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Thread: The Porsche 930 transaxle option

  1. #1

    The Porsche 930 transaxle option

    Hey there everyone,

    So in the years that I have been building transaxles for the GTM Community one of the strongest options around still tends to be the Porsche 930 4 speed gearbox. I was recently working with a builder on one of these and realized that this gearbox is often over looked, so I thought I would put some stats up on this for everyone to take a look at.

    Quite a few builders in the past have asked that I try to find a gearbox for them that has nice long gearing, with a 60 MPH 1st gear and a top speed that will be over 200 MPH. This can be somewhat difficult with the more modern 6 speed units, as gearing for these is not as readily available, but with the 930 option it comes set up with exactly these specs for the GTM.

    There are two different ways that you can order this gearbox. You can utilize it in a inverted position, which is what I tend to recommend the most for GTM builders, or you can have the ring and pinion flipped over. Basically both configurations will work with the GTM but running this gearbox inverted will over some additional case strength, as well as a slightly better axle geometry for the GTM which is a good thing as engine space is somewhat limited already.

    The 930 is a shaft shifted gearbox which means that you can use the shifter setup that comes with your kit, but I usually recommend that builders go with the cable shift conversion as setup tends to be quite a bit easier, and the shift quality a bit better as well.

    So here is what you are looking at for gearing on the 930:

    1st gear 2.250 62 MPH at 7250 redline
    2nd gear 1.304 108 MPH
    3rd gear 0.890 158 MPH
    4th gear 0.625 225 MPH

    This gives you a nice cruising rpm at 70 MPH of 2258, which makes this a very nicely geared option for the GTM. From a strength point of view the 930 is still one of the strongest gearboxes that Porsche ever had designed. It has been a wide variety of their turbo cars and parts availability is very good, as well. Gearing options are abundant, as are clutch and differential options.

    So what about cost? Okay so here is what I came up with in terms of building one of these for the GTM.

    $6500.00 Porsche 930 gearbox, completely rebuilt, with stock ratios, open differential, cooler in and out ports installed.
    $795.00 Cable shift assy complete
    $646.00 Adapter kit, flywheel, pilot bearings, and bolts
    $1230.00 Stage II clutch kit
    $80.00 Slave Cylinder
    $450.00 Conversion kit to Hydraulic actuation

    $9701.00 Total plus shipping.

    Naturally there are always going to be additional options open for this gearbox, but in terms of the basics, you can put your hands on one of the strongest gearboxes around, complete fresh and ready for installation for a fantastic price.

    I just wanted to share this with everyone as this option does sometimes slip through the cracks with all of the new technology and is still one of the better ones out there. Please let me know how I can be of help, and happy building everyone.

    Erik Johnson
    The Race Line
    (970) 344-7761 phone

  2. #2
    Eric,,,, as memory serves there is no rear mount like on the G50 correct? If my memory is correct (and of course it often isn't) how would we mount the rear portion of this???

    GTM #22 - Worlds slowest build

  3. #3
    Fred you bring up a good question, and yes a alternative mount would be needed to fit the 930 gearbox. This should not be too terribly hard however as there are areas available on the 930 to allow you to bolt a mount to it on the rear. It is not the same kind of donut mount that the G50 has but there is space available to bolt a mount to it just the same, so what we are talking about here is a pretty simple frame modification. I am sure that there are at least a couple of builders here who have already done this.

    I can certainly help to come up with a good solution.

    Erik Johnson
    The Race Line
    (970) 344-7761 phone

  4. #4
    Is there a LSD available for the 930??

  5. #5
    We are going to be using a 930 from a 88 turbo car and it has a factory lsd in it.

  6. #6
    Yes there is certainly a very good Limited Slip Differential available for the 930 as well. Please let me know if you are interested in this option, and I will be more than happy to discuss it in length with you. Feel free to give me a call.

    Erik Johnson
    The Race Line
    (970) 344-7761 phone

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