550 aftermarket springs and shocks

Thank you for pointing me to the right thread.

 

As some of you may know i have had a 575 for 18 months. Great car but porpoises too much. I upgraded the shock ECU (and the steering ECU) to the FHP items. Improves the car. But not enough. Now re-looking at springs. And, "tis the season" to do it. HGTC and FHP springs unavailable. I have emailed Daniel at Ricambi about the "Cosmos" springs (208678) but assume these are also NLA as he'd have offered these when I inquired about a year ago. This means going aftermarket.

I have read this thread twice along with the referenced thread on spring rates and looked at the lefthander chassis (LHC) website.

This is the best post I have found on spring rates, posted by Rick in 2011:

"I had the local Ferrari dealer remove the aftermarket springs that were in my car and test the spring rates as I could no longer live with the "trampoline effect" in the car. Following is a comparisson of the different spring rates for the car with different packages...

OE FHP HGTC

Front: 320 375 400

Rear: 235 245 245"

[i have edited out the comments and details of Rick's aftermarket experience as ot salient here].

Front.
Earlier in this thread the stock front spring is highlighted as 128.6mm in diameter (5 inches) and 276mm (10.8 inches) free (uncompressed) length. The HGTC spring has been described as 10.25 inches free length and the FHP item, 238mm (9.37 inches). Diameters the same across all variants.

It would seem to me the simplest way to improve front springs is to replace the stock 320lb front spring with the Lensing p/n 1073015400 available from LHC. This is a 400lb, 9.5 inch long (free length) 5" diameter (i assume OD) spring. While iit is 3/4" shorter than the Hgtc spring it seems this should work as it is approximately the same length as the FHP spring. They are about $50 each. Hard to beat that.

John (Cribb), I think you went with the Lensing springs. Any feedback? Do you know if the spring mounts need to be modified in any way?

Rear.
The upgrade in spring rates from 245 from 235 is small and perhaps not noticeable except by the most discerning drivers. (The rear is also helped by the bar upgrade.) This raises the question of whether to change the stock rear springs and I think this comes down to the range of adjustment on the sprimg perches (threaded collars) for the rear ride height. The stock rear spring is 284 mm in free length (11.2 inches). The FHP spring is 259mm (10.2 inches).

Anyone know the range of adjustment available on the collars?

If the spring is just too long, while they can be cut (ugh) anyone know where to obtain a 4.25 inch diameter 10.2 inch long 245lb spring?

Last, anyone see any issue with any of this?

EDIT: I have just checked the adjustment range on the rear perch. Looks like there is about 3 inches of thread below the current collar setting. Looks to be more than enough.
Philip

 

I have TWS Japan coilovers kit installed on my 550. the shocks are adjustable with hard to soft.
The dial is located on top or the shock absorber, so adjustments a bit complicated.
Suspension light comes on every time I start the car but this is only problem I have.
The car handles amazing .

 

Philip, yes I'm using the Lensing 5" x 350 lb x 8.5" free length springs on the front of my 550 with the hydraulic lift setup and they're working well.

The diameters quoted on the LHC site are indeed OD's, so for the 5" category, the heavier springs will have progressively smaller ID's. For 350# and 400# springs, this shouldn't affect the perches, but there's a rubber dust shield with stamped steel upper collar that fits snugly into the 350# spring, but probably wouldn't fit without some effort into the 400#, due to its smaller ID. This dust shield can be eliminated, but I always try to study the consequences of eliminating something the OEM provided. Car makers rarely miss an opportunity to cut costs, so if something is there, there's probably a good reason for it.

One point you may have overlooked in your spring search is that with our coilover setup, you need springs with both ends closed and ground flat, which means those 400lb x 9.5" springs you referenced will not work as only one end is closed and ground flat, while the other end is open. The only other Lensing models (besides mine) that are built this way are their 11" & 13" free length conventional springs.

