Keen conversion Brain! :) tight and sexy! I am using my Festool wood router with a 45 degree bit (with bearing) to make 45degree chamfer on aluminum. perhaps you can do something with that info..

Thanks guys! I'm glad it's finished too!

I was hoping for a slightly cleaner wire routing, but I ran out of room. But I was able to put all the excess wiring, the UBEC, and the capacitor (for the UBEC) in a little box under the ESC. The steering servo wire was VERY long, but instead of shortening it, I wrapped it around an itty-bitty space under the receiver.

The Quark is silky smooth so I'm glad I chose it over the MM. I set the neutral range to narrow and now slow speed control is impressive IMO, not that I'll be going slow much. :)

Serum, what do you think I should chamfer? Unless I find a weakness in the current design, this project is done, but I like to keep new ideas in mind for future projects.

Brian, my Jammin buggy is very similar to the Hyper 8. I was wondering what was involved in mounting your battery packs the way you've done (very neatly).

Are they bolted into the chassis only? Are you using spacers to raise the chassis side to make them level with the dust guards? How much height clearance does it leave below the canopy?

Yes, the battery trays are bolted only to the chassis. I didn't want ANYTHING on the plastic dirt guards, especially something as volitaile as Lipos. Don't need to be dragging my Lipos over dirt and rocks if the dirtguard breaks! :026:

Anyway, I used some nylon bar stock as a spacer because it is light, easy to work with, and self threads easily. I think I got it from McMaster Carr. It's about 10mm thick and about 20mm wide IIRC. 10mm is the perfect height to clear the dirtguard "nibs" (the little protrusions that the screws go into). Below is a pic of what I mean - the screw placement in the final design is a little different than this, but you get the idea:

http://scriptasylum.com/forumpics/batt_tray.gif

As far as canopy clearance, I'm good. The shallowest part of the body is right at the edge of the sides, and the batteries don't go over that far. I still have about 3/4" or more of clearance at the worst spot. However, I did raise the body mounts about 6mm to gain a little wire clearance, so make that about 13mm without the raised body.

Well, after playing around with the buggy a little outside (difficult to find dry pavement with all the snow melting around here - but I'm not complaining!), I am quite happy with it. It is VERY fast...almost too fast from what I calculated. That got me thinking a little and then found that I got the 2d rather than the 2.5d! Lol, that would explain the difference in speed! I may have to drop from a 14T to something a little smaller like a 12T or 13T for cool running this summer.

You should be pushing over 50+ mph with the 2d; you think the quark could handle such a hot motor? Also, was it a shipping error that got you the 2d or you mistakenly ordered it?

BTW your buggy looks really good!

Bye:018:

Thanks! No, I ordered the 2.5. I think it was a simple shipping mistake (I verified my order). Unfortunately, I didn't notice it until I started questioning why it was going so fast. lol. I obviously soldered it up and ran it so I can't just exchange it. No biggie really.

I think the Quark will be just fine, especially since I've added a little extra cooling. I'm more concerned about the batts heating up under the extra load in the heat of summer. I emailed Mike asking what he thought. If it will run a little hot, I'll just see if I can order a smaller pinion to reduce the motor load a little.

Edit: Wow, I already got a response from Mike! He says I should be fine. He's running the Quark with the 1515 1y in his Maxx with no pack heat issues. So, I think I'm all set.

Sounds good. So about how much did this system set you back... like the 125B and Neu 1512/2d. Also, are you using a UBEC? And from what cemetary said, it'll be pushing 50mph, what kind of run time(s) are you getting?

Mike is making a motor mount for me right now for my 1/8 buggy, so I am still deciding what system to run in it.

Thanks

I don't even want to think about how much this cost me; I'd have to shoot myself! :002: You can probably get a pretty close figure by adding up the parts from the RCM store, then add the base kit. Then, there's the metal stock used for some of the custom parts. Not to mention the time. Ugg. Makes me cringe just thinking about it.

Yes, I'm using a UBEC. The UBEC, capacitor (for the UBEC), and any extra wiring is located in a custom box under the ESC to keep everything tidy. :)

I haven't run it enough in one shot to get a runtime figure yet. I was outside for about 10 minutes at a guess and the batts didn't dump, and they were at a storage charge of about 3.8v/cell. Hard to say. I'm hoping for a solid 25 minutes. If not, I'll just pick up the 2.5d later and use the 2d in my Revo since it has more gearing options.

