Various Baja 5b questions and a possible new project
 

So this goes out to the 5b owners, and I also have some electronics questions for a savvy members...

First I was wondering what a 5b roller weighs? This would be minus the motor, tanks, and pipe, but with the electronics and servos...

Next, the width inside the chassis would be helpful.

Now, on to the power questions. I have a few 1527 motors. I figure that a 1521 will not be enough, but will a 1527? Winds are 2y and 2.5y, 635 and 500kv repectively. CC spec the motors for 2250 watts, or 3 horsepower. Is this enough for the 5b? It is a heavier vehicle than I am used to. But is is 2wd and that will not load a motor as much as a 4wd will. My motors have 8mm shafts, and I have found 1.5mod pinions in 12 and 14t. This will give around 45mph with the 1527 2.5y on 12s lipo.

My battery selction includes a pair of 6s 4500 30c polyquest lipos. These are spec-d at 135amp cont, so at 70% effeciency that is around 5.5hp, much more than the 1527 should pull.

As far as esc choice goes, I am stuck on the hv110. Not sure if there are other choices... Trying to stay around 200 bucks, may even try to scare one up used. I like that esc due to its programability. And it supposedly has a decent startup for an air esc. Now can I safely run it on 12s, or would I be better suited on 10s? Pushing stuff is not usually a good idea, but if it can handle 12s it will save me having to reconfigure my lipos (even though I can do that in my sleep now).

Now at 110amps and 12s lipo that gives about a 6.5hp potential. This has me wondering if I should go with a more powerful motor.

Any thoughs or critism (or just silly pics) will be greatly appreciated. I will examine some other motors and report back. As usual I am trying to keep my costs down, but still have a well performing setup.

Well, looking at the other neu motors seems like the 2215 that ole FD chose is not rated for much more than the 1527. I understand that the 2215 has a larger diamter rotor than the 1527 so it should have more torque. Given the lower kv and high gearing I guess the increase in torque will be a good idea.

Thoughts?

Didn't you say in another thread that you had two like-wound 1521 motors laying around? I think you know where to find your torque- and your horsepower. :yes: Yeah it costs more 'cause you need two ESC's and have to make a dual motor mount, but it would be one-of-a-kind!

True, I have been thinking of doing that. Maybe run a pair of cheaper escs, like the turnigy sentilon esc from HC...

I will have to eyeball the specs on those. It would cost the same as the hv110... Not sure of the performance.

Now with a pair of the 1521 2y motors (I have a pair of those) with 12 tooth pinions on 12s lipo would yeild speeds around 60mph... May have to step down to 10s as that would know of 10mph or so. 50 sounds more in line... Or I could scare up another 1521 2.5y. A pair of those on 12s with 12t pinions would be just about right.

4000+ watts sounds good to me, hopefully the lipos can keep up...

Anyone know if the 5b has any optional spur gears? Like a larger model. Now I could go with the 5t trannt, it is geared lower, right.. Not much though.

I'm a huge fan of the Sentilon ESC's. It ran my GTP with a 1515/1y, 6s, and 30/40 gears better than a MMM. The slow startup will help the drivetrain last longer- and I assume you are using mechanical brakes since you're looking at the HV110. If you have the batteries (haha) for the 10s/dual 1521 setup then that is what I would do. With 10s there is plenty of headroom on the Sentilons, and 100A would be more than sufficient because the running load is split between two motors/ESC's. On top of that I bet Neil would put you on his Awesome RC's page! :mdr:

10s... I can do that with the cells I have. I may have to give this a try. Lets see what I can do to actually get my hands on the 5b. 50mph sounds like fun. Hopefully the lipos can handle it...

Hey WN, did you ever get the Sentilon to startup well? I just went back and read the thread you had. You gearing was steep...

Looking at the baja 5b it has a 17t pinion so the stock motor must do something like 15k rpm max. With the 1521 motors on 10s I am getting 28k rpm, so I think 2 of them with 12t pinion will do the job.

Heres the calc, eyeball it and see if I got it right???

Differential Ratio: 1
Transmission Ratio: 2.4000000000000003
Other Ratio: 1
Spur Tooth Count: 57
Pinion Tooth Count: 12
Total Voltage: 37
Motor KV: 780
Tire Diameter (inches): 6.6875
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0.025
Spur/Pinion Ratio: 4.75 : 1
Total Ratio: 11.4 : 1
Tire Circumference (inches): 21.01 inches (533.64 mm)
Total Motor Speed: 28860 RPM
Vehicle Speed: 50.37 mph (80.91 km/h)
Effective KV Value: 780
KT constant: 1.73 oz-in/A

I did actually. I set the Texp low on the radio and it helped a lot. The MMM (V2) still had trouble even after I played around with the settings. IDK why. I put the MMM in there because the Sentilon was still a bit jittery on take off. This was with the 30/40 gears. I replaced them with 20/51 gears for "normal" driving and the Sentilon would light up all four tires on command, as would the MMM.

The SC data looks fine. You do have tire ballooning at 0, but that only affects the top end. Can you get any smaller pinions if you need to? Or do the 1521's have an 8mm shaft...? I hope you can pull it off... It will definitely out-perform the gas version. With two motors it will (still) weigh less, but have twice as much power!

12t is the smallest I can find. They do have 8mm shafts... I could swap out to a different spur, but I think the mod 1.5 is there for a reason. Looks like the dual motor mount plate will be fairly easy to make, but I would like some sort of rear motor support.

Thinking a clamp style mount like FD did, minus the tape, silicone and bottle caps. I wonder where else I can get a 39mm clamp mount? I do not want to buy from FD, that is for sure. Mega has 36mm mounts, I wonder if any of the boat places have clamp mounts? More seraching to do now...

Ding! Found this from OSE: http://www.offshoreelectrics.com/pro...jwr-mount-flat

A couple of bucks cheaper than FD, and I know Steven well.

Hey Lincpimp the few bajas i have seen that are converted have been with larger motors, like the 2200 series NEU the very large lehners and the Plettenberg Bolido. As far as speedy goes i have only seen people use the CC Hydra 240 and mechanical brakes or the schulze 40-160. Converting a 1/5 scale is a big dollar exercise. I would stick to the one motor though. There is one on youtube on 9s and one already converted for sale on Ebay, or finedesign rc, though i wouldn't go there. See finedesign just to get the specs and see what he is running and what it would cost to convert. Hope this helps.

If you haven't been there already: http://www.hpibajaforum.com/.

It's a great Baja resource.

Thanks guys. I have done some preliminary research (mainly cause I am bored) and it seems like most people do use 1 larger motor and esc.

However, I do have 2 motors, and buying a pair of cheaper escs to run them would most likely be the cheapest way out. Looking at the 5b I think I can perform the conversion without much modification to the chassis and parts, so if it does not work I can always put it back to gas power. Since I am getting a complete rtr, I may play with it before I convert it...

I should be able to get my hands on it in the next few weeks, so we will go from there. I need to sell some more stuff to fund this project though...

A 1527 will not be powerful enough to run it the way you would like. Atleast use a 19 series motor and nothing less. The 22 series is suggested.

I'd go for a 3080 or a Bolido, but thats just me...