DA_cookie_monst

iTrader: (1)

just build as per instructions..... thats what I do.

tiko

iTrader: (35)

That’s exactly what I did but I almost have zero rebound on the front shocks and just a little on the rear once. I also found the thread on page 19 where one of the guys posted the David Jun’s explanation on how to build this shocks. I have tried that also and I get the same results. What I would like to know do most off-road car shock work mostly like this. To me it seems like that the springs are doing the most of the work.

DA_cookie_monst

iTrader: (1)

springs are springs, dampers are just that, dampers, once you start building in rebound on them, they become hybrid units and far less consistant.

pgeldz

Real quick guys...

What pinion to use with a Novak Hovak Sport 8.5 sytem (stock spur gear)?

Will the kit 17t be good?

Any help would be greatly appreciated.

- Paulie

DA_cookie_monst

iTrader: (1)

17 or 18 would be a good ball park pinion.

pgeldz

Sweet! Thanks fro the speedy reply. The reason I'm going with the Havok in the first place is because the ESC puts out 6V, which will allow me to use my Futaba S9551 (short profile) servo in HRS (High Response Mode).

This servo is lighter than the Hi Tech unit I was using with the MM 5700 combo, and is faster and more torque as well.

I'm hoping the lighter weight of the servo will balance out the chassis a little better with the 3800 Orion Carbon Race Spec batteries I'll be using.

I would have just left the MM 5700 combo in there, but that ESC only puts out like 5V - that, and the fact that the Havok 8.5 should give a little more "feel" as far as throttle modulation goes. Our track is very loose/dusty so I think that may help a bit as well.

The good news is I have both 17t and 18t pinions!

Thanks again,



- Paulie

BugFreak

Had my first (carefull) run last night..
Indoor track with lots of jumps

I LOVE THE CAR...

Soo nice and balanced almost right out of the box!
(slipper, one-way and aeration dampers)

linger

iTrader: (1)

Hi Paulie,
Here are some thing I found:
The front steering link - if you flip it from the stock setting, it makes the steering more agressive and nervous - especially on turn in. This makes the steering tie rods mount a little further back from the stock position.

The rear aluminum arm mount is a GREAT hopup over the plastic pieces. You will notice that they milled in vertical slots instead of holes. This way, you can add spacers (2mm I think) and have the inner hinge pins lower for more antisquat. This seems to reduce chassis slap. I also have a number of spacers on the rear-front arm mount.

Since you have the TRF shocks - you should run limiters in rear or the chassis will just feel wrong. You will need to add somewhere between 3-5mm of spacers to limit droop. I run the stock pistons and use 35 weight front and 30 weight rear.
If you run the stock rear shocks, the shock bodies are too large in diameter so it won't fit the TRF springs. The stock spring is also a bit too stiff, which causes the rear to bounce around during big jumps.

The TRF spring rates are listed here:
http://www.oople.com/forums/showthread.php?t=14332

pgeldz

Thanks for the tips!

Some questions though...

For the TRF shocks, I used 35wt oil all around. I did not run any limiters in the rear because I thought I read somewhere that David Jun suggested more droop than the kit setting, which from what I've rear shouldn't be a problem with the rear dogbones - I thought it's only a problem with the rear CVD's because they are too short. Is that not the case?

I also read somewhere (I think David Jun also suggested this, can't remember) to run the shocks in the outer most position on the bottom. That's where I have them right now, and I'm using the second most inner hole on top.

I'm not done with the build yet, but the chassis is mostly complete. Just need to add electronics and wheels/tires.

So far, the droop is such that the rear dogbones will not fall out - not even close.

The front doesn't seem to have enough droop though and I may move the top position of the shocks to the 3rd from inner (second outside hole) to get a little more droop up front - not sure if it's needed though.

As for the antisquat to reduce chassis slap, do you only run spacers in the rear/front and rear/rear as you mentioned, not all the way around?

What shock position are you using?

I'd like to make this car pretty decent for a loose/dusty/rough, 1/8th scale Buggy track with big jumps, without crazy chassis slap. Hopefully I'll find a setting that works.

I'm pretty good at setting up my touring cars, but this offroad thing is new to me.



- Paulie

Roman

iTrader: (28)

www.oople.com have a very good build review of the DB01 with lots of info and great pics.

Badazz45

iTrader: (6)

Just had my first two races and I love this car! Been out of off-road for a few years and this is my first 4wd buggy (besides Optima) and was looking for some help as to what motor to run when I step up to mod. Have to run novice now due to no 4wd stock class, but I turn faster/more laps with my 17.5 than some of the bottom mod guys. No one runs a Durga so I am not sure if I should go with 10.5 when I step up or something faster like 8.5? Any replies would be helpful.

dimblum

I run a Novak 17.5 as well for my Durga - same reason as you, to race in the Stock class. You will find that the 17.5 can be pushed to speeds near 30mph with safe gearing.. Most of the 4WD MOD guys at my track will top out with a 6.5. Anything faster is -too- fast for our track.. Check to see what the top drivers are using at your track to get a good feel for top controllable speed.

