Alignment question vs subframe shift?

Discussion in 'Suspension and Chassis' started by strengthrehab, May 7, 2018.

  1. strengthrehab

    strengthrehab TMO Race

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    Strange scenario

    I had my car aligned yesterday. Specs are right at -2 camber, but one tire seems to be more "inbound" than the other when measured from the fender lip.

    Does this really matter? Is my front subframe shifted? Car has never been in an accident.


    HMMM.


    Anyone experience this?
     
  2. JAJ

    JAJ TMO Race

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    Shop laser-based wheel alignment systems are famous for being out of calibration, producing results that are good enough for grocery service but not for track duty. The pro's I know rely on string for race car setup because, even though it's simpler and cheaper, it's actually much more precise.

    My point is that it's probably not your subframe.
     
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  3. VoodooBoss

    VoodooBoss Rick Moderator

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    Post the photos when you have a chance.
     
  4. racer47

    racer47 All I got left is fast

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    The front k member can easily move 1/4" left to right and maybe as much as 1/2". There are alignment holes that you can see from under the car that may not be exactly centered but should be pretty close.

    Where is the top of the strut in relation to the hole? Is one side closer and does that match up with the tire that further from the fender?

    Overall, its not a big deal. If the rear end is square in the car and front is aligned well, 1/8" or 1/4" left or right on the k is not going to hurt anything.

    After I had my k member loose for the second (or maybe third time), I found the alignment holes and took extra time to center it left/right and front/rear. It can move more than you may think.
     
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  5. strengthrehab

    strengthrehab TMO Race

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    Passenger side (was at -1.9 when put on alignment machine)
    [​IMG]

    Driver side (was at -2.1 before it was touched)
    [​IMG]
     
  6. strengthrehab

    strengthrehab TMO Race

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    I believe the calibration of the machine was off based on the positioning of the strut nuts in the strut tower opening.

    Damn it.

    I ordered a digital camber gauge.
     
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  7. strengthrehab

    strengthrehab TMO Race

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    Yes the one that is farther from the fender is closer to the inner edge of the strut opening
     
  8. JAJ

    JAJ TMO Race

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    Possible, for sure. The strut nuts would be off if the k member was off, so it's not definitive.

    Good call. A string, a weight and a ruler are cheaper and more accurate, but the gauge is a good compromise.
     
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  9. racer47

    racer47 All I got left is fast

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    I looked at the alignment marks on put on my k member last night. The max travel left to right is more like 1/4" not 1/2" as I speculated above.

    Its hard to get the k exactly centered with the motor in the car. I wouldn't worry about it.

    All I did originally was adjust both struts to the max camber allowed by the strut tower holes. Then I measured each side and one was about 0.2 degree less than the other. So I adjusted the higher camber side to be equal to the other side.
     
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  10. strengthrehab

    strengthrehab TMO Race

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    yeah i figure its not a huge deal as long as each are the same measurements/angle
     
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  11. yotah1

    yotah1 TMO Race

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    I was under my 350 the other day, and since we did a camber and alignment for track specs, I know my subframe is off to one side. I've had that in my track car in Europe and was suspecting the same here. At -2 of camber on both sides, one strut was maxxed out to the edge of the hole, the other one was almost in the middle. So i checked under my car the other day.

    Front subframe on my 350 is off to the left by 4mm (a bit less than 1/4"). So i went into our database at work, and the bolts are 12mm OD, while the holes in the chassis are 19mm ID. That leaves 7mm of difference, so about 3.5/4mm of range to be offset to one side or the other. I guess mine is maxxed out to one side...

    Spoon Sports in Japan produces something called RIgid COllars, that are machined inserts that fit between your subframe and the chassis, and slide over the bolts. They basically remove any play whatsoever and center the parts correctly. Nothing is available for S550 though they have a kit for S197 that would fit but they refuse to sell the front subframes inserts for me to test fit them as they have not approved them on a S550 yet. Japanese can be a bit stubborn...

    End result : i'm getting some custom machined for my car in June so I can fit them and get my car straight!
     
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  12. strengthrehab

    strengthrehab TMO Race

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    Interesting I will be under mine soon so I will check
     
  13. racer47

    racer47 All I got left is fast

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    That sounds like a good idea but they want $300 for something that is basically a bushing. I guess I'll stick to my steel ruler. I bet I'm within 1/32", close enough for me.

    https://www.amazon.com/SPOON-Rigid-Collar-50261-MUS-000-Front/dp/B00KQG9UKY
     
  14. yotah1

    yotah1 TMO Race

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    Yep it's expensive, but it's also forever. Whereas I've seen racecars needing the subframe to be re-aligned every couple races because of the lateral loads they were getting in some corners. I like the peace of mind that these give me. it's on, and it stays that way and stays straight.
     
  15. racer47

    racer47 All I got left is fast

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    Maybe @pufferfish can make some of these for a more reasonable price. Plus I'm local to him so maybe I can test a prototype set. I won't even charge him for the test :)
     
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  16. 8250RPM

    8250RPM TMO Addict

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    Exactly!!!
    Thank you!
    I also use strings. It’s more time consuming but I trust my measurements more than a machine.


    Sent from my iPhone using Tapatalk
     
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  17. racer47

    racer47 All I got left is fast

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    There is nothing wrong with laser alignment equipment. The quality of the results are all based on the skill of the operator. The laser is a lot faster and more accurate than strings. I used to have access to one and it was awesome.
     
  18. JAJ

    JAJ TMO Race

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    Laser machines are absolutely capable of doing as good a job as string, but they're a lot more complicated and they have a lot more moving parts. They're designed for speed, intended for service centers that have to get customer vehicles set up and out the door as quickly as possible. They have their place. But walk through the paddock at a race track where the pro's are racing, and where a tenth of a degree actually matters, and lasers are conspicuous by their absence. Even the big teams - the ones that could buy a laser system with the rounding errors on their food budget - all use string.
     
  19. racer47

    racer47 All I got left is fast

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    I've raced out of the pro paddock, not just been there. Have you been in an indy or nascar shop? They have laser alignment and setup rigs. Races are won back in the shop. They prioritize what needs to go on the road. Strings work, no doubt. But just because you may have seen them in the pits does not mean that is the preferred method.
     
  20. TMSBOSS

    TMSBOSS TMO Addict

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    The accuracy of a laser system is tied to its setup. Setting up a portable laser system would likely take hours. At the track teams likely string it and move on.
     

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