The Definitive Nissan Crossmember Thread

Thread in 'Technical Questions' started by Doritofu, Nov 26, 2015.

  1. Doritofu

    Doritofu Active Member

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    I don't usually make threads in this section, but I had I whole bunch of measurements left over from a project so thought I'd share.

    I'm doing an engine swap into my S13 but wasn't sure which crossmember would work the best, so I decided to pick up a couple and compare them. The crossmembers I was testing were the S13 SR20DET, the R32 RB20DET and the R33 RB25DET.
    Key thing to note first, A31, C33 and R32 crossmembers are all the same.
    For the differences between S13 and S14 crossmembers check out this thread:
    silviav8forums.com :: View topic - Hooker S13 & S14 LS Engine Swap Kit

    Let's get started. (pictures at the end to show where specifically I was measuring from)

    S13 SR20DET CROSSMEMBER
    -Engine mount holes - Radiator Support 560mm
    -Central xmember holes - Sway bar 285mm
    -Engine mount hole - Engine mount hole (inner) 485mm (ie the distance from the drivers to passengers side holes)
    -Engine mount hole - Engine mount hole (outer) 530mm
    -Engine mount hole - Chassis Rail (lower) 94mm
    -Engine mount hole - Chassis Rail (upper) 70mm (center 82mm)
    -Central Xmember holes - Chassis Rail 185mm
    -Mounting surface angle Driver : 53° Passenger : 53°


    R32/C33/A31 RB20DET CROSSMEMBER
    -Engine mount holes - Radiator Support 435mm
    -Central xmember holes - Sway bar 285mm
    -Engine mount hole - Engine mount hole (inner) 470mm
    -Engine mount hole - Engine mount hole (outer) 515mm
    -Engine mount hole - Chassis Rail (lower) 88mm
    -Engine mount hole - Chassis Rail (upper) 65mm (center 76.5)
    -Central Xmember holes - Chassis Rail 185mm
    -Mounting surface angle Driver : 53° Passenger : 52°


    R33 RB25DET CROSSMEMBER
    -Engine mount holes - Radiator Support 435mm
    -Central xmember holes - Sway bar 315mm
    -Engine mount hole - Engine mount hole (inner) 405mm
    -Engine mount hole - Engine mount hole (outer) 505mm
    -Engine mount hole - Chassis Rail (lower) 95mm
    -Engine mount hole - Chassis Rail (upper) 87mm (center 91mm)
    -Central Xmember holes - Chassis Rail 185mm
    -Mounting surface angle Driver : 15° Passenger : 16°




    Engine mount holes to Radiator support: (used the sharp fold in the metal shown here at 560mm)
    DSCF5640_zpslhfkmlsv.

    Central Crossmember holes to Sway bar: (used the outermost side of the sway bar, parallax ftw)
    DSCF5634_zpsrjgmz6ko.

    Engine mount holes to Chassis Rail (lower): (the straight edge was resting across the tops of the chassis rail)
    DSCF5776_zpswxbvvzkn.

    And how I measured the mounting surface angle:
    step 1, actually level.
    DSCF5587_zps1cnuwfp2.
    step 2, this thing.
    DSCF5590_zpsafxsmvac.
    step 3, be really happy when the subframe for a car built in the 90s matches the angle of en engine built in the early 80s, for a completely different car.
    DSCF5665_zpsrjon4cup.


    The main point wasn't really to measure the distance to rad support etc.. but to find the difference between the three, so I just picked and easy location to measure to and repeated for all 3.

    The key differences are that when compared to the standard SR crossmember,
    -R33 crossmember mounts are 125mm further forward and 9mm lower as well as being roughly 15°
    -R32 crossmember mounts are 125mm further forward and 5.5mm higher and are approximately the same 53°

    And if you're interested in seeing me try to drop an FJ20ET into my S13 Silvia ~shameless self plug~ then check out this thread:
    http://www.driftworks.com/forum/drift-car-projects-builds/224726-backyard-build-nz-s13.html


    If anybody else has some other crossmembers and they want to put some more info up here than feel free, also If someone else has a less ghetto way of recording the angles and they turn out to be different, then okay...
     
