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7.5" vs. 7.625"

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  • #1

    7.5" vs. 7.625"

    My question is, is there actually a difference in the carriers and housings of the 7.625 vs. the 7.5? or is it just the outer diameter of the ring gear? I'm doing a posi swap in my 92 and I have a 7-5/8 ring gear but i've come to find that you can only buy 7.5 gears. So when I purchase a 7.5 posi carrier is it exact to the 7.625 that is currently in my car?

    and I'm throwing back and forth what ratio to get between 3.23 and 3.42. I'll probably go with the 3.42 but I want to hear everyone's opinions as well.
    1992 RS 305 TBI, 700r4, 3:42 gears, Detroit TrueTrac Limited Slip, MSD wires, coil, cap & rotor, Hypertech Chip, 180 degree thermostat, 200 degree fan switch,
    Tags: None
  • #2
    Originally posted by 92RS
    My question is, is there actually a difference in the carriers and housings of the 7.625 vs. the 7.5? or is it just the outer diameter of the ring gear? I'm doing a posi swap in my 92 and I have a 7-5/8 ring gear but i've come to find that you can only buy 7.5 gears. So when I purchase a 7.5 posi carrier is it exact to the 7.625 that is currently in my car?

    and I'm throwing back and forth what ratio to get between 3.23 and 3.42. I'll probably go with the 3.42 but I want to hear everyone's opinions as well.
    so you have a 9 bolt rear end. there are a couple places to get gears for it. i have 3.70 gears in my 9 bolt. i think summit sells the 3.70 set but it's not listed on their site that i'm aware of. i think yukon gears also sells some 9 bolt gears.

    http://www.9bolt.com/
    87 GTA: it's winter time, all tore apart

    ConElite: "Im 22, have had my TA since I was 21."

    "I wont lie, I have a heavy foot, but at the same time I know when its the safest to ring out a gear or 2."

    Comment

    • #3
      forgot to answer the part for which gears to get. that all depends on what you want to do with the car. is the car an auto or a stick? if it's a stick you can use a steeper gear, such as a 4.11. i run 3.70 with the 700r4 auto. with stock size tires, at 80 mph i'm right around 2800 rpm in OD.
      87 GTA: it's winter time, all tore apart

      ConElite: "Im 22, have had my TA since I was 21."

      "I wont lie, I have a heavy foot, but at the same time I know when its the safest to ring out a gear or 2."

      Comment

      • #4
        nope, i have a 10 bolt rear end
        1992 RS 305 TBI, 700r4, 3:42 gears, Detroit TrueTrac Limited Slip, MSD wires, coil, cap & rotor, Hypertech Chip, 180 degree thermostat, 200 degree fan switch,

        Comment

        • #5
          Lots of people refer to the 7.625" ring as a 7.5". I'm not sure how or why this started. But the 7.5" that most people refer to is in fact a 7.625".

          I hope I got my facts straight. It's been a long time since I messed with an fbody. However, I did swap out ring and pinion in my s10 and it is the same as an fbody.
          LS15 Power! Another LSx engine coming soon.

          Comment

          • #6
            If you look in something like the Summit catalog, you will see that they sell a single type gear for the small 10-bolt rear, referred to as a GM 10-Bolt 7.5/7.625" 1.438" diameter, 27-spline pinion. The gears fit both sizes.
            Fred

            381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

            Comment

            • #7
              what's the 9 bolt? 7.75?
              87 GTA: it's winter time, all tore apart

              ConElite: "Im 22, have had my TA since I was 21."

              "I wont lie, I have a heavy foot, but at the same time I know when its the safest to ring out a gear or 2."

              Comment

              • #8
                The Australian Borg-Warner 9-bolt rear uses a 7.75" ring gear, and a smaller diameter pinion gear.

                http://www.drivetrainspecialists.com...ner/index.html
                Fred

                381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

                Comment

                • #9
                  Originally posted by Injuneer
                  The Australian Borg-Warner 9-bolt rear uses a 7.75" ring gear, and a smaller diameter pinion gear.

                  http://www.drivetrainspecialists.com...ner/index.html
                  I added that link to my favorites.
                  2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning

                  1995 Z28, many mods, SOLD

                  A proud member of the "F-Body Dirty Dozen"

                  Comment

                  • #10
                    Originally posted by 92RS

                    and I'm throwing back and forth what ratio to get between 3.23 and 3.42. I'll probably go with the 3.42 but I want to hear everyone's opinions as well.
                    What motor and trans?

                    Comment

                    • #11
                      DTS makes great parts. they are somewhat near me and i've talked to the owner a few times. he posts over at 3rdgen.org in our section. always very helpful with questions.
                      87 GTA: it's winter time, all tore apart

                      ConElite: "Im 22, have had my TA since I was 21."

                      "I wont lie, I have a heavy foot, but at the same time I know when its the safest to ring out a gear or 2."

                      Comment

                      • #12
                        Originally posted by Joe 1320
                        What motor and trans?

                        305 TBI w/ 700R4
                        1992 RS 305 TBI, 700r4, 3:42 gears, Detroit TrueTrac Limited Slip, MSD wires, coil, cap & rotor, Hypertech Chip, 180 degree thermostat, 200 degree fan switch,

                        Comment

                        • #13
                          does anyone know anything about the Detroit Truetrac LSD??? My main question is how the axles are retained in the carrier. by C-clip like mine are in my 92 or are they retained at the wheel bearing/hub?
                          1992 RS 305 TBI, 700r4, 3:42 gears, Detroit TrueTrac Limited Slip, MSD wires, coil, cap & rotor, Hypertech Chip, 180 degree thermostat, 200 degree fan switch,

                          Comment

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