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308 Brake Master Cylinder Upgrades....?

Discussion in 'Technical Q&A' started by greg328, Oct 26, 2005.

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  1. greg328

    greg328 F1 Rookie

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    #1 greg328, Oct 26, 2005
    Did a search, but no real hard info/part #s on upgrading to a larger MC.

    I'm about to undertake a brake upgrade on my 1977 308 GTB. I'm doing larger rotors, and 4-piston Wilwood Superlites. I've yet to resolve the rear park brake issue, so I may not do the rears at all until I figure out a solution.

    My questions are:
    1) If I only switch out the fronts, will that require a MC upgrade? These calipers probably have twice the piston volume of the stock ATEs.

    2) Assuming I'm able to find a park brake solution, and I install all 4 calipers, will a single, larger MC handle the increased fluid volume? Or will it require a dual MC setup, like the one I read about here (I think that was PMA1010). I MUCH prefer to keep it simple if possible!

    3) Isn't the Porsche 914 brake system the same as 308s? Does that include the 914 master cylinder? What is the OEM bore on 308/914 MC, and what is the proper step-up bore for a 4-piston caliper set-up? Would a 911 brake master cylinder be an upgrade choice? Are there any mount-matching issues, or will it bolt in? Will the OEM reservoir suffice/fit a larger MC?

    I know I have many questions, but where else can a guy go to get such Ferrari in-depth tech advice but FerrariChat??!!

    Thanks in advance,
    Greg
     

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  2. BigTex

    BigTex Seven Time F1 World Champ
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    #2 BigTex, Oct 26, 2005
    You need to chat with Roland Linder....

    He is the ONLY person I am aware of, who has re engineered the stock F40 brake system to dual MCs to help Steve Parr and others overcome the imbalance in the F40s performance and it's braking capabilities.

    You have already spoken with the normal braking system gurus here.

    Roland is on the mend from surgery, and may be inclined to spend the time you'll need.........
     
  3. BigTex

    BigTex Seven Time F1 World Champ
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    #3 BigTex, Oct 26, 2005
    You could try Pinnacle Motorsports or Vintage Cars, both here in Houston......
     
  4. greg328

    greg328 F1 Rookie

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    #4 greg328, Oct 26, 2005
    Thanks BigTex. You're quick!

    Greg


    PS--are you driving your 308s these days?
     
  5. BigTex

    BigTex Seven Time F1 World Champ
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    #5 BigTex, Oct 26, 2005
    Nope....parked them for Rita out at the ranch, and only yesterday found my battery charger! LOL!

    They invited me downtown for the Art Car World Series party, but I was taking Jr. out to see Dick Dale, King of the Surf Guitar.......

    I'm afraid the 'stros are really missing Larry Dierker. We had dinner with him the other evening and just talked golf and Ferraris......sigh.
     

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  6. BigTex

    BigTex Seven Time F1 World Champ
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    #6 BigTex, Oct 26, 2005
    Greg328,

    Go to the supercar section and check it out ...

    Roland and Chris parr are there right now and have posted pics of the dual MC upgrade...looks sharp!!!!!! Not Cheap........
     
  7. greg328

    greg328 F1 Rookie

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    #7 greg328, Oct 26, 2005
    That's an awesome set-up.

    Not sure how it translates to a 308, but it might..!

    Greg
     
  8. BigTex

    BigTex Seven Time F1 World Champ
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    #8 BigTex, Oct 26, 2005
    The F40 was built from the 308, you'd be surprised at the interchangable parts......
     
  9. greg328

    greg328 F1 Rookie

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    #9 greg328, Oct 26, 2005
    True...

    Greg
     

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  10. Dave

    Dave F1 Rookie

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    #10 Dave, Oct 26, 2005
    To determine if you will need a new master cylinder, and of what size,
    simply do a little math with your new rotors and calipers.
     
  11. Dave

    Dave F1 Rookie

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    #11 Dave, Oct 26, 2005
    The steering wheel! ;)
     
  12. pma1010

    pma1010 F1 Rookie

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    #12 pma1010, Oct 26, 2005
    Last edited by a moderator: Sep 7, 2017
    Greg:
    You know my reservations on what you are attempting. That said, the pictorial reference and associated spreadsheet maybe helpful. I have not looked at the spreadsheet for some time so can't aid interpretation beyond what is obvious. From memory we used 3/4 F, 7/8 R MC with 2lb RPV (F). Was designed for big brakes all round and required a lot of pedal pressure (I think the 355 calipers are either 32/36 or 36/40, you'll need to check). Worked well on the track and I could lock either end. Brake set up sourced from CNC and mounts where booster was. Need to fab up a rod (non trivial, it is a stressed item) and a mounting plate and cut and weld pedal and bell crank to double leverage to close to 6:1.
    Good luck.
    Philip
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  13. greg328

    greg328 F1 Rookie

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    #13 greg328, Oct 26, 2005

    Well, I'm at about double the caliper piston displacement, if I do all 4.
    Less if I do just the fronts. Rotors are thicker also.

    Trouble is, I don't know at what threshold the OEM MC is rendered sub-par.
    Put another way, how much of an increase in fluid volume can the OEM MC handle? Maybe it's enough, if I just do the fronts. Probably not, if I do all 4.

    Do my Goodrich SS lines make a difference? They appear to be a little smaller gauge than the OE rubber hoses. That would be a plus...

    Greg
     
  14. don_xvi

    don_xvi F1 Rookie

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    #14 don_xvi, Oct 26, 2005
    355 brakes are indeed 36/40.

