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Post by Steve P5b on Oct 17, 2014 20:22:10 GMT
www.youtube.com/watch?v=DDmz0tibVGM So you don't get them out of phase when overhauling your UJ's as it can cause vibration, here is some handy information as explained in the U Tube clip
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Post by enigmas on Oct 18, 2014 10:39:31 GMT
Nice little video Steve, it certainly illustrates the out of phase condition clearly. What it doesn't illustrate is a universal joint at the centre position and a change of angle at this mid point as in the P5s. I imagine the same deal applies, but there is perhaps a greater out of phase situation at centre...hence the need for those very loose P5 centre mounts and that "odd ball" little spring under the centre mount assembly (let's it jiggle about a bit so vibration isn't transferred to the body if held too rigidly) Note: If you lower the rear suspension ( the axle moves up) the last segment of the shaft that bolts to the diff flange is at a lesser angle (so less out of phase at centre) Any views on this?  |
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Post by johnwp5bcoupe on Oct 18, 2014 18:42:05 GMT
Nice little video Steve, it certainly illustrates the out of phase condition clearly. What it doesn't illustrate is a universal joint at the centre position and a change of angle at this mid point as in the P5s. I imagine the same deal applies, but there is perhaps a greater out of phase situation at centre...hence the need for those very loose P5 centre mounts and that "odd ball" little spring under the centre mount assembly (let's it jiggle about a bit so vibration isn't transferred to the body if held too rigidly) Note: If you lower the rear suspension ( the axle moves up) the last segment of the shaft that bolts to the diff flange is at a lesser angle (so less out of phase at centre) Any views on this? As you know Vince the P5b set up is a compromise if you do the sums the working angles are out on the UJ's also the flange faces on the GB and Diff at normal ride height. |
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Post by Steve P5b on Oct 18, 2014 21:48:01 GMT
Nice little video Steve, it certainly illustrates the out of phase condition clearly. What it doesn't illustrate is a universal joint at the centre position and a change of angle at this mid point as in the P5s. I imagine the same deal applies, but there is perhaps a greater out of phase situation at centre...hence the need for those very loose P5 centre mounts and that "odd ball" little spring under the centre mount assembly (let's it jiggle about a bit so vibration isn't transferred to the body if held too rigidly) Note: If you lower the rear suspension ( the axle moves up) the last segment of the shaft that bolts to the diff flange is at a lesser angle (so less out of phase at centre) Any views on this? As I see it is the entre bearing and two shafts reduce the angle of each uj as apposed to using only one prop shaft that would require larger working angles. As you say the mounting of the centre bearing is sloppy to reduce vibration, not so with other cars of similar design. Over engineered as some other rover stuff? I'm not sure of your comments regarding less out phase if the angles are changed due to lowering rear suspension, just reduced angles, not less phased, as we are dealing with two separate props. Regards |
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Post by enigmas on Oct 18, 2014 23:03:53 GMT
Steve out of phase has to do with angularity. If the shaft is straight (one piece) or nearly straight and the universal joints are matched, there's no out of phase situation. Out of phase on a hookes joint is caused by variations in the rotation speed due to the angularity of the operating joint. A straight shaft technically wouldn't require any universal joint. Most one piece tailshafts using hookes joints cancel out the out phase rotation cycle if setup correctly. The issue with the P5 shaft is the joint in the middle which introduces another angle. Ideally the first section of the shaft should be in line with the engine crankshaft and gearbox mainshaft and the second section (with the matched for phase joints) angled down. The whole assembly should also make a 'straight' line if viewed from above.
As an aside when I had the differential of my coupe modified to run a 2.9:1 ratio, the pinion was slightly offset to the PS. Due to this, a slight out of phase situation was induced...felt mainly at very low speed and when under load. This introduced another angle from the centre bearing back when viewed from above (birds eye view). The fix was to modify the centre mount so the centre bearing was moved slightly to the PS. The whole assembly runs at a very slight diagonal angle but the assembly viewed from above makes a straight line. This small modification cancelled the out of phase situation in the shaft. It's been like this for 20 years now and still runs the same universal joints.
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