Project-Scuderia

Lightweight Battery Option #3

Specification..................................................................................... Braille B-128L
Chemistry.........................................................................................Li Ion
Weight .........................................................................................8.8 lb (4.0 kg)
Length.............................................................................................10.0"
Width.............................................................................................. 3.25"
Height @top of SAE terminals............................................................... 6.5"
Pulse Cranking Amps (PCA)..................................................................1482 A
Mean Cranking Amps @32F (MCA)......................................................... not avail
Cold Cranking Amps @0F (CCA)............................................................. not avail
Capacity (C/20 Rate) (Equivalent Capacity).............................................30 Ah (90 Ah)
BCI Group..........................................................................................n/a
Voltage.............................................................................................12V
Reserve Capacity (25 A discharge to 10.5 V)............................................ not avail
Recharge time (50 amp charger, @25C, from 10.5 V to 90% charge)............. not avail
Price.................................................................................................$2,099.00

Braille B-128L

Pro's
- excellent weight savings
- higher PCA
- higher capacity

Con's
- high price
- requires mounting adapter
- potentially unstable chemistry
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Lightweight Battery Option #4

Specification..................................................................................... Braille ML-30C
Chemistry.........................................................................................Li Ion
Weight .........................................................................................9.3 lb (4.2 kg)
Length.............................................................................................6.6"
Width.............................................................................................. 5.2"
Height @top of SAE terminals............................................................... 6.9"
Pulse Cranking Amps (PCA)..................................................................1658 A
Mean Cranking Amps @32F (MCA)......................................................... not avail
Cold Cranking Amps @0F (CCA)............................................................. not avail
Capacity (C/20 Rate) (Equivalent Capacity).............................................28 Ah (84 Ah)
BCI Group..........................................................................................n/a
Voltage.............................................................................................12V
Reserve Capacity (25 A discharge to 10.5 V)............................................ 100 minutes
Recharge time (50 amp charger, @25C, from 10.5 V to 90% charge)............. not avail
Price.................................................................................................$2,099.00

Braille ML-30C

Pro's
- excellent weight savings
- higher PCA
- higher capacity

Con's
- high price
- requires mounting adapter
- potentially unstable chemistry
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Lightweight battery Option #5

Specification..................................................................................... Braille Intensity i34CE
Chemistry.........................................................................................Li Ion
Weight .........................................................................................9.7 lb (4.4 kg)
Length.............................................................................................10.4"
Width.............................................................................................. 6.8"
Height @top of SAE terminals............................................................... 5.5"
Pulse Cranking Amps (PCA)..................................................................1320 A
Mean Cranking Amps @32F (MCA)......................................................... 1200 A
Cold Cranking Amps @0F (CCA)............................................................. 960 A
Capacity (C/20 Rate) (Equivalent Capacity).............................................25 Ah (75 Ah)
BCI Group..........................................................................................34
Voltage.............................................................................................12V
Reserve Capacity (25 A discharge to 10.5 V)............................................ not avail
Recharge time (50 amp charger, @25C, from 10.5 V to 90% charge)............. not avail
Price.................................................................................................$1,627.49

Braille Intensity i34CE

Pro's
- excellent weight savings
- higher PCA
- higher capacity
- no mounting adapter required

Con's
- high price
- potentially unstable chemistry
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I am setting the ride height of the Scuderia for a track setup. Starting from the Factory settings on the Scuderia of 114mm front and 136mm rear, I am lowering it 12%, which brings it down to 100mm front and 120mm rear, which preserves the recommended 20mm rake.

Examining the factory-recommended measurement points for the ride height in the diagram below, the rear measurement point is actually enclosed by the undertray. Perhaps coincidentally, the gap from the bottom of the chassis at the measurement point to the bottom of the undertray below it is exactly 20mm (seen in the second photo below). So, measuring the ride height with the undertray left in place, the clearance for my track setup is 100mm front and rear.

So I machined four posts to 100.00mm height to make the ride height measurements faster and simpler.

Getting the car properly configured is important, and there are a number of items to set/confirm.

