chain to shaft transfer case

[docnugent]

I just bought a chain to shaft transfer case from a '79 XS1100 to use in a Morgan-style trike (two wheels in front, engine in front, driveshaft to a single driven rear wheel). This application would require the transfer case to run "backwards" - that is, the input from the engine would be the shaft drive and the output to the rear wheel would be via a chain sprocket.

Should there be any problems with putting the load on the shaft that's usually the output?

Thanks in advance, and apologies to any who might be offended by this misuse of Yamaha parts.

M D "Doc" Nugent

[fusionking]

Yer guess dude

I'm lost. I know that box isn't 1:1. I don't think it has the gears cut to run backwards. Could also have lube and thrust issues. That don't mean it won't last. Please give us more details. I've looked at that box with other applications in mind before, nice unit. I'm sure Jesse James would find something to do with it.

[docnugent]

Thanks for the heads up about the ratio - the seller told me it was 1:1, but I see the specs page here (for '79 models) says:
"Transmission to-jackshaft reduction
- straight-cut gears, 0.936:1 ratio
Jackshaft-to-driveshaft reduction
- spiral-bevel gears, 1.056:1 ratio"

Since I'm new to these boxes, I'm not sure what the parts are properly named. Is what I've been calling the chain-to-shaft transfer case actually called the jackshaft-to-driveshaft (spiral/bevel gears), or does it include that PLUS the transmission-to-jackshaft (straight-cut gears)?

As to "running backwards" - it would run backwards in the sense that the shaft would face forward in the trike rather than facing the rear of a bike, but I'm not sure that it would it run backwards in the sense that the backside of gear teeth would get the wear. I'll have to turn it by hand to get a sense of that.

In addition, it could be that the trike's driveshaft would rotate counter to the "usual" direction so turning the unit around front to rear would cancel out the shaft counterrotation (if there is any).

I'd provide details as you asked, but don't know what would be relevant. I do appreciate info on the unit.

M D "Doc" Nugent

[docnugent]

ASCII blueprint

I just thought of a way to convey the major parts layout of the trike I'm proposing:

from FRONT >---------------------------------> to REAR:
Car engine/trans > driveshaft > shaft end of Yamaha case > sprocket side of Yamaha case > chain > sprocket on rear (drive) wheel.

If it matters, the engine is a 68hp inline four.

M D "Doc" Nugent

[docnugent]

Pictures

I just threw together a web page that shows the inspiration for this project:
http://www.carcentric.com/SpitTrike.htm

M D "Doc" Nugent

[Jeff]

I'm just trying to picture this in my head. LOL

The only thing I can see that might cause a problem is the fact that on an XS1100..... the crankshaft and primary drive chain rotate OPPOSITE the rotation of the rear wheel. As in..... looking from the left side of the bike..... the crankshaft and chain rotate clockwise.... while the rear wheel rotates counter clockwise. The crank on these bikes runs backwards from most other bikes. I can't remember which way the driveshaft turns though. LOL

I'd make sure the output of your car transmission would turn the driveshaft in the correct direction to load the proper driven side of the gears.

[docnugent]

Thanks, Jeff -

1. I didn't know "looking from the left side of the bike..... the crankshaft and chain rotate clockwise" but I'm also not sure whether the chain is on the left or right side of the bike (from the rider's perspective). Sorta sounds from your description like the chain's on the left side of the bike. Is that correct?

2. In the picture of the transfer case on my web page above, is the unit in it's correct operating orientation, or is it upside down? I don't know if the plug that can be seen is a fill plug or a drain plug.

M D "Doc" Nugent

[Jeff]

In your picture... the trans is sitting as it would be oriented on the bike. The driveshaft goes down the left side of the frame.

[Jeff]

Someone else please correct me if I am wrong.... as I am from time to time. LOL

[Jeff]

The primary drive chain actually goes down the center. It comes off the center of the crankshaft between the cylinders.

[fusionking]

What chain?

I don't think that chain connects to that box! These bikes are not some chain thing converted afterthought like other bikes! They began life as shaft drive so when you speak about chain on the bike you almost lose me altogether. (don't worry it happens to me all the time) Anyway you oughta get the rest of that bike and put that box back on and you will be much happier.IMHO

[docnugent]

New knowledge - good news!

When I turn the sprocket flange on the transfer case clockwise by hand, the splined shaft also turns clockwise. As I understand your input, Jeff, that's the direction of rotation the case was designed for when in use in the bike.

The car's flywheel (and driveshaft in forward gears) turns counterclockwise when viewed from the driver's seat facing forward. If you turn around and face the rear of the car, the driveshaft therefore turns clockwise.

Ergo, with the car driveshaft driving the splined shaft on the Yamaha transfer case, the car going forward will spin the transfer case in the direction it's been designed for. (Backing up will spin it backwards, but that's slow and infrequent.) Furthermore, the sprocket will then also turn clockwise, so a chain will turn the drive wheel/tire in the forward direction!

Sounds like a definite maybe to me - anybody see a potential glitch given what I've discovered? Would the 68hp engine of the Spitfire will be too powerful? I can't find any hp or torque spec for the XS1100 . . . .

Feelin' lucky,
M D "Doc" Nugent

[docnugent]

Enlighten me, please

Fusionking,
I'm the newest of the new here, so explain to me what DOES the shaft with the four hole flange get its power from if not a chain?

The flange I'm talking about is shown in the lower right corner of this picture:
http://www.carcentric.com/79yamahaXS1100case.jpg

M D "Doc" Nugent

[mitch]

he he

He got ya there Garry, it is chain driven in reality

[Jeff]

That 4 hole flange is where the driveshaft connects to the unit.... it is the output. The driveshaft which connects the middle drive (the unit you have) to the final drive differential at the rear wheel.