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R180 Rear differential question

('06-'08) 
5K views 3 replies 3 participants last post by  fraktal 
#1 ·
I have the Suretrac LSD from a JDM SG9 STI

question, if you had 04 STI rear differential case could you put the SG9 STI rear suretrac LSD in it though the USDM 04 STI is DCCD?

or another option could you use a V7 WRX STI rear differential case which is non DCCD and put the SG9 STI rear Suretrac differential in it and make it work?

The rear SG9 STI diff case/carrier I got is damaged.

Thanks.
 
#2 ·
dccd only affects the center diff in the transmission casing, so dccd vs nondccd won't matter. all r180 cases should be the same, just make sure you user the correct ring and pinion gears to match your transmission/front diff (not sure if there were differences in gear ratio between impreza sti and fsti models)
 
#3 ·
There definitely is a difference,

03-07 JDM SG9 STI ratios - 3.636 2.235 1.761 1.346 0.891 0.707
01-03 JDM WRX STI V7 ratios - 3.636 2.375 1.761 1.346 1.062 0.842

03-07 JDM SG9 STI ctr diff: Viscous (4kgf) / front diff: A.P. Suretrac / rear diff: R180 Suretrac

01-03 JDM WRX STI V7 ctr diff: Viscous (4kgf) / front diff: A.P. Suretrac / rear diff: R180 Suretrac
 
#4 ·
the actual gear ratios in the transmission do not matter. you need to make sure you match the transfer ratio of the transmission with the proper final drive ring and pinion gear ratio in the rear differential. that is the "gear ratio" that funky was referring to.

so the real question is what transmission do you want to match this rear diff with? i'm assuming by your user info you still have the stock 5MT in your fxt?
 
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