First time buggy conversion - need some input
 

I'm new to this forum and new to the world of brushless. I plan to convert a Mugen MBX5 so I could use some input from you guys. I already got a lot of great tips from Serum, but you like to have some more input from more than 'just' one person. ;)

Motor and ESC: I don't want to spend too much money, so my idea is to use a Feigao motor and the Warrior 9920. The idea is to start with 12 (or 14) NiMH cells. Now I cannot decide between the 8XL and the 7XL. It seems that the 7XL is on the edge for the 9920?

Gears: as far as I know, the nylon Kyosho spurs won't fit the Mugen diff. So I want to fit a Kyosho diff in the Mugen. Gears I want to use: 46 tooth spur and a 14 pinion.

Engine mount: it seems that a modified E-Maxx engine mount is the easiest way to mount the motor. I have seen some very nice engine mounts on this forum, but will the E-Maxx mount suffice?

Hi Martin, Welcome.

No, the emaxx mount is not a wise thing to use. since it's a simple straight plate it's hard to get it on the chassis/diff without too much flex. (flex is killing for the spur/pinion)

You are better off with getting an L profile aluminum and make your own mount.

the kyosho won't fit the mugen. that's for sure.. You could ask Mike to have you made an adapter plate to fit the Mugen diff. that way you can use a 51T spur.

The 7XL works very well in a buggy on both 12 and 14 cells. The 8XL will give you slightly longer run times and will get a bit less hot.

I used the 7XL and loved it in terms of power and temperatures.

The 7XL is most certainly not the limit for the 9920 on 14 cells. Some users here even used it on 18 cells on the 9920.. (it RIPS) that is pushing it, though but since you are leaning towards the C can with the heatsink you will be fine with the 7XL on 14 cells.

The 8XL however will run slightly cooler and give you a bit longer runtime. But it will also run a tad slower.

RChippie can confirm the power of the 7XL on 14 cells in a Mugen buggy.

I can't recall if the HB diffcup fits the Mugen diffholder, this HB cup would enable you to use the kyosho diff, but you would also need a set of new internal gears (HB uses a 4mm x-pin) and it also uses 6mm output cups, so you would need these as well. (that is, if it fits at all)

BTW i think you might find this handy;

OK, I was already afraid the E-Maxx mount would cause too much flex...

So the Kyosho diff won't fit the Mugen diffholder? I bought a second hand Mugen MBX5 and I still have a Kyosho diff lying around. As soon as the Mugen arrives (I don't have it yet), I will try to somehow fit the Kyosho diff. If it's too much work I will look for a solution you suggested.

You could design a new diff holder out to fit your chassis. Then you
wouldn't have to worry as much about flex.

@m_podt: I too am converting a buggy (Hyper 8) and I sent the whole thing to Mike so he could custom make a diff mount/motor mount unit. Send him an email describing what you want and he can quote you an estimated price. I won't mention the actual price, but I will say it is more than fair considering he is going to custom machine a mount from scratch according to my specifications.

I just designed them myself brian. Then got mike to machine them out.
It works and you are right. The prices are good to me.

I wasn't too happy with NiMh weight...

4-5LiPo 10L

Artur

I know you mentioned that the last we spoke (actually "typed"), but wasn't sure since there are a few minor changes to yours. Maybe if Mike does use your design, it'll be a tad cheaper. :) Even so, still worth it IMO.

Yeah, I read the thread about your conversion. However, I live in the Netherlands, so sending the whole buggy to Mike and having it sent back will be quite expensive...

You could either ask Mike to make you the adapter get a HB diff. Worst case scenario with the HB diff; you need to make a lower plate to place the two centerdiff holders a bit further from eachother.

Perhaps a 5 to 6 mm adapter will put you where you want to be, using the kyosho spur and the Mugen diff.

OK, thanks for the input up to now. First I will order the parts I need. I decided to order the 7XL and the 9920, the 46 tooth nylon Kyosho spur and a 14 tooth pinion. A decision on the motor mount will come later, as I want to fully rebuild the Mugen first and get an idea where to put all the parts.

And then... batteries. I limited by choice to the following cells:
GP 3300 mAh
GP 3700 mAh
GP 3900 mAh
GP 4300 mAh
As far as I know these are all suitable for high power applications. Is there any difference in quality?

Imo get the gp3300's or maybe the gp3700's for a little more runtime ;

They are VERY durable cells, Just and FYI, The higher the capacity of a cell - the less it can put out.

GP3300's and 3700's are the ones that push out the largest power.

stay away from the 3900's. somehow they are worth poop. i never heard a good story about them.. (only one time; when they went to town, got drunk, jadajada) the 4300 are nice for runtime but not for the durability and voltage under a high load.

IMO a nice in betweener would be the 3700's.

So that limits the choice down to only two cells. Thanks for the input.