F355 Updated Throttle quadrant | Page 2 | FerrariChat

F355 Updated Throttle quadrant

Discussion in '348/355' started by 275GTB, Feb 20, 2017.

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  1. Culprit

    Culprit Formula Junior
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    Apr 4, 2011
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    Ian
    Did this update last year and noticed no improvement... still stuck with the sticky throttle. Passengers think I can't drive a manual :( Replaced the throttle cable too and lubed the pedal etc. Will try to sync the intakes soon, that's the last variable.
     
  2. MAD828

    MAD828 F1 Rookie
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    Oct 8, 2011
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    Elliott Caras
    Are the roller bearings all good in the linkages? The grease from factory goes like glue.
     
  3. spaghetti_jet

    spaghetti_jet Formula Junior

    Jan 5, 2005
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    I went through this whole saga too. I fixed everything from soup to nuts: I serviced the throttle pedal, new throttle cable, new needle bearings, throttle plate and bypass balance, everything except the updated quadrant -- I still have the old style quadrant.

    One of the parameters that most impacted drivability was to leave a good amount of slack in the throttle cable at idle. I left quite a bit of slack while making sure that I got WOT with the accelerator fully depressed. Getting just the right amount of slack made a big difference for my car (once all the other things were sorted). If the throttle cable is taught at idle my car becomes very hard to drive smoothly in town.
     
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  4. MAD828

    MAD828 F1 Rookie
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    My experience is different, I removed almost all the slack in my throttle cable, the slightest touch of the pedal will result in revs rising, yet it is smooth as silk to drive.

    My biggest issue at the moment and the reason I removed the slack is the throttle plates are not 100% open at full pedal throw. There is more to be had if the throttle is fully depressed and you put you hand on the throttle linkage in engine bay there is still some amount to go. Are you going to the lock stops almost?
     
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  5. spaghetti_jet

    spaghetti_jet Formula Junior

    Jan 5, 2005
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    Very interesting the difference from car to car, just goes to show that the whole system needs to be considered. I get WOT on the 8 butterflies (cams on the stops) before the pedal maxes out.

    Do you have the new or old quadrant? IIRC, the throttle pedal has adjustable stops.
     
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  6. MAD828

    MAD828 F1 Rookie
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    The pedal stop is at the limit of throw before going to far and pressing into the plastic pedal surround.

    The throttle quadrant was modified by Ferrari they are basically the same but pulled apart and re welded in a new position so the angle changes. I think my linkages weren’t adjusted enough to compensate.
     
  7. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Sounds like I should just leave mine alone; it is more of a minor nuisance or a quirk that I have learned to live with. I wish I could better articulate what I am feeling. It is at the initial onset of pedal travel. I can't say it is sticking, and since most of the time the pedal is beyond that point, it is not that very noticeable.

    I would love to hear from more who have swapped out the lever to hear about before and after results.

    That is a disappointment, Culprit. Like others have commented, I would take a good look at the bearings at the pedal, and at the lever.

    Perhaps someone has a more positive experience to share?
     
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  8. spaghetti_jet

    spaghetti_jet Formula Junior

    Jan 5, 2005
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    OK, so what I think I've done by slackening the cable is to partly simulate/compensate for still having the old quadrant. The effect is similar, in that the throttle pedal is further depressed for a given throttle plate opening.
     
  9. spaghetti_jet

    spaghetti_jet Formula Junior

    Jan 5, 2005
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    Since you still have the old quadrant, as I have, perhaps you could try slackening off the accelerator cable slightly as an experiment to see if that has any effect?
     
  10. Culprit

    Culprit Formula Junior
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    I replaced the bearings at the engine end, didn't actually change any parts at the pedal. Now that you say it, the pedal actuation isn't really smooth even when the car is off... not sure if it's the root of the issue but I'll order a couple of these 101677 bearing parts and see if it helps.
     
  11. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Good idea. Please let us know if these make a difference.
     
  12. jjtjr

    jjtjr Formula Junior

    Aug 29, 2016
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    john truskowski
    The "flat spot" that you are referring to is prevalent in my car too, and mine is a late 95 build. I can't imagine that many new owners of these cars didn't complain about it back then, and Ferrari became aware of the issue through the dealer network. But it sounds like the updated lever doesn't fix it? It feels like the vacuum is holding the throttle bodies closed, and when you push the pedal hard enough past tip in, the movement gets easier causing a lurch. I find this to be most prevalent when at cruising speeds with steady state throttle.
     
  13. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    That is what I would like more information about......As you mentioned, customer feed back resulted in a different part, and there is no manufacturer that willingly and arbitrarily changes a part that cost any amount of money. Must have been done for a reason...???

    Surely, someone has a success story with the upgraded part?
     
