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My Cen GST Brushless conversion

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Old 11-01-2010, 07:26 AM
  #1  
lomdel
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Default My Cen GST Brushless conversion

I just finished my (rather simple) brushless conversion of the Cen GST. Here's what I used and a few close-up pics of how it looks all hooked-up. She runs great, but I needed to dial in a lot of negative expo (-25%) to get her to accellerate smoothly.

1 Motor - Castle Neu 1520 1600kv
2 ESC - Mamba Monster V3. Space beside motor too small and had to mount the ESC to the carry handle.
3 Motor mount - Tekno RC for Castle/Neu motors
4 Pinions - Stock 17/21t clutchbell pinions threaded onto RC-Monster 2-speed Pinion adapter for 5mm shaft
5 Spur/Gearbox - Cen GST 7.7 stock spurs and 3-speed gearbox (no mods)
6 Batt trays - Tekno RC batt trays with 10mm foam tape underneath and fixed to TVP's with velcro Tekno RC batt straps
7 Batts - 2x 5000mah 5S 18,5V 30C lipos in parrallel for 10000mah 5S 18,5V output.
8 Removed 5-cell Rx hump-pack. All servos driven by main batts through Rx.
9 Mechanical braking done by throttle servo via a servo Y-lead. No braking and no reverse programmed into ESC. Because I used a Futaba 3PM system with the Castle ESC, I had to reverse the throttle channel. This resulted in the brake servo applying brakes while holding full throttle. Therefore I had to reverse the servo direction by switching the servo Potentiometer- AND Motor wires and re-soldering them.

This is a quick and simple conversion. If you want to eliminate the gearbox in favour of a single spur/diff set-up, it will become much more complicated. I am too lazy for complicated. This set-up works and she is plenty fast! It also has the added advantage that it can be switched back to nitro quickly and easily.
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Old 11-01-2010, 05:35 PM
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Maj_Overdrive
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Default RE: My Cen GST Brushless conversion

Nice conversion, I like the simplicity of it. What part of the throttle response wasn't smooth? Off the line? I'm wondering if the one ways and the 3spd had anything to do with it. Also how are the shock springs doing supporting the weight of 10,000mah?
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Old 11-02-2010, 01:29 AM
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Default RE: My Cen GST Brushless conversion

Yes, the lack of a first gear clutch means that the one-way bearing of the first gear spur kicks in quite hard when pulling away from a stop. But the programmable smooth start from the Mamba Monster ESC solved this (mostly) and the pull-away is smoother now. Still haven't reached 3rd gear, but haven't hit 3rd with the nitro mill either. The presence of the complicated stock Cen gearbox means there is some gear noise and a lot of power is probably getting lost in the gearbox, but that must do for now. I will replace the old one-way with a new one and replace a few gearbox-bearings and she will be good for a lot of runs more. I use her only for bashing and not racing (anymore)...
I actually removed two of the front shocks to try and save weight and inserted some shock spacers to help cope with the weight of the electronics. For bashing she handles ok, but some tweaking would be needed if racing is intended.
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Old 11-03-2010, 04:26 AM
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Default RE: My Cen GST Brushless conversion

New eBay bought GST body arrived yesterday. Side batteries infringe a little but not too much.
I also have one of these ( http://www.cenracingdirect.com/index...OD&ProdID=4260 ) on order as well as a set of GSR wheels & tires to see what difference the smaller wheels will make.
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Old 12-04-2010, 12:00 PM
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vangsoe
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Default RE: My Cen GST Brushless conversion

HI guys
I was going to do the same with a GST i have, but i turned out using a GSR in stead. Not so heavy as the GST because of the axles etc. I did fit a GST centerdiff inside the gearbox though - and i am using a Tekno clutch adaptor fitted to the engine, and driving the stock 2 speed GSR gearbox. Enginemount, engine cooler mount, ESC mount - sort of a hydralic mount with 2 small shock absorbers etc. are all homemade.
A 8 kg brake servo brakes with 4 GST disks. A 10 kg steering servo should handle the steering with the stock GSR wheels.
I am going for 2 pc 5000 amps 3S, which should be plenty for the 1800 kv Robitronic engine i have mounted.
I will post some pictures later - most likely tomorrow. Just need to figure out the "close up" abilities of my digi camera first :-)

A question for you Lomdel : I want to make the paralell battery connection as well. Can you get these Y connectors i see on the photo - or is it a home-made solution ?
Whats the square of the cabel you are using ?
What kind of effective driving time do you get out of the 2 x 5000 amps ?.

