changing diff ratios - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
Ford Forum Ford Forum

» Auto Insurance
» Featured Product
ยป Wheel & Tire Center

Go Back   Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > The Garage - Tech Forums > Trans | Driveline
Register Home Forum Active Topics Photo Gallery Auto Loans Garage Mark Forums Read Auto Escrow

FordForums.com is the premier Ford Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 07-21-2003, 04:19   #1 (permalink)
In a blue Galaxy
 
Cobra's Avatar
 
Join Date: May 2001
Location: Geelong, Victoria
Posts: 5,716
changing diff ratios

For anyone who has put in 3.73 or lower on thier falcon, was it worth it? I am thnking of 3.7 or 3.9 gears for my XR6 (EL), just wanted to know if it worked better on the quarter, and how much more it revs to on the hgihway. Mine sits at 2100rpm in 5th. I don't do many highways kays, only up to melbourne then and when. Although we would all love better fuel economy, it's not that much of an issue to me. I would use more fuel to go faster anyday!
__________________
O.F.R #12
1999 AU XR8
14.594 @ 94.40mph
152.2RWKW (APS dyno)
Switchable Shift Kit, K&N panel filter, Lukey straight thru mufflers, momo gear and steer,
DBA slotted rotors/Bendix ultimate pads (front), Pioneer MP3 head unit and BA XR carpet mats.

Member of the Society Against Stupid SMS Language
Cobra is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 07-21-2003, 04:29   #2 (permalink)
Registered User
 
302_supra's Avatar
 
Join Date: May 2003
Location: Brisbane
Posts: 605
i wouldnt go any shorter than a 3.7 My current diff ratio is 3.9:1 and imo it revved the toyota engine too high. I have decided that im going to change it to a 3.5 gearset when the 302 goes in.
302_supra is offline   Reply With Quote
Old 07-21-2003, 05:15   #3 (permalink)
Birth, Drift, Death...
 
Rollin's Avatar
 
Join Date: Jun 2002
Location: Drifting Brisbane...
Age: 32
Posts: 3,039
Re: changing diff ratios

the revs on the freeway also depend a lot on your gearbox ratios.

Cobra as you can see by the other thread in this section, im now trying to orgainse a 3.9 diff for my car, im getting a housing+ axles etc next thursday, it will depend on how long the shop takes to build it as to how long it will take to get in the car.

currently it sits on 2000rpm in 5th gear at 100km/h with 3.45:1 diff (which you also have as your car is an XR) and i figure it will sit on 2255rpm at the same speed with the 3.9s.

formula is:

rpm (at whatever speed you choose) divide by current diff ratio, then multiply by new diff ratio -

2000/3.45*3.89 = 2255

so if your 5th gear in your gearbox is the same as mine, you should have no dramas.

the only thing im wondering about is 1st - its already pretty short now, with the 3.9s it might be too low.

if you are willing to wait about 2 weeks i can give you a definitive answer.
__________________
Slick, Quick and Fulliii SIK!!!
Proud TQE Operator

197.4hp at the wheels, 14.505@152.46km/h
Tuning in progress...
*CLICK TO SEE MY XR6*
I can get new Genuine Holden/Ford/Audi/Land Rover/Honda parts cheap, PM me!
Rollin is offline   Reply With Quote
Old 07-21-2003, 07:19   #4 (permalink)
In a blue Galaxy
 
Cobra's Avatar
 
Join Date: May 2001
Location: Geelong, Victoria
Posts: 5,716
Re: changing diff ratios

Hey thanks Rollin. Yeah I anticipate your results. It's not like I need to know now or anything. Just trying to get info for a mod that i will eventually do down the track.
__________________
O.F.R #12
1999 AU XR8
14.594 @ 94.40mph
152.2RWKW (APS dyno)
Switchable Shift Kit, K&N panel filter, Lukey straight thru mufflers, momo gear and steer,
DBA slotted rotors/Bendix ultimate pads (front), Pioneer MP3 head unit and BA XR carpet mats.

