456 vs. 575/550 steering?

Hi there,

I have all 3 cars now. 99' 550M, 03' 575MM, and 03' 456MGT, and all 3 cars are in gated manual stick 6 speed shift. And I used to own a 97' 456GT also gated stick 6 speed.

The 456MGT steering feel slightly tighter and a bit more refined than my old 97' 456GT, but that could be cause of the 456MGT is newer and less mileage. The 550M feels just right and tight, the power steering plays a good role here. My 03' 575MM feels quite different from the 550M, the power assisst plays a big role here. The 575MM feels lighter and a bit more artificial... But my friend's 05' 575GTC feels the best among all Maranellos and 456s. It has a firm, tight, smooth feel, and when the car speed picks up faster and faster, the steering feels even tighter, job very nicely done by Ferrari...

I once heard from a friend who did a 456MGT steering conversion using the 550M system, and he seems to liked it. I am happy with my 550Ms and 456MGT, but I do wonder if I can update my 575MM to the GTC version.

Alex Lin

 

You can improve feel on all the 456-575 cars by fitting the FHP steering ECU, if not already fitted. This ECU is really a glorified relay, and the price has risen recently. It schedules hydraulic boost to the steering. Although only listed for the 550 and 575, it fits the 456M, at least, and probably the 456, as well.

http://www.ricambiamerica.com/product_info.php?products_id=206992

All the 456/M and 550 cars, and 575Ms after Assembly Number 52556, have a steering position sensor that improves suspension reaction to steering inputs, tightening down the relevant shock absorbers based on steering lock before the roll sensor can feel the car begin to roll. This feels like an improvement in steering feel.

It is not possible to upgrade early 575Ms with the steering position sensor because too much was changed. This included new front and rear wiring harnesses and new Motronic DMEs to read the steering sensor data and send signals to the new shock absorber/suspension ECU.

See below for the 575M changes. Assembly Number 52556 is approximately Serial Number 1353xx, Nov/Dec 2003.

Taz
Terry Phillips
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Hi guys. I have a 2000 456M GT that has good steering, maybe overboosted at slow speeds, but tightens up at speed.
I also believe that when the sport switch is on, the steering feels even better. Is this your finding as well?

Thanks,
Jay

 

Jay- As far as I know, the steering ECU is independent of the Sport switch, but, like the steering position sensor mentioned above, the stiffening of the shocks is felt as the steering being more responsive to inputs.

On F1 cars, obviously not on 456-550, it also speeds up shifting.

Taz
Terry Phillips

 

Always thanks for the great info. My 03' 575MM is the earlier model car which does not equiped with the steering wheel sensor, and most likely the GTC steering ECU would not work on my 03' 575MM... So, I will live with FHP steering ECU for now which is also nice.

Alex Lin

 

These Servotronic relays come up from time to time on eBay for other cars, and at much more attractive prices than Ferrari's (no surprise). Whether they're the same or not.....

I took the plunge this morning and purchased one for an Aston for GBP 38.00 (about 55 USD), and it has the same ZF reference (C3 ZFLS) as the Ferrari relay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=220691464082&si=wQbRd8bLY0voOTjSR%252FXbxxaNNS4%253D&viewitem=&sspagename=STRK%3AMEWNX%3AIT

If I can open it up to have a look without destroying it, I will. If it's potted and can't be opened, I may just go ahead and plug it into my 550, and hope it doesn't let the smoke out of the system. If no smoke, it'll be interesting to see what effect it has on the steering feel.

 

will that work on a 575 also ? what happens if u just pull the relay and go without ?

 

Would be great if it was a cross reference. Certainly looks like the same part.

Reminds me- didn't someone start a cross-reference list or table for parts? I remember a thread a while back on the subject and it would be a great resource for us all.

 

Erik,

Great find and thanks for sharing Keep us posted and report back here if the DB9 servotronic works. If it does WOW!!!!

 

Thanks but it was John's find not me...

But I'm sure hoping!

 

The DB9 relay will probably work, but what do you have once it is fitted? All the 456-Superamerica Steering ECUs look the same, but the hydraulic pressure scheduling is different in all of them. For instance, the DB9 steering has 3.0 turns lock to lock, while the 575M has 2.2 turns lock to lock. The ECU will take that into account.

Taz
Terry Phillips

 

Taz, all good points, but it's tough to find detailed info on this system to make an educated judgment.

I've just missed ZF today - it's nearly 5PM here in North Africa, and Germany are an hour ahead of us, so I'll put a call in tomorrow morning to see if they'll turn loose any information.

 

John- There is not much detailed info on ECUs in Ferraris available to the public. In most cases the ECUs are produced by the part manufacturer like ZF for power steering and Bilstein and Sachs for the shock absorber ECUs and then programming is added to make them compatible with Ferrari's version of the Motronic DMEs, CAN network, and whatever sensor inputs are available. Ferrari uses a varying number of accelerometer and steering position sensor inputs for the suspension ECUs and the Servo-Tronic/hydraulic steering ECU gets inputs from the Motronic ECU on speed, roll, pitch, etc. Other manufacturers have similar, (but how similar?), programming.

Taz
Terry Phillips

 

Measure the resistance between the terminals with an ohmmeter and compare to the Ferrari part to make sure you don't have a NO contact when it is NC on the other. And, If the coil resistance measures the same you should be ok with keeping smokey at bay.

 

Exactly; I'm guessing there's probably a personality prom inside this thing that tells it that it's going into an Aston setup, not a Ferrari. But, I could be wrong, and I hope I am, so that it could be possible for people to save $900 or so on these.

Thanks, but I'm guessing this little widget isn't really a relay, but is actually a very clever little hydraulic spool valve controller that is packaged in a relay looking case, with relay looking pins on it. I'm also guessing its output is a PWM waveform of some sort to control the hydraulic valve, and eventually the pressure in the system. But that's just me guessing; I'll hopefully know a little more after talking with ZF tomorrow.

 

What does progressive steering really do? The ability to change the hydralic pressure to vary the heaviness of the felt steering does not change laptimes or quicken the response time from steering input to slip angle of the tire on the road. Or do I just not understand electronic manipulation of power steering? I have never looked into it. I know people can feel differeneces but do those felt differences make you any faster?

 

FBB,

Maybe there's something to the FHP steering ECU upgrade in everyday driving. I know on the track where things are happening fast on the road course or on long straights where I'm carrying a lot of speed, the 550's stock steering ECU is more than adequate.

Barry

 

Just an update, I was able to speak with one of ZF's support engineers in Germany, very briefly before our line was cut, and he informed me that it was very doubtful an Aston controller would work for the Ferrari, for many of the reasons Taz spelled out earlier in the thread.

The "C3 ZFLS" reference on both controllers is not the P/N at all. The C3 refers to the "family" or generation of the Servotronic system, and ZFLS is actually the abbreviation for the name of the company, ie ZF-Lenksysteme.

The "real" P/N for the thing is that 10 digit number that begins with 7038 (visible on the Aston controller, but hidden on the Ferrari). I was in the middle of asking him for the Ferrari P/N when our line was cut, and I couldn't get out again. I'll give it another go on Monday, but for now, I wouldn't recommend anyone running out and buying one of these as I did, in the hope that it'll work in their 550/575.

 

Last update to close this out. They confirmed the controller for the Aston (7038 900 293) would not work for the Ferrari. Different P/N, different calibrations, etc.

The ZF P/N for the Ferrari controller is 7038 900 288

They would not quote a price on the Ferrari controller and referred me back to the dealer network. No surprise there.