1/8 scale buggy conversion - help please!
 

Ok I've finally decided to go for it!! I have never had a desire to run nitro so I have zero experience with 1/8 buggies. I do run lipo/brushless in my TC but that is sensored stuff so I don't have much experience with any of this. So hopefully the people here on the forums can steer me in the right direction.

First what I plan to use it for.... almost exclusively racing.

Budget... somewhat limited... I don't want to go all out just to make sure I like racing a buggy first. Then can upgrade later if needed.

Also would like to use some existing electronics/batteries if possible. Not absolutely critical but preferred.

First step... what buggy! I have a couple options so far...

1) Ofna Hyper 7 roller... I can get one for $100
2) Ofna Ultra ???? ... as of yet unidentified as to the exact model... roller, loads of parts, tires, etc... only used a few times -- $50 - $75
3) GS Storm .... roller minus shocks... price not set but probably around $50.

I know there are others but these are local and pretty cheap so I'd like to use one of these if possible. I "think" any of these would work but I'd like your opinions also. I have heard the 7 is a good conversion but I get more with the Ultra (assuming I can figure out what it is for sure). Would some version of the Ultra work ok and others not? I don't think I want to go the Storm route just because the LHS stocks very little GS stuff... but could get it if needed.

What is everyones opinion? One thing that may help in the decision is I want a 2 battery setup so I can hook up my 6 cell or 2S lipo in series and still use them in my other vehicles.

Thanks,

Paul

and what electronics have you got available you want to use?

Welcome to the forum.

Ok I'll go on to the next step in case its easier just to figure out the whole thing at once.

ESC - Mamba Max
Motor - don't know... when I look at the calculator it usually comes up a Wanderer 8XL but I'm not sure I'm entering all the info properly..(like for speed and gearing I'm just kinda guessing). I don't mind using a fan and such but don't want to fight heat problems. I don't need to blow away nitros with top speed. Track is I would say medium sized with one straight. Its an electric friendly track. Again I'm guessing but my feeling is that I'll be tons quicker so I don't need the the same top speed. Would you agree?
Batteries - 15 min mains is all I need for batteries. If I can find another 6000 to match mine I will use that. If not I'm leaning towards the True RC (2) 7.4V 15C 6400 or the (2) Trakpowers. I want to be able to use them in my other vehicles and these will fit. One major question here is I plan on 14.8V but can I get a system that would work great on 14.8 and pretty good on 7.4V. I'm guessing probably not but thought I'd ask anyway.

Next... miscellaneous

1) Motor mount... sure that won't be too hard to find and depends on vehicle
2) Mount batteries somehow
3) Gearing - spurs/pinions
4) Make the Nitro guys jealous
5) Am I forgetting anything?

Added to list
1) External BEC
2) Heat sink/clamp for motor

Thanks.. I've been lurking around for a few weeks trying to get educated!

I'd go for the Hyper 7. Parts are plentiful and the buggy drives well. For an inexpensive setup, I'd stick with the MM (disconnect the internal bec) and run it on 4S lipo. If you can rig it, the trakpower packs would be perfect. For a motor, I'd go with an 8XL or 9XL.

When I first started all of this large scale conversion stuff, I was worried about being fast. Since I've gotten settled in, I've found that it doesn't take much for an electric to be competitive on a track. In my vehicles, I've gone from the 7XL, to the 8XL, and am now running the 9XL. What I like about the 9XL is that it is very gearing friendly. I just started running the 9XLs and have found that I can go from sedate to being too fast for our track with just gearing changes.

Since you are running 15 minute mains and just want to be competitive on the track, I'd have to give some serious thought to a 9XL; however, if you do want it to be a bit faster, go with the 8XL. I haven't done any formal testing, but to be able to comfortably run a 15 minute main, I think that a 5Ah pack would do you nicely. If not, you could try the 6Ah packs, but I haven't had much luck with those.

As for gearing, I'd say that 16/46 would be a good place to start for the 9XL and 14/46 for the 8XL.

