9" diff conversion - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

XDman · 12-13-2003, 20:24

hi all
i was just wonering what would be involved with changing my 2.9 something ratio 10 bolt diff (LSD) to a 9" diff with say a good ratio for street light drag racing, my dad says you have to shorten the tail shaft etc is it really worth the effort to put a 9" in cause i geuss you could use the wank factor saying 'yeh.. i got a 9" '

ohh its going into a XD with a warm 302C

p.s. i dont have alot of knowledge on cars

Soxx · 12-13-2003, 20:45

9" goes into XD easy because XD's still have leaves.
You may need a tailshaft.

Rick.

mongrelEB · 12-13-2003, 20:52

I heard that the 9" diffs chew a lot of power - is that true or was I being bullshitted? :)

Soxx · 12-13-2003, 21:08

It was just discussed briefly in another thread the other day.
I'm of the view that the extra loss is extremely minimal, say 1% to 2%.
I know I could not feel a difference when I put the 9" in my XH.

Rick.

XDman · 12-13-2003, 21:54

in cairns some parts are hard to come by its very rare to find a nine inch'er with decent ratios and in good condition, so if i do find one, all i have to do is get a different tail shaft and everything should fit nice and easy?

clevo · 12-14-2003, 16:47

Also are you running drums or discs on the rear? Disc 9inchers are more expensive. With a 302 I'd go a 3.25 or 3.5 ratio.

If your XD is fairly stock your current diff should be heaps strong enough for a 302, even if it has 300hp. Don't change it of you don't need to.

Paul

XDman · 12-14-2003, 16:52

we managed to find an lsd with disc brakes but my mate rekkons hes never seen anyone break that diff only twisted an axle so apparently they are pretty strong, can you get different ratios without having to buy a new dif or is it too hard to get a different ratio with the same dif?

xdc351 · 12-14-2003, 21:10

I did not need a different tailshaft on mine, XD with a top loader and an XB 9".

A good ratio is 3.5:1 and gears can be changed in a couple of hours, my favourite place to get 9" parts delivered directly to your door is http://www.vpwmailorder.com and they sell every ratio you could ever really want.

My 9" likes to destroy seals instead of axles, but I haven't been able to kill it yet...

RevHeadRon · 12-15-2003, 05:11

i recently changed the 9inch out of my 81 fairlane and replaced it with a borgwarner one, tailshaft was the same length but the uni joints were different, and depending on what the previous set up was you may need to consider your handbrake cable, because the ones for disc and drum are different.

oh and before i forget if you go from having drum rear end and install a disc brake differential you might run into problems with the rear brakes sticking on this is because of a brake pressure valve in the Brake Master Cylinder which retains a small amount of pressure in the lines for the drum brakes.

DansEdgli · 12-15-2003, 12:27

How much would 9 inch conversion cost to get done in an XF, is a 9 inch really necessary? IS there any other alternatives? I would like to have disc brakes as well as i dont have them.

My XF has 351 in it.
Thanks
Dan