360 430 Lowering Process - Ferrari Life
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post #1 of 2 Old 03-16-2009, 04:44 PM Thread Starter
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360 430 Lowering Process

Lowering A 360 or 430

Before one drops the vehicle height one must know if the current height is a factory setting. This is done by measuring the length from the bottom of the spring resting washer (part into which the spring bottom sits) to the center of the lower shock bolt. The factory values are as follows:

Front Shocks Rear Shocks
Yellow markings: 155.2 mm –156.2 mm 171.7 mm – 172.7 mm
White Markings: 153.7 mm – 154.7 mm 170.6 mm – 171.6 mm
Red Markings: 152.2 mm – 153.2 mm 169.5 mm – 170.5 mm

If the front spring is not removed from the car, you can still measure the above distances to verify if you are at original settings before you start the lowering process. You will need a thin metric ruler that starts at 0 mm at the very edge of the ruler, because you are going to measure from the top of the lower shock mounting bolt to the bottom of the upper spring support ring. Slide the ruler down along the shock body so that it slips between the shock’s lower mount and rests on the securing bolt.

The lower front shock bolt is 12 mm in diameter. So you will add to the measurement you make of that or 6 mm for the total length, and compare that with the above.

Alternatively if measuring the shock is difficult the car’s height can be measured before lowering.

Find a suitable location to measure the before and after heights. Make sure the car is on level concrete so your measurements are accurate and then get under to measure the height!

It is also important to know both the OEM height measurements and the points from which the measurements should be taken.

OEM height measurements are: front at 125.2 mm (4.929”) and the rear is 146.8 mm (5.779”).

Front: ahead of the front wheel at the structural member body side of the wheel and just forward of the lower A frame securing bolt. There is a rubber drain tube there. Measurement is just behind that tube on the aluminum frame. See photo on right.

Rear: forward of the rear wheel at the structural member body side of the wheel which is right below the curve of the lower air scoop as seen from the external side of the vehicle.

Ferrari suggest that each seat should be weighted with about 150 lbs of ballast and about 50 lbs in the trunk for proper height measurements and for proper height alignment purposes. That might be a bit over the top, but one should bear in mind that when lowering the vehicle w/o such ballast weight that the car will sit a bit lower with driver and then again slightly lower with passenger.

There are two wrenches that greatly assist the shock height adjustment. Hill Engineering makes one for the lower locking ring P/N: LNS-02. It is about $50.00. This tool works extremely well if the shock rings are loosened when the spring is within a compressor.

If one is working with the spring on the vehicle, the Hill wrench is very difficult to use. It is a bit wide and straight which is difficult to get within the wheel area! Unfortunately Hill does not yet offer one for the main coil support ring which requires the greatest effort to lower the vehicle!

McMasters-Carr offers a variety of spanner wrenches that are tremendous for adjusting coilovers. Go to: http://www.mcmaster.com/#spanner-and...renches/=wj7ul

The main 360 shock spring collar has slots spaced at 90 mm’s in diameter. The McMaster’s spanner wrench P/N: 6975A22 will fit this. This is a fantastic wrench and makes adjusting the spring securing ring an easier task.

The lower adjustable locking nut has slots at 70 mm’s in diameter. Their P/N: 6975A21 wrench should work, but the Hill wrench will also work although it may be easier to use the 6975A21 wrench from McMasters with the shock still on the vehicle.

Calculating vehicle drop is based upon the number of downward turns of the spring retaining ring. Total body drop is affected by the Motion Ratio which is the ratio of shock travel versus wheel travel. It is equal to the Shock Travel (in inches) per 1 inch of Wheel Travel. Motion Ratio is used to account for the different suspension geometries and the resultant mechanical leverage on the spring. In almost all cases, the Motion Ratio is less than 1.

One can generally calculate the Motion Ratio by simply dividing the shock travel by the wheel travel. Example if the shock travels 0.5 inches and the wheel travels 1 inches then the motion ratio would be 0.5/1 = 0.5.

It is believed that the Motion Ration of the 360/430 suspension is about 0.70. The value cannot be found in the Ferrari workshop manual for some reason, but it is believed to be accurate. Thus the formula below is based upon the 0.70 value for the Motion Ratio. M.R. 0.80 is shown for reference.

So lets say you want to achieve a 1" drop. Basing the calculations on the MR value as 0.70, 12 turns will drop your vehicle 1" (25.45 mm/cm/1.5mm = 16.97 turns X 0.70 = 11.88 turns/cm).

The threads on the Ferrari shock body are pitched at approximately 1.5 mm which means that every turn of the ring should equate to a drop of 1.5 mm.

This means that for every downward turn of the spring support nut with a motion ratio of 0.70, you would get about .084” of downward travel of the body. The specifics are for two M. R.’s are below:

Motion Ratio –0.70 Motion Ratio - .80
# turns Distance mm Distance Inches Body Drop Body Drop
2 turns = 3.0 mm = 0.118” 0.167” 0.147”
4 turns = 6.0 mm = 0.236” 0.33” 0.295”
6 turns = 9.0 mm = 0.354” 0.50” 0.442”
8 turns = 12.0 mm = 0.472” 0.67” 0.590”
10 turns = 15.0 mm = 0.591” 0.83” 0.737”
12 turns = 18.0 mm = 0.709” 1.00” 0.884”
14 turns = 21.0 mm = 0.827” 1.17” 1.032”
16 turns = 24.0 mm = 0.945” 1.33” 1.179”
18 turns = 27.0 mm = 1.063” 1.50” 1.327”
20 turns = 30.0 mm = 1.181” 1.67” 1.474”

Remember that these figures for the 0.70 Motion Ratio are based upon lowering the vehicle with the factory springs in place!

First photo is the front height measuring point
Second photo is the stainless steel clamp in place
Third photo is ABS/brake wire support being removed
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Last edited by Gcalo; 03-16-2009 at 04:55 PM.
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post #2 of 2 Old 03-16-2009, 08:06 PM Thread Starter
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Join Date: Feb 2006
Location: San Ramon, Calif
Ferrari Life Posts: 3,627
Table correction from above.

F.L. did not pick up my spaces properly.
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