    #1 Doritofu, Nov 26, 2015
    Last edited: Dec 13, 2019
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  2. H05TYL

    H05TYL Member

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    I've got an r32 with an empty engine bay so I thought I'd check the angle of the mounts with the Level app on my phone.

    The cars not perfectly level (2° slope side to side) and I got 43° on one side and 41° on the other. I measured each angle several times, and checked camber front & rear, and found them to be repeatable within 0.2° (with a similar margin to the actual camber measurements too).

    Unfortunately the S14 in the garage has an engine in it, so I can't check the angle on that subframe.

    Hopefully someone else can measure one and prove my dodgy app numbers wrong - or I can take some measurements, use some trigonometry and work it out.
    Anyhow, cool info dude, thanks for sharing.
     
  3. Doritofu

    Doritofu Active Member

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    Thanks for checking that out, good to have some actual measuring device. I think the reason we may have got different values is because when I was doing it my ghetto way, I was measuring from the horizontal, and maybe your phone measures from the vertical. (which makes sense if its for camber checking)
    Come to think of it, that makes sense, ~50° + ~40° = ~90°

    I've also made a change to the original post, the R33 crossmember is not 180mm below the tops of the chassis rails, and the other 2 aren't 84mm either, they are all 185mm, I really managed to mess that one up when I was measuring it, but yeah, they're all the same.
     
    #3 Doritofu, Nov 29, 2015
    Last edited: Nov 29, 2015
  4. H05TYL

    H05TYL Member

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    Yeah that's measured from the vertical. I hadn't even thought about yours being measured from the horizontal! Makes sense now!
     
  5. fikemoster

    fikemoster Member

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    Awsome thread and has really helped me out as I always thought the r32 crossmember sat the engine lower but that isn't the case. It's actually the highest crossmember. You linked the thread about s13 vs s14 crossmember and they mentioned that there is a height difference between them bit they never actually said what it is. Don't suppose you ever found that out.

    I'm putting a rb30 in my s13 and I need to get the engine as low as possible. As my rb25 is pretty tight on the bonnet as it is. But that is using a r32 setup

    Thanks mike
     
  6. Doritofu

    Doritofu Active Member

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    So I recently purchased another crossmember because why have 1 when you could have 4.

    I thought I'd just got an S13 subframe, turns out I bought an S14 one and this whole time the subframe I thought was an S14 was actually an S13. The 3 subframes I have compared so far have been; S13, R32 and R33.

    I have gone back and fixed the first post and will now go over the differences I found between the S14 and my old S13 crossmembers.

    For starters checking the angle confirmed what other sources have found with the S13 mounting surfaces being between 43.5° and 46.5° from the vertical and the S14 surfaces being between 49.5° and 51.0°

    So what that means is the S14 mounts are about 5.3° shallower (more horizontal) than the S13 mounts. Which you can tell by eye when you have them side by side.

    fc78tte.

    S14 in front S13 behind (purple)
    2u162je.

    The placement in the engine bay is the same other than the slight difference in height. From what I found, the S13 mounts sit approximately 6mm higher than the S14 mounts which matches what people have been saying for years but now we have an actual number. To put that into reference, both crossmembers have slots for the engine mounts, allowing them to be adjusted up and down. The S13 slots give a total range of 6mm up and down, S14 slots are slightly smaller, only about 4mm of range.

    So what this means is that an engine mounted on an S13 subframe in its highest adjusted position will be 12mm higher than the same engine mounted on an S14 subframe in its lowest position. Though in reality almost all mounts will be in their lowest position when installed, so the practical difference in height is only 6mm.

    In terms of design the S14 subframe has fewer spot welds holding it together but more seam welds and a slightly redesigned support bracket. It also lacks the small valley that the S13 has for its power steering lines and also has an additional bracket welded on to one side.

    [​IMG]

    [​IMG]

    Both are compatible with either vehicle meaning that the difference in height and angle don't affect engine placement enough to stop the engine fitting.

    Summary:

    S13 sr20det subframe:
    Mounting Surface Angle: 45.0° (avg)
    Mounting Surface Height: 141 mm

    S14 sr20det subframe:
    Mounting Surface Angle: 50.3° (avg)
    Mounting Surface Height: 135 mm (6 mm lower than S13)
     
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