XP Falcon diff change ?????

[Anonymous]

Hi Guys
I own an XP falcon with an XC 250, 3 spd borg worner and is sill running the origional diff (4.00:1).
I have been kicking the idea around of replacing the diff to get the revs down on the open road (better economy, less engine wear etc, but don't really want to lose the bottom end power!
The two types of centre replacments i am looking at are 3.08 or 2.92.


Would it be a wise move to do the swap?, which size would be best?
And will i notice alot of bottom end power loss?

Thanks

 

[addo]

BY three speed BW, do you mean manual or auto? Column or floor shift? And is the motor stock?

 

[Anonymous]

It is a 3 spd auto, floor shift.
The engine has a 2 brl 350 holley, mild cam and extractors.

 

[addo]

OK, that's more help! Probably around 3.23 or so would be ideal; 2.92 could get a little sluggish off the mark unless that's not an issue. You might find (they are reasonably available) an XM/XP centre with 3.25 to swap in.

 

[Anonymous]

Thanks mate.
So you think all in all i should ditch the 4.00:1, it would be the best thing for the overall performance, engine wear, enconomy etc.

 

[addo]

The 4.- ratio was made for mild load lugging, where speeds on the open road weren't a priority. Since your priorities are different to this design brief, it's best to make the vehicle suit you. An overdrive manual box would be a different approach; if the overdrive was .75, this is like going 3:1 anyway. Depends if you like the slushie or not.

 

[Anonymous]

I reckon i'll go for the 3.23, seems to be the best option for my current needs, planning to do some long open road trips this year anyway!
Thanks for your help mate!

 

[Anonymous]

You will find that the 3.2:1 diff was fitted to xm-p's that had the 200 super pursuit motors and as an option for the 170 pursuit. the 140,170 motors had a 3.5:1 std. and commercial vehicles got the 4.0:1. But that was nearry40 years ago and i'd say theres been a bit of swapping since then.