Chain driven final drive?

[Boostinjdm]

here is a crazy stupid idea that occured to me while taking a piss.  What about chain driven final drives.  Say you have a three link or trailing arm setup.  How bout driving a shaft placed half way down the arms with the cvs and then chain driving the stub axle.  My gut says you could get more reduction with smaller sprockets and more wheel travel with less cv angle.  Any thoughts?  Not that I would do it, but I thought I would throw it out there.  Some penalties I can think of is unsprung weight and maintenance.

[fabr]

i see the point about the cv's but you're going to add a bunch of length to the buggy like that.

[Nutz4sand]

You mean something like this?? (Granted these are rough but the ideas there.

[Boostinjdm]

not as extreme as that Nutz.  But along the same lines.  Where those off the MBN thread?

[Nutz4sand]

They are on MBN as well but they came off my puter. I made those a while back.

Extreme? What mean you by extreme?? The closer to the frame the better for the CV as its less weight at the wheel area. You will move less there and thus can use smaller and cheaper CV's due to that. especially scince nealry all the torque is delat with after this part in the chain to the wheel. (Especially helpful with a sled motor that needs deep gearing) and the sprockets not sticking down in the middle of the chassis. (You can see my awesome sled motors indicated in the pic!!    )

It was what I was playing with the idea fer in the first place. Long travel with ease of deep gearing for a sled engine.

[Nutz4sand]

Heck I have even been playing with a rear design that instead of a trailing arm like that it uses a swingarm JUST like a motorcycle. But wide enough for a big paddle tire but with a chain feeding it from the front just the same as the pics above or more correctly said just like a motor bike. Would actually have a bar down each side of the tire and a axle all the way across.

Have to figure out handling with two swing arms with a tad bit of angle for rear toe in and the camber changes due to the mounts. I am thinking mounts on a swing arm would react just like mounts on a trailing arm. 

Below is VERY crude but only took me a couple minutes but imagine the tire like that. (I like things that are different and this qualifies._ Be easy to make it look good. Like put flames on the outside bar!

[Boostinjdm]

I think we're on the same track.  I can see your points.  what I was thinking was more towards the middle of the arm.  so you could get similar travel with type 2's that you could with 930's.  and I was thinking somewhere around 2/1 final so your chaincase or cassette or whatever you plan on doing could be half the ratio. for ground clearance ofcourse like you said.  The reason I say middle of the arm is so that you could keep the standard engine and primary shaft layout and to keep the final drive chains shorter to reduce floppage. (I know it's a technical term)
I don't think the weight penalty of the final drive would be anywhere as bad as it seems.  If you think about it...moving the cv halfway up the arm would reduce your unsprung weight by half the cv weight.  mounting a sprocket in it's place would gain some of that back, but not all of it.  then the chain and the sprocket and shaft would gain back some more weight, but being halfway up the arm, the unsprung weight is only half what the components weigh, right?  so I guess what I am thinking is that the unsprung weight penalty might be in the 5-10lb range over a standard setup.  Not sure though, I could be all wrong here...just what my gut tells me...

[Nutz4sand]

I do realize that the angle in my last pic is VERY extreme. Its jsut to show the tire/swingarm, idea.

I see where you are headed Boost but I agree with Fabr that is you just ran it down as a typical drivetrail in would make for long rear arms.

As you can see in my first drawing above a sleds chain case is depicted. These can have reverse and its easy to tap power off the bottom shaft (especially when its more speed and less torque your tapping) 

As you can see I do like the idea. I would simply find a way to get it to the front like my pics as it makes for a better overall layout and function IMO.  Its my prefferred as the CV's will BARELY move as compared to at the back or halfway down even. Its just what I like! 

For a bike motor I was looking at a common driveshaft adaptor (like the dwarf cars use) and then putting a sprocket outside the motor and running it forward to the front shaft. Certainly not as easy as the sled motor and no reverse.   

[Boostinjdm]

For your idea of haveing the cvs close to the frame you could just put the chaincase ahead of the sled engine.  or for a bike engine put together a simple two gear gearbox and mount the engine backwards behind it.  You would get some ram air goin and have the pipes at the back.

[Nutz4sand]

For your idea of haveing the cvs close to the frame you could just put the chaincase ahead of the sled engine.  or for a bike engine put together a simple two gear gearbox and mount the engine backwards behind it.  You would get some ram air goin and have the pipes at the back.

With the driver in front of the motor I am not sure about ram air and if a two smoker you need the motor farther back for the frigging pipes. I would rather do it this way and not molest the pipes. Plus if the gearcase was in front it might interfere with the pipes to. I would prefer to keep the loads "factory" as in the way the belt pulls against the mounts and all. Makes belt setup MUCH easier too.  The chain running forward off the lower sled shaft is pretty easy to do so it works on several levels for me.

(side note) Fabr has at one time on MBN pointed out that you cannot run power foward with a chain like I am indicating as the pull being on the bottom and the slack being on the top will not work. But it can be made too work just as fine as frogs hair. And thats pretty fine.     

[Engineer]

This is what I always envision, a final drive that moves the outboard CV connection up.  You can always get more droop than down travel because of frame clearance.  This would allow the CV to work both ways more evenly, and maybey be closer to neutral at ride heigth.

The black circle is the tire.

The red circle is the large gear.

If you put the small gear where the green one is then rotation is normal to drive forward, and the CV is elevated 3-4 inches.

If you put the small gear where the blue one is then rotation is reversed.  Rear engine Busa 4-seater anyone?  Or with a VW style tranny set it up however you want it by changing direction in the tranny.

This outboard reduction would greatly reduce the stress on the rest of the drivetrain.  As always the downside is unsprung weight.  However each unit would only be handling half the horsepower so they could be lighter.

You could make the units with integrated 5-link or trailing arm attachment points.

[Boostinjdm]

I had thought about that earlier also, only with chain drive.  I wonder if you could set it up for some quick change gears?

[SPEC]

I built these a couple of years ago for mega travel, independant rear in a micro sized buggy...18'' of travel...easily... and only 52''wide...Hell I could get it down to 48''
Extra long jackshaft, an extra collar for the driven clutch, inboard brake. with 2 driver sprockets...
2 chains running down the cantalevered shock trailing arms to a Z-car indy carriers...NO CV or U-JOINTS to deal with no axles to twist off...
Intrested?

[Yoshi]

I've always wanted to do a setup like a hummer but have never pursued the idea due to the weight of another gearbox on the wheels, but it would give you more travel, give you more axle clearance, and put the axles straight out for normal use which puts more power to the wheel......

[SPEC]

I've always wanted to do a setup like a hummer but have never pursued the idea due to the weight of another gearbox on the wheels, but it would give you more travel, give you more axle clearance, and put the axles straight out for normal use which puts more power to the wheel......

You and I talked about the outboard chain drive, on cantalevered arms quite some time ago, I built well almost got them built, But haven't even looked at that buggy in months...