How do i know which diff i have?
Joined: Aug 1999
Posts: 19,282
Likes: 103
From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: How do i know which diff i have?
How the car was originally equipped and what's in it now are sometimes very different things. Years may have passed since the fluid in the diff was changed. Take this opportunity to do that and to verify your set-up:
Here's how to determine the ratio (jerk the diff cover and look): Numbers are stamped on the ring and pinion:
41 : 15 = 2.73
41 : 14 = 2.93
40 : 13 = 3.08
42 : 13 = 3.23
41 : 12 = 3.42
41 : 11 = 3.73
JamesC
Here's how to determine the ratio (jerk the diff cover and look): Numbers are stamped on the ring and pinion:
41 : 15 = 2.73
41 : 14 = 2.93
40 : 13 = 3.08
42 : 13 = 3.23
41 : 12 = 3.42
41 : 11 = 3.73
JamesC
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: How do i know which diff i have?
An 88 GTA 5.7L would have come with either a 2.77 9-bolt rear end, or a 3.27 9-bolt rear end. What RPM are you at in drive (not 4th gear) on the freeway?
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