7 and 7 1/2 Inch diff

[Dave Eastwood (Gadgetman) - Club Chairman]

And just to return to the original question, the 7 and 7.5 refer to the size of crown wheel. Hence the larger crown wheel and pinions being stronger. (Some of the American Ford diffs go up to at least 9", that I've heard of, anyway).

Its a common misconception that the size refers to the crown wheel, whilst they do differ, 7" ad 7.5" reflects the size across the diff casing where the main top bolt goes through.

That's what I originally though too, but was told by many that it was a common misconception...  

[stu999]

And just to return to the original question, the 7 and 7.5 refer to the size of crown wheel. Hence the larger crown wheel and pinions being stronger. (Some of the American Ford diffs go up to at least 9", that I've heard of, anyway).

Its a common misconception that the size refers to the crown wheel, whilst they do differ, 7" ad 7.5" reflects the size across the diff casing where the main top bolt goes through.

That's what I originally though too, but was told by many that it was a common misconception...  

Gadgetman 8s correct. The misconception is that it refers to the casings.

Early Sierras had 6" diffs. And 9" diffs were/are available for big power Cossies

[amgas]

So what does it take to fit a 7.0 inch differential in place of where the 7.5 one was?

Swapped mine over the winter - not too bad to do ( but a lot harder than when fitting a diff to a new chassis )

Basic steps as I remember them are :-

1) Loosen propshaft to diff bolts with handbrake applied

2) Unbolt drive shaft lobro joint bolts from diff then remove propshaft to diff bolts

3) remove rear stabiliser to diff bolts, remove chassis to diff bolts, lift out diff

4) Remove and replace diff with new one - to change to a 7" you will need a spacer and threaded shaft at the top of the diff - factory can supply

As with anything it sounds easy, but is more fun when you have restricted access etc. In my case the job also involved removing and re-fitting the following to gain access :-

1) RAC roll bar brace bars to remove boot box

2) Fuel pump to gain more space to remove diff

3) Top panel of centre tunnel to gain access to propshaft bolts ( made easier because I had made it removable when building, but could be pop riveted in place )

4) Passenger seat - had to do this to remove seatbelt, which was needed to remove carpet to gain access to top of the tunnel ...

The above might have been easier if I had better access under the car, but most of this was done from above the car, in a single garage with the car still on its trailer