[Atul]

Hi All,

I drive a '99 550M that's been updated with the FHP steering ECU and the 575 HGTC anti-roll bar, as well as the new COP (Coil on Plug) system from MarnelloSkunkWorks (separate report to follow on this system - it works very well indeed).

I've been tracking the car here in the UK and find the stock springs slightly soft for the track. Does anyone have experience fitting the FHP (Fiorano Handling Pack) springs on a 550? To the best of my knowledge, the FHP kit was only made available after the 575M was released, so there are likely not too many 550's with FHP springs floating around. I am guessing that the addition of the FHP springs to the car also require the FHP Suspension ECU replacement. How is the ride of the car affected - is it too harsh in town? Any feedback would be appreciated.

If there any aftermarket spring that's the equivalent of the FHP springs? Any experience with these will also be appreciated.

-- Atul

[tazandjan]

Atul- FHP was available on the 550 (look at the parts catalog on Ricambi's site) and either the FHP or 575 HGTC springs will work fine on a 550 and tighten up handling. Before I did that, though, I would put the 550 FHP shock absorber ECU on the car and see how you like the difference. Only the 550 had an FHP shock ECU, the 575M did not. Using the parts catalog will teach you many things about your car.

Ferrari Parts, Ferrari Accessories, and Ferrari Performance Products - Ricambi America, Inc.

Ferrari Parts, Ferrari Accessories, and Ferrari Performance Products - Ricambi America, Inc.

[cribbj]

Atul, there are a few posts & threads on here about the feel of the car with FHP springs. A search should bring up some good info.

Springs are cheap to experiment with - I would consult your Group C guy and I'm sure he would have some ideas for some spring rates that would perform better on the track and still not jar your fillings out on the street. There are several custom spring winders in the UK that will wind nearly any spring that you want.

As a starting point FWIW, the stock spring rates with the "red" dotted Eibach's are around 308 lbf/in for the fronts and 222 lbf/in for the rears.

I'm currently experimenting with some 350 lbf/in springs for the front along with a hydraulic front lift setup to help clear speed bumps, etc.

[cribbj]

Here is a table I constructed to show the differences between the various springs available on our 550's and 575's. Owners of the 575 WSM will recognise "most" of this table as being right out of section F1.01

I've included Ferrari's "given" Flexibility which is their way of showing spring rate.

Below the Given Flexibility I've run the spring rate calculation from that given figure, in order to show the rate in a more understandable form to many of us (pounds force per inch of spring movement)

Then below that I've shown the Rates and Flexibility calculations that I ran from Ferrari's Static and Dynamic loads and spring length changes, which is the correct way of calculating the rates. This is a good crosscheck of the Given figures and calcs derived from them.

There's a lot of information here, as it's right out of an Excel spreadsheet, so in the next post I'll include just a summary table with the free lengths and spring rates shown, which should be clearer.

[cribbj]

Here's the summary table which just shows free lengths and spring rates. These are what most people use to go searching for, and comparing different springs.

BTW, our springs are 5" OD (+) and 4.5" ID (+)

[tazandjan]

John- Handy tables, thanks. The calculated data matches very well. Have never seen any data on the HGTC springs, but it must be out there somewhere. The critical thing on the FHP springs is that they are considerably shorter than the regular 550 and 575M springs. You might want to add wire diameter to those tables.

[cribbj]

Originally Posted by tazandjan

John- Handy tables, thanks. The calculated data matches very well. Have never seen any data on the HGTC springs, but it must be out there somewhere. The critical thing on the FHP springs is that they are considerably shorter than the regular 550 and 575M springs. You might want to add wire diameter to those tables.

Taz, yes good idea on including the wire diameters, and I've also gone ahead and included coil diameters.

However when I referred to Ferrari's specs for the wire & coil diameters for the rear FHP springs, I noted they were shown to be the same as the "Yellow" springs. Since you can't have two springs with different spring rates, but with the same wire & coil diameters, I don't believe Ferrari's wire & coil diameter figures are correct for the rear FHP's, so have shown them in my table as "N/A".

If anyone has HGTC spring data, I'd be happy to include the calcs here.

[KonaDog06]

Atul, if it helps I've added FHP to my 575. The last part of the package installed were the springs. They made the single largest improvement. However, if your primary focus is the track, IMO they may not be firm enough. I don't track mine. With the 575 and FHP, it is still a comfortable GT car going down the road, far from harsh and you can still feel the weight moving around into turns, just less than the standard suspension.
If you are looking for improvement on track with a nice ride for the street, FHP springs will help. Also, from what I've read, 550's with FHP may be firmer than 575's with same.
Bill
FL

[Atul]

Taz,

Thanks for the info. About the FHP Shock ECU - is this part number 175949? Seems inordinately expensive, about $2500. Or am I mistaken. I'll have a word with Ricambi.