Member of the Society Against Stupid SMS Language
Cobra is offline   Reply With Quote
Old 07-21-2003, 14:14   #5 (permalink)
Registered User
 
Join Date: Jun 2002
Location: queensland
Posts: 1,134
Re: changing diff ratios

Quote:
Originally Posted by Rollin
2000rpm in 5th gear at 100km/h with 3.45:1 diff (which you also have as your car is an XR) and i figure it will sit on 2255rpm at the same speed with 3.9s

the only thing im wondering about is 1st - its already pretty short now, with the 3.9s it might be too low.
For those interested, there is a way to fix this. You can build a direct bolt in replacement V8 spec T5 for an I6 with a 2.95 first instead of the 3.28 or 3.5 version. You can run an ultra high fifth gear also, so it will do 2040rpm @ 100km/h with 3.9 diff. This can be done with XR6T spec internals.
__________________
If you're not driving a manual you're really just steering.
WBT56 is offline   Reply With Quote
Old 07-22-2003, 00:35   #6 (permalink)
In a blue Galaxy
 
Cobra's Avatar
 
Join Date: May 2001
Location: Geelong, Victoria
Posts: 5,716
Re: changing diff ratios

Quote:
Originally Posted by WBT56
For those interested, there is a way to fix this. You can build a direct bolt in replacement V8 spec T5 for an I6 with a 2.95 first instead of the 3.28 or 3.5 version. You can run an ultra high fifth gear also, so it will do 2040rpm @ 100km/h with 3.9 diff. This can be done with XR6T spec internals.
Yeah but how much is that going to cost? The price of doing that would probably excessivly override the bit of extra fuel that you will save.
__________________
O.F.R #12
1999 AU XR8
14.594 @ 94.40mph
152.2RWKW (APS dyno)
Switchable Shift Kit, K&N panel filter, Lukey straight thru mufflers, momo gear and steer,
DBA slotted rotors/Bendix ultimate pads (front), Pioneer MP3 head unit and BA XR carpet mats.

Member of the Society Against Stupid SMS Language

Last edited by Cobra; 07-22-2003 at 00:37.
Cobra is offline   Reply With Quote
Old 07-22-2003, 00:53   #7 (permalink)
Registered User
 
Join Date: Jun 2002
Location: queensland
Posts: 1,134
Re: changing diff ratios

Quote:
Originally Posted by Cobra
Yeah but how much is that going to cost? The price of doing that would probably excessivly override the bit of extra fuel that you will save.
The cost would be no more than buying a rebuilt T5 anyway. The point was that you can go the low diff gears for performance in the first four, and still have the economy in fifth.
__________________
If you're not driving a manual you're really just steering.
WBT56 is offline   Reply With Quote
Old 07-22-2003, 02:41   #8 (permalink)
In a blue Galaxy
 
Cobra's Avatar
 
Join Date: May 2001
Location: Geelong, Victoria
Posts: 5,716
Re: changing diff ratios

Quote:
Originally Posted by WBT56
The cost would be no more than buying a rebuilt T5 anyway. The point was that you can go the low diff gears for performance in the first four, and still have the economy in fifth.
While having a more durable T5 aswell? XR6T runs the V8 gearset, but it's supposed to be able to take more torque too. How much better would this gearset be combined with the 3.9 diff for performance? And how much is buying a rebuilt T5?
__________________
O.F.R #12
1999 AU XR8
14.594 @ 94.40mph
152.2RWKW (APS dyno)
Switchable Shift Kit, K&N panel filter, Lukey straight thru mufflers, momo gear and steer,
DBA slotted rotors/Bendix ultimate pads (front), Pioneer MP3 head unit and BA XR carpet mats.

Member of the Society Against Stupid SMS Language
Cobra is offline   Reply With Quote
Old 07-22-2003, 04:22   #9 (permalink)
Registered User
 
Join Date: Jun 2002
Location: queensland
Posts: 1,134
Re: changing diff ratios

Quote:
Originally Posted by Cobra
While having a more durable T5 aswell? XR6T runs the V8 gearset, but it's supposed to be able to take more torque too. How much better would this gearset be combined with the 3.9 diff for performance? And how much is buying a rebuilt T5?
This is as good as the T5 gets. This is T5Z specs. This box with 3.9 diff is the same O/A first gear as an XR6 box with a 3.5 diff, so you don't ruin first gear. Performance increase will depend on state of tune and engine mods. A fully rebuilt V8 spec T5, with all new parts except for cases and mainshaft, will normally cost about $2200- $2400 outright. (no exchange)
__________________
If you're not driving a manual you're really just steering.
WBT56 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > The Garage - Tech Forums > Trans | Driveline



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
diff ratios and quarter miles.... Rollin Trans | Driveline 14 01-28-2003 00:21
XF diff and gearbox ratios? NZ Trans | Driveline 3 01-27-2003 02:17
Diff? Ratios? vbman187 Trans | Driveline 3 11-17-2002 22:15
Diff Ratios and Fuel economy smith Trans | Driveline 28 06-20-2002 03:49
Diff Ratios, Commodores etc. jaytyn Trans | Driveline 5 07-19-2001 15:37

Powered by vBadvanced CMPS v3.2.2

All times are GMT -7. The time now is 07:32.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.6.0
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.