Cool. Once you do get a full run time, do you think you can PM me the run time, or post it here? One last question, lol (sorry for so many)... with the 2.5d and everything else the same, do you think that the speeds would be able to remain between 45 and 50mph? Will the run times also be significantly longer than the 2d? I was tryign to use your speed calculator, but wasn't sure what to put for gearing, or tire diameter of a 1/8 scale buggy tire.

Well, as you know, runtime depends on a lot of factors, but with all else being equal, I could use the 2.5d and gear up and get the same runtime and speed as what I have now because the motor would be loaded more.

What I was shooting for was about 35mph for track use. With all the gearing (standard buggy diffs, 46T spur, 14T pinion), and with 4s batteries, I chose the motor that would get me near 35mph, which was one with a kv around 2000rpm/v. Since this motor spins faster, I'll probably get a smaller pinion to compensate. This will reduce the top speed closer to what I want, help unload the motor a bit, help runtime, and keep things cooler.

I use 4.25" as the tire size.

And yeah, I'll post runtime. But it will be closer to actual race time before I take any serious measurements. That's assuming I get good enough to even try racing this year.

Ubec?
 

Stupid question: Is a UBEC anything like a BEC? If so, why do you need one, since the Quark 125 comes with a BEC? If not, what the heck is it? And why do you need a big capacitor to go with it?

Sorry to trouble you with such elementary questions.

Nice Buggy!
 

By the way, I'm very impressed with the factory-quality conversion of your buggy, BrianG. I'd like to do something similar myself, once I learn more about brushless motors and LiPo batteries. I'm sure I'll have more ignorant questions for you soon.

A bec is a battery eliminating circuit and only allows so much voltage. A UBEC converts the voltage from your batt pack to send 6v to the rx, thus eliminating using a rx batt pack.
With disconnecting the bec circuit and running the ubec, you can run a higher voltage at cooler temps through the esc without frying the bec in the esc...make sense? lol

Good answer newe! :)

To add to what he said, the BEC in the ESC is "linear" and can generate a lot of heat depending on load (servos) and main cell count.

And the term "BEC" just means "Battery Eliminator Circuit". The "U" in UBEC is "Universal". Really, the terms BEC and UBEC are interchangable, but when the people here say "BEC", they usually are referring to the ESC integrated one, while if they say "UBEC", they mean the external switching one.

The capacitor is not required, but it does help filter noise out from the power lead, which may help stop potential glitching. And, it also provides a little extra current boost if the servo(s) need it (especially when they begin moving from a stop).

And thanks for the comments. :)

Thanks!
 

Thanks for your replies. BrianG, now I see your (U)BEC explanation on your RC calculations site. I guess I needn't have asked. Here's a follow-up question: how does one determine the capacitance required? At what frequency do you find most of the noise?

I usually just use a 1,000uF rated ~10v. If you are using a heavy duty servo, you could go up to 4,700uF, but the cap will be physically bigger.

Most of the noise will probably be at whatever the BEC switches at (I've seen anywhere from 20kHz to 250kHz) and will be most evident at higher loads. And since this BEC also supplies DC power to potentially sensitive receiver circuits, I take no chances. :)

Weight Distribution
 

BrianG,

Thanks for the reply. What weight distribution did you strive for when assembling this buggy? I assume you wanted equal port/starboard, but did you aim for equal fore/aft, or did you want more weight on the rear wheels?

I was shooting for almost perfect right/left distribution than fore/aft. But the amount of space under the canopy was a limiting factor in front as well. The ESC and receiver are about as high as I can go before it starts hitting the shell. I figure I can tweak the spring preloads for the weight and then compensate for less-than-ideal jumping attitude by tappign the brake or whatever.

Looking forward to the vids, Brain. *hint* :D

Looking forward to receiving a video camera. *hint* :dft012: :027:

How are those ofna gaskets for the center diff working? Any problems?

I'm working on a Hyper 7 - yes, one rev. behind conversion right now... Does anyone know if that motor mount that is used in the Hyper 8 conversion in this thread would fit the Hyper 7?? The designs look VERY similar.

