Prop Shaft Orientation.

keynsham1

Active Member
I am just reassembling my prop shaft. When the sliding end is fitted, it goes on by aligning two arrows so that the end is aligned correctly with the main shaft. But interestingly according to the manual, this makes one end of the prop shaft 144 degrees out of line with the other! I know that when a prop shaft is not in perfect alignment, the ends then to speed up and slow down during a single rotation and so it is common practice to have them out by 90 degrees (I seem to remember) to counteract this, but 144 degrees is odd! Weirder still, the earlier cars with final drive suffix A are out of alignment by only 107 degrees!

Can anyone enlighten me on why these unusual angles are required?

Rover Book1.jpg
 
It's all to do with vibration issues caused by the long pinion shaft IIRC. Because the driveshafts are equal lengths the centre of the pinion flange isn't on the centreline of the car. When the diffs were modified the angle of offset was changed at the same time. Rover did like to over engineer stuff. I just line up the arrows , without reading too much into it and the job's a goodun. I don't ever remember massive vibration issues even when they were't aligned correctly, which a lot weren't. Still it was always another little job for me.
 
If the two connecting end flanges are not parallel the yokes have to be offset to keep the two running at more or less a constant velocity . When the 90/110 land Rovers were introduced the front prop has the yokes out of phase because the front diff is angled upwards. Mechanics used to working on the old Series vehicles , which had the yokes in phase , were doing the same on the 90/110 creating significant vibration issues .
 
I had assumed it was to do with vibration issues. They were certainly sticklers for detail though. It is hard to imagine that slight change in orientation could have had much effect, but I suppose it is a sum of a number of components which set up vibration so to be successful, all need to be removed however small!
 
Mechanics used to working on the old Series vehicles , which had the yokes in phase , were doing the same on the 90/110 creating significant vibration issues
o_O I had my prop-shaft modified by a prop-shaft modifying company, as soon as I handed the standard prop-shaft over the counter, they spotted the yokes were out of alignment. It never occured to me they should be.
The modified prop-shaft has been running with yokes inlign. :oops: I have a vibration, above motorway speeds, when on private or closed roads.;)

just line up the arrows , without reading too much into it and the job's a goodun.
Harvey where are the arrows? Are they obvious, I've not looked for them yet?

G
 
Harvey where are the arrows? Are they obvious, I've not looked for them yet?

G

The one on the short yoke is normally in line with the grease nipple, the one on the prop is on the tube, within an inch of the weld joining the tube to the splined section. The arrows themselves are about 1/2" long, and the head is about 1/8" wide.
 
The arrows on my propshaft are shown below. They are stamped in very lightly. I had to look carefully to see them!! On the yolk as Harvey says, in line with the grease nipple and on the wider part of the shaft itself.

Shaft 1.jpgShaft 2.jpg
 
My old 3 litre had a vibration on pull-away which Jon Backhouse quickly traced to the prop' arrows being out of alignment. And to paraphrase Harvey, the job was indeed, a good'un.
 
Are folks finding the arrows line up EXACTLY ?
Mine don't. I can go a little one side or the other.
 
There is a tolerance on the angles 107 deg + 6 deg and 144 deg + 4 deg. I imagine this is because the arrows don't always perfectly align.
 
When I was scrutineering open wheeler race cars it was quite common to see misaligned UJs on short drive shafts, and I often wondered how long they lasted, but it wasnt a safety issue so I never questioned it. For my money the best type of prop shaft is the double CV jointed ones as used on the SD1.
 
Just got a P6b auto propshaft for my Lt77 conversion. The UJ yokes were exactly aligned, not matching the arrows - about 2 splines off. Took a while to locate the arrows, the marks were very light and incomplete. The UJ at the diff end was knackered.
 
Back
Top