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Old 06-20-2004, 02:57   #1 (permalink)
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Going from 3.23 to 3.73 Diff Gears

Just wanting opinions on anybody that has done there diff gears on a XR8 with another ratio like 3.73 or simular. Currently i have the stock gears which has 3.23 ratio. Is there alot of improvement? Any major change driving on the highway in revs and fuel? Whats it roughly cost to have gears done?
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Old 06-20-2004, 03:17   #2 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

i have 3.9's in the bum of my car. They are great. you get awesome acceleration.

I just do under 2000rpm at 100km/h, as the final gear ratio is 0.62, and the normal 5th gear ratio is 0.68.

Is yours Auto or Manual.
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Old 06-20-2004, 03:17   #3 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

I dont know whether this will help you or not, but i will post this anyways
I used to have 2.92 gears in my XD (302 toploader) and went to 3.25 gear set. I found that i got better fuel economy (go figure, probably because it takes less torque or force to move that amount over a certain distance). Take off was noticeably better (from losing to a vx by about half a car length, and then beating it by half a length). But there isnt much change in the highway cruisyness, i found that it was still very drivable, although your going for a more dramatic gear change.

Hope that helps.
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Old 06-20-2004, 03:18   #4 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

If it is a manual get 4.1's its awsome.
I have 5 speed with 4.1's in 5th on the freeway at 70mph the car is doing 2500rpm with 26"tires or 235/60/14's
Dont be scared of going to low the aceloration is awsome.
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Old 06-20-2004, 03:52   #5 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

Forgot to mention guys car is auto. Currently when i do 100km/h it sits well under 2000rpm. At about 110km/h i reach 2000rpm
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Old 06-20-2004, 04:40   #6 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

See if this helps you out. It's a spreadsheet I did.

Just change the diff ratio and tyre size to work out speed in gears at certain revs.

It's currently set up for C4 ratio's with an overdrive but you can change the ratios to suit any other box as well.
Attached Files
File Type: xls STROKEXD Gear Ratios.xls (26.5 KB, 45 views)
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Old 06-20-2004, 05:01   #7 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

Quote:
Originally Posted by Thomas
Forgot to mention guys car is auto. Currently when i do 100km/h it sits well under 2000rpm. At about 110km/h i reach 2000rpm

there has been alot of debate as to whether the auto will work with any diff higher than 3.45's.

I had 3.9's in with the auto, and it was acting really strange. i could have the pedal to the boards, and it wouldnt change out of first, (without power mode too). kickdown speeds were stuffed too.

eventually only 1st and 3rd gears were working.

you may be best to put in 3.45's if you dont intend to convert your car to a manual
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Old 06-20-2004, 21:34   #8 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

Quote:
Originally Posted by OED666
i have 3.9's in the bum of my car. They are great. you get awesome acceleration.

I just do under 2000rpm at 100km/h, as the final gear ratio is 0.62, and the normal 5th gear ratio is 0.68.

Is yours Auto or Manual.
What type of box are you running?
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Old 06-20-2004, 21:53   #9 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

i have a T5, with XR6T and V8 internals. Also the 5th gear ratio was swapped for a lower one
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Old 06-21-2004, 01:00   #10 (permalink)
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Re: Going from 3.23 to 3.73 Diff Gears

From what I've read, you can't do lower than 3.45 in EF/EL+ because everything screws up and it won't be cheap to fix..
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