The Top Mitsubishi Galant VR-4 Resource

Join the best E39A 1991-1992 Mitsubishi Galant VR-4 community and document your GVR4 journey.

  • Software Upgraded - Reset Your Password to Login
    In order to log in after the forum software change, you need to reset your password. If you don't have access to the email address you used to register your GVR4.org account, you won't be able to reset your password. In that case, follow the instructions here to regain access to the forum.

Rear diff ratio

GTX

Well-known member
Joined
Apr 13, 2012
Messages
100
Location
Toronto, Canada
Hi all,

This question if for you, trans-axle gurus:

I have a W5M31 transmission, which corresponds to 1991 N/A AWD Galant. I need to find out what ratio is in my rear differential (it is one the car and there are no labels on it). So far I was able to find the following:




I have a feeling I have 3.545 ratio in the 3 bolt open diff on the car, since it is a N/A engine and I found some references to that. However, I dont want to ruin my central viscous diff by putting in rear 3 bolt Viscous LSD (B17 3.545) in case I'm wrong. Theoretically I could rotate one wheel and see how many revs the drive shaft would make. 3.545 ratio should give me 4 to 7, and 3.9 diff should give pretty much 1 to 2, but I think there is an exact info somewhere in your heads /ubbthreads/images/graemlins/smile.gif

many Thanks!!
 

EMX5636

Well-known member
Joined
Jun 28, 2008
Messages
1,631
Location
Bucks County, PA
We just had a similar question in here from a guy with an Eagle GTX in Canada. I'm pretty sure they are the same ratio as the Galant GSX which was like 2.8xx something.
 

GTX

Well-known member
Joined
Apr 13, 2012
Messages
100
Location
Toronto, Canada
so, if that is correct, then I cant use 3.545 diff unless I change my front diff to the required one. My central diff might seize up, right?
 

89Patches

Well-known member
Joined
Jan 30, 2013
Messages
723
Location
Ontario Canada
Yup you'll end up killing your center diff.


If I were you I'd ditch the stock trans and look from a JDM trans with a 3.909 final drive and swap the rear diff gears for 3.909. Since your N/A right? it would really wake your car up having the shorter final drives.
 

slugsgomoo

Well-known member
Joined
Oct 16, 2003
Messages
3,776
Location
Tacoma, WA
Pretty sure the turbo final is 4.929 and the GSX final is 5.208, which means that he'd get some fuel economy due to dropped RPM, but the taller gearing would make it less peppy.

Honestly you could just swap the ring & pinion from your current diff to the turbo diff, and be fine, if I'm remembering right.
 

GTX

Well-known member
Joined
Apr 13, 2012
Messages
100
Location
Toronto, Canada
My goal is to have LSD. I have another 4g63t, but no gearbox for it. Have to put on my thinking cap what to do. Powerfull engine with short gears is the goal.
 

89Patches

Well-known member
Joined
Jan 30, 2013
Messages
723
Location
Ontario Canada
I am talking the final drive of the diffs being 3.909.


GTX: There is a guy in Scarborough that has a JDM trans but it will have to be taken apart to put the 3.909 ring gear back in (which he has) And I also have the 3.909 rear diff gears.
 

GTX

Well-known member
Joined
Apr 13, 2012
Messages
100
Location
Toronto, Canada
Thanks "89patches"! PM sent. Thanks everyone, you are so helpful!!!
 

cheekychimp

Well-known member
Joined
Apr 19, 2004
Messages
7,333
Location
East Sussex, U.K.
When I was messing about with the gearing on my project car, I was trying to do a hybrid gearbox using both the GGSX final drive and 3.909 gears. I remember that one of the reasons that we couldn't make it work was that the rear ring and pinion gear from the GGSX would not fit over a standard EVO III/VR4 LSD.

If you go with a standard VR4 diff then you probably will need to mess about changing gears etc so that you can use the 3.909 or 3.545 rear ring and pinion so that it fits over the LSD body.
 
Last edited:
Support Vendors who Support the GVR-4 Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications RixRacing RockAuto RTM Racing STM Tuned

Recent Forum Posts

Top