GBMUD Posted May 19, 2015 Share Posted May 19, 2015 I have a vibration when on power at 65-70. Looking at the propshaft today it is not phased as I would expect - one joint is at 45 degrees to the other unlike the rear one which has both yokes on the shaft inline. Should I realign it or assume that it is correct? I understand about correct phasing to cancel out the sine wave speed thing, but my mechanic friend says he sees lots like mine from the factory, hence the question. I am on my mobile but will try to do pictures... Thanks Chris Quote Link to comment Share on other sites More sharing options...
GBMUD Posted May 19, 2015 Author Share Posted May 19, 2015 ...in the 'correctly phased in my mind' position I found the splines very tight. Chris Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 19, 2015 Share Posted May 19, 2015 The phasing is different front to rear... Details of vehicle will allow looking it up in RAVE, a 90 I think, but what age? Quote Link to comment Share on other sites More sharing options...
GBMUD Posted May 19, 2015 Author Share Posted May 19, 2015 Sorry, I should have said, 2005 Td5 90. The rear is as I would expect, the front not so. Any reason why it should be different? Chris Quote Link to comment Share on other sites More sharing options...
jackmac Posted May 19, 2015 Share Posted May 19, 2015 Sorry, I should have said, 2005 Td5 90. The rear is as I would expect, the front not so. Any reason why it should be different? Chris There is a reason, I can't say I know it though. To answer your query, your props sound fine. Rear in phase, front out of phase Quote Link to comment Share on other sites More sharing options...
western Posted May 19, 2015 Share Posted May 19, 2015 Front uj's are out of line to allow for angle changes at front axle, applies to all pre Puma 90/110, according to genuine workshop manual, I posted the relevant page a while ago. Quote Link to comment Share on other sites More sharing options...
elbekko Posted May 19, 2015 Share Posted May 19, 2015 The front has radius arms, which means the front UJ does very little work, and will need different phasing. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted May 19, 2015 Share Posted May 19, 2015 When the flanges are parallel to each other like on the rear axle, the yokes are in phase. When the flanges are not parallel, the yokes are arranged at 45 degrees like the front axle. If you look at the front diff, the nose actually points up towards the transfer box. Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted May 19, 2015 Share Posted May 19, 2015 Because on the rear axle the flanges are on parallel planes the two UJ angles are always equal and opposite (ignoring articulation here), so the variations in rotational speed that are inherent to all UJ-style joints are also equal and opposite, thus they cancel themselves out. Hence rear prop has the yokes in phase. The front axle diff nose points up towards the transfer box as pointed up out above, this means the angles and therefore the speed variations are not equal and opposite and so will never cancel themselves out completely. The phasing specified by Land Rover is a best attempt to match the sine wave forms of this speed variation together to try and smooth it out as best as possible. I had it in my mind the angle was something like 20 degrees but it may well be 45 as above. There should be alignment marks on the propshaft tubes themselves. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted May 19, 2015 Author Share Posted May 19, 2015 Thanks everyone. Today's task was to change the transfer case for a 1.2 from a Discovery, but while the props were off I decided to try to trace this vibration issue. As I said, the problem was at 65-70mph when accelerating and was pretty annoying. With the new transfer box fitted and the props refitted as they came off (but freshly greased, there was no apparent tightness in either before greasing) I took it for a test run out on our controlled environment closed test track where there was no sign of vibration up to 85mph, so as far as I am concerned the problem has gone away. Of course, it could be engine/damper/DMF/clutch/gearbox generated but since I will never drive above that speed in the real world the problem has now been solved for me. Perhaps it was the 1.4 transfer box, perhaps the extra gearing just fixed it by lowering revs. Anyone know what speed I might now expect to feel the vibration with the 1.2 in place of the 1.4, assuming it is engine related? I could revisit the test environment to conduct further tests to see if the problem remains at the same engine speed or if it was more likely transmission related. Cheers Chris Quote Link to comment Share on other sites More sharing options...
western Posted May 19, 2015 Share Posted May 19, 2015 one other thing, the sliding joints of each prop should be at the transfer box end Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted May 19, 2015 Share Posted May 19, 2015 Well Chris, the 1.2 gearing is 14% higher than the 1.4 but I'm too lazy to calculate the new speed and therefore the revs ? Mo Quote Link to comment Share on other sites More sharing options...
GBMUD Posted May 19, 2015 Author Share Posted May 19, 2015 I suppose that at 14% more than 65-70 will be the same revs? 74.1-79.8mph. Didn't vibrate. Chris Quote Link to comment Share on other sites More sharing options...
GBMUD Posted May 19, 2015 Author Share Posted May 19, 2015 Just had a fiddle with Nige's gearing calculator and with a little reverse calculation/guessing I make it 2500-2650RPM at those speeds which works well for a 14% difference with the different ratios. Chris Quote Link to comment Share on other sites More sharing options...
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