Correct tire sizes (I used the 'middle weight' set of my three sets of tires & wheels, which comes into play later, when I corner balance the car)
Correct tire pressure (halfway between cold and hot pressures),
Correct fuel load (50%)
Correct cockpit load (weight of driver, including driving gear and helmet, placed on driver seat and in driver footwell)*
Storage compartments empty
front and rear anti-roll bar disconnected

*Car is set up for a solo driver (no in-car instructor)
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After four rounds of adjustments to the front springs and three to the rears, I got the ride height set. The closer you get to the bottom of the travel limts, the more non-linear the adjustments become, so linear extrapolation does not work well for predicting the outcome of the adjustments. The rear springs are close to the limits of the threaded bodies on the dampers but the coils are still under a lot of compression, so they behave more linearly, with a motion ratio around 2.5 mm/thread. The front springs have a lot of travel left on the threaded bodies, but are almost completely unloaded, so predicting ride height change based on the motion ratio does not work so well. The final result is shown in the photos below. The 100.00mm ride height represents the minimum, so for corner balancing (coming up next), I will only raise two corners. I won't lower any corners to adjust the balance.
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It depends. Unfortunately, you have to disconnect one front and rear link and attempt to re-connect them (with weight on the wheels) to see how much pre-load is in the suspension. Not a fun task with the stock drop links.

I will still be running the BBS FI's. I currently have a set of stock tires mounted on them. So, they won't change the ride height. They will affect the corner balance, but my third set will affect the corner balance in the other direction. That's why I picked my 'middle weight' wheel+tire set for the corner balance.

 

Since I put stock size tires on my BBS FI's, I have not had any more rubbing issues.

 

Having the right tools is half the battle. That goes for adjusting the corner weights too. A set of four corner scales is a must have. I have a set of Intercomp wireless 8800# (4000 kg) professional scales.

A roll-on/roll-off setup like I have for my 2-post lift is nice-to-have. It makes the job go way faster and easier. It was the only way to get the Scud up on the lift without jacking the car up just to get the rear lifting arms under the car. And that was before lowering it to its current height.
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I agree with all you stated in theory. I learned the same things in undergrad physics. Of course, we all made lots of simplifying assumptions in that class....

The rear springs appear to be progressive-rate springs (non-linear), even though they are constant diameter. The coil spacing is not constant on the rear spring. See the pictures of the front and rear springs below, which illustrate the difference between constant coil spacing and progressive coil spacing. The closer the spacing, the lower the spring rate (less force to compress the spring the same distance). This is not unusual anymore, as spring manufacturers can do amazing things with the latest coil winding machines. But, that was not the problem.

Where the front got REAL non-linear was where the spring perch was so low that the spring was fully un-loaded, and was actually shorter than the total allowed travel between upper and lower perches. So, when I set the car back down, the effective spring rate was zero, until the car came down on the springs, at which point the spring rate jumped up to the springs' initial rate. The photo below indicates the front springs are linear rate (or near linear rate). The problem was solved when I raised the lower perch up enough to put some load on the spring at full extension.
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Again, all true using simplifying assumptions. The two key simplifying assumptions are:

1) The two points where the Anti-Roll Bar (ARB) is attached to the car are perfectly equal with respect to both ARB attaching points on the L and R suspension. This assumption is good when you set the ride height, but goes out the window when you corner balance the car, because you are changing one of those relationships when you raise/lower one side to transfer weight. And you never move both in the same direction on the same axle. Weight-jacking is always done diagonally.

2) The ARB is not bent or tweaked. The ARB could be twisted in its static state, with one lever arm higher than the other when at rest. This is more likely on the front ARB of the Scud because it is a 1-piece ARB. The rear 2-piece ARB has one adjustable lever arm that could be re-indexed if the bar was permanently twisted. But, the splines are coarse, so its adjustability is very limited (like 20 degree increments). See photo.