You might be able to accommodate the 11" springs by dropping the lower spring perch nut down a bit, but don't judge the amount of available travel by the amount of thread on the shock - it's not all useable. We've found that with the front suspension in full droop, the lower spring perch nut will foul the anti-sway bar bracket with about 15 threads or 22mm left below it. (Note, this is only applicable to the front - we haven't experimented with the rear springs as yet. And this is applicable to the 550 - your 575 might be different.)

The comments about the spring ends needing to be closed & ground flat are applicable to both front & rear.

I have a contact in the UK who will wind you nearly any spring you want at about double or triple the price of the Lensings (plus freight from the UK), but you have to know what you want. He won't get involved or take responsibility for any suspension engineering or calcs.

 

Thanks John, helpful input. Let me get more closely acquainted with the suspension and I'll come back to you. I'm guessing the dust boot is there to keep foreign matter from the shaft and preserve the seals so there would be a cost to eliminating it and doubtless a little struggle to make it fit. Did you try the 400lb springs in yours or were you not able to make fit?
Philip

 

Philip, I didn't try the 400# springs, as the 350 pounders are working fine for me, however I do have a dust boot here and can try to fit it on a 400# spring for you. I'll come back to you a little later today on this.

 

Thanks John. That would be helpful. I race and have access to machine shop facilities and a machinist so if they need to be "encouraged" to fit, we can make it work. I think I have found 400lb, 5" OD, 10.5 inch long springs where both ends are closed. (I am confirming the latter.)

Approximate math suggests the 400lb spring will compress 3.5 inches versus 4.4 inches for 320lb (stock spring) so they'll need to sit 0.6-inches lower on the shock body to provide an equivalent ride height without further adjusting for the hgtc ride height specs. I'll look at it all and take some measurements tomorrow, but I'm guessing these will work.

Philip

 

Philip, I tried, but couldn't encourage the dust boot to fit down into the 400# spring even with a 2x4 on top and a 5# mallet. I'll have another go at it with some silicone spray on the rubber & spring tomorrow. I'm sure once/if they're in and the spring goes through a few cycles of compression & rebound, they'll loosen up a bit - I just don't know if the wall thickness of the rubber is sufficient to prevent it from holing through, though.

I think LHC sells some dust "gaiters" for coilovers that are mounted on offroad vehicles to guard the shock rods against mud/sand, etc. - these might be a suitable substitute if you really want to protect the shock rod, but as I'm sure you well know, there are many cars with coilovers which have no protection at all for the rods & seals.

 

John, thanks for the effort.

Does anyone know the change in ride height for the FHP/HGTC package versus the stock 575?

I have the FHP guide Taz had originally posted where, for example, the laden (two people at 75kg each plus 1/2 tank gas) front ride height is measured to the trailing fanblock bolt at 196.5mm but don't know the stock equivalent. Anyone?

Philip

 

Terry had previously posted the ride height data I am seeking in the SN / AN thread. Here's the data with thanks to Terry:

"All heights plus or minus 5 mm with full tank of fuel and 75 Kg (165.3 lbs) in each seat. Rest of the alignment specs, too, under the same conditions. Caster is fixed at 5 deg 30'.

Standard 575M: Height: F 196.5 mm, R 201.3 mm Camber: F 1 deg + or - 10'. R 1 deg 30' + or - 10'
Toe-in: F 3 mm + or - 0.5 mm, R 3.5 mm + or - 0.5 mm

FHP 575M: Height: F 186.7 mm, R 194.2 mm Camber: Same
Toe-in: F 3 mm + or - 1 mm, R 4 mm + or - 1 mm"

So, with the crude assumption that the shock is between 45 and 60 degrees to the vertical (this can obviously be measured or estimated from the suspension drawing in the WSM) the change in collar position is between 1/3 and 1/6th of an inch to effect a 0.4 inch change in the front ride height. Taking the larger of these to be conservative (0.3) and adding my earlier calculation of the change in collar position for the stronger spring (0.9) less the change in the FL of static spring (0.3) tells me that to achieve the FHP / HGTC ride height, the 400lb, 10.5 inch spring will need to be located up to 0.9 inches further down the shock body than my current set up. I'll look later today but I can't see this is an issue.

