Small Block Drive Shaft Spring--Why?

[SmithSwede]

Changed the rear tire yesterday and greased the splines on rear of drive-shaft on 2013 Guzzi Stone.

Put it all back together, but now realize from studying the parts diagram that I reversed the order of the spring (GU94321099) and the plate.   Looks like the plate fits in front of the circlip on the coupling, then the spring fits between the plate and a hole at end of drive shaft.   

Sigh.  I'll take it apart and do it right.   But does anyone know what exactly is the function of this spring?   Yes, I know, it pushes backwards...but why do we want that?

[Chuck in Indiana]

Well, think a bout it. What does the "coupler" do? What will happen if it's free to move forward?  ;D

[SED]

I think the reason is partly as a retainer and perhaps damp out a rattle. And it may keep the plunge joint wearing where they want it.  If the coupling sleeve had its disk fixed into it (with 2 circlips for example) the coupling sleeve would be permitted to move back and forth between the drive shaft and the spline on the bevel box, but it would probably rattle so you'd want a spring there anyway.  It may also dampen some chatter as the driveshaft spins and suspension moves up and down.

[steamdriven NZ]

The spring is important! It forces the driveshaft forward, keeping the centre of the universal joint concentric with the centre of the swingarm pivot. Remember that the female driveshaft spline forward of the UJ is a sliding fit on the gearbox output shaft (sliding forward until it bottoms out) , so it would also be free to move rearward except for the action of the spring keeping it pressed fwd into the output shaft. The driveshaft end is specifically drilled to take the spring to stop it cocking over.

I would imagine that having the two centres not being aligned could cause "some issues" considering the physics involved, with this thing doing a fair few revs as well as the gyrations with suspension movement and shock loadings when you hit a decent bump.

The spring acts on that disc keeping the coupler located on the pinion spline in its correct position too.

The first time I thought about all this I thought "Really? Thats' quite low tech" but hey it works well and has never been an issue that I have heard of.......

Kev.  

[kevdog3019]

The spring keeps the coupler in place. To be more specific, it keeps constant pressure on the coupler retainer so that movement can't occurr.

[sib]

I haven't had mine apart yet, so please excuse the naive questions:

Where does the circlip (N) go? Is there a groove for it in the coupler (L)?  Or is there a groove in the bevel drive adapter fitting (P)?

Thanks.

[kevdog3019]

I haven't had mine apart yet, so please excuse the naive questions:

Where does the circlip (N) go? Is there a groove for it in the coupler (L)?  Or is there a groove in the bevel drive adapter fitting (P)?

Thanks.

Good questions:  There's a groove for the circlip in the coupler for the disc to sit against.

[sib]

Good questions:  There's a groove for the circlip in the coupler for the disc to sit against.

Kool, thanks.