Turbo Joe

iTrader: (41)

I use 415 rear body posts...MUCH beefier than the RS4 posts. They have the same offset, cost about the same and bolt right up.

Artificial-I

iTrader: (17)

We know nothing about rubber tires. At least on the R40. I used to run rubber tire exclusively until my r40. I still run rubber on my pro4 since thats all they allow at my track.

But most likely you will want soft tire. The harder the insert , the less grip , more response and less wear. Softer insert , more grip , more wear , less response.

I would go with a softer insert and softer tire. May wear fast , but the r40 needs grippy tires or its like trying to drive on oil.

Minus

Ok thanks

So a softer tires like D20 pit shimizu and a medium insert can be a good choice in wet tracks.

Artificial-I

iTrader: (17)

Thats probably a good start. All I know is the r40 says basically for use with foam tires and on blown paved race tracks. I think this is right on the box.

I know a few of us have tried rubber tire on the r40. All I got was massive wheelspin.

Minus

Thank you

Rapid Roy

I used sorex 36r's at my last parking lot race because the track was so damp in the 1st heat. I used the same setup as foam, or maybe 1/2 degree less camber, can't remember for sure. It was pretty slippery, but much better then the foams on damp pavement. I have run rubber at low grip/dusty surfaces too and they hook up a little better then foams. So there are times when rubber works. I always try the foams 1st though.

ProE

My R40 has the oneway diff in the front. So that means no braking in front. Do I still need a strong servo for throttle/brake, or could I use a more generic servo. maybe something like the futaba 3003.

What should the ratings of this servo be when a oneway is used in front?

Artificial-I

iTrader: (17)

Throttle servo "strength" has never really mattered to me on most my nitro vehicles. If anything its "speed" you want so you get quick throttle response and quick brake response. If anything strength is going to harm the carb linkage or put more wear on the brake disc and like components.

I have used the s3003 mostly or any cheap laying around servo for throttle. If I find some cheap faster servos that work well and have low torque I also use those. Right now even the s3003 isnt rated as the fastest , it does beat out a few other servos in response and speed even if they are rated faster than the 3003.

The other good thing about s3003 on throttle , is less drain on the battery , easier to pull close with a TRS (throttle return spring). I really cant find a much better throttle servo if you ask me. Especially when its only $10 dollars.

Otherwise I have tried them all. The stronger the servo , the harder it seems to close via TRS to where its almost impossible, in which your putting so much tension on the spring anyways your making the throttle servo work hard to fight that tension. Especially a metal gear servo , the plastic gear seems easier to move about without power.

The other thing is with one-way you really cant use the brakes at all. I know when I race I dont use it at all with the one-way. I never touch them. Just a waste of time to me and gets you thrown off balance trying to get back on the throttle correctly after playing with a car with a one-way on brakes.

All you need is a good TX that can vary the travel on the brake and dial it in to where you can brake and not spin out. Which you will find is almost non-exsistant braking. Otherwise I think throttle servo strength is a weakness on most on-roads and makes the car more touchy with the brakes and all the factors above. Save money , weight and power and go 3003 on the throttle all the way. Unless your used to having fast servos you wont really notice. Its best for throttle response...everything else strong/exspensive servos are overkill on throttle. Ill admit ive run digital fast servos on throttle. It feels nice and crisp and responsive...but what car really needs super fast throttle response. When grip needs to be maintained , smoother slower is better. But this comes down to individual prefrence. Ill just say personally , im all for the s3003 on throttle.

Artificial-I

iTrader: (17)

Yeah never tried it in the wet, sounds kinda fun. I just know once I tried rubbers in a parking-lot on my old r40. I thought , my god no wonder it says this on the box. It was nearly a joke. Power on and I would immediatly have to control the car in a turn...rather than let it settle through. It was kinda cool though , basically became a drift vehicle.

I probably should have used some grip compounds , cause the tires were a bit dry. On my racer2 , same exact tires work great. So , I just figured it was a setup of the R40 causing this and to warrant the suggestion right on the r40 box.

AMGRacer

You want a fairly stong brake servo no matter what diffs you are using, but more so with a one-way. What makes you spin out with a oneway is locking the rear tires, so therefore maximum braking is achieved when you are just before the lockup point. However that all assumes a nice linear force being applied to the brake disc, which with a standard servo and the stock R40 brake does not happen.

The stock R40 brake is for some bizarre reason a stamped piece of metal. Now there is no way a stamped piece of metal will be flat, and none of my brake discs have ever been. You ever had a real car with a warped brake disc? The shudder like all get out and your braking suffers. Same with a rc car. If your brake disc causes your braking mechanism to "shudder" then it is because it is going through a series of higher and lower braking forces as the disc rotates. Now remember that highest braking is achieved when you are just before lockup. If you are pulsing through the braking system you may only be able to achieve maximum braking force for 20% of the disc rotation, the remainder of the 80% is less force because of the uneven braking surface meaning you slow down more slowly.

The same thing happens when you use a weak braking servo. You cannot see it easily, but trust me a stock servo pulses badly under higher braking loads because they do not have sufficient holding torque. This happens even with a perfectly flat brake disc. Again see above why this is bad.

The optimum setup for high braking power with a oneway is a servo with a good holding torque (coreless digitals) a flat disc brake (the HPI optional one works very well) and teflon brake pads. The teflon brake pads make it almost impossible to lock the rear wheels even under super high braking loads, perfect for a oneway use. Mugen makes them and so does Kyosho, you can easily adapt them with some mods to the R40.

With my braking setup I can brake very hard with the oneway setup and not spin out. Clearly not as hard as with a front diff of course.

Artificial-I

iTrader: (17)

Coreless is indeed much better for smoother motions. Most digitals are coreless for that matter.

I need to get some of those teflon pads though. What are those part #'s. I would like to be able to use the brake some. Ive tried the s9451 on the braking side, still spun out to the braking was very dull. Same as my cheap s3003. But the throttle response was nice. Some truly cant stand slow throttle. I dont mind once Im used to either or.

Also how does your TRS work on the car with your strong servos. I know mine were impossible to pull back.

HarKonnenD

iTrader: (23)

Welp, I think I'll definately get a nice digital servo for my R40. The hi 945 seems good, but...ehhhh...mehh...I'll get another JR Z9000s ! It costs $105, but well worth it. The urge to drive the R40 with the 30% is really growing...I must RUN! Snow is on the way for the weekend. Anyway, I didn't get the pexi glass since it was too expensive so I picked this up for $8 and all I need are guages. WOOHOO!!! Lastely, just need a tire truer though I got plenty of time. I pretty much go out for a run when I have time anyway as well as weather permitting.

AMGRacer

Coreless also has a much higher holding torque. As I mentioned above you cant brake harder with a good servo if your disc is not right. You need to get the brake force right up to just before locking. A solid or tight rear diff will help as well as no tweak.

I never use a TRS.

B.LaFrance

While building the transmission on my 2005 Edition R40 I seem to have stripped the two screws on either side of the clutch (one black one silver). Is there any way I can buy just those screws or am I going to have to buy an entire transmission assembly? I searched Tower and Buy HPI for the part numbers and nothing came up 94275 and 94276

B.LaFrance

Upon closer inspection, the screws do not actualy looked stripped at all, still nice little hexagons... however my 2.5mm alen wrench is too small for them and my 3mm is too big. Which is odd because I got them in the two speed clutch with the 2.5mm in the first place. I tried SAE sizes and get the same results, either too small or too big. Has anyone else had this problem before? Maybe I need to invest in a better set of drivers.