1/8 buggies and electric conversions some questions - RC-Monster Forums

hemiblas · **1/8 buggies and electric conversions some questions -** 02.09.2013, 08:58 AM

I have a couple questions on 1/8 buggies. A long while ago I picked up an rd logics 1/8 buggy. Converted to electric, first run broke a rear driveshaft. These are hardened steel. On the second run I shredded the rear diff. Put that project away. Then I recently bought an ofna lx2e. First run the front center diff seems to have exploded. I used the same setup in both. Mtronicks truck esc on 4S with a feigao 8l motor, 14 tooth pinion.
I still run my emaxx truck still with my feigao 7xl which is a much more powerful motor with no issues.
Are buggies just not up to the task of brushless power? I cant believe that I have broken two buggies and its just coincidence.

Thirdgen89GTA · 02.09.2013, 12:23 PM

Quote:

Originally Posted by hemiblas

I have a couple questions on 1/8 buggies. A long while ago I picked up an rd logics 1/8 buggy. Converted to electric, first run broke a rear driveshaft. These are hardened steel. On the second run I shredded the rear diff. Put that project away. Then I recently bought an ofna lx2e. First run the front center diff seems to have exploded. I used the same setup in both. Mtronicks truck esc on 4S with a feigao 8l motor, 14 tooth pinion.
I still run my emaxx truck still with my feigao 7xl which is a much more powerful motor with no issues.
Are buggies just not up to the task of brushless power? I cant believe that I have broken two buggies and its just coincidence.

Never heard of RG Logics, but I've never snapped a shaft on any of my 1/8th scale stuff. Not even with my Jammin truggy using 6S lipo on a MMM/Castle 1717 combo which I know puts out way more power than your setup.

Is it this buggy: http://www.google.com/url?sa=t&rct=j...,d.aWc&cad=rjt

rcs2022 · 02.09.2013, 01:03 PM

Same here, Got a kyosho Inferno MP7.5 in a garage sale for 75 bucks After upgrading my savage to mamba xl2 and 1717, put the original savage esc and 1515 motor in the Inferno (after converting it to brushless; not a nitro guy), running it on 6s and i can say its quite durable.

Thirdgen89GTA · 02.09.2013, 01:05 PM

8th scale buggies are known for their durability. At least, the ones that have a competition bred cousin in the ranks.

The major difference between most 8th scale buggies is materials and suspension/steering geometry. They are all pretty much the same layout. The losi 8ight is one of the most "out there" buggies in terms of design but even so its still quite standard.

hemiblas · 04:56 PM

Quote:

Originally Posted by Thirdgen89GTA

Never heard of RG Logics, but I've never snapped a shaft on any of my 1/8th scale stuff. Not even with my Jammin truggy using 6S lipo on a MMM/Castle 1717 combo which I know puts out way more power than your setup.

Is it this buggy: http://www.google.com/url?sa=t&rct=j...,d.aWc&cad=rjt

Yeah, thats the one.

I'm running a smaller motor than you guys on 4S. The only thing that I can think of is that the mtroniks doesnt have any type of punch control, but those setups you guys have are making much more power than me.

nativepaul · 02.09.2013, 10:37 PM

Don't kid yourself that its low power just because its a small motor.

A motor will draw as many amps as it needs to to pull the gearing you have at the speed its KV and voltage determine, a bigger motor just has more thermal mass to heat up slower and more surface area for better heat disipation, a 7XL will handle more power than a 7L for extended periods while keeping cool enough for a long service life due to the aforementioned better cooling. The 7L and 7xl have the same number of turns, and the same diameter rotors and cans, making it very likely that they both have the same gauge wire making up the windings, if we look at short term power capability the windings will fuse at the same amp draw and the same voltage is on both so the are capable of the same absolute power.

The 7L is 3511kv which on 4s is about 50,000RPM, a 7XL is 2382kv which is about 33,350RPM, so if the gearing is the same the 7L will be pulling a lot more power than the 7XL in order to spin the extra speed. As gears get rather inefficient at 11teeth and under so if I assume you use a 12t pinion with typical buggy 3.3:1 diff ratios and 4.5" tyres, it is geared for 50 mph (+any ballooning) and pulling more than average amps to do so (most buggy racers seem to gear for about 40mph depending on the track), a 7XL in the same buggy would be up to an 18 tooth pinion before it is making the same power as the 7L.

Torque is not only related to the size, magnets, pole count and KV of the motor but to the current flowing through it, while a huge low KV motor like the 1717 will have a much higher KT than than the 7L, .86oz-in/A vs .39oz-in/A if the little 7l is screaming its guts out on 4s about to melt it will have MANY more Amps flowing though it than a 1717 running cool on 6s and could be producing dogbone breaking torque.

A 7L is not really suited to 4s, you would be better off on 3s with a 13tooth pinion which would give you 40mph, cooler running, and less breakages. if you want to stick with 4s I would recommend a motor with a much lower KV (somewhere in the 2000 range), and though I have several, I wouldn't recommend a Feiago nowadays, Leopards are a fair bit more efficient for not much more money.

_paralyzed_ · 02.12.2013, 10:37 AM

Also, as far as buggies go, those two are kinda cheap/weak.

The ultra's are the base entry level model for ofna. RD Logics is really more of an aftermarket parts company than a reputable vehicle manufacturer.

I have an ofna ultra lx1e and with proper setup (shimmed diffs, thick center diff fluid) it is a good buggy, but nowhere near as stout as my ofna hyper 8.5.

If I were you I'd give the ofna another go and I'd sell the rd logics to some schmuck on e-bay.

And to answer your original question, buggies are the most durable 1/8 scale r/c's out there. The low weight, and low rotational mass of the wheels and tires keep parts happy.