I like John's suggestion though - of looking into some aftermarket springs. The question is, is the FHP Shock and absolute necessity? I wonder what it's precise function is.

-- Atul

Originally Posted by tazandjan

Atul- FHP was available on the 550 (look at the parts catalog on Ricambi's site) and either the FHP or 575 HGTC springs will work fine on a 550 and tighten up handling. Before I did that, though, I would put the 550 FHP shock absorber ECU on the car and see how you like the difference. Only the 550 had an FHP shock ECU, the 575M did not. Using the parts catalog will teach you many things about your car.

Ferrari Parts, Ferrari Accessories, and Ferrari Performance Products - Ricambi America, Inc.

Ferrari Parts, Ferrari Accessories, and Ferrari Performance Products - Ricambi America, Inc.

[Atul]

John,

Thanks for the very detailed data about the suspension rates of the stock vs. FHP packages. The ECU requirement seems a little odd - any idea what the FHP suspension ECU does? Not sure if MSW is planning a 'special' version of this chip as well - that might be useful...

I did discuss this with my Group C guy and his advise was to simply put in some stiffer springs with the same length (to be able to easily clear bumps, etc.). His thoughts, however, are that the 550 is firm enough without new springs. He's also an instructor at the Ferrari Owners club track days and was at Donington Park yesterday. He did 3 hot laps with me as a passenger and I can tell you that even with stock springs, the car's performance limits are very high indeed. Another 550 owner on the track had the FHP springs and suspension ECU; his opinion was that the new springs were quite comfortable on the road as well. I guess I'll have to put all the data together and think about it all.

I'll send you a PM for the full spreadsheet.

Thanks,

-- Atul

Originally Posted by cribbj

Atul, there are a few posts & threads on here about the feel of the car with FHP springs. A search should bring up some good info.

Springs are cheap to experiment with - I would consult your Group C guy and I'm sure he would have some ideas for some spring rates that would perform better on the track and still not jar your fillings out on the street. There are several custom spring winders in the UK that will wind nearly any spring that you want.

As a starting point FWIW, the stock spring rates with the "red" dotted Eibach's are around 308 lbf/in for the fronts and 222 lbf/in for the rears.

I'm currently experimenting with some 350 lbf/in springs for the front along with a hydraulic front lift setup to help clear speed bumps, etc.

[Atul]

Bill,

Thanks for the feedback. The overall consensus seems to be that the FHP springs are stiffer but may not he THAT bad after all, for street driving as well. I'm considering the package seriously, since I do plan on tracking the car a lot here in Europe.

-- Atul

Originally Posted by KonaDog06

Atul, if it helps I've added FHP to my 575. The last part of the package installed were the springs. They made the single largest improvement. However, if your primary focus is the track, IMO they may not be firm enough. I don't track mine. With the 575 and FHP, it is still a comfortable GT car going down the road, far from harsh and you can still feel the weight moving around into turns, just less than the standard suspension.
If you are looking for improvement on track with a nice ride for the street, FHP springs will help. Also, from what I've read, 550's with FHP may be firmer than 575's with same.
Bill
FL

[cribbj]

Originally Posted by Atul

John,

Thanks for the very detailed data about the suspension rates of the stock vs. FHP packages. The ECU requirement seems a little odd - any idea what the FHP suspension ECU does? Not sure if MSW is planning a 'special' version of this chip as well - that might be useful...

I did discuss this with my Group C guy and his advise was to simply put in some stiffer springs with the same length (to be able to easily clear bumps, etc.). His thoughts, however, are that the 550 is firm enough without new springs. He's also an instructor at the Ferrari Owners club track days and was at Donington Park yesterday. He did 3 hot laps with me as a passenger and I can tell you that even with stock springs, the car's performance limits are very high indeed. Another 550 owner on the track had the FHP springs and suspension ECU; his opinion was that the new springs were quite comfortable on the road as well. I guess I'll have to put all the data together and think about it all.

I'll send you a PM for the full spreadsheet.

Thanks,

-- Atul

Atul, I'd think the FHP shock ECU just has a more aggressive curve for the bypass valves in the shocks which control their damping, much as the steering ECU varies a valve in the P/S system to control the amount of power assist.

If the system works as it should, it shouldn't affect the ride on the street, but it should stiffen it up quite a bit on the track (the sport switch, accelerometers, speed, steering & TPS all are inputs into it.)

