Brake lines

[rb77413]

Ok the Barracuda is down due to broken brakes. Well actually the master cylinder is shot. No sense in replacing the single tyoe MC. I have an aluminum MC. I need to "T" of the front outlet port on the new MC to get both fronts and run an adj proportioning valve for the back. Only thing is what is the dia of the brake lines. 3/16th? Sumitracing sells stainless and steel lines in a couple different sizes. Would it be bad if I went bigger? I would think the pedal would have to travel further to obtain the same pressure. Right or wrong.

[bbeckwith]

Hi Manic,

I just did the brake lines on my Duster. The lines are 3/16" I would recommend you practice making your double flares a little bit prior to replacing your lines so you make good flares the first time. My first few attempts were awfully crooked till I got the hang of it. I agree with you about the larger diameter lines, seems like you would be pushing a greater amount of fluid through the lines but not sure if that would give you a firmer feel pedal or not.

Bruce

[72Challenger]

No, the size of the lines will not change the amount of fluid moved. The only thing that determines how much fluid moves through the lines is the size of the piston in the slave cylinders, while the size of the piston in the master cylinder will determine the amount of pedal travel.

While a smaller line will cause a given amount of fluid to travel further through the line, the actual volume is unchanged. There is no advantage in going to a larger line, you should use whatever size is correct for the fittings that are used on the master and slave cylinders.

[rb77413]

OK but the bigger lines take a greater amount of initial brake fluid to fill the bigger line. So a bigger line on one side will cause uneven braking. We have the smaller diameter mopar MC. This MC will need more pedal travel to equal the volume displaced by the bigger version right? On the brake lines, are all cars 3/16th. I will just buy the line from summitracing. Thanks

Bob

[72Challenger]

Yes, a smaller diameter MC will require more pedal travel to get the same braking force. On the other hand, the pedal pressure required will be less.

Have to disagree with your statement about uneven braking from different size lines however. Yes, it takes more fluid to fill a larger line. But no matter what size the line, whatever volume you push in from one end, the same volume will come out the other (assuming you've bled the lines completely.) Doesn't matter if it's a 3/8 inch brake line or a sewer pipe. Now if you had a different diameter piston in the slave cylinder, that would be a problem.

Of course, having a different size line on each side would cause all kinds of confusion with regard to matching the fittings. Wouldn't recommend it, but it wouldn't affect the braking if you did get everything to seal up properly.