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Thread: AKG shorty subframe bushings

  1. #1
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    AKG shorty subframe bushings

    Can anyone explain exactly how these work, & what to expect out of them? There is so little information available, except copy & paste on retail websites. AKG part #SFZMD12

    http://www.akgmotorsport.com/catalog...ion%2FBushings

    AKG lift (Copy).JPG

  2. #2
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    They will raise the subframe relative to its mounting points, basically lowering the car that 12MM maintaining the same suspension geometry as before lowering, IE the Camber and Toe curves. They do require the ability to adjust ride height at the spring as well as reducing travel by the same amount, basically closing the space between the upper and lower spring perches. Also fuel tank clearance on the Z3 will be compromised.

  3. #3
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    If the car has already been lowered, this will drop it another 12mm, but retain the already changed geometry that the lowering springs provided? What would happen if you then added a 10mm spring pad? Or would it be a better idea just to go with normal length bushings & correct the geometry some by stacking spring pads? I have Dinan springs installed & the back looks like it dropped more than the front.

  4. #4
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    Quote Originally Posted by albrazzi View Post
    They will raise the subframe relative to its mounting points, basically lowering the car that 12MM maintaining the same suspension geometry as before lowering, IE the Camber and Toe curves. They do require the ability to adjust ride height at the spring as well as reducing travel by the same amount, basically closing the space between the upper and lower spring perches. Also fuel tank clearance on the Z3 will be compromised.
    Not exactly. The upper spring perch is on the body, not the subframe.
    These won't change your ride height, but they raise the subframe relative to the wheels, restoring suspension geometry as if the car was riding 12mm higher.

    They'll also screw with your driveshaft and differential alignment, so it's not necessarily something you want to do unless you have a solid need for it.

  5. #5
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    Better idea to do normal length urethane on the sub-frame, rubber on the differential, & stack pads underneath the springs?

  6. #6
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    Quote Originally Posted by spacecowboy View Post
    Better idea to do normal length urethane on the sub-frame, rubber on the differential, & stack pads underneath the springs?
    If you're trying to raise the rear of the car a bit, yes, this would be the way to go.

  7. #7
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    Quote Originally Posted by Gofast View Post
    They'll also screw with your driveshaft and differential alignment, so it's not necessarily something you want to do unless you have a solid need for it.
    Ding Ding Ding! Winner, Winner, Winner.
    Given the z3 has a 2 piece drive line and a center support, this would be a real concern for me unless someone could explain away why it's not.
    Dan "PbFut" Rose

  8. #8
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    Quote Originally Posted by Gofast View Post
    Not exactly. The upper spring perch is on the body, not the subframe.
    These won't change your ride height, but they raise the subframe relative to the wheels, restoring suspension geometry as if the car was riding 12mm higher.

    They'll also screw with your driveshaft and differential alignment, so it's not necessarily something you want to do unless you have a solid need for it.
    Yea I guess what I was trying to say is if you are lowering then this will lower the trailing arm pivot point (more acurately lower the body on the suspension) as well maintaining the same geometry as before lowering. Of course most people lower more than 12MM anyway so the benefits are negligible.

  9. #9
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    Wouldn't stacking pads raise the ride height, & also help reduce some of the camber induced issues from lowering springs?

  10. #10
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    Quote Originally Posted by spacecowboy View Post
    Wouldn't stacking pads raise the ride height, & also help reduce some of the camber induced issues from lowering springs?
    Yes. Because the camber issue is caused by lowering, raising the ride height will help alleviate it.

  11. #11
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    Old thread, new product option:
    https://www.condorspeedshop.com/coll...ant=1159285473

    Looks like these are the best of both worlds, they raise the subframe 12mm but then also include spacers to drop the diff back into alignment? Could that be right?

    I've seen mention of fuel tank clearance issues on the Z3 M. Is this a real concern? Is any modification needed, or can these bushings work as-is?

