One-piece driveshaft

[drako323]

Hey guys, I couldn't seem to find a relevant older topic, so I opened this one:

Has anyone had any experience from a one-piece driveshaft on a 86?

It should be lighter, and theoretically have less transmission losses due to smaller U-joint angle changes.

Any opinions?

[BOOMEX]

i have tested one one my 86 and i realy dislike it.(until your 86 is a race car)

you can realy feel the gain in the transmission lossbut whene you it the 100km/h there are a lot of vibration and whane you go up 110 the vibration beacome realy strong.

i have tested against a 171hp civic and it seam quite the same...

i hope it help you.

[NoHachi]

Same here: unless you have the pinion angle set spot on, you'll have an ENORMOUS problem with vibrations.

I'll report back if I can manage to get things under controll with pinion preload settings.

[drako323]

Thanks guys!

Maybe a big rubber damper ring would cure the vibration...?

[NoHachi]

No, its harmonic vibration sadly.

[ToFu Ben]

NoHachi Wrote:No, its harmonic vibration sadly.

what about make it different in length ?

[jondee86]

Considering that Toyota chose to make the OEM driveshaft a two-piece
design (which is more expensive) I figure they must have had a good
reason for making that choice. However, there are many cars, including
Toyota's, that work fine with one-piece driveshafts.

Max Misawa over at Club4AG sells one-piece shafts with Supra
rebuildable U-joints, and his customers seem more than happy with the
performance. So perhaps it comes down to the mass of the components,
U-joint angle and the clearances in the connected gearsets ?

Big Toyota's do run rubber donuts in the driveline, and I imagine they
are there to dampen torsional resonance ? Maybe using a two-piece
driveshaft serves a similar purpose ? Hey... interesting topic, and I hope
we can get a few more posts from people who have played around with
different setups.

Cheers... jondee86

[Roku_trueno]

I assume that if you balance carefully the driveshaft , you won't have any harmonic vibrations, right?

[NoHachi]

You will if you get enough of a misalignment on the yokes. Sadly pinion angle varies with the amount of torque transferred through the pumpkin and the amount of anti squat/dive. So a comprimise is needed. Then there is the torsional harmonic mode of the axle itself which could end up in the frequency range of the engine.

Summary: even if you have a perfectly balanced axle(rotationally) you can and will still get resonance from other sources( unless everything is set correctly).

[jondee86]

One of the difficulties is that the driveshaft tube itself is subject to a
sinusoidal movement relative to the position of the input and output
stubs. This occurs at a frequency twice that of the rotational frequency
of the input/output stubs.

It is almost inevitable, that this torsional vibration will (at certain speeds)
coincide with one of the system resonant frequencies. In the worst case,
the effect will be an annoying vibration that rises to a peak at a particular
road speed, and then fades as your speed increases i.e. you can "drive
through" the vibration.

Because it is a system resonance, it can and will be influenced by other
rotating components. Anything that rotates, from the engine fan to the
rear wheels, can change system resonance. Car manufacturers will go
to a lot of trouble to counteract system resonance, and it is rarely a
problem when cars leave the factory. However, once owners start
modifying the car, resonance problems (noise or vibration) can occur.

Cheers... jondee86