    Greg, if nothing else, maybe your enthusiasm will drive me to actually build MY planned brake upgrade this winter! I may even know the hot setup for Brembo calipers... hehe
     
  15. don_xvi

    don_xvi F1 Rookie

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    #15 don_xvi, Oct 26, 2005
    Actually, rotor thickness and any small difference in brake hose diameter (but did you really look at the ID???) won't matter. Using stainless hoses helps in that they won't "waste" any of the fluid you're moving out of the MC by balooning, but nobody's really taking brake hose expansion into their calculations for this stuff anyways. As for how much the OE MC can handle, recall that Eric was concerned when he was designing the Brembo front setup that it would be too much of a compromise on pedal feel to begin with, but then again, he's a brake engineer. Those that are just enthusiastic drivers report it's great. So I think we can say that the 36/40 setup is already borderline. Going bigger is going to put you way into the grey.
    One key piece of info that doesn't seem to be available is the bore of the stock MC. Then MC stroke (or, I believe, Phil even has the info to go to pedal travel) could be converted into pad movement. This would also be good info to have on hand for evaluating what size MC is DESIRED! Something might be able to be adapted (a European car specialist would be a good friend on finding what that might be), but you've also got to know what size you're working with and what you're trying to put on! ;)
    P.S.-the brake calipers have similarities with the 914, but that doesn't mean the MCs are anything close to interchangeable. I've never noticed any comparisons of 308 MCs to anything else here on Fchat...
     
  16. greg328

    greg328 F1 Rookie

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    #16 greg328, Oct 26, 2005
    Thanks Don, good info.

    The obsession continues!!

    Greg
     
  17. Sean F.

    Sean F. F1 Rookie

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    #17 Sean F., Oct 27, 2005
    Sell them. Buy the Griodisk set up. You'll be lots of time and lots of money ahead.
     
  18. greg328

    greg328 F1 Rookie

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    #18 greg328, Oct 27, 2005
    Sean,
    Not gonna happen. My set cost 1/3 of the Girodisc setup, and they're larger.
    Not as pretty, though! The Girodisc hats and brackets are definitely nicer finished, but my stuff is sturdy and functional.


    How will I be ahead $2000? That's how much I saved. Getting my system to work won't cost me near that!
    Plus, I'm doing the install myself.

    I spoke to the builder of my set, Concours Automotive, in California.
    He assured me this setup works fine w/ OEM master cylinder, but might have a bit longer pedal. He's tested it.
    It was designed for the 308.

    I'm not gonna install the rears until I figure out the park brake...



    Greg
     
  19. gerritv

    gerritv Formula 3

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    #19 gerritv, Oct 29, 2005
    If it helps anyone, the MC on my 308GT4 was replaced by one from a Dodge mini van. The MC half of the brake booster apparently was an exact fit with the Dodge part. (They replaced the outer half of the booster along with the master cylinder.)

    Gerrit
     
  20. greg328

    greg328 F1 Rookie

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    #20 greg328, Oct 29, 2005
    Thanks Gerrit, that's interesting...

    Brief update, I test-fitted my new large rotors and calipers tonight--perfect fit. My ugly brackets did the job perfectly. The Wilwood 4-piston Superlites are about twice as large, yet weigh less than the stock ATEs! The new rotors are about the same weight, but over an inch larger.

    Didn't have to drain all the brake fluid, just the local fluid at each corner.

    I'll top off and bleed once everything's in place.

    Greg
    77 308
     
  21. wildegroot

    wildegroot Formula 3
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    #21 wildegroot, Oct 30, 2005
     
  22. greg328

    greg328 F1 Rookie

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    #22 greg328, Oct 30, 2005
    Will,
    That's great info!! I'm going to PM you on the park brake topic in the next few days. I need to find out who to go to to machine my rear uprights, not to mention the caliper challenge...!

    I'm wrapping up my front install today--I'm waiting on the rears until I resolve the park brake install.....

    Greg
     
  23. wildegroot

    wildegroot Formula 3
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    #23 wildegroot, Oct 30, 2005
    Sounds good.

    Wil
     
  24. greg328

    greg328 F1 Rookie

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    #24 greg328, Oct 31, 2005
    OK, my front Wilwood Superlite 4-pistons and larger rotors are installed and working properly.

    Reall simple install--hardest parts were

    A) access to the inboard brake line connection (tight space)
    B) OEM caliper mount bolts were HARD to remove.....

    The car now has much more braking power, and I don't really notice the increased front --vs-- rear bias, altough it obviously is there.

    My brake is now a bit longer. Not unusable, and I'm sure I could get used to it, but I'd rather locate a larger master cylinder to solve this. When I finally install the rears, for sure I'll need to upgrade the MC.

    So, the search is on, for a master cylinder upgrade. Gerrit on here said that a Dodge van MC worked on his 308 GT/4? Are the MCs on a GTB interchangeable with a GT/4? Is there a larger one available?

    Greg
     
  25. chrismorse

    chrismorse Formula 3

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    #25 chrismorse, Oct 31, 2005
    Last edited by a moderator: Sep 7, 2017
    Greg,

    Here are two possibilities. The Mr Parker from Precision Brake runs $230, while the Wilwood unit is less than $100.

    Both units are designed for a fore/aft pull, so it looks like in addition to building a bracket to mount the unit around the back of the disc that one would need to either fabricate a pivoting lever arm to change the motion 90 degrees or to install a longer cable and housing that could be routed to a bracket for a straight pull. I am thinking that the lever arm & pivot offers a bit more flexibility in geting the length of pull and variable mechanical leverage. In particular, if more mechanical leverage is given to the stock handbrake mechanism, it could offer a bit more holding power.

    The Precision Brake unit, Mr Parker looks well made compared to the Wilwood unit.

    Rather than reinvent the wheel, i would like to ask if anyone has experimented with this type of unit, in particular has anyone worked out the linkage??
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