  12. #12
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    Watch for fuel tank interference at the TA mounts. If you've welded on any alignment correction tabs you will very likely have a problem. OEM pivot points will be danger close.
    Dan "PbFut" Rose

  13. #13
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    Quote Originally Posted by PbFut View Post
    Watch for fuel tank interference at the TA mounts. If you've welded on any alignment correction tabs you will very likely have a problem. OEM pivot points will be danger close.
    Danger as in don't do it, or danger as in it will be hard to install or something like that?

    I have all stock bushings now with height adjustable coilovers. Seems like the best thing to do for a sporty street and autocross car is these offset bushings, rubber diff mount, rubber RTAB bushings, and no weld-in adjusters. Removes enough play in the suspension to increase performance but leaves enough rubber to provide peace of mind for the drivetrain. Lets me get a little lower without messing up camber or toe curves, and don't have to worry about offset bushing binding or spinning...?

  14. #14
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    You are on the right path. Just be aware, the mounts on the carrier that the trailing arms attach to are fairly close to the fuel tank on the Z3. If you end up needing to weld tabs on those mounts to allow for adjustments to the TA alignment, you will very likely not have enough room for the tabs. When I say danger close, it is just that…You will likely be very close to the tank. Every car is slightly different so be aware when you are setting the carrier back into place to watch that tank area. And remember it does move. Also note, the added camber as a result of lowering the car is not a bad thing for track, but it does mess up tires on the street if the toe is off any at all. It is why I would be cautious with these “lowering bushings” You might fix the camber, but toe could still need attention and if you have to increase the size of the mount to accomplish correct alignment, its likely going to hit the tank.
    Dan "PbFut" Rose

  15. #15
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    The Ms don't have the absurd amount of static negative camber that the Z3s do.

    Lowering an M 1" to 1-1/2" doesn't have the overabundance of negative camber of even a stock Z3, so why bother to raise the subframe? Listen to Dan, his knowledge and experience is based on a very considerable amount of on-track use.

    Worst scenario yet, is the serrated adjustable toe/camber kits; they cannot even be used without cutting them down.




  16. #16
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    Moving the subframe within the unibody has nothing to do with the static suspension camber/toe settings. It majorly affects anti dive and anti squat geometry, affects roll center position, and the shape of the dynamic camber and toe curves. It is a very important adjustment point that pro teams put a lot of effort into. We, unfortunately, have near zero adjustability in this point, even less than the E30 guys. This is mostly due to the plastic fuel tank being in the way.
    Last edited by rf900rkw; 03-04-2018 at 12:23 PM.

  17. #17
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    Also, realize these bushings do NOT lower the car. Indeed installing them with no other changes will raise the rear about an inch, if
    my ICU bed bound mathematics is near correct.
    Last edited by rf900rkw; 03-04-2018 at 01:14 PM.

  18. #18
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    Quote Originally Posted by rf900rkw View Post
    Moving the subframe within the unibody has nothing to do with the static suspension camber/toe settings. It majorly affects anti dive and anti squat geometry, affects roll center position, and the shape of the dynamic camber and toe curves. It is a very important adjustment point that pro teams put a lot of effort into. We, unfortunately, have near zero adjustability in this point, even less than the E30 guys. This is mostly due to the plastic fuel tank being in the way.
    I love it when you set me straight, and I'm counting on you doing that for some time now!

    (I hope you're feeling back in top form soon)

    - - - Updated - - -

    Quote Originally Posted by rf900rkw View Post
    Also, realize these bushings do NOT lower the car. Indeed installing them with no other changes will raise the rear about an inch, in my ICU bed bound mathematics is near correct.
    Getting good meds, are you?

  19. #19
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    I think it also would change the alignment of the driveshaft to the differential. The kit I have from Condor has spacers for the carrier to differential mounting that drop the differential in relation to the carrier.

    Without visual references in front of me, confined as I am to the tiny display on my phone, however, it's possible (probable) what what I'm picturing is completely wrong in every way conceivable. (and now I'm worried that I put the bushings in upside-down; so much for feeling relaxed)

  20. #20
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    Some apples to oranges, but compare moving the subframe upwards to be like raising the front attachment points of the classic four link suspension much loved by the solid axle crowd. We complicate it by having a single skewed arm that also carries the spring seat (fulcrum point).



    And yes, the meds are good.

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