CST malfunction and tire size | FerrariChat

CST malfunction and tire size

Discussion in '612/599' started by EP328, Apr 13, 2016.

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  1. EP328

    EP328 Formula Junior
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    Ed
    #1 EP328, Apr 13, 2016
    In order to get the Pilot Super Sports on my '09 599 GTB 315s were fitted on the rear. Standard 305 on the front on 20" challenge rims. At slow speeds, about 25 mph, in wet mode the CST has been activating and applying right side brakes on gentle left hand turns.

    The dealer has been checking the car and determined the 315 rear tires are the problem.

    A search on this subject indicates 315s should not be a problem.

    As posted previously, my car suffered driver side rear axle coming off the transaxle due to attaching bolts not being torqued by dealer tech after a clutch replacement. My thoughts were the CST problems are related to the axle failure, with it flopping around on the car until the car came to a stop.

    What do others think about the dealer's diagnosis?
     
  2. Cyphur01

    Cyphur01 Rookie

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    Nick Johnson
    #2 Cyphur01, Apr 13, 2016
    I think you need to go to a new dealer. 315 mpss have been nothing but flawless on 07 599. It seems to me like they are trying to lay the blame for their mistake elsewhere.
     
  3. Roupin

    Roupin Formula 3

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    #3 Roupin, Apr 14, 2016
    No problems here with stock sized front tires and 315 rears.
     
  4. johns930

    johns930 Formula 3

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    #4 johns930, Apr 14, 2016
    changing tire height can throw cst codes, i never have that problem on my 599/612s, but i do have that on my 458 when i go different size than stock, but if u put it in race mode or above, like esc or cst off, no warnings ever, but ur on ur own which is what i like, not for everybody.


     
  5. tazandjan

    tazandjan Three Time F1 World Champ
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    #5 tazandjan, Apr 14, 2016
    Sounds like your problem may be the fronts, not the rears, unless I read your post incorrectly. On a 599, stock fronts are 245/35 20 and 305s are standard on the rear.

    315s on the rear and standard 245/35s on the rear should not affect ABS/stability control, since that is less than a 1% change in rear diameter.
     
  6. Caeruleus11

    Caeruleus11 F1 World Champ
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    #6 Caeruleus11, Apr 14, 2016
    I had no problem with MPSS 315s on my car for several years....
     
  7. EP328

    EP328 Formula Junior
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    #7 EP328, Apr 14, 2016
    Stock on the front, 245/35 20 and rears are the 315/35 20. I thought the diameter difference should not be a problem. The dealer has physically/visually and electronically checked the sensors and could not find any issue. When they got the "wave" readout (whatever that is) that pointed to the tire size. The dealer sold me the larger rear tires so changing out, if it comes to that is on their acct.
     
  8. tazandjan

    tazandjan Three Time F1 World Champ
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    #8 tazandjan, Apr 14, 2016
    Ed- MPSS tires were not available in 305/35 20 last time I checked. In the rain mode, CST has very low thresholds for intervention, so what you are seeing with a V12 with 449 lb-ft of torque and gearing like a drag racer does not surprise me. I have never used the rain mode in my 575M (434 lb-ft), preferring to just use a delicate right foot and early upshifts until the tires are warm, if they ever are.
     
  9. EP328

    EP328 Formula Junior
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    #9 EP328, Apr 14, 2016
    MPSS still not available in 305/35 20. The CST intervention was happening at low speeds (~25 mph) either coasting or minimal throttle through moderate left hand turns. I am hesitant to give up the mPSS so perhaps I just leave the car in sport mode at a minimum. This of course assumes the tire size is causing the problem. Based on what I have researched so far, no one else seems to have issues with 245/35 20 fronts and 315/35 20 rears.
     
  10. tazandjan

    tazandjan Three Time F1 World Champ
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    #10 tazandjan, Apr 14, 2016
    Ed- Sounds like the best solution. No sense chasing after gremlins. There are plenty of safety back-ups in Sport.
     
  11. Makuono

    Makuono Formula Junior
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    #11 Makuono, Apr 14, 2016
    Taz,

    Ed's (EP328) 599 is a MY09, do you think that possibly his CST is different (more sensitive) than prior 599s? hence this behavior?
     
  12. tazandjan

    tazandjan Three Time F1 World Champ
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    #12 tazandjan, Apr 14, 2016
    Ricardo- Even though his is a Motronic 7.3.2, 7.3.2 was introduced in late Summer/Fall 2007, so I doubt it is any different from late 07 and later 599s. I have not heard from too many owners using the rain mode at all, so it would not surprise me if all of them do it. That is a bunch of torque and really low gearing, even idling along.
     
  13. trygve11

    trygve11 Formula Junior
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    #13 trygve11, Apr 15, 2016
    Last edited: Apr 15, 2016
    Verify exact and matching tires pressures left to right. Then measure and confirm the tire diameter is identical left to right.

    Report back...
     
  14. EP328

    EP328 Formula Junior
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    #14 EP328, Apr 15, 2016
    Yes, done prior to each driv. 35 front and 32 rear.
     
  15. EP328

    EP328 Formula Junior
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    #15 EP328, Apr 15, 2016
    --UPDATE--
    Today I drove the car with a technician from the dealership. Drove the car on a twisty road where the CST previously activated. Lucas Valley Road for those interested. Drove the route in "wet" mode about 25 mph and then the same loop in "sport" mode at same speed.

    During the "wet" mode drive, the CST warning activated several times on left hand turns and in one instance brakes activated. When the same route was traveled in "sport" mode, no CST intervention at all.

    The tech and service manager concluded the slightly taller 315/35 tire ( ~ 1/2 inch circumference ) is causing the issue in "wet" mode. The dealer will check with FNA if there is a software patch / adjustment for the larger tire.

    In the meantime the car will stay in"sport" mode. And I will keep the MPSS.
     

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