Fun Fact - The rear ARB has a removable lever arm on one side, not for the purpose of adjustability, but because Ferrari ran the ARB through the chassis bulkheads. It is not attached with brackets.
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Here are photos of front and rear coilovers after I finished setting the ride height and corner balancing the car. You can see that the rear coil has nearly run out of travel, with the lower perch close to the end of the threaded body. The lower front perch still has plenty of travel left on the threaded body, but the spring is only about 10 threads away from being fully un-loaded. Lowering below that point would require a longer spring or a helper spring.
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After several rounds of adjusting coilovers to set the ride height, I was grateful that the corner balance went faster and smoother. Having the scales built into a drive-on platform helps a lot, as does the wireless display. I was able to remain in the car (as ballast) with the wireless display in the car with me, and drive on/drive off.

The scales are Intercomp SW 100315-RFX.
Each scale has a 1000 kg (2205 lb) capacity with 0.1% (1 kg/2.2 lb) accuracy. So, the total weight of the car is accurate to +/- 9 lb.

Photo #1 shows the baseline corner weights, after setting the ride height. Cross weight distribution is calculated by adding the weights from opposite corners and dividing by the total weight.

LR to RF = 48.86%
RR to LF = 51.14%

Real dang close for no adjustment. The factory would probably let this go out the door, as is.

I made one adjustment (half-turn) to raise the RF corner (increasing the ride height adds weight to that corner and the opposite corner, and reduces weight at the other two corners).
Photo #2 shows the corner weights after the first adjustment.

LR to RF = 49.95%
RR to LF = 50.05%

This is very close. Note that a half-turn on the perch moved as much as 23 pounds from a corner.

I made one more adjustment (half-turn) to raise the LR corner.

Photo #3 shows the corner weights after the second adjustment.

LR to RF = 49.96%
RR to LF = 50.04%

This is even better, but it is really a false sense of success. The difference is so far inside the accuracy of the scales, that it really does not represent a difference.

Next, I re-attached the two disconnected drop links to the sway bars WITHOUT adjusting them for pre-load.

Photo #4 shows the corner weights after the drop links were reconnected.

LR to RF = 49.56%
RR to LF = 50.44%

The 0.4% change across the total weight of 3289 lb represents a pre-load of 13 pounds, which was a large enough change to be measured even given the accuracy of the scales. So, this demonstrates the importance of adjustable drop links.
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It is important to note that I had already dialed out the pre-load once when I installed the adjustable drop links. So, the 13 lbs came from one small adjustment in the corner balance. I have no doubt that you could get 100+ lbs of pre-load from a major suspension change.

You do not have to disconnect them if you just want to weigh the car on corner scales. But, yes, you have to disconnect them for corner balancing. If you don't, any adjustment you make at one corner will be carried through the ARB to the corner at the other end of that axle. If you did that, you would spend all day chasing your tail, the car would never balance, and you would end up with hundreds of pounds of pre-load.

 

I was curious to see how swapping among my three sets of wheels and tires would affect the ride height settings, and the corner balance, so I mounted up the stock Scud wheels with the Bridgestone RE-11 tires (255/35ZR19 front, 305/30ZR19 rear) first. Here are the results:

LR to RF = 49.67%
RR to LF = 50.33%

The difference proved to be negligible. The overall weight is up by 10 pounds, as expected, based on component weights measured awhile ago. The Scuderia wheels are slightly heavier than the 16M wheels, and the Bridgestones are heavier than the Pirelli P-Zero Rossos. The corner balance is essentially the same because the relative difference between the front and rear wheel weights are proportionate to the vehicle's overall front-rear balance. Which makes sense, since the designer would want more grip/more tire on the heavier end of the car.

The change in ride height was more pronounced. The front RE-11s are 7mm taller (radius) and the rear RE-11s are 11.8mm shorter (radius) than the stock Pirelli sizes, which effectively wipes out the desired 20mm front to rear rake. So, the ride height and corner balance should be reset when the front and/or rear tire rolling radius changes significantly.
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This time, I mounted up the BBS FI wheels with the stock Pirelli P-Zero Corsa tires (235/35ZR19 front, 285/35ZR19 rear). Here are the results:

LR to RF = 49.65%
RR to LF = 50.35%

Note the huge drop in overall weight of 59 lb just by changing wheels and tires, but only a miniscule change to the balance. Also, the rake returned to normal with the stock tire sizes, with just a drop of 4 mm in ride height from increased tire wear (the Rossos are nearly new, and the Corsas are nearly worn out).
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