You've just had a bit of dumb luck.

Thirdgen89GTA · 02.12.2013, 01:00 PM

Quote:

Originally Posted by _paralyzed_

Also, as far as buggies go, those two are kinda cheap/weak.

The ultra's are the base entry level model for ofna. RD Logics is really more of an aftermarket parts company than a reputable vehicle manufacturer.

I have an ofna ultra lx1e and with proper setup (shimmed diffs, thick center diff fluid) it is a good buggy, but nowhere near as stout as my ofna hyper 8.5.

If I were you I'd give the ofna another go and I'd sell the rd logics to some schmuck on e-bay.

And to answer your original question, buggies are the most durable 1/8 scale r/c's out there. The low weight, and low rotational mass of the wheels and tires keep parts happy.

You've just had a bit of dumb luck.

Pretty much this. The Ultra series uses cheapo cast metal for the diffs. The Ultra line is from Hong-Nor, and while they produce a ton of models, the only GOOD Hong-Nor cars are the Jammin/Nexx series. These are their competition level stuff.

Diff problems have always been an Ultra liability.

ZippyBasher · 02.12.2013, 05:20 PM

Quote:

Originally Posted by Thirdgen89GTA

Pretty much this. The Ultra series uses cheapo cast metal for the diffs. The Ultra line is from Hong-Nor, and while they produce a ton of models, the only GOOD Hong-Nor cars are the Jammin/Nexx series. These are their competition level stuff.

Diff problems have always been an Ultra liability.

HIGHLY DISAGREE

As Paralyzed said, it was probably just dumb luck with the Ofna. There is noting wrong with the Diffs on the LXe. My dad has been beating his for over 2 years with a 1717 and 6s. No Diff rebuilds front, center or rear. Please shim your diffs and they will hold up to ANYTHING you can throw at them. The buggy tires will break traction before you break a diff if they are assembled correctly...

Give the LX2e a second try, they are the best buggy for the price... The only "upgrade" it needs is an aluminum rear toe plate. after that its a TANK.

Thirdgen89GTA · 02.12.2013, 07:00 PM

Quote:

Originally Posted by ZippyBasher

HIGHLY DISAGREE

As Paralyzed said, it was probably just dumb luck with the Ofna. There is noting wrong with the Diffs on the LXe. My dad has been beating his for over 2 years with a 1717 and 6s. No Diff rebuilds front, center or rear. Please shim your diffs and they will hold up to ANYTHING you can throw at them. The buggy tires will break traction before you break a diff if they are assembled correctly...

Give the LX2e a second try, they are the best buggy for the price... The only "upgrade" it needs is an aluminum rear toe plate. after that its a TANK.

It was a bad design when it debuted, its still a bad design today.

Hobao 7 > LX line any day of the week. I'd rather convert a Hyper 7 than buy a LX2 based buggy.

For budget 1/8 e-buggies right now I'd be all over the Nexx8, its actually meant to race and compete on an even level and its an evolution of the Jammin series cars which have proven track records.

ZippyBasher · 02.12.2013, 07:10 PM

Its not a bad design, It keeps up with my 8ight just fine.

But this wasnt about racing... It was about a weak differential. Which is not any weaker than any other 1/8 diff I've used and rebuilt.

Bottom line is the LX2e is a GREAT STARTING/BASHING BUGGY, If your into racing you probably wouldnt want an entry level buggy in the first place. IMO

_paralyzed_ · 02.12.2013, 07:14 PM

Quote:

Originally Posted by ZippyBasher

HIGHLY DISAGREE

As Paralyzed said, it was probably just dumb luck with the Ofna. There is noting wrong with the Diffs on the LXe. My dad has been beating his for over 2 years with a 1717 and 6s. No Diff rebuilds front, center or rear. Please shim your diffs and they will hold up to ANYTHING you can throw at them. The buggy tires will break traction before you break a diff if they are assembled correctly...

Give the LX2e a second try, they are the best buggy for the price... The only "upgrade" it needs is an aluminum rear toe plate. after that its a TANK.

In the buggy world ultra diffs are known to be a weak link... shimming helps tremendously.

ZippyBasher · 02.12.2013, 07:32 PM

Well.... Maybe I am the one with Dumb (read GOOD) Luck.

We have an old Ultra LX with a 1518 and 6s my brother drives and
My dad's LX1e with 1717 and 6s. Not one broken diff yet. 2+ years running.

_paralyzed_ · 02.12.2013, 10:54 PM

Quote:

Originally Posted by ZippyBasher

Well.... Maybe I am the one with Dumb (read GOOD) Luck.

We have an old Ultra LX with a 1518 and 6s my brother drives and
My dad's LX1e with 1717 and 6s. Not one broken diff yet. 2+ years running.

My lx1e's diffs are fine too, on 6s with a 1515. I believe newer diffs may be stronger. My Ultra nitro buggy ate diffs all the time.

They just have a bad reputation, that is all we're saying.

hemiblas · 01:06 AM

Thanks for the info guys. The feigao motor is actually the 8l not the 7l so it pulls a few less rpm per volt than the 7L mentioned above. I got around to taking the lx2e apart and it turned out that nothing was damaged. The front center shaft(grub screw from the cap joint) came loose and the ball bearing on the diff came off. I put the ball bearing back in and tightened up the center shaft cap joint and it looks good. I thought the gears were stripped but they were fine. What got me worried is I could smell burnt/smoke coming out of the center diff, but it turned out to the joints cap rubbing and turning that made it get hot.

The RD logics is junk. It was a good looking buggy, but just couldnt hold up to a brushless motor. I'm going to give the lx2e another run and see how it goes.