Thursday, July 23, 2015

My list of recommended upgrades and modification for the Redcat Racing Ground Pounder ( part 1)

In the time I have owned a Redcat Racing Ground Pounder I've broke a few things my list and my step fathers can be found here .  Link                 

The first thing you should look in to upgrading on the Ground Pounder is the motor : 

Really I find the top speed pretty good but I feel the truck needs more torque for driving in grass and driving off road . 

My  recommendation  is a 550 motor with 19-22 turns here are a few examples :

Redcat Racing Part # 28446  sells for about $16.99





Traxxas Titan  (21T) Part # 3975 sells for about $21.49 





Thunder Tiger  part # PD9221 sells for about $27.99





My second upgrade I recommend is to upgrade pinion and spur gear . 






Part # bs801-014 is a 43 tooth mod 1 spur gear made from a composite plastic that can replace the stock spur .
About $10.00











Part # MPO-017 is a steel version of the BS801-014
About  $14.00







Now you will need at least 1 pinion that has a Module 1 tooth profile . If you are using a motor with a 1/8th inch shaft " like the ones listed above " here are a few options.


Pinion Gear, 9T/12T x 3mm, Mod 1 part # ECX232028 

about $13.00 for a pair 



OFNA 3mm Bore Mod 1 Pinion Gear  about $12.00 each  

11 tooth = Part # 21316
12 tooth = Part # 21314
13 tooth = Part # 21315
14 tooth  = Part # 21306
15 tooth = Part # 21311
16 tooth = Part # 21312











Wednesday, July 15, 2015

Why a 1/16 scale Traxxas transmission maybe good for your crawler .

So here is my reasoning .

 The 1/16 Traxxas transmission is a very small unit and is very compact .

 It has pretty much proven its self to be a strong and durable transmission as its quite common for people to buy a Traxxas 1/16th scale Revo or Summit and install 1/10th scale truck wheels and rubber and then install 540 or 550 brushless systems intended for 1/10th scale car's and trucks .

So what pushed me over the top and made it my must have transmission ? The gear ratio flexibility . The transmission is designed as a double gear reduction where the center gear(s) are not a idler like most transmissions in RC but acts as a jackshaft . Traxxas designed the transmission so that its ratio could be changed by swapping 2 gears shown in picture below circled in green .




The reason for this was because they have and are using  this transmission in several chassis configurations that use different size tires . So whats the transmissions ratios well you can choose 1.93 or 3.71 . OK so that doesn't tell you much . Here is a couple of examples showing the gearing extremes of this transmission vs a Axial AX10 transmission and the old Traxxas 272 magnum. the axle ratio listed is for a AX10 or HPI king axle and the motor is a generic kv rating for a 35 turn 3 pole 540 motor .    


Axial AX10 2.60 Traxxas 272 magnum Traxxas 1/16 3.71 ratio  Traxxas 1/16 1.93 ratio 
Low

Differential Ratio: 2.92
Transmission Ratio: 2.6
Other Ratio: 1
Spur Tooth Count: 96
Pinion Tooth Count: 12
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 3.22
Low 

Differential Ratio: 2.92
Transmission Ratio: 2.72
Other Ratio: 1
Spur Tooth Count: 90
Pinion Tooth Count: 12
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 3.27
Low

Differential Ratio: 2.92
Transmission Ratio: 3.71
Other Ratio: 1
Spur Tooth Count: 55
Pinion Tooth Count: 18
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 5.9
low

Differential Ratio: 2.92
Transmission Ratio: 1.96
Other Ratio: 1
Spur Tooth Count: 55
Pinion Tooth Count: 18
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 11.17
High

Differential Ratio: 2.92
Transmission Ratio: 2.6
Other Ratio: 1
Spur Tooth Count: 72
Pinion Tooth Count: 30
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 10.72
High 

Differential Ratio: 2.92
Transmission Ratio: 2.72
Other Ratio: 1
Spur Tooth Count: 76
Pinion Tooth Count: 31
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 10.01
High

