Unsprung Weight (NA6)

Wheels, Suspension, Brakes & Tyres questions and answers

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Magpie
Speed Racer
Posts: 7468
Joined: Fri Feb 11, 2011 12:49 pm
Vehicle: NA6
Location: Purga, QLD

Unsprung Weight (NA6)

Postby Magpie » Sun May 22, 2016 6:39 pm

Shell front suspension was removed to start calculating motion ratios and unsprung weight etc.

ImageIMG_1377 by Eipeip, on Flickr

Weights (kg)
Lower Control Arm -------------3.30 (bushes, no alignment bolts)
Upper Control Arm -------------1.61 (bushes, no long bolt)
Hub -------------------------------5.32 (inc heat shield)
Disc -------------------------------4.70 (NB8B)
BC ER's----------------------------4.00 (external canister no longer unsprung as it is now in the engine bay, about 0.5 kg saving)
6UL's ----------------------------15.15 (c/w 205/50/15)
Calliper --------------------------X.XX (NB8B)

Motion Ratio (from middle alignment bolt hole)
229 to Suspension mount
313 to Lower ball joint
400 to face of hub

Using the face of the hub (and 80° angle of damper) the motion ratio is 0.564, however Fatcat Motorsports says http://www.fatcatmotorsports.com/FRC_1_6NA/FCM_MSDS_1_6NA.htm 0.66. Using the lower ball joint distance the motion ratio is 0.721.

Personally it is the wheel that generates the movement so the arm length should be to the face of the hub. If you were to manually calculate the motion ratio you would jack the wheel up a certain distance and measure the movement on the damper.

Next weekend the rear will be done.

project.r.racing
Speed Racer
Posts: 3722
Joined: Sun Jan 18, 2009 10:16 pm
Vehicle: Non MX-5
Location: Glasshouse Mountains, QLD

Re: Unsprung Weight (NA6)

Postby project.r.racing » Sun May 22, 2016 9:54 pm

Would the steering arm be part of the unsprung weight?


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