Shortest ratio in an EF diff?? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Rmyers · 08-25-2004, 12:42

Hey guys, just wondering what are the shortest diff ratio's people have fit into there EF diff housings?? I was told that you cannot fit bigger than 3.45:1 in there?? Is this true?? I'm looking to get 4.11's but just need to know whether the information i was given was accurate... If not, are you able to use an EA housing instead??

Thanx in advance :)

jonbays · 08-25-2004, 15:27

3.45:1 is the lowest (highest ratio) fitted by ford but BTR do 3.73, 3.89' & 4.11 crownwheel and pinion sets.

3.7:1 are generally agreed to be the go for a street car with a manual. AN auto could go to 3.9 but auto's get tricky with the ecu controlling the change up speeds.

santoitaliano · 08-25-2004, 21:02

i have 3.7 in my car and it is a reallly great gearing with the 5 speed....

highly recommended.. if you can find it! heard that 3.7's are the rarest, then 3.9's are becoming rare... so 4.11's are the new thing...

NC Steve · 08-25-2004, 21:45

I have 4.11s in my Fairlane, but I think I overdid it a little when choosing the 4.11s. It takes off great but highway driving is a pain, so unless you have another car you can use for highway driving I wouldn't recommend 4.11s. Also cos it is reving faster and not moving as quick the car can overheat very quickly. If I was to do it all again would probably get 3.7s aswell just so it doesn't rev too fast on the freeway.

frdpwr · 08-25-2004, 22:24

in my ef ive got a set of 411's. they had to change the diff housing though. apparently there are tp types of housings one of them you can upgrade the gears and one you cant. all up it cost me 1100. for a set of gears, mini spool and change the diff. but its worth it cos it goes heaps better

INJECTED250 · 08-26-2004, 02:16

You can get the gears brand new if needed. there around 400

FPVWEPN · 09-02-2004, 18:08

yhe the ef housing is fine for 4.11's it holds my ed 4.11 lsd centre and works a treat in the manual :) contrary to what other people might say i feel that this is the best ratio if u dont really leave town like myself :)

TyreToaster · 09-02-2004, 18:48

Its funny you know, running 4.11s with the 4spd auto is the same as running 2.75's with a 3spd auto or 4 speed manual such as the single rail or toploader.

But you dont see to many of the non-overdriven owners complaining.

If you have 4.11's with the 4spd at 100kph you are doing 2500rpm.
If you have 2.75's with the 3spd at 100kph you are doing 2500rpm.

But everyone who has 4.11s thinks their car drinks more than say a 3spd with 2.75s would just becuase they have 4.11's.

jonbays · 09-02-2004, 19:49

never looked at this way of course but yes the maths are correct 1:1 3rd gear or top gear and 0.68 4th gear so a 2.75 / 0.68 = 4.04

Just shows what we get used too today.

I had a three speed manual floor shift VG hemi 2Brl Pacer in the 70's and you just forget what it was like really. You just remeber the good bits. Like before it caught fire and burned to a shell!

Walkinshaw · 09-02-2004, 20:33

Its just that people dont want to sit at over 1900rpm @ 100kmh thesedays, and anything over 9l/100 on the highway is shocking.

4.11 makes 1st on the auto a really good takeoff ratio, yet funnly enough its still not as low as say a commo auto with a 3.45:1 or 3.46:1 rear end.