Diff gears.

**Mont5.0** · 01-05-2008, 08:44 AM

G,day.
Wondering where and what to get for my 5.0. are 3.7's easily available?-car is 4 speed auto. what would be the best to get it off the line quicker but still drivable on freeway?

st33l3y · 01-05-2008, 09:20 AM

Mate, if you still want it driveable on the highway (i.e. not revving its head off) get a stall converter. That will definately get you quicker off the line.

**Mechan1k** · 02-05-2008, 08:20 AM

really ... 3.7s don't really bring the revs up too much when it comes to freeway speeds.

Several people on here have 3.7s ... and highway economy hasn't really changed.

What is in there now????
I can't remember what was used for the 8s and Fairmonts .. I doubt it would have been 3.08 though ... maybe 3.23 or 3.45.

What's it rev at now at 100km/h????

**Mont5.0** · 02-05-2008, 08:39 AM

about 1900rpm

**Mechan1k** · 02-05-2008, 08:44 AM

Hmmm .. sounds like you may have 3.08s in it then ... although yours is the 8.
My 6 is around the 2,000rpm mark at 100km/h and it has 3.23s in it.

If you can get a look ... there should be a label on the driver's side of the diff (may need a clean to read it) stuck on that will tell you the ratio.

**Mont5.0** · 02-05-2008, 08:52 AM

my ute used to sit at 2000 (xr6) and it was 3.45's. i am thinking they are 3.23-but you dont think 3.7's will make much of an improvement?

**Mechan1k** · 02-05-2008, 08:57 AM

I was really looking in 3.7s for the ute (as I have 3.23 now).
It would be great around town though with 3.7s ... just getting off the mark ... and in-gear acceleration would be better. Fords 1st gear is sooo long it is not funny anyway.

I don't think it would affect your highway running too much ... ask GK and Sly ... and a few others that may have 3.7s ... from what I have heard ... it's not as bad on fuel as people make them out to be.

**Mont5.0** · 02-05-2008, 09:00 AM

Fuel aint really my issue, its just the sluggish take off's that give me the sh!ts.

**Mechan1k** · 02-05-2008, 09:01 AM

Tell me about it ... try it on a factory LPG vehicle too ... LOL
Maybe 3.9s might be even better for launches

**Mont5.0** · 02-05-2008, 09:09 AM

Where would be a good place to start, as far as prices and availability. Out west would be good but your mate at liverpool may know?

**Mechan1k** · 02-05-2008, 09:23 AM

There's a good place in Smithfield ... can't think of the place off the top of my head ... might be Diff Technics or something ... I am pretty sure Stav might know though of the place ... it is in Long Street Smithfield.

EDIT: Gear Exchange Services ... 10 Long Street Smithfield.

DavesXr8 · 02-05-2008, 09:43 AM

I put 3.9s in the XR8 and it has been the best thing i have done i cruise at 100kph at 2250 my average fuel with easy driving is 13lt/100ks.

I had 3.45s in it before there is no more slug on take off now

:

**Mont5.0** · 02-05-2008, 09:47 AM

auto?

DavesXr8 · 02-05-2008, 10:04 AM

Yer mate she is an auto, best mod i have done to her.

MADED-6 · 02-05-2008, 01:38 PM

yeah mine has 3.9's and id suggest them fror an auto and 3.7's for a manual.
i had 3.7's in my ed and that was good but i recon 3.9's with an auto would still be to tall.
and yeah mine sits the same as davesxr8 on the highway.
cheers josh.

ratman · 02-05-2008, 01:47 PM

Borg warner do 3.73s and 3.91s for the Falcon diffs so they are easily available.
I went 3.73s in mine from 3.27s, it was a worthwhile jump (5spd manual) as with 3.45s you'd hardly notice the difference. 3.91s in an auto might be revvin a bit on the highway runs, though you'd definately have a lot more punch from the line.

blackers10 · 04-05-2008, 09:16 PM

i have a 2800 stall in my fairlane(its a 6 tho)
gives it ALOT more poke off the line

also Wadsymoo has a 2800 stall in his AU fairmont ghia V8 (has the 200kw motor and a cam in it)
and it boogies off the line quite nicely

just means the car revs harder to get going but its not stupidly annoying like a 4500 stall would be