Thanks Angel...That's kinda how I've been thinking. At least I'm close and did learn a few things from reading the forums. Also I forgot about the External BEC.... I was planning on that just forgot to add to my list. I'm gonna edit above so I don't forget it!

I would go for the Hyper7 parts and hop up's are avalable.

Motor mount? you can get mikes ofna mount.

Spur? The Kyosho 46t plastic spur should bolt up to the ofna diff with a mod1 pinion.

Motor? There is many options to go with I will let someone with more buggy knowledge fill you in on that. 14.8v to 7.4v it's going to be hard to find a motor that will work good on both voltages.

Battery mounts just look around at some of the conversions here and see what works.

15min of runtime should be very easy on 4s.

I have never driven any of those buggys, but when I was asking about my Lightning 2 pro quite a few peeps sugested a Hyper 7, I discounted it as I would have had to sell the engine to even out the price and thats a PITA. If I had a roller that didn't rattle too much available for $100 or even £100 I would have gone for it.

That isn't a huge deal ... The batteries will probably be my last purchase so I was kinda hoping I could run it before I got another lipo because I might have to buy 2. So it would be fairly short term that I would consider running 7.2V - 7.4V anyway. I know I need to consider the size for fitting in the buggy but I pretty much know the physical size since I will be getting something that will fit my other trucks/cars.

With the batteries, you kind of have to pay attention to the physical size of the packs. Very few are alike in dimensions. I have Hyperion, Kokam, Maxamps, and TrueRC packs and none of them have the same widths. For a buggy, an 8Ah pack is a pretty tight squeeze. The Kokam 4800, flightpower 4900, and maxamps 5000 4S packs should fit nicely under the body. The buggy will handle better with these smaller packs too.

If you can, I'd suggest getting 4S packs, rather than trying to run two packs in series. I just think it's easier, although not as flexible as far as using the packs in other vehicles.

For 4S, whatever you do, get good packs. Flightpower, trakpower, Kokam, Maxamps (5Ah) are good packs and will deliver all the power that you need for a track setup.

I'm pretty familiar with the non-standard size deal with lipos. With my other vehicles I can basically go a max of (H) 26mm - (W) 47mm - (L) 150mm..... everything kinda needs to fit those dimensions. Yes I agree that the 4S would be easier and I may go that route but I need to stay with 7.4V for flexibility unless wiring two 7.4's in series is a bad idea. Ideally I would like to get the trakpower but a little spendy compared to some other options. Especially since I already have a balancer for ployquest/hyperion taps. I have gotten 33 min run time with my 6000 and Novak 4300 in TC...so I would think 15 min with a 4900 should be no problem....but not positive... extra weight and all considered.

ok now Angel has me thinking about getting a 4S.... that would probably save me getting another charger. I could get away with what I have as far as chargers go in the short term anyway. So is there balancing issues here to consider. I guess originally I would have thought 2 batteries better with weight evenly distributed on each side. But I suppose if the battery is on one side and the motor on the other that might balance it also. Is this a huge issue to consider for an 1/8 conversion?

Also thanks for the responses so far... keep them coming. Nothing here is completely set in stone so I'm pretty open. The MM ESC is about all I'm committed to so far. Hopefully tonight I'll be able to check out the 2 Ofna's and make a decision on the chassis I'll be using. I've been pretty 50/50 on the roller I want but am leaning towards the Hyper 7 right now. Any final words on the Ultra ???? ... Our Offroad track director said he thought it would be fine for my purposes but he has only driven a conversion of someone's in Des Moines not actually built one. Whoever that was (if your listening) he loved it.

I run three 1/8 scale conversions and run single packs in all of them. The weight distribution hasn't been an issue at all. They all fly straight off of jumps. They do, however, handle better with the lighter packs.

BTW, I don't know if you've seen this yet, but...http://www.rcuniverse.com/magazine/a...article_id=467

Oh, there are going to be balancing issues. If you are running two packs, you'll either have to charge each one individually, get two chargers with two balancers, or make a harness to charge and balance both batteries in series. With a single pack, you don't have to do all of that. Just plug it in and hit charge.

