Brake line type and sizing, 10mm -- inverted flare? Options

[campbellcj]

Can somebody please confirm the hard brake line type that is used on our cars, i.e. is it 10mm inverted flare, straight or ???? I am contemplating some tweaks such as an adjustable prop valve and not sure what flavor to order while sitting here at the 'puter desk. (IMG:style_emoticons/default/idea.gif)

TIA,

[Brad Roberts]

You should'nt have to order anything. Most PepBoys carry the straight lines in stock...if not Napa's or Kragens.

The longest I have seen in their bins are 3-4 feet long.

I cant help you with the line size. We use braided most of the time (-3 or -4)


B

[ArtechnikA]

Can somebody please confirm the hard brake line type that is used on our cars, i.e. is it 10mm inverted flare, straight or ????

Brad is correct, 10 (x 1,0) European "double / bubble" flare. available at FLAPS everywhere in lengths from about 6" up in 6" increments. i think i've got some 5' sections, but i haven't needed them ... if you -really- need an intermediate custom length, there are tools available to shop-form the flare - didn't we just have a thread here about that ? anyway - Snap-On is one source for such a toolset.

[campbellcj]

Sorry I wasn't clear on the post. My main question is: which flavor/size of aftermarket adjustable prop valve would I use in place of the stock one, with the stock lines?

Obviously if I put it inside the cabin, I will fab up some new lines. I need to check if that is race class legal for me, though. If not then it's going on the engine firewall where the "tee" currently sits.

[ArtechnikA]

My main question is: which flavor/size of aftermarket adjustable prop valve would I use in place of the stock one, with the stock lines?

i've got (but haven't installed) a lever-actuated Tilton unit Automotion sold for a while. for some reason, i'm remembering Wilwood from prior conversations about adjustable proportioners. i'd expect (but i could be wrong) that a rotary knob style would have finer control over bias than the lever style with its detents.

Porsche uses much higher brake line pressures than many manufacturers so i'd be sure whatever unit you get has plenty of range. it -should- be pretty simple to mount it on the tunnel, forward of the firewall, where there's already an inline connector ...

i was very happy with the initial bias in my system (S calipers front with Turbo pads, widened 914.6 calipers on vented disks, 23mm MC, Tee) and planned to use the adjustable proportioner only so i could tweak a little more bias to the back in the event of rain.

(in case that sounds counter-intuitive to the peanut gallery, it is because there is significantly less fore/aft weight transfer in slippery conditions...)

[campbellcj]

Yep I was thinking knob-style on the tunnel, if the GCR's allow. In most circumstances, I have been happy with the bias of my current setup with the tee, but there have been a few days where I wanted literally just "one click" more towards the front to stabilize the car. As you said, it is mainly a factor in traction-challenged situations i.e. drizzle or dirt/oil on track.

I will probably wait until some other upcoming projects (involving weight changes) are done and the car is re-aligned and corner balanced, which obviously will alter its behavior somewhat.

[steve@ottosvenice.com]

Like This?

[steve@ottosvenice.com]

And this?

[steve@ottosvenice.com]

OR This? 10x1 threads on this one.

[Brad Roberts]

Yeah !! The top one is the coolest for cockpit adjustment (if you have a balance bar type of pedal assembly)

We use the second one if we feel the car needs one. Typically mount it near the shifter if the rules allow.


B

[fiid]

I want to put in a propotioning valve too - the stock thing is full of bad fluid that I have been unsuccessful in getting out. Not good.

The second one looks good, and also not too imposing. Does one just put this in the circuit to the rear, and replace the stock 50lb block thingo with a T? How does the top one work???


How hard is it to retrofit antilock? Just another crazy idea - wondered if anyone had thought of it.

[ArtechnikA]

Does one just put this in the circuit to the rear, and replace the stock 50lb block thingo with a T? How does the top one work???

How hard is it to retrofit antilock? Just another crazy idea - wondered if anyone had thought of it.

the top one only works if you use a dual master cylinder system like race cars - one for the fronts, one for the backs. the knob turns the flexible cable which turns a jackscrew in the pedal cluster that changes the location of a pivot giving more or less mechanical advantage to the front or back master cylinder. it's the best system but it is not trivial to fabricate or install.

the hydraulic pressure-relief/pressure regulator types (pictures 2 and 3) work like the much-maligned 914 proportioner, but they are easily adjustable while the OEM one isn't (and is really heavy and hard to bleed besides.) but yes - goes in the line to the back before the tee.

for antilock, the hard part would be finding a way to add power brakes in a car with floor-mounted pedals and finding room for the vacuum servo - and finding a vacuum source to power it with. the BIG reason 911's went to suspended pedals was to make room for the power brake booster, although improved clutch operation (with an over-center spring) was a factor too.

anyway - after you make the power brake thing work, it's 'only' a matter of fitting wheel sensors to the 4 hubs and finding an ABS controller from a car of comparable weight with similar weight transfer characteristics and similar wheel rates. lots of cars use the Teves 060 ABS controller...

once upon a time, some company made a device called 'Safety-Braker' that worked like the air column in your house plumbing, and temporarily relieved the pressure spike associated with a locked wheel. i'm guessing liability, product quality issues (the quality was very high, meaning low margins...) and the widespread availability of 'real' antilock systems fiinally did them under, but i used the parts on my 914.6 and later my GTi SOLO-II car and thought it was A Good Thing. however, it seems to have gone the way of the friction spring damper; too bad...