Is it a posi, & ratio?

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#1HotRod

Member
Joined
Aug 17, 2004
Messages
392
87 GN, 2nd owner, nice car w/ stock motor & drivetrain. Guess not all GN's were positraction?, this one peg-leg. Don't have build sheet. How can I tell if it's a malfunctioning posi, or is an orig. open diff; & gear ratio? Appreciate it.
 
If it is the original rear, check the option sticker on your trunk lid. The code for posi is G80.

Alternatively, you could jack the rear of the car up (with the front tires blocked, and the car in neutral). If it IS a posi, the tires will rotate in the same direction. If not, the tires will spin in opposite diections.
 
Thanx. I knew about tire rotation but don't know if they do that anyway when/if posi is broken. Guess GN's came with either differential. I'll look at the trunk stickers; you know the codes for gearing options?
Better yet...let's trade places (Spring in Hawii is Great!) & cars awhile & I'll test the difference :D
 
Originally posted by BLACK6PACK
stock is 3.42 which is perfect for our turbo cars.

I'll second that. There was no other code because they all came with 3.42
 
All 86 and 87 GN's came with the 3.42 gear ratio and the 8.5 inch rear. Some were open, not sure how many though. I know my 86 GN is open, and hate every second of it, lol. If it doesn't have the G80 on the trunk sticker, then its open.
 
Thankz guys. In the trunk I go, probably stuck with an open diff.
I'm thinking Maby a 3.73 would give greater accelleration, & fine on highway with od, but traction would only get worse. Although mine still sucks, I'm surprized (no, hopefull for) at some of the low 60 foot times. Y'll have good weekend.
 
The 3.73 MIGHT help acceleration in the first 100 yards, IF you can get traction. But would more than likely give slower times in the 1/4 mile. The 3.42 is perfectly matched for the stock tire diameter and transmission, and going away from it takes a lot of tuning to get back that "matched" performance.
 
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