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Author Topic:   Lack of brake pressure and excessive pedal travel
WesternAuto17
Dirt Freak

Total posts: 248
posted May 20, 2002 08:59 AM
Here's the deal -

Wildwood Reverse mount master cylinders and pedals
1" bore on both
Nylon brake lines
Four wheel 11" Impala disc brakes

Here's the prblem -

The brakes are completely bled and I'm only getting about 300psi on the front and 150psi on the rear. There's no fade, but these pressures seem really low. Are they? Also, compared to my old car with stock manual brakes, there's a ton of pedal travel (2 or 3 inches). Others have posted not having any trouble with nylon lines, but I don't know what the problem is.

Thanks.

techmaster35
Dirt Freak

Total posts: 259
posted May 20, 2002 10:03 PM
the lines are swelling. run steel lines. the nylon is expanding and your brakes seem soft but it might also be the master cylinder. it might be draining past the piston and losing pressure.

powerglides
Dirt Full Roller

Total posts: 69
posted May 21, 2002 06:38 AM
Did you bench bleed the master cyls. before you hooked up the lines?

WesternAuto17
Dirt Freak

Total posts: 248
posted May 21, 2002 09:25 AM
No I didn't bleed to master cylinders w/o the lines. How would I do that? Just remove the lines and pump it a few times? This is the first time I've used this type of set up. Will not doing that cause the problem techmaster is describing?

This wouldn't be the first bone head move in this project. Man, building a new car is a lot of work.

owracer
Dirt Maniac

Total posts: 115
posted May 22, 2002 07:18 AM
I agree with techmaster on the brake lines. Use steel, nylon sounds weak and dangerous. I have seen people use it with no problems, but it scares me. When you look at brake pressures, the smaller the mastercyl bore, the more pressure it will produce, and the larger the caliper piston, the more pressure it will produce. With the set up that you have, if you have the balance set equally, you should have equal pressure front and rear. To bench bleed the M/C's, you will need to disconnect your brake line from it, remove the cap, connect a flexible line to the brake line port and run it back over into the fluid resivoir. Fill the M/C with fluid and keep the end of the line submerged in the fluid. Now pump the M/C until you don't have any air bubbles and reconnect it to the brake system and rebleed the system at the wheels.

WesternAuto17
Dirt Freak

Total posts: 248
posted May 22, 2002 08:57 AM
I'll try that.

I may call the nylon experiment a bust, but they can't be the whole problem. Too many other people have had no problem with them.

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