Front diff yoke movement.

**steveG** · 21st February 2014, 12:58 PM

Originally Posted by PeterH

SteveG, it's definitely inside the diff, the whole yoke moves, the uni joint is new, no movement of the uj at all.
I probably overstated the movement, had a close look yesterday, it is more like 1 - 2mm movement, I was only guessing at the 3 - 4mm I stated earlier.
It has no vibration at all under about 70 kmh, but as you get closer to 80 kmh and upwards it gets worse.
At the moment I'm only driving locally, I don't want to do any big trips until I have this sorted.

If the nut was to come loose it will allow the flange and bearing to move back slightly along the pinion shaft and allowing radial movement in the bearing.
Yes, the whole yoke would move and the movement would be from "inside the diff", but only because the bearing has been allowed to move away from its cup.

As I said earlier - its unlikely but not impossible. Quick to check and easy to fix if it was though.

Steve

**PeterH** · 21st February 2014, 07:27 PM

Just to clarify SteveG, when you say nut, are you referring to a nut inside the diff housing?
If so, I'll definitely check that out, but I have no experience with diffs, I'd need some guidance on what I was looking for if you can offer any advice.

**Outback 1** · 21st February 2014, 07:54 PM

He would be referring to the nut which holds the yolk on (outside)

**PeterH** · 21st February 2014, 08:15 PM

Sorry for all the questions, so I'm guessing I'd need to remove the front drive shaft to gain access to the nut in the middle of the yoke?

**steveG** · 21st February 2014, 08:21 PM

Yes, referring the nut that holds the flange onto the pinion shaft.

I'm not familiar with the P38 diff so am assuming its pretty standard like other LR diffs.

This is a older style LR diff but gives you the idea:

The shims set the bearing cones the correct distance apart, and the nut clamps the flange and spacer onto the whole lot to hold it together.
If the nut was to come loose then the bearing cones could move apart which would allow play in the shaft.

If the nut is still tight then most likely the bearings are stuffed.

Steve

**steveG** · 21st February 2014, 08:22 PM

Originally Posted by PeterH

Sorry for all the questions, so I'm guessing I'd need to remove the front drive shaft to gain access to the nut in the middle of the yoke?

Correct.

Steve

**PeterH** · 21st February 2014, 08:30 PM

Well then, I might just have a crack at that tomorrow! Will let you know the outcome. I'm searching for torque values for that nut, can't find any info on this.
Does anyone know what the front yoke nut should be tightend to?

**PeterH** · 21st February 2014, 08:54 PM

Looks like the diff drive flange should be 74 foot pounds/ 100 nm from what I can gather for a later model P38, with a 15mm bolt, apparently earlier versions had a nut that was tighter.

**Hoges** · 21st February 2014, 10:50 PM

A 12v rattle gun like the ones sold for undoing wheel nuts, is an excellent investment for undoing flange/yoke nuts/bolts. There's a safety issue also in that you don't need a long lever to crack the initial tension... also saves blooded knuckles etc in case something slips... how do I know this...?

**PeterH** · 22nd February 2014, 03:08 PM

Got under there today and checked the bolt, sadly it was tight. Tested it with the torque wrench and it did not budge.
So it looks like a good second hand diff centre going in next week.
Will keep you posted.

Thread: Front diff yoke movement.

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