365's Brake Proportioning Valves - Rear | FerrariChat

365's Brake Proportioning Valves - Rear

Discussion in 'Vintage (thru 365 GTC4)' started by samsaprunoff, Mar 30, 2020.

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  1. samsaprunoff

    samsaprunoff F1 Rookie
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    Sam Saprunoff
    #1 samsaprunoff, Mar 30, 2020
    Good day All,

    This is a cross post to one I created in the 365/400/412 section (https://www.ferrarichat.com/forum/threads/brake-proportioning-valve-rear.619313/), but thought I would post here as the part is used on other 365 models.

    Apparently, the rear brake proportioning valves used (Item 7 - Part 105041) on the 365 cars are rather unique and were spec'd specifically by Ferrari. With that said it looks like no rebuild kits were or are are available and so I was curious what others have done (replace, clean up, or used something else, etc).

    Thanks in advance!

    Cheers,

    Sam

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  2. samsaprunoff

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    #2 samsaprunoff, Mar 30, 2020
    Good day All,

    This valve is a brake pressure limiting valve. Effectively this valve limits the maximum brake pressure to the rear brakes so as to ensure they do not lock in heavy braking and also to ensure that the front brakes receive maximum braking.

    I found more info from Internet searches along with an Ate document that describes these valves. I posted more details in the cross post link I posted in my previous post.

    Cheers,

    Sam
     
  3. TTR

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    #3 TTR, Mar 30, 2020
    Are you sure the document/text you found is referring to functions of these valves ?
     
  4. samsaprunoff

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    #4 samsaprunoff, Mar 30, 2020
    Last edited: Mar 30, 2020
    Good day Timo,

    I am reasonably confident, as the data/info comes from the C4 workshop manual (very similar units to these) which corroborates the operational info stated in the Ate document. I will confirm their functionality once I take the units apart and analyze them. That being said if my understanding of the device, etc is in error please post up and share your experience and knowledge of these devices.

    Cheers,

    Sam
     
  5. TTR

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    #5 TTR, Mar 31, 2020
    It’s been few years since I disassembled/serviced/restored some of these on 365 GTB/4s during major brake overhauls, but seem to recall them to be just manually adjustable regulators for (brake fluid) hydraulic pressure, although they may feature a by-bass function to compensate for or prevent overload.
    Encountering these first time about 15+ years ago made me wish I had access to brake dyno to adjust them accurately, but since nobody around here has one, I’ve learned to do without adequately.
     
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  6. samsaprunoff

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    #6 samsaprunoff, Mar 31, 2020
    Good day Timo,

    Thanks for your response. Indeed, your recollection of the device's operation matches that of the C4 manual and the Ate document as well. They look to be adjustable as you mentioned, but there was not a lot of info on the adjustment level, etc. I did find a bit of actual data in the C4 Manual and so I will test mine as they are to see how close they are to this level.

    Thanks again for your post!

    Cheers,

    Sam
     

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