T-maxx transmission with brushless motor - RC-Monster Forums

10:21 AM

Hey guys, I've been running a brushless setup for 5 or 6 years with an E-maxx transmission in a little chassis I made about 10 years ago. It was based on Clodbuster axles at the time, and is now based around another Tamiya axle, the Txt-1/Juggernaut design.

Anyway, the latest setup is a shulze speed control running 14 cells through a Hacker B50 9L. It has plenty of power and it took quite a while to get the driveline robust enough to hang in there long enough to be any fun.

However. The driveability of the brusless setups has always left something to be desired in the way of slowly easing forward (like for crawling over obstacles) and quickly changing from reverse to forward and vice versa. Also the cogging with decent timing advance is just not desirable. It can be minimized, but the machine will never ease around like a brushed setup.

And because of the brutal power output I have always just dealt with these relatively minor things.

However:

What if instead of asking the brushless motor to stop and start, reverse and then rotate forward again constantly while traversing an obstacle, we instead just pretended it was a gas engine?

What if you just had it set so that it would always be spinning slowly at an rpm where no cogging would ever take place and let a clutch similar, if not the same as for a nitro engine, attached to the shaft. Then the motor could just "idle" there, ready to rock on a moment's notice.

And as you slowly increased the power with the speed control, the rpm would increase and the clutch would start applying torque to the transmission and you could ease over obstacles without any cogging, and without having to go faster than you wanted.

Then to reverse, just use the reverse in the T-maxx tranny. It would shift from 1st to 2nd on it's own just as designed as well.

Just seems like the brusless motor might perform better from a driveability standpoint if it were allowed to just sit and idle and then apply power and reduce power but never have to actually stop and reverse all the time.

A side benefit would be the ability to use a much cheaper non-reversing speed control, and non braking (as the braking will be done via the disc brake on the transmission).

What do you all think?

I would love a little torque converter in there. But I think a nitro car clutch would work.

lincpimp · 10.24.2008, 10:49 AM

you could use the tekno clutch adapter and use the tmaxx tranny. Personally I would spend the money on a better brushless sytem and some lipos. The 9l on 18cells is a bit much, maybe go to a 9xl and regear. That will help the low speed torque, and I am sure temps will be better.

Welcome to the forum, how about some pics of this hybrid r/c!

aqwut · 10.24.2008, 01:05 PM

Quote:

Originally Posted by Charles

Hey guys, I've been running a brushless setup for 5 or 6 years with an E-maxx transmission in a little chassis I made about 10 years ago. It was based on Clodbuster axles at the time, and is now based around another Tamiya axle, the Txt-1/Juggernaut design.

Anyway, the latest setup is a shulze speed control running 14 cells through a Hacker B50 9L. It has plenty of power and it took quite a while to get the driveline robust enough to hang in there long enough to be any fun.

However. The driveability of the brusless setups has always left something to be desired in the way of slowly easing forward (like for crawling over obstacles) and quickly changing from reverse to forward and vice versa. Also the cogging with decent timing advance is just not desirable. It can be minimized, but the machine will never ease around like a brushed setup.

And because of the brutal power output I have always just dealt with these relatively minor things.

However:

What if instead of asking the brushless motor to stop and start, reverse and then rotate forward again constantly while traversing an obstacle, we instead just pretended it was a gas engine?

What if you just had it set so that it would always be spinning slowly at an rpm where no cogging would ever take place and let a clutch similar, if not the same as for a nitro engine, attached to the shaft. Then the motor could just "idle" there, ready to rock on a moment's notice.

And as you slowly increased the power with the speed control, the rpm would increase and the clutch would start applying torque to the transmission and you could ease over obstacles without any cogging, and without having to go faster than you wanted.

Then to reverse, just use the reverse in the T-maxx tranny. It would shift from 1st to 2nd on it's own just as designed as well.

Just seems like the brusless motor might perform better from a driveability standpoint if it were allowed to just sit and idle and then apply power and reduce power but never have to actually stop and reverse all the time.

A side benefit would be the ability to use a much cheaper non-reversing speed control, and non braking (as the braking will be done via the disc brake on the transmission).

What do you all think?

I would love a little torque converter in there. But I think a nitro car clutch would work.

I did a conversion on a T-maxx and it was fun, but I wouldn't do it again. it's a very quite start when the clutch catches on, makes you wheelie instantly at first..
To solve the cogging problem with the schulze ESC, try adding a few extra capacitors.. I did this to all of my 18.??? series ESC and it elimated the low speed cogging. I'm not a big fan of the E-maxx tranny either, it makes it hard on the gears and drive train.. a Nitro -> BL conversion is my favourite. Using Sub $100 ESC and Sub $50 Motors seems to work very well...

02:19 PM

I didn't even think about pictures of my ole truck.

http://www.youtube.com/watch?v=pZSBOo2dFVc

http://www.youtube.com/watch?v=6H7HqxBWUSw

Those pictures and video are of the current setup. You can see the cogging.

lincpimp · 10.24.2008, 02:33 PM

Looks cool, I like live axle trucks. I think going to an xl motor and some caps would cure the cogging issue. The 9l is a bit small for that setup, and the kv is too high, IMO.

J3110 · 02.11.2009, 07:31 PM

Quote:

Originally Posted by aqwut

I did a conversion on a T-maxx and it was fun, but I wouldn't do it again. it's a very quite start when the clutch catches on, makes you wheelie instantly at first.

Just in case you happen to still be reading this thread, I'm in the process of trying this with an old .16 t-maxx, kinda like this:

I thought having the auto tranny, mech brakes etc would be cool, but if it's not worth it, then I'd rather go another route.
Did you try loosening the spur slipper to reduce the initial bucking, or was it just something you had to get used to?
Thanks in advance.

J3110 · 02.15.2009, 03:44 PM

Slowly making some progress here. Threw the T'E-Maxx together yesterday to check things out and the bucking isn't all that bad, actually and shouldn't be a problem at all for it's intended use.
Of course, you wouldn't wanna try crawling with this kinda setup, but for running around a track where you're trying to stay moving, I think it should be ideal.