9 inch diff

[GLENN 70]

The tru trac is a must for starters and the problem is the gear set ,its a real problem with noise from the gears these days no mater what brand . Where in Brisbane are you ? . If not way out and to far from the Gold Coast I could come and help you . Once a diff shop has the centre it might take a week for them to sort it out .. Ask Ryan / shelby mustro on here he had one done last year .

[GLENN 70]

Mert why would you take out the diff housing ?  Or do you think he should take the complete diff in to the shop and get them to do the job ? . No a bad idea and makes it an easier job but will need a 11/16 ring spanner or a tube socket for the U bolts .  Will still have to pull the axles and leave the brakes behind .

[mert]

I guess I assumed with a new centre restoring/painting the springs/housing and new bushes was part of the process..  you are right, not needed if you are OK to just pull the center and replace it... doing that saves a lot of work if you leave the leafs/housing in place.

I'm a "while I'm at it..." type...!   

[GT350Lad]

Thanks Guys, awesome replies and big help. Really appreciate it. I am in Brissy north side. I think I'll pull the center and get someone to put a tru track in with gears that I am still deciding.
Any other tips? I am looking forward to it

Cheers

[staddy]

GT350lad there are a few of us northside brissy if you get stuck , not hard to come around to give you a lift / advice etc . just call out , cheers

[GT350Lad]

Thanks guys, much appreciated.
I wonder now how the GT350 drivers tolerated the 3.89 ratio? Quick but bloody high revs

[mert]

Quick but bloody high revs

Yep.  Gotta remember the late 60s muscle era in the US was based on stoplight-to-stoplight speed, 1/8 of a mile in a straight line was the focus... not anything resembling a well-rounded, good handling, "performance" car.

One set of original specs, not impressive by any measure in comparison to today's standards. 

0-100 19.0 secs
Quarter Mile 15.6 secs @ 94 mph
Top Speed 124 mph @ 7,000 rpm
3rd gear 107 mph @ 7,000 rpm
2nd gear 76 mph @ 7,000 rpm
1st gear 50 mph @ 7,000 rpm

[GT350Lad]

Yeah they are brutal figures, quick to 60mph and revving the whole way!

[Richstang]

If you want a 9", just get one made up.
The 9" I had built up for my 66 coupe a year ago was made from a F100 big shoulder housing, you see F100 diff everywhere below $500 complete and most from the factory had 3.55 gears and 31 spline, just use the F100 centre and change it over to 28 spline spiders/LSD/Lockright/etc. 3.55 would be great with a overdrive or maybe just bearable without for around town driving.
Only if I was going to do again I would stick with a small shoulder housing (F100 pre 73) as Mustangs are so small in the wheel well/axle hump area and it makes it hard to run the exhaust.
Supply your 8" diff housing and F100 9" housing and centre to a good diff builder and he can swap the centre of the housing from 8" to 9" and you can reuse you existing brakes and axles, no issues with U bolts at all too.
As for axles, Mustang 8" and 9" axles are week, you are more likely to blow a axle before a diff centre even with a 8" centre. Just use the axles as they are until you blow them (not that you would unless you are a drag racer)
When I had made up my Mustangs 9" diff I used a Galaxies 28 spline axles that are a lot stronger and heavier in construction and don't taper down after the splines, the smaller Galaxie axle became the new long and the longer Galaxies was cut down and resplined.
Do your research here and outside this forum. There are a lot of other things to spend on than a diff.
I have had 2 custom 9" diffs made up and have only $1600 in total tied up with them.