Steering shaft u-joint phasing?

69427

69427

The Artist formerly known as Turbo84
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Clinging to my guns and religion in KCMO.
I'm getting the steering put back together. I moved the rack a touch to try to tweak the steering geometry, and while trying to get the steering shaft to fit again I got to wondering how critical is the u-joint phasing. The steering column and the rack input are at two entirely different angles in space. There's obviously not a speed issue like on a driveshaft, but are there bind-up issues possible? Previously I've just tried to get the u-joints phased so that they look somewhat like a driveshaft, but I'm still a bit curious because both u-joints look like they are stuck with always being at odd angles to each other. Am I worrying excessively, or am I way off base here?

Thanks,
Mike
 
Mike,

Take a look at the Technical Section of the Woodward Precision Steering catalog. He has a pretty good discussion of steering u-joint phasing. There are actually two issues -- one is phasing of the u-joints, and the other is the angle issue that you describe. Phasing is more critical when it comes to feel and consistency of rotation rate, where the angle is most critical if you approach the limits of the u-joint. I try to stay under 25 degrees.
 
Any 'phasing' issue was taken care of by the intermediate shaft I happened to use, I got it out of a junkyard winter 01-02, and reworked the u-joints at each end, it was a double D type shaft with a rubber steering coupler on one end....never have understood just what that rubber disc is supposed to DO, so I have it just by happenstance.....I remember the top joint was at such a severe angle I had to grind some clearance on the bottom of the U's but it's been working fine,....even if used manually with no pump assist....:smash::eek:
 
Well, I've misplaced a couple of the u-joint set screws, and while I was looking around for them I got more curious about any bind-up issues (although I've never noticed any in the five years I've been running this setup). I'm used to any shaft with u-joints having a "free" end to deal with any length change issues while the shaft rotates. Transmission output yokes have slip joints (and even on the rear axles of our C3s the wheel has the opportunity to move outward if needed). On my steering link both u-joints are locked with set screws to the steering column and to the rack (which both are bolted solid to a structure). Theoretically is there any chance of bindup here (although, as I've said, I've never noticed any steering tight points while turning the wheel)? I looked at the Woodward site, and didn't see anything that said not to lock each u-joint to the shaft (ie: no mention of letting one spline area be able to move in and out during rotation).

Not trying to overthink stuff, but it's just got me curious. Is there a length change when the shaft turns in a setup where the two ends are at noticeably different angles in space?

Thanks again.

(Now, back out to the shop to find those lost set screws.)
 
I'm going to say that there is no change in length through the joint regardless of the angle. You do lose power through the angle but I expect it is constant/rotation angle. Most machine design manuals recommend 15 degrees or less.

Phasing two non-equal angles kind of makes my head hurt!
 
Having been through the U-joint vs CV on the rear axles... seems like fertile ground for CV joints on a steering column. Hmm... wonder how size and loads "scale" in this application.

Ahh - maybe we should just go "fly-by-wire"


Cheers - Jim
 
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