Diff Replacement

[stuffedpike20]

Hi everyone.
Can I ask, how far do you have to pull out the half shafts in order to be able to remove the diff?

Thanks, John.

[philthehill]

About 6 " each side.

[stuffedpike20]

Brilliant. Thanks Phil.

[stuffedpike20]

One more question if I may..... the main diff gasket, the big round one, would you put it on dry-or use some sort of gasket goo to seal it?
Thanks, John.

[philthehill]

As regards the diff gasket - just lightly smear both faces with grease - no need for goo.

If you are thinking of pulling the diff to check the crown wheel and pinion ratio there may be no need. The ratio/tooth numbers are stamped on the diff nose casing at or near the top on the outer face of the bolt flange. Not easy to see but may be better (and easier) than pulling the diff.

[stuffedpike20]

Thanks Phil.
I am getting round to finally fit a 3.9 diff that I bought some time ago. I posted about it a while ago, and I am still concerned that there is too much play in it.
The outside of the flange moves about 8mm before contact, which seems a lot to me, and I am concerned that the 'whip' created when taking up the drive might snap a half shaft.
I was reassured last time I posted that this would not happen, so I am going to try it and see.
Thanks, John.

[philthehill]

The three things that cause a half shaft to snap are:-

1. Letting the clutch out sharply with high engine revs.

2. Driving hard which results in a wheel lifting, spinning through no contact with the road and then dropping down contacting the road resulting in a shock loading of the half shaft.

3. Constant axle tramp resulting in shock loading to the half shaft.

All three of the above can contribute to eventual failure of the half shaft.

8mm at the periphery of the pinion drive flange I would not consider excessive.

Fit the 3.9 and be dammed

[stuffedpike20]

Thanks Phil.
Someone gave me a 4.2 diff with much less play, which is why I was concerned.
Are pickup half shafts more likely to break than other minors? Seem to get more axle tramp from my pickup; is that the light back end, or just my bad driving?

[philthehill]

The half shafts are the same whether they be car or pickup.
The lightness of the rear end of an pickup does not help and is compounded by the stronger road springs.

The only way to overcome the possibility of a broken half shaft is to fit stronger ones which are available from the usual suppliers.

[stuffedpike20]

OK. Thanks Phil.

[stuffedpike20]

I went to fit my diff today, and the gasket did not fit.
I bought two gaskets a couple of years ago and put them in my dry shed, but they seem to have shrunk.
I tore one when fitting the diff.
Is there any way of un-shrinking the remaining gasket?
Thanks, John.

[philthehill]

Try soaking it in oil overnight.
When fitting the gasket lightly smear with LM grease on both faces.

[stuffedpike20]

Thanks Phil!

[philthehill]

Another solution to the shrinkage problem is to soak the paper gasket in water for a short period of time.

Now I must go and check those diff gaskets have in the cupboard.