  14. jjtjr

    jjtjr Formula Junior

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    I know. But there are times when a manufacturer will attempt to correct a flaw with a "new" part, and not succeed. I can remember when GM had a recall on wiper motor covers to fix them from just stopping while driving. The root cause was linked to cracked solder joints on the board, but the "new" part wasn't any better than the old one. In this case though they did make some changes to the geometry, but that may have only resulted in making it better and not completely fixing the issue.
     
  15. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    ^^^^^^^understood

    I think the factory swap was done late in 1997, so how about some input from folks with 98 and 99 cars?
     
  16. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Just noticed on initial depression, there is about 1/2" free play and then the pedal seems to hit "a wall." That is my flat spot. With a little more pressure, the pedal begins to engage the throttle and starts to rev. As previously stated, it is not a big issue and I have learned how to get around it; however, there are times when it is more noticeable, but again its not one of those critical things that is like a dart in the ass.

    I think the reason it is not a big deal (for me) is because it is at the very beginning of engagement. 90% of the time, I am "thru" that point, and even when starting from a stop, it is pretty easy to smoothly move thru it. ( hope that makes sense)

    I guess I should disconnect the pedal from the linkage and isolate whether it is binding at the pedal, or at the throttle lever. Guessing its the lever......

    jjtjr: is your flat spot also at the very beginning of pedal travel?

    Is the pedal free play normal?
     
  17. jjtjr

    jjtjr Formula Junior

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    Yes, it is only the first part of the movement. The only time it is a problem is during steady state cruising, when trying to slightly accelerate. It causes the car to shutter and surge, but like you I have learned to ease around it and get a smooth transition. I believe it is a design flaw that never really got resolved, and that is in part because so many owners learned to deal with it.
     
  18. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    I am fortunate that my symptoms are very minor. Thanks for the info.
     
  19. Kokose7en

    Kokose7en Karting

    Dec 5, 2019
    207
    SF Bay Area
    I have a similar “sticky throttle”. In which there is a pedal resistance off of idle then all of a sudden the tension releases and the engine revs more than intended. I removed the quadrant/bell crank, I have the old part. I re-welded the 2 pieces as accurately as I can to the picture showing the updated angle. I felt like it turn out great.

    After it is reinstalled, the “stick initial throttle” is still there. No noticeable change. I actually think it is something to do with the throttle bodies as I only feel the initial tension of the throttle when the engine is on. The stickiness isn’t felt when the engine is off.
     

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  20. spaghetti_jet

    spaghetti_jet Formula Junior

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    Nice work. I was thinking of doing the same with my quadrant.

    given your symptoms, if you have cleaned and lubricated all the pivot points/bearings at the pedal and throttle quadrant and if the throttle cable isn’t sticking, then it sounds like you are left with balancing the throttle bypasses.

    The whole system needs to be in good shape to get good low speed driveability.
     
  21. jjtjr

    jjtjr Formula Junior

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    I agree that at least some of the issue has to do with vacuum holding the throttle body plates closed. Most port fuel injected engines only have one throttle body, and ours has 8. That equals a lot of surface area for the throttle mechanism to overcome, and I know that the older cars with carbs would be subject to the same condition but perhaps the geometry is different on those cars.
     
  22. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Audi, any update?
     
  23. audi_328

    audi_328 Formula 3
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    Jul 13, 2005
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    Still sitting on my workbench, throttle still jerky. Thanks for the reminder; I didn't do many miles last season and the car's been put away since last fall, out of sight out of mind. I'll make a point to get to it this soon, especially now that spring's here (knocks on wood).
     
  24. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    After replacing my early style throttle lever with the later style, I can report that my flat spot is gone! Much smoother and linear acceleration; very happy that I jumped in the pool. I learned to "drive around" the flat spot with my foot, but that "wall" was always noticeable. Now, it doesn't matter if I am gingerly cruising around town, or mash the pedal to the floor, it's all smooth! Highly recommend.

    To recap:

    161826 (on the left) was installed on cars up to Assy number 28137. Ferrari superseded that number to 175234 (on the right) and was installed from 28138.


    Image Unavailable, Please Login


    Because of the different angles, the throttle cable adjusting nuts needed to be threaded down more than an inch. Other than adjusting the cable, installation was simple.
     
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  25. Culprit

    Culprit Formula Junior
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    Apr 4, 2011
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    Wow nice congrats! I'm so envious! You did nothing except replace the quadrant? I replaced that part but got no change, like some others previously posted.

    Feels like this issue should be easier to solve... it's just a cable pulling on some flaps but somehow we can't figure out a repeatable fix. With my car on some days the 'flat spot' is so bad in city driving it makes me want to push this thing off a cliff. I want to do the throttle body tuning with my mechanic, but we don't even know exactly what we're trying to do. Just syncing them up should in theory make things better?
     

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