AU UTE Diff RATIOS?

Gonz · 02-12-2008, 10:09 PM

I want to change my Diff ratio, ive got an XLS V8 Auto, im sure it might have like a 2.9? in it now.

What Diff ratio options do i have for my ute? im after something around 3.7's? also what spline numbers do they come with? ill need a strongish set up and cant afford a 9" atm.

anyones help who may have the answer or experience with having changed there own ratio (info on road speed/RPM etc) will be much appreciated,

cheers,

Gonz.

The Monty · 03-12-2008, 03:11 AM

It would have 3.08's.

If you get different diff gear, dont get the cheap ones off Ebay, they are old and weak.
Your options are 3.23, 3.45, 3.73, 3.89, and 4.11's.

Gonz · 04-12-2008, 08:56 PM

cheers...

whats better as i need to use this ute for a daily drive this coming year so it will see plenty of freeway driving, will the 3.89 be too much or should i just go with a 3.73??
what RPM will it have at 100km/h with either ratio?

i am a 4 speed Auto!

Gonz.

StealthAu · 04-12-2008, 10:19 PM

Quote:

Originally Posted by Gonz

cheers...

whats better as i need to use this ute for a daily drive this coming year so it will see plenty of freeway driving, will the 3.89 be too much or should i just go with a 3.73??
what RPM will it have at 100km/h with either ratio?

i am a 4 speed Auto!

Gonz.

Firstly I'm pretty sure all utes got 3.23's from factory except the xr's which had 3.45's. On the highway at around 105k's I sit on around 2500rpm with 3.89's and auto

schuldiner · 04-12-2008, 10:38 PM

positive the utes got 3.23's(except xr's) as thats what came in mine. i've just put in some 3.7's and i reckon my speed is out by about 15% and at about 110kmh i'm pulling 2,500rpm. this being an increase of about 300-400rpm(manaul) i couldn't see the 3.89's being more than another 50rpm. there is a calculator floating about i'm sure someone will pop in and give you a link. i purchased a new speedo gear for $12 from ford and the guy reckons every extra tooth on the gear is worth about 5-7% which sounds right as i was told to get the black gear which has i think 23 teeth as opposed to the grey gear with 21 teeth which is in my gearbox at the moment. i was told anything more than 3.7's in a non xr diff will involve modifications to the housing which will make it more expensive.

Gonz · 05-12-2008, 09:38 PM

Quote:

Originally Posted by schuldiner

i was told anything more than 3.7's in a non xr diff will involve modifications to the housing which will make it more expensive.

hmmmm, ill have to look into that!!

and yeh, i was going to ask about the speedo gearing, do they cater for 20" wheels?

cheers,

Gonz.

DoreSlamR · 05-12-2008, 09:48 PM

What about LSD on an XLS? did it get the XR8 ratio?

schuldiner · 06-12-2008, 03:29 PM

as far as i know the XR was the only one that got the 3.45's otherwise you would feel your buying an XR just for the different bodykit they need the slightly higher ration so they pull a bit harder. or at least thats how i've figured it. with the 20 inch wheels if you find the calculator thing i believe you input that as well. i dontk now for sure but i think 20's would throw your speedo out just enough to maybe compensate for 1 extra tooth on the speedo gear. the other option is to go to jaycar and buy a corrector box for about $50 someone posted a part number on here some time ago. otherwise i was told bya company i could buy what seems to be that same box for $250 so i figured even if i cocked up the $12 gear a few times it'd still be less than half the price i was orignally quoted.

5.0 ED · 06-12-2008, 06:53 PM

its easy to calculate, just take your rpm at 100 devide it by your diff gears, and then times it by the new ratio and it will tell you your new rpm at 100

So if your doing 1950rpm at 100kph with 3.23's
1950/3.23 = 603.72
603.72*3.73 = 2251rpm
603.72*3.89 = 2349rpm

CRAIGAU3220 · 06-12-2008, 07:17 PM

Just got a quote from a diff shop in perth, to go from 3.45 to 3.9 and he said nothing about mods to diff housing, Said they had done quite a few to 3.9 ratio.
Drive in drive out $ 1350.00, That's with motive gears.
As far as speedo correction goes i have the luxury of a flash tune box so he referred me to a speed shop down the road from them, they will correct it for a carton !!

5.0 ED · 06-12-2008, 07:32 PM

Yes 3.89's and 4.11's go straight into normal diff housing, have done both before.

Gonz · 06-12-2008, 11:14 PM

Quote:

Originally Posted by 5.0whiteaughia

its easy to calculate, just take your rpm at 100 devide it by your diff gears, and then times it by the new ratio and it will tell you your new rpm at 100

So if your doing 1950rpm at 100kph with 3.23's
1950/3.23 = 603.72
603.72*3.73 = 2251rpm
603.72*3.89 = 2349rpm

cheers, your the man, once i get home ill check what ratio i currently have and go from there, i thought i had like a 2.9 or something, it feels so high, it does sit under 200RPM at 100km/h, i know that much!!

Quote:

Originally Posted by CRAIG, AU3 220

Just got a quote from a diff shop in perth, to go from 3.45 to 3.9 and he said nothing about mods to diff housing, Said they had done quite a few to 3.9 ratio.
Drive in drive out $ 1350.00, That's with motive gears.
As far as speedo correction goes i have the luxury of a flash tune box so he referred me to a speed shop down the road from them, they will correct it for a carton !!

so they supply the gears and bearings? $1350.00, sounds like an ok price to me! what shop did you go to? so i recon if i just give em the diff, gears and bearings it should come well under $600 i would like to think?

cheers,

Gonz.

CRAIGAU3220 · 07-12-2008, 12:29 PM

Wa Diff Centre Ph 9314.2303

Gonz · 07-12-2008, 08:04 PM

cheers craig, ill let you know how i go with them!!

Gonz.

FGII-XR6 · 07-12-2008, 08:19 PM

here is a speedo calculator that makes it easy http://www.fordmods.com/forums/Speedo-Calc-d30.html

CRAIGAU3220 · 07-12-2008, 09:26 PM

Quote:

Originally Posted by Gonz

cheers craig, ill let you know how i go with them!!

Gonz.

No prob's

Gonz · 09-12-2008, 12:19 AM

Quote:

Originally Posted by au3xr6

here is a speedo calculator that makes it easy http://www.fordmods.com/forums/Speedo-Calc-d30.html

ahh, sweet, you guys are all over it, thankyou very much, ill post up what the out come was!!

cheers,

Gonz.

superroo · 09-12-2008, 11:50 AM

The housing problem is only with the sedans 3.08 sized housing. It is smaller than the 3.23 or 3.45 housing.
Hence when people go to put 3.45 or 3.73 into their standard sedans, it doesn't fit due to the gear set being bigger than their old set.

Cheers

Gonz · 12-12-2008, 10:43 PM

excellent, well thats good to know, you lot are a wealth of knowledge!! all i need to do now is find the gears!

cheers,

Gonz.

StealthAu · 13-12-2008, 08:13 AM

Quote:

Originally Posted by superroo

The housing problem is only with the sedans 3.08 sized housing. It is smaller than the 3.23 or 3.45 housing.
Hence when people go to put 3.45 or 3.73 into their standard sedans, it doesn't fit due to the gear set being bigger than their old set.

Cheers

I had no issues, I was asked what my ratios were and when I told them they advised they had the issues with the 3.23 housings.
Who knows.....