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Brake Hard lines at master cylinder size and thread
Does anyone know the hard line size and thread type/size that goes to the brake master cylinder? Car is an 86 951 if that matters. Thanks in advance. - Wayne
Pretty sure iirc when I converted to manual brakes I used metric ISO/DIN bubble flare fittings for 3/16” tube 10x1mm thread pitch. You’ll obviously need the correct tool for the bubble flare as it’s not the common type used for SAE fittings.
Yep! all are 10mmX1.0...+! on what MAGK said.! What kind of line are you using? Steel or copper or stainless? Copper would be my choice if I had to do it all over again. Mine's in stainless, very hard to manipulate and bend. You'll need a special flaring tool to do flares with this stuff. Copper-nickel is the easiest, and it won't corrode due to salt or anything. Required by the state of Maine on replacement of steel lines by their DOT. Steel is probably good for the other parts of the country with a pretty long life. Prewsume that you won't drive your "beast" in winter with snow, etc.
Since a track isn't being made here in Oahu, HI anytime soon, I've decided to try and tuck my wiring and try to get the engine bay as minimal aka clean as possible. Got inspired by Cass944 back in the day and I will be getting a new rust free shell to start, which is incredibly hard to come by here in Hawaii. 😂 😂. Going to attempt to install the Chase Bays brake booster eliminator since I have not seen one 944 with it yet. It'll probably be cheaper to go this route as I need to replace my brake booster, master cylinder and resevoir anyway. This engine bay with a 951. Will try to anyway. This is the cleanest engine 944 engine bay, ever. Aside from the other concourse genre engine bays. Thanks for the info! 🤙🏽
2 things to consider on the chase bays -
it's made with 4 bolts to replace the booster, but the 944 firewall only has 3 bolts - for the cereal bowl thing that the booster hangs on. so you won't have a MC right on the FW, you'll still be using the cereal bowl.
also, they attempt to discuss this on their site but their MC is only a single circuit - the 944 (and all cars since about 1970) have been dual circuit MCs, so you still have some brakes even if the other circuit fails.
on a 944 (and most RWD cars) the split is front vs rear. FWD cars are typically diagonal split (1 front and opposite side rear, per circuit). in the unlikely event their MC o ring(s) fail on you, you'd have no brakes at all.
Surprised chase bay can stomach the liability exposure selling single circuit M/C replacements for dual circuit (federally mandated since 1968?) brake systems.
Crash caused by failure of their replacement M/C = unlimited liability.
I wouldn't get near one....
Rolls Royce actually split the circuits so that one piston of each caliper is on A and the other on B. So even with a circuit failure you still get 4-wheel braking.
As others have said, to maintain the integrity of the dual circuit braking system you can make your own plate that fits where the booster mounts, then use two masters with a balance bar connecting them.
Here is my manual brake set-up before I fitted it:
Surprised chase bay can stomach the liability exposure selling single circuit M/C replacements for dual circuit (federally mandated since 1968?) brake systems.
Crash caused by failure of their replacement M/C = unlimited liability.
I wouldn't get near one....
True, but don't single them out. What else is out there? Untested aftermarket control arms, cast Chinesium wheels, brake lines made of garden hose, ball joints of unknown origin.
I've seen the "world's best control arms" break. 99% of aftermarket parts aren't very good - that includes all the "big" names. Anybody can make something and put it on the internet.
There are very few companies (outside of an automotive manufacturer) that make aftermarket parts that are real, tested, certified parts.
Last edited by FrenchToast; 11-13-2021 at 10:15 PM.
Hey Mike.. what's it like with a manual setup? My old VWs of course were manual brakes and felt fine but they are much lighter cars! Would you recommend this for daily driving?
Hey Mike.. what's it like with a manual setup? My old VWs of course were manual brakes and felt fine but they are much lighter cars! Would you recommend this for daily driving?
No absolutely not for a daily, it’s really just for a dedicated track car. It feels better (more feedback) and you can adjust the bias on the fly for track conditions which is useful. It also doesn’t require any extra effort when you get used to it, but the first few laps, after driving with power, is pretty wild.
Surprised chase bay can stomach the liability exposure selling single circuit M/C replacements for dual circuit (federally mandated since 1968?) brake systems.
Crash caused by failure of their replacement M/C = unlimited liability.
I wouldn't get near one....
Isn't it a requirement to have a dual braking system for track cars as well? Obviously I don't know for certain, but I've read certain classes at least require it. I can't imagine why you'd not want to incorporate this, even on a 100% scratch built track chassis. The safety benefits are too profound to hit the road without it.
Isn't it a requirement to have a dual braking system for track cars as well? Obviously I don't know for certain, but I've read certain classes at least require it. I can't imagine why you'd not want to incorporate this, even on a 100% scratch built track chassis. The safety benefits are too profound to hit the road without it.
No absolutely not for a daily, it’s really just for a dedicated track car. It feels better (more feedback) and you can adjust the bias on the fly for track conditions which is useful. It also doesn’t require any extra effort when you get used to it, but the first few laps, after driving with power, is pretty wild.
It does take some getting used to!
I just had my 1.8t swap car (2500 lb.) out to Thunderhill yesterday. Stock master but needed to delete the booster to make everything fit.
After a whole day, I still don't have 100% confidence in braking ability...
I guess it's wiser to sneak up on it anyway.
11-10-2021, 07:10 PM
Brake Hard lines at master cylinder size and thread
