RCCrawler Forums

Rauto13 · 08-06-2009, 11:28 AM

Would i be feasible to use an 1/8 scale buggy diff for a transmission? It looks like it would be fairly simple to mount a spur gear and it looks like you could us the brakes on the front and rear as digs.

The problem I see is that is a differential and may not send power to both the front and rear wheels, but with a heavy enough grease, I think this may not be a problem.

Maybe I could use a torque sensing diff or something like that.

Is this feasible?

JeremyH · 08-06-2009, 12:01 PM

What tranny? Does it have a ball or planetary gear diff that could be locked?

jeepcj578 · 08-06-2009, 12:29 PM

you would have to lock it with some jb weld or something like that.
or i think that the ofna 1/8 scale dirt oval late modle has a locked diff or spool from the fact.

the only down fall is you will not get enuff gear reduction out of it for crawling.

sweli · 08-06-2009, 01:05 PM

Are you going to direct drive a shaft from the motor to the dif? So motor would mount sideways on the chassis plate?

Most difs are 3:1. So trans 3:1 x your difs at 3:1 would mean a 9:1 overall ratio to the wheels.
The Pinion and spur in most rigs multiplies this by another 6:1 (up to 9:1) for a overall ratio of 50:1 (up to 80:1) to the wheels.

You could use a gearhead motor with it that could get you to that ratio.

oldhippie · 08-06-2009, 02:56 PM

Yes it might work but it would be heavy and wide with the motor sticking out the side. If ya mounted the motor on top the diff/trans it would mess the cog. I get the idea of the spur mounted to the diff input and brakes on each output. I guess the question is why?

sweli · 08-06-2009, 03:01 PM

Dig around the net for Kyosho Blizzard threads (snowcats). They have a solid axle, semi-open dif, and brakes on each axle end. It is how it steers.
Simular to what you are thinking about (turned 90deg).

I would like to do that with a lockable/unlockable (traxxas summit) dif on the rear of a crawler, in place of dig.
Power the outter wheel and lock the inner wheel of the direction you want to turn. (= 3 wheel drive DIG).

Offroader5 · 08-06-2009, 03:06 PM

Depends on if you're talking about the "diff" or the "center diff". By diff, I mean axle diff....center diff being the central "trans" in a 1:8 buggy.

If it's the center diff...then it could be possible since it will already have a spur gear...you'd only have to find the particular pitch (mod1 or mod2 usually) pinion gear that fits your motor shaft.

It would be no different than converting a nitro 1:8 to brushless. You may even be able to find a motor plate already available that fits to the central diff depending on which vehicle you're using as a donor.

There are a few that they make center diff lockers for....or you could do like already mentioned and just JB the diff gears to lock it up.

Rauto13 · 08-06-2009, 09:56 PM

The reason for my thinking on this was so that you could use the front and rear brakes on a center diff as a dig setup for a shafty and you could mount the motor down low on the chassis.

The more I think about it, the less I think it would work, if you locked the diff, then there would not be any way to use the brakes mounted on the diff as a dig setup. If you didn't lock the diff then the diff would likely just send power to whatever axle had the least resistence.

If there was a way to lock the diff when not using the brakes for dig, to send equal power to each axle, then unlock the center diff so yo could use a brake on one end or the other for dig, then it might work. You would need a diff that could be locked and unlocked remotely to do what I was thinking. Don't think there is such an animal in the r/c world.

Thanks for the input.

sweli · 08-07-2009, 02:29 PM

Quote:

Originally Posted by Rauto13

If there was a way to lock the diff when not using the brakes for dig, to send equal power to each axle, then unlock the center diff so yo could use a brake on one end or the other for dig, then it might work. You would need a diff that could be locked and unlocked remotely to do what I was thinking. Don't think there is such an animal in the r/c world.

Thanks for the input.

Traxxas Summit Dif

customcrawlerV1 · 08-15-2009, 12:59 AM

this might not be quite right but it might work.
Hong nor torsion diff. you would be able to use a brake as a digg but it is ideal for crawlers as it sends power to where the most grip is.

hop ive helped

08-06-2009, 11:28 AM	#1
Rauto13 Newbie Join Date: Sep 2007 Location: Pryor Creek Posts: 20	Trying to think outside the box... Would i be feasible to use an 1/8 scale buggy diff for a transmission? It looks like it would be fairly simple to mount a spur gear and it looks like you could us the brakes on the front and rear as digs. The problem I see is that is a differential and may not send power to both the front and rear wheels, but with a heavy enough grease, I think this may not be a problem. Maybe I could use a torque sensing diff or something like that. Is this feasible?

