dennisbernal91z

iTrader: (2)

Like the title says, what is the point of the larger 1/4" to the rear? Inline tube says there is no point. Mopar has done 3/16 everywhere forever. Ford does on some things. Hot rods are almost all only 3/16 all over. I want to do it this way.

Thoughts?

BlackenedBird

iTrader: (5)

Why redo something that obviously works already?

Gibson27

iTrader: (1)

because if you have a all original 82 like me with SAE fittings, your gonna be in for a time looking for the "ghost" fitting that is the 9/16 for the 1/4 line to the master cylinder. I have 1/4 line here to do the replacement but i cannot find the fittings.

BlackenedBird

iTrader: (5)

I would think any place that makes custom hydraulic lines would have the fittings, if that is all your looking for. I have a place just up the road that does that.

But what he was asking about line size difference, not SAE vs Metric fittings.

//<86TA>\\

iTrader: (14)

this fitting?
http://store.fedhillusa.com/a244.aspx
if it is, you can thank me later

//<86TA>\\

iTrader: (14)

but no, you will never find the proper fitting with the rear hard line if you use the smaller 3/16 4.75mm tubing.

whats so hard with using the 6mm or 1/4" line? fittings are available. Look in the link i posted to . FedHill has everything. why reinvent the wheel

Gibson27

iTrader: (1)

FTR... I thanks 86TA already lol.

Funny thing is that I scrapped a 84 i had and that master cylinder has bubble flares, I also bought stainless flex hoses off ebay for the 84. So to use these on my SAE 82 camaro I need to buy bubble to inverted flare adapters lol.

So much fun....

dennisbernal91z

iTrader: (2)

I am not trying to re-invent anything. I am a mechanical engineer and am wondering why they did that. Thats all. Well at least thats the first part. Second part is, I don't have a single brake like in my 700HP Procharged camaro right now. I want to route all my own lines from scratch, I don't have anything right now so I would like to buy a HOT ROD kit that someone sells, like Inline Tube does. This is what I did with wiring. I ripped all the GM stuff out and wired the car with a HOT ROD kit. Now I have easier access to my fuse pannel and all my wires are labeled with what they do.

Anyways, it doesn't look like anyone has any real engineering reason as to why GM used 1/4". Interesting that if it is "needed" then why hasn't everyone done it. Line size has nothing to do with pressure output. The line size at your calipers in the rear is still 3/16, just like the front.

Gibson27

iTrader: (1)

Not trying to cause a stir but I though line size could affect pressure output, or at least the amount of force you need to exert.

If Force=PressureXArea , then Pressure=Force/area so....

if 100lbs of force/ a area of of lets say 10 inches to make it easy then it creates 10lbs of pressure.

If we decrease the area by half then 100/5= 50lbs of pressure.

So if i am right, which is not all the time at all, then the smaller the diameter of the line (line size) the more pressure is applied to the brake cylinders and caliper pistons when the same amount of pedal force is applied.

Now it's been a while since I did any hydraulic calculations so if anyone wanna confirm that the formula is correct?

RBob

iTrader: (1)

The formula is correct. However it doesn't appply to lines. Just the M/C bore to caliper/wheel cylinder bore.

Line diameter doesn't affect the pressure out versus the pressure in, of the line, end to end.

What it does affect is frictional losses and volume displacement.

99% of our 3rd gens have rear drum brakes. They require more fluid to operate, hence the larger diameter lines. Which ties into the frictional losses to operate the rear brakes. Have to move more fluid to operate them.

The down side of larger diameter lines is expansion. With pressure the expansion of the line creates the need for more fluid. A larger diameter line requires more fluid, which makes the brake pedal travel greater.

When using 4-wheel disc brakes with modern calipers, a 3/16" line to the rear is better then a 1/4" line.

RBob.

dennisbernal91z

iTrader: (2)

RBob: I couldn't have said it any better myself. This is why I asked the question in the first place.

You opened my eyes to the rear drum brake point. Thank you.

I feel much better running my lines the way I wanted to now.

New CPP master, Bindo line lock, C5 ZO6 fronts and stock disk rears, all plumbed with 3/16" double flare line.