John, can you see any reason why there would be interference with anything?

Terry's post also provides helpful data for the rear ride height change (7mm or 0.27 inches). Assuming the rear shock is about 60 degrees to the vertical, the change in collar position with be about 0.25 inches. Same commentary.

Interestingly, beyond ride height, the FHP settings put a bit more rake in the chassis (which I interpret will cause more aero load on the front at higher speeds) but don't materially change the camber, castor or toe at the front or the rear. There's a bit more rear toe to keep the back end planted but the FHP tolerance embraces the stock spec.

On my old 308, toe and camber were adjusted by shims on the lower control arm inner "forks". Is the 575 the same? Anyone done this?

Philip

 

Philip, if it helps, I'm getting right at 50mm vertical lift with my hydraulic setup with a ram that extends 40mm. A few trig calcs should produce what the shock angle is.

Offhand, no, but then applying our experience with the 550 suspension to the 575 is almost like apples and oranges because of the difference in shocks, etc. I would think though, that the position of the lower spring perch wrt the antisway bar bracket should be the same or close.....

 

Thanks John. Where are you measuring in relation to the wheel axle? Front lip or top of wheel arch?

The geometric drawing on Page F12 of the 550 WSM indicates the shock is at an angle of 60 degrees.

 

Philip- The 456, 456M, 550 and 575 variants all use eccentrics to adjust camber. It was an experiment and Ferrari did not like the results and changed back to shim adjustment on the 612 and 599. The eccentrics make adjustment very easy, but tend to be easier to knock out of alignment.

For $125, Ricambi will sell you a complete 575M WSM that has all that data. A quick peek at the parts catalog also shows the eccentrics for adjustment compared to the shims on the V8s and later V12s.

 

Philip, top of wheel arch.

 

Thanks for responses.

I've been digging around on the car and see the eccentrics now, Terry, thanks.
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Having looked around the shock, I think there's limited potential for interference for the springs i am looking at excepting what I interpret to be the flexible ABS plumbing on the lower control arm. As you can (hopefully) see in the pic the bracket that holds the plumbing will likely contact the lower collar of the spring when the spring is at full droop. The good news is I think this can be moved slightly by using the appropriate spacer. The securing bolt seems to be the upper end link fastener and this has sufficient threads to add a spacer to move the item out of the way. If not, a longer bolt and spacer will work too. All the lines are flexible and looped so i think they can be moved without concern if needed.
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A question for any of you that have removed shocks from your 575, the suspension control enabled by the "Sport" button connects to the top of the shock. The connection is shown in the pic below. Does the connector screw into the top of the shock so that undoing the retaining nut releases it, or is it a pigtail that's disconnected from its harness and removed in one piece with the shock?
Philip
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Looking at the picture on Ricambi's site it appears to be a pigtail from the shock shaft.

Looking at the price on Ricambi's site it truly is a shock

 

I am looking at ride height prior to installing a set of 400lb front springs on my 575. I have been measuring the existing ride height. It has lead to a set of questions, below.

Background.
My car is a US spec gated 02 575. I am the 4th owner, although I know the third owner only kept the car for a few weeks before trading it back the the same dealer (Continental) for a 360. I purchased the car in July 2011. At the time, all niggly things were fixed (visor droop, AC panel replaced, new tires etc). Soon after purchase, i changed the shock and steering ECUs to their Fiorano spec counterparts to reduce porpoising. It is now time to do springs.

SET UP:
Tires set to hot pressures (35psi), 10% over cold (32). Tires are not new but have approximately 8mm of thread depth. Front 255/40x18, Rear 295/35x18. Continental DW Extreme.

As it sits, car has 7/8ths tank of gas (so 20lbs lighter than full). I am going to assume that Ferrari's ride height spec is with a full tank of fuel. Helpful to confirm.

