Rover front prop shaft uni phasing question.

[up2nogood]

Thought I'd bring this question in here.

We have established that all front prop shafts on RR & Disco's (correct me if I'm wrong) are set up out of phase from the factory.

What I don't understand is why my Discovery series 1 vibrates if I put a measly 2" spring lift in it and Range Rovers don't?

D2's are OK, because they have a double cardan joint in them. But what about Rangies? They don't have double cardan joints?

I even asked Dobinsons (when I got the springs) and they said they don't recommend a 2" spring lift in D1's because of the vibrations from the front shaft.

I'm trying to find a solution that doesn't involve spending $700 odd at Hardy Spicer!

[Reddo]

Hi

We have a 2" spring and 2.5" body lift in out D1 and so far no bad vibes at all.

Had one front UJ vibrating with slight wear accentuated by the increased drive/UJ angle, and no doubt a lack of grease on dissasembly. Replaced and it's all good now. Can't see why u would have a problem unless the shaft is out of balance, or the UJ/Splines are already worn, or maybe the bearing on the pinion or TC output is slogged out??

PS I put the UJ in phase - cause the Disco books says to do so. Only some RR models (Vogue?) recommend slight out of phase UJs, and no one in the whole world knows why LR did this.

PPSD also had some loose bolts on the rear UJ/TC flange interface that cause a similar bad vibe. Easily fixed!

[up2nogood]

PS I put the UJ in phase - cause the Disco books says to do so. Only some RR models (Vogue?) recommend slight out of phase UJs, and no one in the whole world knows why LR did this.

That's probably the source of my vibration with the 2" lift. Both my Disco's have the front shafts out of phase. I have no idea why, except for angle compensation?

The thought was that if you aligned the unis correctly the shaft would vibrate. But that's not the case with yours, so I reckon that might be the answer to my problem!

[shakes]

alot depends on the condition of the uni as well - if it has worn into itself at the std height and the you lift it, the UJ is still trying to run at its original angle if that makes any sense?

I had massive vibes after I lifted my swb patrol, turned out to be uni's were a lil worn.

Simon

[up2nogood]

No discernable play in the unis.

Gonna try rephasing and see what happens.

[rick130]

Defender front shafts are phased

The front shaft which is shorter than the rear is
’phased’, with the joints at each end, A and B
mis-aligned as shown.
The phasing is necessary on the front shaft only to
allow for greater variation in angular changes.

[tony cordell]

re phasing a standard prop is a waste of time
you need a D2 prop or a bespoke double cardan one made
see propshaft section here for details pics etc:
http://forums.lr4x4.com/index.php?showtopic=4731

[up2nogood]

But I only want to lift 2". How come Rangies don't have this problem with a 2" lift, or do they?

[Bush65]

No problems with my disco I.

The u-joints on the front driveshaft should be out of phase.

The reason is the engine and transmission slope down toward rear.

When u-joints are in phase, they should also be parallel. This is great for the rear drive shaft, just point the diff pinion up so it is parallel with the transmission.

But for the front, the diff pinion would have to slope down, which increases the angle of the driveshaft (bad!!).

The rotational out of phase of the front u-joints cancels the affects from not being parallel.

This is not usually a problem with a lift, unless you fit castor correction bushes or radius arms.

The only way to correct the castor, without affecting the driveshaft, is to rotate the swivel balls.

[ISUZUROVER]

The u-joints on the front driveshaft should be out of phase.


The reason is the engine and transmission slope down toward rear.

Are you sure? I though it was that the diff nose was pointed up. Series LRs had equal UJ angles at the front and unis that were in-phase. I fitted a Stage 1 diff/axle to my IIA, which is angled up like rangie/110/disco diffs. On the stage 1 they ran a double cardan front prop to solve this, but I just installed the front prop out of phase and had no problems.

[Bush65]

The u-joints on the front driveshaft should be out of phase.


The reason is the engine and transmission slope down toward rear.

Are you sure? I though it was that the diff nose was pointed up. Series LRs had equal UJ angles at the front and unis that were in-phase. I fitted a Stage 1 diff/axle to my IIA, which is angled up like rangie/110/disco diffs. On the stage 1 they ran a double cardan front prop to solve this, but I just installed the front prop out of phase and had no problems.

Yes, as sure as I am that the Pope is catholic.

With coil sprung rovers (possibly because of more upward travel of the front axle), the engine is raised up at the front (engine and transmission slope up down toward rear). So the front output shaft from the t/case points up.

To have u-joints in phase, the front diff pinion would have to slope down. But this would increase the angle of the u-joints and axle droop would have to be restricted.

All coil sprung rovers, except those with double carden jointed driveshafts or independent front suspension, have the u-joints on the front driveshaft out of phase, to compensate for the u-joints not being parallel.

The angle that the front diff pinion points up is important to avoid vibrations of the front drive shaft.

The radius arms ensure that the diff pinion angle increases as the springs lift the front and the angle of the u-joints increase. When people fit castor correction radius arms to lifted rovers, they often get vibrations in the driveshaft, because the angle of diff pinion is altered.