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R31 ratio

Started by _youngy_11_ , Apr 25 2007 10:31 PM

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11 replies to this topic

#1 _youngy_11_

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Posted 25 April 2007 - 10:31 PM

Hi,

As alot you have know, ive fitted a Skyline R 31 diff to my LX torana.

Posted Image

From what i have read the diff should have a fairly short ratio either 3.89 or 3.7:1.

But i have taken the diff out to spray it and when i turn the crown wheel about 2.4 times the wheel studs do a full revolution.

Does this mean its a 2.4:1????? :cry:

I was holding he other wheel studs so only one was spinning while turning the crown wheel.

Differential - Ratios
From R31info

Skyline:

Manual (lsd and open)� : 3.7

Automatic (lsd and open) :3.89

Pintara (not sure on manual)� : 4.11

GTS2 (both auto and manual)� : 3.89

Speedo is driven off the gearbox, therefore putting a manual gearbox with an auto diff will put the speed out 5% (speedo will read higher than actual car speed).

From the skyline forumForum

Cheers

Edited by youngy_11, 25 April 2007 - 10:39 PM.

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#2 rodomo

To advertise here, call 13TORANA

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Name:R - O - B Dammit!
Location:Way out west of Melbourne Awstraylya
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Posted 25 April 2007 - 11:51 PM

I don't know much about your diff but I don't like the way your sway bar is mounted. I would rather see the flat plates welded and gusseted to the housing. I can see those "U" bolts wanting to move around the axle tube as the bar works. The sway bar doesn't naturally want to twist if you know what I mean.

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#3 _CHOPPER_

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Posted 26 April 2007 - 09:52 AM

To get the exact ratio for your diff, drain the oil and remove the rear inspection plate. Turn the crownwheel and eventually you will see the ratio stamped into the crownwheel. Clean up all surfaces, install a new gasket, re-install cover, torque bolts to spec and add sufficient oil.

Done.

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#4 _WYLDLC 6_

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Posted 30 April 2007 - 12:28 PM

What's onvolved with shanging ratios in a borg warner lsd diff. With 28 spline axles.
Cheers Chris

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#5 _JBird_

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Posted 01 May 2007 - 01:39 AM

Open the diff cover. Remove the axles. Remove the crown wheel and pinion. Reverse.

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#6 ls2lxhatch

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Location:Perth
Car:LX Hatch
Joined: 29-May 06

Posted 01 May 2007 - 02:10 AM

Tech article for determining diff ratio.
http://www.gmh-toran...ry_view&iden=15

To change the ratio on a BW is just a matter of replacing the pinion and crown wheel. However the pinion gear has to be shimmed into correct alignment with the crown wheel. This is a time consuming job that is best left to professionals. If not correctly aligned the crown and pinion will wear out prematurely.

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#7 _youngy_11_

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Posted 01 May 2007 - 11:00 PM

I took the backing cover off,

The numbers/letters stamped on the crown wheel were

0575 026 MR 3.91 BTRErq2

I think the ratio would be 3.91 with MR being Main Ratio or something like that??

Am i correct??

youngy

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#8 _youngy_11_

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Posted 04 May 2007 - 09:18 PM

BUMP. What do you's make of the code???

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#9 _rorym_

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Posted 04 May 2007 - 09:23 PM

Relax Youngy...Its a 3.9 ratio.
R

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#10 _TORANASS_

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Posted 04 May 2007 - 09:35 PM

When i changed the diff gears in my bro in laws VN SS we used 3.45 out of a VL BW and we also used the shimms that were in the VL diff and it lined up and the gears meshed perfectly.. BW isnt like a banjo or a 9" were you can udjust the lash it has fixed shimms.

Easy job to do.

John

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#11 ls2lxhatch

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Location:Perth
Car:LX Hatch
Joined: 29-May 06

Posted 04 May 2007 - 09:40 PM

It would appear that your ratio is 3.91 which is standard for a R31 auto.

You will find your diff at the bottom of this page. It is interesting to note that the BW is rated for a maximum of 220kw.
http://www.spiceraxl...roducts.htm#srd

Some more information.
http://www.thirdgen....know-about.html