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Propshaft Phasing (or more accurately) out of phasing


Hybrid_From_Hell

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Hi All,

Now have new Clutch, new Primary box (Ta Dave at Ashcrofts :) ) and rebuilt T Box, ...so nearly there

When I picked up the front prop to fit the slider dropped out oh deep joy.. :( so I picked it up

and popped it back together "In Phase" - (no, there were NO Marking at all - how helpfull) and fitted it.

1st Test run shows a rumble felt at all speeds up through the Gear Lever - me wondering.....

Is a 90s front prop supposed to be in phase or out of phase ?

If out of phase how do you set it without any Guide markings, I seem to have in my

mind that out of phase is something like rear yoke being / must lead the front yoke by 2 splines ?

HELP Please !

Nige

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Nope

front should be about 30 degee out of phase, rear prop in phase

Defender workshop manual says ---

the univesal joints on the front porp shaft are, by design NOT assembled in line with one another, nevertheless the alignment marks on the sliding member & prop shaft must coincide when assembling.
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Nope

front should be about 30 degee out of phase, rear prop in phase

Defender workshop manual says ---

Well i knew it was one way or the other!

ill blame the hangover :)

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Bugger, when cleaning up my prop shafts on my project I actually pop marked the splines on the rear but forgot to do it on the front and only noticed when I went to reasemble.

I used the rear for comparison and fitted it the same (in line).

Not being lazy I just tried searching for previous threads but find the new search pretty cr*p compared to the last version :( (or is it just me?). It may be just operator error :D

Can Ralph (or anyone else) confirm exactly how the UJ's should be offset/aligned and is the positioning/alignment/offset of the grease nipples important?

Lucky for me I read this thread as I had never heard of this before :unsure:

Cheers

G :)

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OK :)

I can advise from today the results :

The rear propshafts on 90s and RRs etc is absolutely 100% IN PHASE - ie yokes in line

and the front prop, RR And 90s is 100% OUT OF PHASE

So for mine I set "In Phase" then pulled apart and set the lead UJ / Yoke (TBox end

1 spline is advance and went for a drive - no difference :(

removed and added 1 more = 2 spines in advance - drive = no difference

3 splines = :):D Gone

4 spines = back and different :(

So, front prop set at 3 splines in advance on lead Yoke.

as to if this is 100% as it should be "Out" of phase I don't know but seems fine.

Maybe a grown up will be along with the conversion of 3 splines in terms of degrees which seems to be around 30 Degrees ?

Anyway,

With new (sh good ) flywheel, New ashcroft LT85, reselaed re bearinged re shimmed T Box

and new 3x Prop UJs and out of phase prop........ its like a new truck :D

Nige

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Hi Technically it should be 45deg out of phase, when a single U.J. is working (at an angle) it produces a 'torsional oscillation' at 4 times rotation speed. If the drive flanges are parallel then '0' phase difference as the oscillation at one end cancels the other. If you now introduce a different angle between the two ends the 'torsional oscillation' will not cancel out. You can 'phase' one joint in relation to the other but this only masks the inherent problem. As the prop angle at the diff end (front only) is approx zero (unless a lift kit has been added) the other (gearbox) end is constantly fighting it. Fitting a 'double cardan' at the gearbox end reduces the oscillation to that produced at the diff which is usually minimal. I thought LR front props had a 'King' spline to ensure correct alignment??. If your still reading this Nige has the practical approach which does work, kind of, double cardans are a pain particularly on a comp motor. Regards

Ian Ashcroft

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I did mine one or two splines only and it's quietened down totally...

It's definitely not 45 degrees out of phase and I've never found any arrows on the prop when cleaned up and on the bench.

As I've manageed to re-aling several times I can only assume there is no king spline as you suggested Ian...

I'll have a look at the spare in the garage tonight!

Neil

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