Differential Ratio: 2.92
Transmission Ratio: 3.71
Other Ratio: 1
Spur Tooth Count: 45
Pinion Tooth Count: 31
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 12.42
High

Differential Ratio: 2.92
Transmission Ratio: 1.96
Other Ratio: 1
Spur Tooth Count: 45
Pinion Tooth Count: 31
Total Voltage: 8.40
Motor KV: 1565
Tire Diameter (inches): 5.
Top Speed (MPH): 23.51


Now you probably wont use the 1.93 ratio in a crawler but the flexibility would be nice to have (could throw some touring car tires on and go cruising around the local carpet track at a brisk pace )

So whats the down side ?

 I think the main reason this hasn't found more use in crawlers and other projects comes down to the output shaft size . Its small with a diameter of  4 mm  its smaller than the shafts most drive shafts attach to . Most drive shafts used in crawling have a hole designed for a 5 mm  or 6 mm shaft .   Now the final drive gear that attaches and drives this shaft has a 5mm hole and the shaft its self is 5 mm in the center and is machined down to 4 mm at its ends . The shaft has been circled in the diagram above . By replacing the bearings with 8x5 bearings and replacing the shaft with one that is 5 mm from end to end common drive shafts should be able to be used . I am currently looking for a shaft that will be a drop in replacement but one should be able to be made fairly easily . 





Friday, July 10, 2015

Parts list monster /crawler / mega truck . ( subject to change as the build goes on .)

Parts list so far

HPI 1/10 Crawler King Battery Box, Waterproof Receiver Box & Servo Mount

Crawler Battery Tray$0.99
Ordered: 1$0.99

HPI 1/10 Crawler King Front & Rear Axle Hub Carriers & 8 Bearings

Crawler Axle Carriers$6.49
Ordered: 1$6.49

HPI 1/10 Crawler King Complete Front or Rear Differential & Bearings

Crawler Differential$10.99
Ordered: 2$21.98

HPI 1/12 Wheely King Front & Rear Drive Shafts & Axles

Wheely Drive Shafts$11.99
Ordered: 1$11.99

Traxxas 1/16 Mini Slash Transmission & Spur Gear

mSlash Transmission$13.99
Ordered: 1$13.99





HPI 10 Bullet MT / ST Flux Front & Rear Assembled Shocks & Springs with Oil

eBullet Shocks$8.49
Ordered: 1$8.49

Traxxas 1/10 Telluride 4x4 Drive Shafts, Wheel Hubs & Nuts

Telluride D/S$18.99
Ordered: 1$18.99

Traxxas 1/10 T-Maxx 2.5 Turnbuckles, Servo Saver & Bell Crank

Classic Turnbuckles$5.49







Ordered: 2$10.98



















So I got it in my head to build a low cost monster /crawler .

Deciding I wanted to build some thing with solid axles was the easy part . I'm a cheap person and to to be honest I wanted this project to be as cheap as possible . Mostly because I wanted this to be a trail truck / crawler and I had the feeling that it wouldn't take long for it to turn in to a smallish monster truck or something similar to a mega truck .


I'm gonna have a post dedicated to the parts that I am using for this project and a link will and can be found here . Parts list   after it gets posted . The parts I'm starting with  where purchased from https://www.dollarhobbyz.com and more sources will be added in time as there will be lots of little bits I'm sure I haven't even thought about and I'll probably be adding pieces I will be making my self .

The stars of the low budget show .

A pair of HPI Crawler king / Wheely king axles .

 At $40.45  through Dollar Hobbyz Plus shipping and handling and a little assembly these were the cheapest axles I could find . Given that Most of the Axial based axles seem to be selling for $40.00 per axle These seemed to be the best way to go .



How about a Traxxas 1/16th scale transmission with the 540 motor mount .

At $13.99 for this transmission from Dollar Hobbyz Its a steal and I think it may be a very over looked but great crawler transmission with just a bit of work . My reasoning may take a bit of explaining so expect a link here LINK to a post just talking about this transmission and the reasons why i plan to use it .