I put 175lbs in each seat (10lbs heavier each side than Ferrari's static weight spec of 165 in each seat). So, I am at Ferrari's book spec assuming this is measured with a full tank of gas.
Measuring platform (tested with a spirit level) is level from side to side and from front to back.

MEASURED DATA
I measured two ways.
1. Using Fanblocks, per Ferrari direction.
Front: Measuring to the center of the rearmost fanblock fastener, I record 180mm on LF and same on RF. I think I am +/- less than 1mm on this measurement.

Stock spec (F), US car: 196.5mm +/- 5mm.

Conclusion. Car is riding 16mm lower at front.

Rear:
Measuring to the center of the fanblock bolt on the frontmost fastener LR = RR = 170mm. Again, measured twice. (Rear control arms are at a slight dihedral, like most airplane wings)

Stock spec (R) is 201.3mm +/- 5mm.

Car is measured as riding 40mm lower at the rear than stock. I have heard thar dropping the rear by 40mm was a trick to get it to stick more. Anyone know or have experience?

Putting a level on the front to rear frame rails along the tunnel next to the exhaust confirms the car has some rake (front lower than rear). To anyone who has measured rake, besides the control arm / fanblocks pick up points, where have you measured chassis rake?

2. Using wheel arches. Center of arch taped and marked.
Measured from the floor to the top of the wheel arch, measuring through the center of the wheel cap.

Front.
LF = RF= 673 mm.

Rear.
LR is 670mm. RR comparable.
I am also +/- 1mm on this measurement.

On another site two 575 owners measured their ride heights in a similar way, providing a crude comparison.

First, a 2005 euro spec 575 was measured (without passenger weight and I assume with cold tire pressures as it was sat at a dealership showroom floor. I do not know fuel load). *The corresponding measurements were 685mm F, 710mm R. Second, a US spec 575 of the same MY was measured at 695mm F, 710mm R The Euro car therefore sits 10mm lower at the front than the US car.

Fuel and passenger weight.We don't know relative fuel levels but any differences will mostly be acting on the rear suspension. Also, my car has 350lbs of weight more than either of the above two measured cars, split approximately 50/50 F/R. While i need to pull the weight out for an apples to apples comparison, I calc the weight makes 7mm difference in front ride height and the same on the rear.

Comparison:
Front. Adding 7mm to my measured wheel arch heights to adjust for the unladen car weight equates to 680mm.

The front is 15mm lower than the US spec car and 5 mm lower than the Euro car. The difference in front ride height height versus the US spec car (15mm) is comparable to the measured difference on the fanblock above (16mm) allowing for my measurement accuracy.

Rear. Adding 7mm to the rear ride height to account for the passenger weight versus an unladen car equates to an unladen rear ride height of 677mm. This is 33mm less than either of the two cars measured above and while a bit different from the 40mm I measured above is directly consistent.

Finally, I tried the finger test. Top of tire to wheel arch. Two fingers (Index and fore) to first knuckle. Anyone have a comparable measure on their car?

I think the prior owner had already changed the ride height to something more aggressive, but it doesn't look lowered to my eyeball, hence the request for corroboration.

Philip

 

Carl, thanks. Yes, I get this (and race too) and am trying to understand three things. First, the hgtc settings as a baseline and how far away from these specs I am; Second, the logic of dropping the rear (which other things being equal, will tend to reduce aero load at higher speed and make it more floaty, right?); and Third, raising the rear by 3cm will give the car an "ass high" look which seems inconsistent with my mental image of the car, hence a question on the wheel gaps.

 

Carl, thanks. I tried to download the Corvette paper from SAE. But am thwarted by the PDF DRM not wanting to work with my Mac. It looks informative. SHame

 

Philip- I have never seen ride heights for the HGTC. Have it for FHP, but not HGTC. Where did you see HGTC numbers?

US FHP numbers (racing) show the same ride height for US standard suspension, but Euro FHP ride height is lower. Believe the reason for the US heights was headlight height.

Once your heavy springs are installed, Euro FHP numbers should work fine for your car and the OM HGTC supplement hints that FHP ride heights were used.