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How to tell between S2 and S3 disk rear?

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Old 10-24-07, 03:14 PM
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How to tell between S2 and S3 disk rear?

There is a 7 at the local junkyard that has been modified. It has disk brakes in the rear and an s3 dash, but the junkyard is claiming it is an 83. IIRC, the s2 had smaller axles.

What I want to do is swap the rear into my 85 GS. Is there an easy way to tell the difference between the s2 and s3 disk rears?
Old 10-24-07, 03:28 PM
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Originally Posted by Sgt Fox
There is a 7 at the local junkyard that has been modified. It has disk brakes in the rear and an s3 dash, but the junkyard is claiming it is an 83. IIRC, the s2 had smaller axles.

What I want to do is swap the rear into my 85 GS. Is there an easy way to tell the difference between the s2 and s3 disk rears?
81-83 all had smaller axles.
84-85 had larger axles.
Up to Early 83 had the small driveshaft flange
After that point they had the larger driveshaft flanges.
If the driveshaft flange is the same as yours then it is the later models.
Old 10-24-07, 03:37 PM
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Does anyone have the measurements of the flanges so I can quickly measure them?
Old 10-24-07, 03:40 PM
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Large flange mounting surface is 3 1/4, bolts center to center are 2 5/8.
Old 10-24-07, 03:48 PM
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Thanks. I assume that the small flange is significantly smaller?
Old 10-24-07, 11:11 PM
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if the holes in the flange are threaded its a small flange
Old 10-25-07, 04:19 AM
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If they are vented they are '84-'85 GSL-SE.
Old 10-25-07, 04:57 PM
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Originally Posted by aws140
if the holes in the flange are threaded its a small flange
Correct. Threaded holes = small flange. Non threaded holes = large flange. Also, the threaded holes are not in a true square pattern, they are rectangle, while the non threaded holes are square.
Old 10-25-07, 05:07 PM
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Old 10-25-07, 06:15 PM
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Be aware some 83 GSLs had the bigger axles and bearings per the 84/85 GSL, all calipers/rotors for GSL rear discs are the same
Old 10-25-07, 06:23 PM
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So I got a threaded flange with the large measurements, and two small flange rear ends. what gives?
Old 10-25-07, 07:15 PM
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Originally Posted by aussiesmg
Be aware some 83 GSLs had the bigger axles and bearings per the 84/85 GSL, all calipers/rotors for GSL rear discs are the same
I have never come across the later 83 models having the larger axles. The only thing that I have encountered is the larger flanged diffs.

Have you personally come across this?
Old 10-25-07, 07:19 PM
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Originally Posted by Sgt Fox
So I got a threaded flange with the large measurements, and two small flange rear ends. what gives?
Are you measuring the bolt holes straight across or diagonally?
Old 10-25-07, 07:29 PM
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straight across...
Old 10-25-07, 10:38 PM
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pull an axle, its not hard
Old 10-26-07, 10:02 AM
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S2 has solid brake discs
S3 has ventilated discs
Old 10-26-07, 10:09 AM
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^ not here at least. Only the GSL-SE has vented, the others are solid disc in the rear
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