[tazandjan]

John, Atul- Affirmative, the shock ECU controls the schedule and amplitude of the shock actuator adjustments to the shocks. On the 575M, there is a huge difference between different shock ECU's affects on handling. The 575M is fitted with Mannesmann-Sachs shocks, however, and the 550 with Bilsteins, so I am not sure how much shock ECU 175949 affects handling. The good news is it is a plug and play part that takes about 5 minutes to install, just like the steering ECU. Unless you do the work yourself like John does, swapping springs and then realigning the suspension and adjusting ride height is a more expensive proposition.

John- Note the rear springs on the FHP cars do have the same diameter wire as the regular springs, but are much shorter. This accounts for the increase in spring rates, because the dynamic length on both is the same. It takes quite a bit more force to compress those short springs, which shows up in your flexibility data, where the FHP spring is 12.5% less flexible.

[Atul]

John,

Originally Posted by cribbj

Atul, I'd think the FHP shock ECU just has a more aggressive curve for the bypass valves in the shocks which control their damping, much as the steering ECU varies a valve in the P/S system to control the amount of power assist.

If the system works as it should, it shouldn't affect the ride on the street, but it should stiffen it up quite a bit on the track (the sport switch, accelerometers, speed, steering & TPS all are inputs into it.)

Your explanation is sensible. Trouble is, the FHP ECU and Springs are both extremely difficult to get a hold of. I wonder what might happen if one just uses aftermarket springs that are stiffer (say, at least as stuff as the FHP springs as noted in your tables), with the stock (non FHP) ECU. I guess that will improve handling as well. I'll have a chat with my Group C guy. His initial assessment was that stiffer springs are really what make the major difference for track handling, the downside being that the street ride does get affected.

Another 550 Owner on the track-day yesterday, who had the FHP package installed, explained that the 550 FHP springs were designed so that the initial travel was almost like stock and that they only got stiffer progressively, making the street ride a lot smoother than it might have otherwise been.

-- Atul

[tazandjan]

Atul- The numbers say the FHP springs are stiffer right from the start with much decreased flexibility over the first mm of travel. Note there is also a lower ride height recommended for FHP on the 575M in Europe, mostly because the springs are shorter. I have not seen the 550 tech bulletin on the FHP package, but would assume that was the case for the 550, as well.

Anybody have the 550 FHP bulletin with alignment specs? I have it for the 575M, but the differences in shocks and suspension mean they do not match.

[henryr]

the spring upgrade makes a noticeable difference on the track......

[cribbj]

Taz, just a minor point, but free length by itself doesn’t directly affect the spring rate. The only factors that affect rate are:
1. The diameter of the wire
2. The diameter of the coils
3. The number of active coils (and how they're wound in the stack).

Having said that, a shorter version of a spring wound with the same materials as a longer, is likely to have fewer active coils and this will cause the spring rate rate to increase.

Since you’re confident the diameter of the wire and the size of the coils are the same between the yellow rear spring and the FHP rear spring, I think the FHP spring simply doesn’t have as many active coils as the longer “yellow” springs and this is what caused the rate to increase for the FHP’s.

In my former statement, I had neglected to consider this, so based on the above, I’ve gone back and corrected the table to show the same wire diameter and coil diameter as the yellow springs as shown in the WSM.

Also, I’ve had some communication with HenryR on the side concerning the HGTC springs, and based on the testing he had done by Goldcoast Motorsports last year, it would appear the HGTC's are about 7% heavier (stiffer) than the FHP’s.

I've tried comparing Goldcoast's measured figures for the FHP's against Ferrari's and there's about 35 lb-f/in difference between them, which is "almost" within the range of spring tolerances used by the manufacturers. If the difference is not due to tolerance, it could also be that Goldcoast used a different methodology for measuring rate than Ferrari (Eibach) did. Whatever the reason, it does appear the HGTC's are somewhat stiffer than the FHP's.

[ENZ525]

Originally Posted by tazandjan

Atul- The numbers say the FHP springs are stiffer right from the start with much decreased flexibility over the first mm of travel. Note there is also a lower ride height recommended for FHP on the 575M in Europe, mostly because the springs are shorter. I have not seen the 550 tech bulletin on the FHP package, but would assume that was the case for the 550, as well.

Anybody have the 550 FHP bulletin with alignment specs? I have it for the 575M, but the differences in shocks and suspension mean they do not match.

Here is a copy of the bulletin...

[tazandjan]

Enzo- Thanks, first time I have seen that. Onto the hard drive she goes.

The note that the settings were not for the US, CAN, or AUS can be ignored because I believe they relate to a headlight height requirement.

Interesting to note that for the 550 when this was published, only red calipers were available. On the 575M, and possibly later 550s, all the optional caliper colors were available.

[ENZ525]

No problem Taz, my pleasure...

This is the only FHP bulletin I can find for the 550, it is dated 23rd Feb 1999.