Diff centre nut size

[63 GT]

What size are the nuts that hold the diff centre in?
My car has a leaking pinion seal, so for a quick fix I thought I would swap out the centre with a set of 3:77's I had spare.
Whilst removing the 3:90's I found that I had to use a 9/16 spanner to remove the 8 nuts holding the centre in, my memory may be bad, but I was sure they should be 1/2 inch size. Anyways, the 3:77 wouldn't fit because the studs were to large to fit the holes in the diff centre.
Is this a Lotus thing, Or has my diff been modified?
My car has race history from the 60's and there are signs on the diff of other modifications. The brake backing plates have been drilled with many holes for cooling, the drums have had metal plates welded on the outside for balancing,the drums are stamped on the inside with L and R, there has also been a draind plug welded into the centre housing.

Does anyone know a part number for a pinion seal?
Cheers
Jay

 

[Neilsjuke]

Should be 5/16 unf that a 1/2 AF spanner would fit.
You may not have a English ford type diff put up some pictures better than a 1000 words
Neil

 

[lotustwincam]

I have a vague memory of seeing a service bulletin refering to drilling out the diff and axle to take larger studs. This was an attempt to stop the leaks in the A Frame/alloy diff days.

 

[tommy]

Aeroflow A frame cars use 3/8 studs instead of the normal 5/16, as they are prone to the heads pulling off, even with the 3/8 studs. The 3/8unf nuts are indeed 9/16 af instead of 1/2 af. I know my 65 aeroflow A frame original axle had 3/8 studs, not sure if a late pre aeroflow would be the same. I used long mini wheel studs for the job, when I built my new axle, as they are good and strong.
Just get the holes in the diff housing reamed out to fit and cut your own gasket with the bigger holes in it :wink:
Tommy

 

[63 GT]

No pics available yet.
But deffinately english ford diff.
I have 3 other Cortinas and an escort with similar diffs, I also have a collection of different ratio centres.
My Lotus is 65 A frame originally, but has had diff swapped with GT type with trailing arm mounts.
I'm guessing it was modified during its racing life.