d-wood

I removed my front diff and I put match marks on my propellor shaft but they rubbed off. I also put matchmarks on the front of diff going to drive shaft but they rubbed off.

MudHippy

It doesn't matter. The farthest I go is to match them back up to the "rust shadow" left on the drive flanges. Which either puts them back exactly where they were, or at worst 180° off. Which has never caused a problem for me. And I don't even believe going to that much trouble really matters. But I do it anyway. I can't seem to totally shake that matching them up perfectly myth....for whatever reason. Even though it makes no sense at all.

d-wood

That's kinda what I was leaning towards mud hippy. It doesn't look like anything fits into anything to affect performance.

millball

While it is true that it does'nt really matter how the shaft is bolted back up to the flanges, it is absolutely important that the shaft pieces are correctly stabbed into each other at the slip-joint.

The u-joints must be kept in phase to operate correctly, and the shaft, as a whole, was balanced in the configuration that it was originally joined.

RJR

Yeah, if you think about what happens on the assembly line at the factory, the drive shafts come in pre-balanced, and the flange holes are drilled accurately from the center line. The assembly person just grabs a shaft and bolts it on. They don't have time to try all 4 different orientations to see which is the smoothest, and the shafts are not balanced on the truck after assembly. They don't have time for that either. Good process control makes that sort of hand-crafting at assembly time unnecessary.

So, if Toyota doesn't care which way they shaft gets bolted up, why should you?

I have no idea why the FSM tells you to put match marks on the flanges, except that manual writers are not design or process engineers, and often bring their own misconceptions and biases to the table. Happens all the time in my company.

Edit: Millball is absolutely correct about U-joint alignment

dropzone

iTrader: (6)

to expand on Millball & RJR's info

4Crawler's Driveshaft 101

d-wood

How would you know if it's kept in phase. If I'm understanding correctly, does that have to do with the flatness as they join?

MudHippy

What he means is...don't pull the shaft apart at the slip joint/splines/yoke...unless you know how to put it back together correctly. That's where phasing comes into play.

d-wood

Right on. Thanks for explaining that.