Tks buddy - and have a fantastic week-end

Best regards from freezing Denmark

Niels Vangsoe


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Old 12-04-2010, 07:38 PM
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lomdel
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Default RE: My Cen GST Brushless conversion


ORIGINAL: vangsoe
A question for you Lomdel : I want to make the paralell battery connection as well. Can you get these Y connectors i see on the photo - or is it a home-made solution ?
Whats the square of the cabel you are using ?
What kind of effective driving time do you get out of the 2 x 5000 amps ?.
Hi. I made the parallel connectors myself. I don't have very good soldering skills, but the shrink tubing covers up the mess below luckily. They work great though. I use 8 AWG wire where possible, but the Mamba Monster comes stock with 10 AWG wire. The connectors are all 5,5mm bullets from Hobbyking (cheap and solder easily). I have never run the truck until the low-voltage cut-off kicks in, but for such a heavy rig, I get more that ample run time. About 10 - 15 mins I guess. Just make sure the pinion adapter is secured and set-screw Loctite on the shaft. The gears take strain to get the truck rolling. But she runs great, fast and the WOW-factor is there. A bit of gearbox noise, but I can live with that...
Please post pics of your rig!!
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Old 12-05-2010, 03:08 AM
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Default RE: My Cen GST Brushless conversion

Hi Lomdel
Tks for your answers bro - appricated !.
I had it up and running today - without the Lipos which i am waiting for now on the 3rd week from Hobbyking - but just with a 12V battery connected.Got the ESC all set up, and it all works great !.
I see what you mean about the noice - but hell - its sounds great when that 2nd gear kicks in !
Brake servo runs as it shall with just a Y-cabel from the receiver. I am using a Spektrum DX2, so i dont have the 3rd channel for mixing - but nevermind as it works.
I´ll try to enclose some pictures here - i will post more later when i get he Lipos:

Hmmm - that did not work as well as your pics Lomdel...i´ll try to get it looking nicer
Niels

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Old 02-12-2011, 06:31 PM
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Default RE: My Cen GST Brushless conversion

I sent you a PM with a few questions about the build with the throttle and braking engaging at the same time.
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Old 05-18-2011, 10:52 PM
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Default RE: My Cen GST Brushless conversion

I recently re-converted my GST to a simpler, faster, cleaner set-up. I removed the entire stock gearbox and servo's, except the steering servo. This saved a lot of weight and reduction in gearbox friction and noise. I the installed the http://www.smrcinnovations.com/ diff/motor holder with a Ofna Mutilator centre diff and some other new bits and parts. Still waiting on my Mamba Monster ESC from a warranty repair, but with the 1600kv Castle-Neu and 5S2P she ought to haul some major ass! I am going to try running the smaller GSR 5.0 wheels to see what the effect on handling and speed would be... Braking would not be mechanical anymore, the Monster must do that now.
Some pics below
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Old 05-20-2011, 06:51 AM
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Default RE: My Cen GST Brushless conversion

Good to see you got yours all set upo, looks good!. I still need to order my Motor and ESC. I used the other Mamba monster set up in my BL Losi XXL since I was waiting on parts. Now I sit and stare at the GST and the new plate kit and I can;t wait to see what this baby can do. Hmm I need to get my act together and build this truck already, too many hobbies lol!
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Old 05-22-2011, 07:33 PM
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Default RE: My Cen GST Brushless conversion

Hey why did you choose to go with brushless what was the top speed and why did you not upgrade to the mtx 8.0 cc engine for you genisis! i love the engine that is in my 7.7 it has great bottom and top end torque and hp..
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Old 05-22-2011, 10:15 PM
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Default RE: My Cen GST Brushless conversion

I am not particularly partial to either nitro or electric, I race both on a national level in my Losi 8ights. For the big GST I had my fair share of pleasure with the nitro version and were then starting to investigate the plug-and-play ease of a brushless system. Since no off-the-shelf conversion kit existed, it was a challenge to see how simple and effective I could make the conversion. This conversion version (lol!) I currently am busy with, should really rock the pants off any nitro GST, I believe...
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Old 06-17-2011, 03:15 AM
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Default RE: My Cen GST Brushless conversion

Some more pics of my build with the SMRC kit.
I chose to use the smaller GSR wheels for better stability and driveability at speed.
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Old 08-29-2012, 02:55 AM
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Default RE: My Cen GST Brushless conversion

At last Cen released the official GST-E! We'll need those conversion kits now, please...
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Old 09-29-2012, 09:27 PM
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Default RE: My Cen GST Brushless conversion

I see CEN listened and made the conversion kits available! I wonder if they'l work better than my custom job?
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