Ride Height Measuring Question

Miata Parts, Intakes, Superchargers, Headers, Exhausts, Shocks, Springs, Sway Bars, Brake Kits, Autocross and track mods.

Ride Height Measuring Question

Postby avera01 » Tue Mar 31, 2020 2:06 pm

First I apologize for this long technical explanation and perhaps someone can shed some light and correct me.

I am trying to determine if my ride height measurements are correct so when the day comes to upgrade the shocks/springs I have a reference point. The noted method in the forums is center wheel to fender lip edge.

I am using two metal squares, one 12" long the other 24". I assembled them back to back inverted; looks like "Z" but the vertical leg is straight up/down. This allows me to insure a flat and level measurement. The shorter square is on top pushing against the top inside of the fender. Where the bottom measuring edge of shorter square lines up with the longer square gives me the measurement of longer square which is added to shorter square.

I know this sound a bit convoluted, but is quite simple. Note, the bottom portion of the wheel well is a bit higher than the longer side of the 24" square indicating its 24" plus. This give me some assurance that my measurements are expected.

I measure each corner of the stock GT suspension (4 years old with 16K miles) and get the following heights:

REVISED 4/1/2020

LR - 25.7" - 11.9" = 13.8" ride height
RR - 25.8" - 11.9" = 13.9"
LF - 26.0" - 11.9" = 14.1"
RF - 25.9" - 11.9" = 14.0"

The first figure is the distance from the floor to the fender lip. I repeated this several times for each wheel to improve precision. Subtracting the distance from the floor to the center cap (which is approximately 11.9") give me a ride height as noted above. The 17" wheel has a radius of 8.5" and the flexed sidewall (215 tires) adds around 3.4" in height.

So the point of this exercise, beside figuring out my "ride height" is that the number I see posted for lowered cars has a ride height of over 13" which does not correspond to what I should be getting given ND GT stock springs and shocks. To me, the definition of ride height is not important, but the relative measurement taken with a consistent method is.

Note, I am measuring from the bottom edge of the wheel lip where the edge of the metal ruler is touching the painted metal fender (I taped the square to protect the paint finish). The short edge project around 6 inches into the wheel well and does not touch the tire. The rulers a vertically and horizontally level when the measure is taken.

Any thoughts?
Last edited by avera01 on Wed Apr 01, 2020 10:23 am, edited 1 time in total.
avera01
 
Posts: 71
Joined: Mon Jun 27, 2011 2:20 pm

Re: Ride Height Measuring Question

Postby njaremka » Wed Apr 01, 2020 5:53 am

You are over thinking it, and those ride height look quite low for OEM springs. I would expect it to fall right within ~14.25 inches on stock springs.

I've measured ride height by just using a tape measure. Get the vehicle as level as possible, then measure from the lower or upper wheel lip to the fender lip, and either add or subtract half the wheel diameter. This way, you eliminate the error in trying to figure the exact center of the wheel hub, and where it falls on the tape measure.
njaremka
 
Posts: 84
Joined: Fri Dec 17, 2010 10:31 am

Re: Ride Height Measuring Question

Postby avera01 » Wed Apr 01, 2020 10:20 am

Hi Njaremka,

I now know what is feels not to be careful with my measurements. Although my technique is reasonably accurate, I used the inside measurement of the longer ruler inside of the outer side measurement therefore the ride height is off (short) by about 1.5" which puts is back into the territory of what everyone is getting with stock springs/shocks. Fortunately the relative difference between the wheels is correct.

Thanks for taking another look and which made me to recheck my methods. Should have done that before posting....
avera01
 
Posts: 71
Joined: Mon Jun 27, 2011 2:20 pm

Re: Ride Height Measuring Question

Postby njaremka » Wed Apr 01, 2020 11:25 am

Measure twice, cut thrice? :P

Those measurements look more in line :D
njaremka
 
Posts: 84
Joined: Fri Dec 17, 2010 10:31 am


Return to Mazda Miata and Fiat 124

Who is online

Users browsing this forum: No registered users and 3 guests