With 1/8th scale buggy's it's easier with a 4s single pack with truggy's you can get away with running duel packs but there is a lot more room.

The Hyper 7 is a much better buggy then the older discontinued Ultra series there still making the Hyper 7 and there is better part's suport oem and aftermarket for it. I have a ultra worlds II and could never get it to run more then about 20min without breaking something in the front end.:032:

Ok that about seals it then... looks like the Hyper 7 Pro unless its a total piece of crap. But I know the guy and I don't think he'd try to peddle a hunk of junk. He said it was in good condition. I just haven't seen it yet.

Yes Angel I have seen the conversion web site... not sure I bookmarked it though... so thanks for posting it.

ok next couple questions....

What motor mount for the Hyper 7? I see a Ofna CR mount on the this site... would that be the one or does Mike have one for the Hyper 7 that isn't listed (or that I can't find). I was considering using the Trinity EMaxx motor plate but I'm not sure how that would work. Specifically the mount is 4.76mm thick, then add and heat sink thickness, and the fact the mount is attached to the diff mount rather than replacing it I would think there would be a problem with the pinion reaching the spur.

ok now excuse my electronics ignorance here... if I go with the Wanderer motor that comes with 5mm plugs and the MM has 4mm (I think). So would I just replace the 4mm on the MM or should I use thicker wires also. Not sure but they look like they are 14g on the MM. Suggestions.....

Not sure if this will fit but I have some old XXX-S chassis around so I was thinking about cutting out the battery tray and using in the conversion. Seems pretty simple... I just hope they fit.

To tell you the truth, I don't even remember is the MM comes with any plugs. I think that the systems (motor/esc combos) some wired up with plugs, but I don't know if the esc alone comes with them. In any case, I believe the 4mm plugs to be too small for the large scale application. I'd go with the 5.5mm plugs, at least. The next time I re-wire everything, I might just go with deans plugs all the way around. The bullet connectors loosen up over time.

Anyway, chances are that you're going to have to do some soldering. I take having to do some soldering as a given. The MM does come with 14 gauge wire, although it is high quality wire. I've rewired all of my MM escs with 12 gauge. The 14 gauge gets quite hot.

I just got my MM yesterday (ESC only) and it does have female plugs on the motor wires. Nothing on the battery wires. I've done plenty of dean's so I guess I can go that route. I suppose its up to personal preference just wonder what others have done.

Mamba Max has 13ga wire

I'd replace those 4mm connectors with at least 5.5mm connectors. The 4mms get HOT and loosen up pretty quickly. Many just egg their female connectors for a tighter fit, but my anal nature tells me that doing that just decreases the surface area of the connection.

Ok I hope this isn't a stupid question...oh well I'll take that chance. Since I'm assuming that nitro motors have a pretty standard mount why couldn't you just use the RC Monster Revo electric motor mount for any nitro to brushless application? Since there are different electric mounts I would guess there is a reason but I don't know why.

The revo uses a rather odd mount; allmost every mount is a bit different.

The Revos actually have a pretty rigid chassis, with bends in them that add to their resistance to flex. That's why the electric motor mount for the Revo works. With an 1/8 scale buggy, you really don't want to mount the electric motor in nitro motor fashion, because of chassis flex.

Of course, some chassises flex more than others, but, in any case, chassis flex can be very bad for your pinion and spur. Generally speaking, a motor mount that is either bolted to the center diff bulk or incorporates the center diff bulk is the best way to go. That way, the motor and center diff move as one unit.

ok that makes sense

Oh my trials and tribulations! Man I can't even get together with these guys to look at their buggies! Sheeesh! I almost scrapped the project for an electric buggy (1/10 scale) but someone talked me out of it. Guess I'll just have to go with whatever comes up first... main thing for me is to get one going then I can switch to a different car later. I'll be back and show my progress if I can ever get this project going! lol Thanks guys for your input so far... it has really helped!

