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Thread: 3/S rear differential discussion, the "H", "G", and the "J" specs, is it JDM, US, UK?

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    Banned Feedback Score 11 (100%) J. Fast's Avatar
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    3/S rear differential discussion, the "H", "G", and the "J" specs, is it JDM, US, UK?

    Might be a cool thread to discuss for a while. A few of us in Colorado have been toying with drivetrain regearing, hybrid diffs, and rear lsd options. I have a few tech'y observations and questions regarding 3/S TT rear differentials.

    First few...

    The "G" series rear differentials. Those are USDM standard viscous rear lsd's. There are two types:

    Type 1) "3" series
    Type 2) "4" series

    Correct me if I'm wrong here... The numbers on the rear differential stamp plate identify the drive and pinon gear in the diff housing. The "3" series belongs to a 5 speed and "4" series identifies U.S. 6 speed, right?

    First question... How many teeth are on the drive gear and drive pinon in the 5 speed rear diff, and the respective 6 speed? Pics anyone?

    Now the mind puzzle... The "H" series rear differential. Those are OEM JDM rear torsion helical locking lsd's. There are also two different types/styles (if you will) of gearing in these rear differential.

    Type 1) "3" series
    Type 2) "4" series

    Correct me if I'm wrong here... The numbers on the diffs identify the drive and pinon gear in the rear differential. The "3" series belonging to a 5 speed and "4" identifies a 6 speed. Well, what are the drive gear ratios for these? Actual pics anyone?

    I have "heard" there are only two rear differentials for the 3/S TT. So the mind puzzle to unwrap is... how many teeth are on the hybrid rear differential drive pinion and hybrid drive gear?

    Call me crazy but what I'm thinking is this, there are 3 different rear differential options available for the 3/S TT. Reasoning? There are three different teeth/styles of ring and pinions available to the TT 3/S. 5-speed, 6-speed, and JDM (MR) 6-Speed. The ring and pinion in the trans mates to the drive and pinon in the rear diff right? If that is the case then there are three, no?

    In the respective United States model 3/S the "3" series differential and "4" series differential are geared differently. Some have said on the other board that a JDM MR geared trans will bolt up to a USDM 5 speed rear diff without burning the VCU which is a "3" series rear differential. If that's the case then what's the gearing in a JDM "4H"

    Anyone have pics of "3" and "4" stamped H (hybrid) rear differential drive gear and the mating pinon?

    Lastly, anyone have any pictures and info on the rear LSD options for our cars and info wether it be for the U.S. models, Canada, Ausie, JDM, or UK models?

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    Banned Feedback Score 11 (100%) J. Fast's Avatar
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    OHH, and does anyone know where I can get just the JDM helical locking assembly or have a part number? For clarification, We're looking for an MHI torsion helical lsd that was a JDM option on a 3/S?

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    I have a B3H hybrid rear LSD waiting to be fitted, and my original diff is B4G.(4WS)

    My hybrid diff is 2WS

    I have no internal pics as yet, but if I do take it apart, I will take some.

    Hybrid LSD seems to be only available as an option on Jap GTO's from 1995 onwards. I was available in 2 forms, 2WS and 4WS.

    I have checked on CAPS, and the hybrid LSD pineapple is fully interchangeable with the standard item. Only trouble is the cost is silly!
    It does mean if you wanted to keep 4WS you could buy a 2WS Hybrid diff and swap the helical part over.

    Marty

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    Twin Turbo verified Feedback Score 5 (100%) GTOJOE's Avatar
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    Correction on above. The 3 series is 2ws the 4 series is 4ws. Remember all JDM diffs have the same ratio regardless of gearbox so all are the same. Internal "pineapple" is identical in both the B3H and the B4H. The outer casing is different to suit Z15A and Z16A chassis.

    Hybrid LSD Rear diff? - 3000GT/Stealth International Message Center
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    Twin Turbo verified Feedback Score 5 (100%) GTOJOE's Avatar
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    Quote Originally Posted by J. Fast View Post
    OHH, and does anyone know where I can get just the JDM helical locking assembly or have a part number? For clarification, We're looking for an MHI torsion helical lsd that was a JDM option on a 3/S?
    B3H part #: MR179436
    B4H part #: MR179437

    Pinapple part #: MR196307 which is the same for both units.

    as per GTOX's post here

    GTOPerformance.co.nz • Login

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    Quote Originally Posted by GTOJOE View Post
    B3H part #: MR179436
    B4H part #: MR179437

    Pinapple part #: MR196307 which is the same for both units.

    as per GTOX's post here

    GTOPerformance.co.nz • Login
    The Hybrid LSD unit, MR196307 is still available on special order from Mitsubishi, for 2700 sterling!
    Also PitroadM have one available, which seems to be the same unit, but I cannot confirm this.

    Second hand is really the only way to go.

    To find a 2WS hybrid LSD you need to find a 95+ GTO MR that is been broken for parts.
    It was only available as an expensive optional extra, so they are quite rare, but there are some out there.

    The 4WS hybrid is another thing........in theory it should have been available as an optional extra on 4WS GTO's, but I have yet to find one with one fitted at the factory!

    Marty

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    Now with more poop-smear Not Verified Feedback Score 8 (100%) IPD's Avatar
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    ratio is the same? then explain why the 5-speed rear doesn't work with the atx, but the 6-speed does.

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    Forum User Feedback Score 0 stealthTT's Avatar
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    Quote Originally Posted by IPD View Post
    ratio is the same? then explain why the 5-speed rear doesn't work with the atx, but the 6-speed does.

    on JDM(also EU) specs, both 5 and 6 speeds gearboxes had the same final gear ratio so that B3H and B4H have the same ratio: 3.545. hope it helped.

    dont know about the auto trans.

    Ilie

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    One day....it will be on 4 wheels. supporter Feedback Score 2 (100%)
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    Question: what are the chances that a Diff like that is still intact...considering every Stock viscus is 99% chance expected to be open if i were you Marty I'd be opening it and checking it ASAP.
    Building a House, Car Mods on hold!
    1996 GTO, Owner since 2003.

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    Now with more poop-smear Not Verified Feedback Score 8 (100%) IPD's Avatar
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    Quote Originally Posted by stealthTT View Post
    on JDM(also EU) specs, both 5 and 6 speeds gearboxes had the same final gear ratio so that B3H and B4H have the same ratio: 3.545. hope it helped.

    dont know about the auto trans.

    Ilie
    then it must be JUST the USDM 5-speed that had a diff gear ratio. i can't imagine that they used a different ratio in JDM between n/a & tt.

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