared to the dirveshaft of the car. The more RPM and mass the more its going to counteract the lightweight low rpm driveshaft. In the end its all the same thing. :)

At work now so i dont know my current gearing (for 27T) off hand. Can check later.

Sorry to sound like a newb but does anyone know where i can find a site buy a spur gear and do i need a specific type to fit the pro4?

Practically any higher grade car that is well set up and familiar to the thumbs controlling it, will do well at club level :)

Some people cannot bond with some cars though, it is all a learning curve, however, the more you times you change car, the more work you have given yourself trying to set it up.

Change one setting at a time and note if it helps or makes things worse, trial and error is sometimes the only way to find out what best suits YOU.

All the best :)

The only bad thing I have to say about the pro 4 is its internal ratio. Its a big PITA when running stock because of the low FDR. I'm running at 3.48 right now with a 76/53 gearing. Why is that an issue? I cant run a larger spur because I wont have the pinion options for tuning(they only make em so big!). And I cant run a smaller spur to give me even more pinion range, because the motor just cant move in far enough to mesh the gears. That said, gearing is totally different from brushed to brushless.

Actually I think torque steer comes from torque and out put of the motor. Shaft cars just seem to work better with 17.5/27t motors. I've used a tc3 with a novak 10.5 and it seems I couldn't control the car out the corners. And everything seems loose.(maybe my setup but the car seem it couldn't handle much)

Brushless motors have two times the torque of a brushed motor. So a 10.5 even a 13.5 gears for a fast track in a shaft car will have some torque steer.

shaft if best for stock racing. And stock racing is where you need a more efficientcy and that comes from shaft.

anybody need new arms?
I have several sets NIB Pro4/Cyclone arms I no longer need.
email me at [email protected]

thanks.

in turkey , in the last years national championship, the 3rd and 4th drivers were using pro 4, actually the 4th driver was using pro 4 hara edition and 3rd used regular pro4 with a little upgrade parts. btw we were racing mod. with 5 cell.
you can be very competitive with pro4 in stock i believe

I'm running an 88 tooth spur with a 57 tooth pinion (3.76 FDR) and the motor fits comfortably. I've test -fit a 61 tooth pinion using the same spur and managed to get everything to fit w/o modifications. I've seen pinions with as many as 65 teeth available, so getting to your preferred FDR shouldn't be too much of a problem.:nod:

Thanks for the info.

One thing i will admit is i hate gearing and figuring out ratios. It sucks all the fun out of RC for me, im not here to do math.

Can someone recommend a good spur/pinion combo for running 13.5? Ill be on a fairly tight track, Jackon in NJ.

oeoeo- are you running 88/57 with a 13.5 on your pro4?

That gearing seems high for a 13.5. Try 88/46 in 13.5. This gives you a 42mm rollout and is probably a good start depending on the size of your track.

www.gearchart.com

Welcome to your new best friend.

There is a free program that I use all the time, called "RC Gears". I don't remember where I got it (but i got it from the forums here... do a search).. but you simply type in the internal drive ratio of your car (each model car is unique, my Xray is 1.7 for example), type in the number of teeth on your spur, type in the number of teeth on your pinion, and it gives you your final drive ratio. No need to worry about "roll out" with a touring car.

But even if you dont have the program, it is painfully easy to do the math. To get your gear ratio, simply devide the your spur, by your pinion. Then multiply THAT number, by your car's internal drive and vuala.

For example, on my Xray I am running a 38 pinion, and a 100 spur. That gives me:

38/100 = 2.63

I then multiply that by 1.7 (Xray internal drive ratio) and you get:

2.63 x 1.7 = 4.47.

In short, I am running a final drive ratio of about 1 : 4.47.

Thanks again! I will check all of that out.

The only problem is i dont know how to interpret those gear ratios. The numbers dont mean anything to me :( Whats going to burn me up or i dont know what range i need to to be in.

The number simply means how many times the motor spins, vs. how many times your drive shaft spins. Its the "final drive ratio" Between the motor spinning, and your wheels spinning. The number will START to make sense, once you start to use it. You will start recognizing that a 4.5 is geared kinda low... like if you were stuck in 3rd gear on your 10speed bike. 3.5, is geared more medium high, like if you were stuck in 7th gear on your 10speed bike.

When you are at your track, a certain final drive will be the "Sweet spot" for yoru type of car. A super tiny tight track with lots of corners ... gearing more towards a 4.5 will be better, since you will spend more of your time accelerating out of corners. on a huge track with lots of straights... maybe 3.0 or 3.5 would be better as your car would spend more time at top speed, and less time accelerating. So find the fast guy at your track, and find out what FDR he is using, and you can use that as a starting point. you might not be able to run the EXACT same FDR, as all cars/batteries/motors/ESCs will change that slightly... but it will be a good ballpark to shoot for. Gear slightly lower, check motor temps, and "feel" how much punch and top speed your car has, and work from there. Eventually, the FDR number will just make sense in your head.

I always use the 10speed analogy to beginners, and it makes sense instantly to them. Imagine youre on a 10speed bike, and you have a track in front of you. But, you can only use ONE gear on the bike the entire time you go around this track... What gear is best? 1st gear? 10th gear? In 1st gear, you can start moving really really easy, but you will have very low top speed. 10th gear you will have tons of top speed, but wont be able to accelerate at all. So you need to find the one that works the best for the entire track... somewhere around 5th gear, right? IT all depends on the track in front of you.

So on your 10speed... 1st gear is like having a FDR of 10:1 (10 pedals, to get your tire to spin once). 10th gear, is like a final drive of 1:1 (one pedal, to get your tire to spin once). Think of it that way.

top guy to beat at my local track runs an old tc3 beating everybody else on a regular basis running tc5's,cyclone's and xray's.

Wish I still had mine.....The hara motor mount makes life easier with the pro4 also but its hard to find these days.

Ill have to look into that, i know the stock one is a PITA.

HPI SPRINGS NEEDED!!!!!
 

Hi, Has anyone got some HPI pro 4 springs for sale?

thanks

You still racing man? Havent seen you in a while!:D

Will any 64 pitch spur gear work, or is there a specific type i should be looking for?

As for spring, i would assume that most TC spring are the same size and can swap? No?

I have some AE springs that i use and they fit just fine.

What ive found is the Hot Bodies Racing Spur. Looks the same as my pro 4 spur but meant for the cyclone, can i assume this works? Hole pattern looks the same.

I think the Hotbodies/HPI cars use/come with Xenon spurs which can be ordered through HPI or from SpeedtechRC.

Ok, yea my spur says XENON on it. The other ones i found say Delrin in the description, so i guess those are different types?

Is it just me or is a 64P 88T spur gear for my pro 4 too hard to find?

It's you. :D

http://www.speedtechrc.com/store/ebp...nid=392&id=959

(out of stock)
http://www3.towerhobbies.com/cgi-bin...&I=LXUNN4&P=SM

Here's 87 tooth.
http://www.horizonhobby.com/Products...rodID=HBS68087

Kawada should work.
http://rc-mushroom.com/product_info....ducts_id=10024

Thank you Jimmy! I found the one at tower, but never could find that one on speedtech.