Ok guys here is what I'm planning to do... some of it isn't perfect and I'll upgrade as I get the money but to get it going this is what I have in mind.

Hyper 7 - done
Mamba Max - done (disconnect BEC)
Receiver pack - done (eventually UBEC)
14.4V IB 3800's - done (eventually lipos)
Feigao/Wanderer 9XL 16\46 - need
Emaxx motor mount - done (Just looking at things I think I'll want something different)
Heat sinks/fans for motor and ESC - need

Does that sound ok or is there something there that is a definite no-no? The upgrades are what I want but it would probably be the end of summer before I get it all... hence this starter version.

This should be up and running in a couple weeks if this sounds ok.

Thanks again everyone!!

padailey, you'll definitely want a heatsink for the motor. I was running an RC Monster heatsink, but wound up turning my own that covers almost the whole motor. The Feigao motors, due to their inefficiency, will get hot no matter what you do. I have mine to a point where it will run for just about 1/2 an hour before it reaches 200*F.

I wouldn't bother too much with a fan for the motor. It didn't seem to help me much. I would just go for a 12v fan from radio shack and mount that in a way that cools the esc and if it blows on the motor too, all the better. I run my 12v fan straight off of my 4S lipo pack. Running it on the overvoltage hasn't seemed to hurt it...yet.

Everything else looks good so far.

ok so in the Novak sensored world of motors ... if you thermal the rotors tend to be damaged and will thermal easier the next time. The sintered rotors reduce the heat and are much more difficult to thermal... however the rotors will not be damaged until 250 degrees (or so I've heard) so a thermal does not degraded the performance of the motor. So with the type of setup (MM/Feigao) what is thermalling normally... speed control or motor? And does thermalling the motor damage the rotor at all?

A Neodymium magnet starts loosing its magnetic force at 80 degree C.

completely at 312 degree C; novak/feigao/lehner/wanderer/plettenberg/neu all use the Neodymium magnets.

Sintered magnets or segmented magnets are better suited for partial loads. this has something to do with eddy currents. the segments simple respond better to the signal than a larger lump. (it's like with transformers, the thinner the E's and I's are in the transformer, the higher frequency it is capable of handling. (the more efficient the transformer becomes at higher frequencies)

Might be true for one grade of Nd magnets, but there many different compositions and grades, optimized for different applications.
Our motors use what they call UHT (ultra high temp) grade Nd magnets, but even there you find differences.

And BTW, sintering is a way of manufacturing solid bodies. Basically it means "backing a powder together", or something like that.

DAF

Yeah, it seems to me that all of these rare earth magnets are sintered? (since they don't find them in the perfect round shapes)

i thought you said the magnets lost their magnetic forces at 110 degree?

Maybe that's 100*C? 110*C is 230*F...

yes, C for sure, but that's what I am talking about too.

Any of you guys running 3s in your 1/8th conversions?

I don't think you'll find too many running that config. You'd have to have higher current (about 25% more) at 3s than you would at 4s for the same power.

Well got my motor and such from Mike today... now just gotta mount everything and wire it up.... should be up and running soon!! I'll get some pics when I'm done. Thanks guys for the help!!

Ok I hit a couple snags... first I need to rethink the placement of everything. I'm just a little short on space with my original plan. I'll get that figured out. Then my center diff is binding up pretty bad. Need to get to the LHS and get another gasket.

Then the problem I don't know what to do with. My intention was to get a Wanderer 9XL but when I ordered I didn't specify that so I have a Feigao 9XL. Don't really care just stating it so you know what I have. I hooked it up to my MM outside the car. So its 6V receiver pack, spektrum receiver, servo, MM, 9XL, (2) 7.2 IB 3800's in series.....once through the initial setup I start to run the motor. I don't know what cogging feels like but the initial tugs on the throttle there is a definite stutter in the motor (every time from neutral) . This is under no load on the motor. This can't be right can it? Is there something in the MM setup that could be causing this?