I like the center mounted motor, gives the car a much more balanced look, and I'm sure "feel" on the track.

Also, if I can just use your expertise. I've got a Quark125b controller, and a Lehner 1940/7 Hi-Amp motor that I'm planning on running... will that fit be ok? Or is that under-powered?

@lydiasdad: The gaskets seem to be working well for now, but I really haven't run it all that much. I'll probably end up getting a Kyosho center diff and the Kyosho spur as a spare in case I run into any problems with leaking.

@hunter306: Actually, I was originally looking at getting the 1940/8 but they were out of stock, so I got the 1512 Neu instead. From what I understand, they are comparable power-wise, and the Neu has PLENTY of power. The 125B may be a tad difficult to squeeze in there. I had trouble getting it to fit while allowing proper wire routing and clearance on the shell.

Since the Hyper 7 and Hyper 8 diffs are interchangeable, I would think the mount would work.

The center-mounted motor does look/feel balanced, but a layout with the motor on one side and the batteries on the other frees the area over the CD for all the electronics.

Hey Brian, Thanks for the help.
Couple more questions!

Where did you get your hands on that Center Motor Mount assembly?
--What online store or place sells that part?

Do you still have those 2 unfinished lipo trays? What are the dimensions?
--If you do, I'd like to take them off your hands, let me know where to paypal the shipping money!

Also, I see what you are saying with the Quark125b... it is huge, I've got one in my Electric LST2 and it was a pain to fit, but I think it'll work. These cars have some decent sized trays on them!

I had the motor mount/center diff mount custom machined by Mike. Drop him an email for more info. It is quite solid. He even re-centered the mount for me (stock is set up so it's slightly off-center).

Yeah, there was room on the trays, but I didn't want anything mounted on the plastic for strength. Everything on the buggy is mounted to the metal chassis.

One last question, I edited into my last post...

Do you still have those unfinished battery trays? What are the dimensions, can I pick them up from you?

I made the one for my LST2, but I don't want to go through that hassle again if you've got a couple you're offering!

Sure, I'll be more than happy to get rid of them! Honestly though, they're quite crappy. With some work, they will be serviceable, but will never be pretty. I had already started fixing one of them before I gave up. I'm gonna turn in early tonight (dang cold :mad:1), but I'll get some measurements tomorrow evening and let you know.

That'd be great Brian.

No need for beauty on my rig, just something to secure the packs too would be great!

Just PM me the info when you get it!

Excuse my laziness for not wanting to read all 6 pages of your thread, but who made that centerdiff/motor mount? It looks awesome (as does your entire buggy).

I do believe the center diff/motor mount was made by Mike :).

Yea, look 4 post above yours. :p

Yes, made by Mike. Did a very good job too! Sturdy and purrdy! :)

Oh...wow...I actually read this page (and most of the one before it). I can't beleive I missed this. :007::007: :032:


Does it bolt right on, or do you have to drill holes? Also, did you need custom dogbones or did the stock ones work?

It bolted right on - no extra holes. And those are the stock bones. Not only was the CD moved to center, it was raised about 4mm - enough so the spur clears the chassis. And the bones fit better now than they did when the CD was in the stock location!

I'm sure it helped that I sent Mike the whole buggy so he could take whatever measurements he needed.

BrianG,

Can you tell me what gearing (pinion and spur) you are using?

Thanks.

46T spur and 14T pinion for now. It's VERY fast, maybe too fast since I have a 2600 kv motor in there. I'll probably get a 12T pinion so the speed is more controllable for the track...

Excellent work. So when are we going to see a vid of this beast in action.

I can try using my dig camera in video mode, but I don't think the quality will be that good. At any rate, it's gonna have to wait until the track is nice enough (not muddy) to drive on.

A few people have PM'd me about temps with this setup so I thought I'd do a little running. So, I took it out for quite a while today and this thing is FAST!!! Makes my Revo seem like a turtle and I think it's faster than my Jato. Anyway, ran it for 20+ minutes and nothing ever got even slightly warm... of course, it's like 40*F outside. I wish I could get a vid (and I found I can do a decent Q one with my still camera) but I can't take the vid and drive at the same time. And I'm NOT letting my 9yr old hold the cam! :)