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Measuring ride height

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#21
SaulSpeedwell

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How much of this settling is related to the tire taking a set (flat spotting)?

 

Whenever I leave the car setting for an extended period or overnight, it is with the car rolled off the scales.  That way when the car is rolled back on the scales it is not rolling onto a flat spot caused by sitting in the same spot on the scales.  While I frequently roll the car back off the scales to "bounce it after adjustments, I swear by the use of thin greased slip plates under all four wheels and credit their use for the biggest gain in obtaining consistent/repeatable results.

 

I also set the tire pressures to off-track target pressures to simulate the dynamic tire cross section however I have not been able to detect any measurable cross weight affect from doing this.   

 

Rich Powers

 

I don't think the tire flatspotting matters much, but nothing wrong with eliminating it as a variable.  For those that insist on measuring the pinch welds, then tire stagger, "coning", and changes in tire types (Hoosier, Toyo, etc.) will all affect the "ride height" measurement.

 

The biggest effect I saw on the NB due to "settling" was a big difference in camber, but more worrying - a big difference in front toe due to the hideous bumpsteer.  I noticed this overnight, as I would sometimes quit for the night, come back out in the morning and see how much higher my camber #s were.

 

The NB was always less repeatable on the scales, because MazdaSpeed/AWR left zero compliance in the original '99 SM shock hat setup (I'm not talking about the OEM shock hat setup) - the only "compliance" was the flexing of the body sheet metal and the "bending" (cocking, really) of the shock absorber shaft with respect to its housing - thus turning the shock absorber into a "leaf spring" (except a telescoping leaf spring with a sloppy set of seals in the middle of it).  And people wondered why the shocks turned to junk in hours.  Or minutes.

 

In other words, when you took out a lower shock bolt on an NB SM while it was sitting at ride height, the shock absorber would snap outward (or inward, I can't remember) because it was being "bent" due to the lack of compliance/articulation at the shock hat joint.  This was SOMEWHAT mitigated by the FatCat hats, depending on how apeshit you go on squishing the rubber isolators, or whether you are running the FatCat supplied material to begin with (ahem).

 

Note:  If you try this shock bolt removal experiment at home, you need to support the car at "ride height" on the corner you take the lower shock bolt out on. 


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#22
davew

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To me, this is the most important line in the entire thread:

 

" In any case, if you set your car up using the same rig every time, then it shouldn't matter - over time you will learn what works and you will converge to the best setup for your setup tools and processes."

 

Dave


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Dave Wheeler
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#23
Bi11

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I do both, but the most accurate gauge i use,  is my finger.  after having done a ton of alignments, i can look at a car to tell if its high or low to start with.  I do use the pinch welds as i know what number i am looking for on my car but every car can be a little different.

 

measuring the distance between the the top of the shock and the bottom of the bump stop is the most informative.

 

Do you want me to post a picture of my finger?

Please post a picture of your little finger


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#24
FTodaro

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Please post a picture of your little finger

Drago told me I am not allowed to post any pictures of my body parts, no matter how big they are.


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#25
davew

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Drago told me I am not allowed to post any pictures of my body parts, no matter how big they are.

 

THANK YOU, Mr Drago


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Dave Wheeler
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#26
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#27
Johnny D

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This thread is sure going to the dogs.

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#28
Alberto

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I am re-doing my corner balance after replacing both subframes and a bunch of other parts.  I'm still on Bilsteins for now.  Does this look about right for spacing between the top of the shock and the bump stop?  That's a 3/8' drive extension.  That is rear driver side shock.

Thanks!

 

50061372698_31120958db.jpgUntitled by alberto_mg, on Flickr


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