08-06-2009, 12:01 PM	#2
JeremyH I wanna be Dave Join Date: Sep 2005 Location: Houston, TX Posts: 16,952	What tranny? Does it have a ball or planetary gear diff that could be locked?

08-06-2009, 12:29 PM	#3
jeepcj578 RCC Addict Join Date: Nov 2006 Location: southaven Posts: 1,934	you would have to lock it with some jb weld or something like that. or i think that the ofna 1/8 scale dirt oval late modle has a locked diff or spool from the fact. the only down fall is you will not get enuff gear reduction out of it for crawling.

08-06-2009, 01:05 PM	#4
sweli RCC Addict Join Date: Jan 2008 Location: Lake Michigan Posts: 1,898	Are you going to direct drive a shaft from the motor to the dif? So motor would mount sideways on the chassis plate? Most difs are 3:1. So trans 3:1 x your difs at 3:1 would mean a 9:1 overall ratio to the wheels. The Pinion and spur in most rigs multiplies this by another 6:1 (up to 9:1) for a overall ratio of 50:1 (up to 80:1) to the wheels. You could use a gearhead motor with it that could get you to that ratio.

08-06-2009, 02:56 PM	#5
oldhippie I wanna be Dave Join Date: Feb 2009 Location: 20 miles southeeast of downtown Sacramento Posts: 2,373	Yes it might work but it would be heavy and wide with the motor sticking out the side. If ya mounted the motor on top the diff/trans it would mess the cog. I get the idea of the spur mounted to the diff input and brakes on each output. I guess the question is why?

08-06-2009, 03:01 PM	#6
sweli RCC Addict Join Date: Jan 2008 Location: Lake Michigan Posts: 1,898	Dig around the net for Kyosho Blizzard threads (snowcats). They have a solid axle, semi-open dif, and brakes on each axle end. It is how it steers. Simular to what you are thinking about (turned 90deg). I would like to do that with a lockable/unlockable (traxxas summit) dif on the rear of a crawler, in place of dig. Power the outter wheel and lock the inner wheel of the direction you want to turn. (= 3 wheel drive DIG).

08-06-2009, 03:06 PM	#7
Offroader5 Picky Fab'r/Acetal Junky Join Date: Jul 2006 Location: Arizona Desert/AJ Posts: 3,073	Depends on if you're talking about the "diff" or the "center diff". By diff, I mean axle diff....center diff being the central "trans" in a 1:8 buggy. If it's the center diff...then it could be possible since it will already have a spur gear...you'd only have to find the particular pitch (mod1 or mod2 usually) pinion gear that fits your motor shaft. It would be no different than converting a nitro 1:8 to brushless. You may even be able to find a motor plate already available that fits to the central diff depending on which vehicle you're using as a donor. There are a few that they make center diff lockers for....or you could do like already mentioned and just JB the diff gears to lock it up.

08-06-2009, 09:56 PM	#8
Rauto13 Newbie Join Date: Sep 2007 Location: Pryor Creek Posts: 20	The reason for my thinking on this was so that you could use the front and rear brakes on a center diff as a dig setup for a shafty and you could mount the motor down low on the chassis. The more I think about it, the less I think it would work, if you locked the diff, then there would not be any way to use the brakes mounted on the diff as a dig setup. If you didn't lock the diff then the diff would likely just send power to whatever axle had the least resistence. If there was a way to lock the diff when not using the brakes for dig, to send equal power to each axle, then unlock the center diff so yo could use a brake on one end or the other for dig, then it might work. You would need a diff that could be locked and unlocked remotely to do what I was thinking. Don't think there is such an animal in the r/c world. Thanks for the input.

08-15-2009, 12:59 AM	#10
customcrawlerV1 Newbie Join Date: Mar 2009 Location: Shakespeare Country (stratford) Posts: 16	this might not be quite right but it might work. Hong nor torsion diff. you would be able to use a brake as a digg but it is ideal for crawlers as it sends power to where the most grip is. hop ive helped

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