Jump to content
Sign in to follow this  
BuggyBuilder

Brushless Scorcher.. hopefully!

Recommended Posts

Hi,

Have now built my Sand Scorcher and run it a few times on the beach...so much fun on perfectly flat sand! I'm running a sport tuned motor on 3300mah 8.4v nimh, the speed and acceleration is good but I'm looking for a little bit more speed and better run times. I wish now that I had taken everyone's advice and gone brushless from the start but I had in my head the thought that with my original scorcher and Tamiya 7.2v 1200mah packs I used to get 10-15 mins run time so was expecting at least 20 mins with the new setup - not getting that - 8 mins at most and with quite a sever voltage drop off.

So I've researched around the forum but not managed to find the answers I'm looking for so far....hoping someone knowlageable can help me out!

- Is there a brushless motor that will fit the Scorchers gear casing without the need for drilling / cutting anything - will it 'lock' into place on the pins like the standard 540 / sport tuned..

- Will the clear motor cover still fit on (modified to allow the motor wires through)

- Looking to get a better turn of speed and a much improved runtime than the sport tuned / 8.4v pack gives...what lipo battery type / voltage / motor rating / esc rating should I be looking at?

Again if anyone has a setup in a similar SRB that would work I'd love to hear the specifics... I'm trying to gain knowledge about brushless setups but have absolutely zero experience of them!! I'm UK based so would prefer to hear about products I can source over here if possible...

Thanks in advance!

Share this post


Link to post
Share on other sites

Well you're a brave man running 8.4V/sport tuned in a Scorcher - most people are happy to stick to the silver can motor, mainl;y for fear of rollovers and body damage. If you are only running on soft sand then i suppose you have a cushioning effect. A sport tuned runs at 18,30000rpm with no load at best efficiency (on 7.2V), so you're currently at ca 21000rpm no load on the 8.4V battery.

The other issue with hot motors in the SRBs is the handling - the rear axle/drive really isn.t all that great and even with the optional ball diff in place (a hit n miss hop-up if ever there was one) you still get bad handling - again on a beach probably not too worried or noticeable ;)

I put the ball diff and a EZRun blue can motor (i think its a 9T) in an old SRB chassis - i've only run it once, yes it was fast but too fast to be a realistic speed IMO and handling with that much power on hard ground was nigh on impossible. Its sat on the shelf since (waiting completion in all honesty as much as it being a disappointment). If we assume its the 9T, in which case its rated at 4300kV, so at 7.4V on 2S lipo its spinning at 32000rpm !, ca 40% up on your current set up but its far too much motor.

The motor fitment can be an issue - ive seen some folk skim the motor casing to get them to fit. You will almost certainly have to remove the locating pin in the gearcase too.

If you want to retain the electronics box then you can fit a 2S lipo across the box towards the rear if you limit yourself to a softcase one at ca 2300mAh - this won;t help improve your runtime over current set up though.

I think you have a few options..

1. check for any resistance in the drivetrain - metal ball bearings are normally preferable over the plastic/brass bushing (but drive near salt water and you're asking for trouble)

2. Try another battery - if the 8.4V isn;t getting regular charging/discharging then its possibly down on capacity having developed a memory effect at less than full charge.

3. Try the bigger pinion/smaller spur option from the kit - this will give you more top speed, BUT monitor motor and ESC temps every few minutes of running initially to check you're not cooking them with the extra load

4. Go for another motor - note I didn;t say brushless - brushless is no faster than a brushed motor of comparable rating, just brushless is almost maintenance free.. Something around 330kV on 2S should get you another 15% no load motor speed over your current set up. Step up a little to a ca 3900kV and you're at 30% above current set up

Personally I think anything beyond 3300kV in a SRB on 2S lipo is pushing its capabilities, but on soft sand then maybe 3900kV would be OK. I wouldn't recommend 4300kV (but some people put 5700kV motors in their lunchboxes so its very much up to the individual :lol: )

Share this post


Link to post
Share on other sites

Thanks Percymon, that's great info so far. I'm running this purely on the beach.. here in Weston we have a huge beach and when the tide goes out its completely flat firm sand and perfect for sliding at speed - I haven't managed to roll it yet even with sudden high speed turns.. loads of great spins and power slides though! :D The car has ball bearings all round and has the bigger pinion fitted already - I have left it without the diff hop up as I think that would ruin the fun on the beach. Think given the surface its running on a 30% - 40% gain would make it just the right level of bonkers! Did the EZrun motor fit straight in or did you have to skim the gearbox housing? I'm pretty sure with a little re-jigging I can fit a larger capacity 2s lipo in the radio box.. will have to check that out. :blink:

Share this post


Link to post
Share on other sites

I didn't do anything to the EZRun motor at sll, I can't remember whether u had to remove the pin inside the gear case (I don't think mine had one to be honest but it was jan 2011 and my memory isn't too great with over 50 builds in the mean time lol!). I did have to slot the cover for the wires and the solder tabs are very close to the gear case alloy so probably worth insulating that area or at least checking when you install..

IMG_0333.jpg

Share this post


Link to post
Share on other sites

I've no experience of these but the motor can looks to be the same one used by Hobbywing/EZrun..

http://www.ebay.co.uk/itm/HobbyFans-4-poles-10T-3930KV-Brushless-Motor-For-1-10-On-road-Drift-Racing-Car-/291183432043?pt=UK_ToysGames_RadioControlled_JN&hash=item43cbe2916b

Another option is the Speed Passion 3500kv system from RCMart at $50 delivered - I have three of these (a pair in a mod Clod Buster and another in a Durango DEX210) - they go well, especially for the money. The good point about these is that the motor wires are on bullet type connectors pushed into the end bell of the motor so it'd be easy to use one or two of the exisitng wire hole in the plastic cover and just drill the third..

http://www.rcmart.com/speed-passion-reventon-s30s-brushless-wcompet-p-37495.html?cPath=1560_1301

a shot of one in my mod Clod so you can see the motor connections..

photo11_zps2e0f1770.jpg

  • Like 1

Share this post


Link to post
Share on other sites

I agree with Percymon's first post - I had a SS with a Duratrax 20T motor, the fast gear ratio, Traxxas XL2.5 ESC, and a 3200mah lipo - it was a hand full on a tar road.. If/when I build another SRB it will get a sport tuned or similar motor

Share this post


Link to post
Share on other sites

My brushless rough riders' sporting 3300kv. Had to dial down the "punch power" for the benefit of the ball diff. I probably could get a better run time, but 15 mins and my heads mush any way. Yes, had to mod the motor case. I did away with the radio box, put the steering servo between the shock towers for less slop and run the lipo north-south on the chassis. Percy is spot on, tamiya never intended this sort of set-up.

Share this post


Link to post
Share on other sites

Compromise ? Run the sport tuned on 2S lipo . Longer run times and far less hassle than a hairy brushless set up maybe ? Just fit a lipo alarm to your ESC and you should be good to go .

  • Like 3

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...