RB26DETT with 350Z/370Z gearbox - any ideas how to solve this ->

Thread in 'Technical Questions' started by s15-newbie, May 11, 2020.

  1. s15-newbie

    s15-newbie Member

    Jan 14, 2009
    Likes Received:
    hi there,

    i have a S15 and want to do a RB26 swap, like i did to one S15 in the past.

    this time i want to go for a 370Z transmission i have lying around here.

    parts i want to use:
    • R32 RB26DETT
    • 370Z gearbox
    • PMC motorsport adapter plate
    • OS Giken tripple plate clutch
    i have done a measurement to all parts, the engine (flange, crankshaft), adaptor plate, clutch and gearbox.

    to give me an idea how it would be positioned if using them in current condition (without modification), i draw a simple picture using the measurements i have measured (horizontal measurments are accurate till the release bearing, vertical measurements are fantasy).
    i was 100% sure, that the gearbox shaft and the spline shaft would be out of range but i note a strange thing and would like to know what you would think about that.


    the most important points to find out...
    1. how far the shaft would go into the spigot bushing
    2. how far the spline shaft of the gearbox would go into the spline shaft of the clutch
    3. how far is the distance between the release bearing and the pressure plate

    to make it short.... the adaptor plate does have 20,4mm thickness. so my first thought was to just milling down 4mm of the adaptor plate and 16mm of the gearbox. this would be fine to get the (1) shaft closer into the spigot bushing (current=2mm, after milling=22mm) and (2) to get the spline area of the gearbox shaft closer into the spline area of the clutch (current=3mm, after milling 23mm). about (3) i dont make so much thoughts now as the release bearing is central hydraulic and could get easily raised.

    so my problem i have is, that the spline shaft of the gearbox would be just 23mm into the spline area of the clutch. the total possible lenght of the spline shaft would be gearbox=35mm, clutch=32mm. would you think its enought with just 23mm overlap? i think its not enought.

    in view to the shaft/spigot i could go 25mm more into the bushing from current state, which does mean 25mm+3mm=28mm overlap in spline area. unfortunatelly this would mean much more milling to the gearbox flange.

    the other question would be, how much mm should the release bearing move from "normal" state (closed clutch), till open "state" (open clutch). how can i find that out?
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