I recently posted some gearing help on the RCUniverse thread. If you are interested in re-gearing, this should help:

I wanted to provide a simple method for calculating safe gearing for your Durga.. There is the long (all math) way, and there is the short (gearchart.com) way.. I will cover the easier -gearchart.com- method here.. If you want the long math way I can give it to you, but it is less fun.. Also, if you want to know how I got some of these numbers/ratios please feel free to ask.

This will help you target the -sweet spot- for gearing so you can get the most out of your motor without overheating...

NOTE: The most important thing to make this work is that you have a good idea what your motor "RPM" is and also what the target "Gear Ratio" is for your motor. High end companies like Novak provide this information (as do other brushless motor manufacturers). I found it harder to find this info for brushed motors...

Lets get started with a "real world" example for my Durga when I ran a Novak 17.5 brushless for Novice and Stock racing:

1. First lets go to www.gearchart.com and click "Gearchart Creator" on the upper left side of the screen
2. The "Select an RC Car" pulldown menu does not have the Durga, DB01, etc.. So select "Pan Car (10/12th scale)" and we will fill in the blanks
3. The "Transmission Ratio" is 2.055.. It is the same for "ALL" DB-01 cars.
4. Next enter your "Spur" and "Pinion" sizes.. I switched to an 81T Spur gear and 31T Pinion gear when I installed my 17.5 Novak since it was better suited for the slower motor
5. The "Plot Spur/Pinion" option with the "Middle" setting is fine.
6. Now click the "Gear Ratio" button.. The chart it builds will have key information to see if you will -burn up the track- (yeah) or -burn up your motor- (bummer).
7. In my case I needed to know what Novak recommended as the Gear Ratio for my motor.. I went onto Novak's website and pulled up their gearing recommendations: http://www.teamnovak.com/tech_info/b...r_gearing.html
8. It showed that a 4WD (my Durga) should target a "6" (or 6.00) gear ratio with their 17.5 motor.. My Spur and Pinion combo put me at "5.37" so I was a little overgeared for their spec.. I wanted to push my motor a little bit for more speed, so this seemed fairly safe for a shorter 5min runs.. If I wanted to be right on spec with the Novak chart, then I would gear down to a 28T Pinion since that would be "5.94" which is super close to 6.00..

Ok, so this told me that I'm not likely to turn my motor into a -molten ball of fire- by pushing it too hard.. Now I wanted to get a ballpark on how fast my car might go..

9. The next part was "Rollout".. Rollout tells you how far your car will travel per motor revolution.. My Tire Diameter (measurement from one side of the tire to the other) was 85mm. It will likely be the same for you and most tires you will run..
10. Keep the "Increment" setting at "1mm" and click the "Rollout" button
11. I got "49.73", yipee!! What the heck does that mean.. Well, its telling me my Durga has the potential to travel 49.73mm every time the motor completes one revolution. That's about 1.9 inches.. This isn't too exciting yet, but it will help us get our MPH in the end..
12. The last part was the "Motor RPM".. This is important and requires as little guessing as possible to get an accurate number.. I consulted the "Novak Brushless Motor Spec Chart" to figure this out: http://www.teamnovak.com/products/br...spec_chart.htm
13. The chart says that I am running 2200Kv (or RPM per volt) for my 17.5 motor. I'm using a 7.4v lipo, so I multiplied 2200 * 7.4 to get "16280" which is my max RPM.
14. I entered 16280 as my RPM and clicked "MPH".. The chart showed I had the potential to go 30.2 MPH.. Not bad for a 17.5 Brushless running with pretty safe gearing..

It worked well on the track and the motor did not heat up very much after each 5min run.. In reality, your car will not go quite as fast as the charts say because they do not account for weight, track conditions, friction, etc.. Most lipo batteries will give you an extra kick though because they can discharge at rates higher than NiMH can - i.e. Team Orion 3800Mah lipo has a 30C discharge rate.

Hopefully this will help take some of the guesswork out of your gearing.. If anyone gets any strange results, please let me know. I will be happy to double check your results.

Dan

oople

I made a gear chart for the DB01 over a year ago here:
http://www.oople.com/rc/photos/cars/...-gearchart.pdf

I just go by reccomended ratios for whatever type of motor it is then fine tune it from there depending on speed / how hot things are getting etc. With my 5.5 bonded brushless I was running ~13.00 overall ratio and ~10.50 with a 6.5 sintered.

dimblum

Great chart Oople! I referenced your Durga review when I built my car for the first time. I wouldn't have known to order the aftermarket screw kit without your help. Keep up the good work!

Dan

tiko

iTrader: (35)

I was wondering if anyone has used the motor heat sink and does it work? Also it looks like that you have to modify the original tub to make it work or get the precut tub. Anyhow I just want to know if I should spend the money to buy this part. Appreciate any and all comments thanks.