I think my brakes are boiling....

onefastmustang · #1 (**permalink**) 07-09-2007, 09:27 PM

So I have about 400 miles on the cobra so far in the past 5 weeks. Working out the kinks as I go but now it seems I may have a new one.. Starting off on a drive my brakes are great but as time goes on I feel them start to drag a bit and the pedal gets a bit harder. I believe they are heating up in the engine compartment. One of the lines passes right by the headers. How far should they be from the headers at a minimum?? Would some sort of heat sheild between them work?? Could I be off base.. ??

xlr8or · #2 (**permalink**) 07-09-2007, 09:49 PM

Definitely want to insulate from that heat and have at least a couple of inches of airspace.

onefastmustang · #3 (**permalink**) 07-09-2007, 09:51 PM

Do you think wrapping that leg of the header with some exhaust wrap would do the trick?

pgermond · #4 (**permalink**) 07-09-2007, 09:55 PM

I would suggest you wrap the break line and relocate if possible. There is a heat reflective sleeve for hydraulic lines that works quite well.

CHANMADD · #5 (**permalink**) 07-09-2007, 09:58 PM

Reroute the brake hose. You might find that you do not have enough free play in the master cylinder pushrod.There should be free play on the pedal?

onefastmustang · #6 (**permalink**) 07-09-2007, 10:00 PM

Quote:

Originally Posted by CHANMADD

Reroute the brake hose. You might find that you do not have enough free play in the master cylinder pushrod.There should be free play on the pedal?

there is free play when the car is cold.. as I drive it gets less and less.... I guess I will reroute the line.. It will be a bit of work being that its a hard line..

strictlypersonl · #7 (**permalink**) 07-10-2007, 04:42 AM

There's no way for the system to build up pressure if the free play is correct and the master is not defective.. When the pedal is "un-pushed", there's a return port in the master which will remain open to bleed fluid back into the reservoir.

Bill Wells · #8 (**permalink**) 07-10-2007, 05:55 AM

you might also have boiling brake fluid due to what you are using in addition to the routing of your lines .

if you are using DOT3 fluid , it will boil earlier than other fluids . consider changing to a DOT4 or other that has a higher boiling point . available at your auto parts store . DOT 5 is not usually recommended for cars driven vigorously but is commonly used on non high performance show cars . If you change be sure to flush old out before new in . Bill

onefastmustang · #9 (**permalink**) 07-10-2007, 07:58 AM

Quote:

Originally Posted by strictlypersonl

There's no way for the system to build up pressure if the free play is correct and the master is not defective.. When the pedal is "un-pushed", there's a return port in the master which will remain open to bleed fluid back into the reservoir.

could my wildwood proportioning valve be causing this issue in any way??

rdorman · #10 (**permalink**) 07-10-2007, 08:11 AM

Boiling fluid does not cause the symptoms that you describe. Check on what Stricklypersonl mentioned. Also, check parking brake adjustment.

Curt C. · #11 (**permalink**) 07-10-2007, 08:12 AM

Boiling fluid should result in a softer pedal - right?

Roscoe · #12 (**permalink**) 07-10-2007, 08:16 AM

You should start by insulating the brake line. You could also make a small aluminum heat shield between the headers and line.

Roscoe

rdorman · #13 (**permalink**) 07-10-2007, 08:36 AM

Quote:

Originally Posted by Curt C.

Boiling fluid should result in a softer pedal - right?

Yes. What he might be feeling is pade fad which makes the pedal feel 'harder'. Actually, it is no 'harder' since the fluid is not compressable but he has to press harder to get the car to stop. Even a properly functioning disc brake system will have pad running 200-300 degrees just cruising along the freeway.

One other thought for you Onefastmustang. Be sure there are no residual pressure valves inline with your disc brakes. Good for drums but not generally needed for discs. Master cylinders designed for drums can have them built in.

onefastmustang · #14 (**permalink**) 07-10-2007, 08:42 AM

Lots to try.. Thanks guys.. I guess i have some plans for this coming weekend now.. ;>)

DavidBetts · #15 (**permalink**) 07-10-2007, 08:46 AM

Had this problem. I have Wilwood clutch and brakes masters, brakewise pumping to front Wilwoods and Jaguar rear brakes. Having raced the car, in August (102 degrees), the fluid turns black and eventually detroys the master cylinders. I changed damaged master, flushed and filled, all cylinders, with Wilwood High Temp EXP 600, now it would take temperatures up to 626 degrees to boil and fail. Also ceated and installed a heat sheild to redirect the extream heat from the headers. All has been well for two years now.
Good luck!

onefastmustang · #16 (**permalink**) 07-16-2007, 08:33 AM

So I solved this problem. It was the rod inside the booster needed some adjusting. Back when I started puting the car together I took it for a spin and the brakes were crapola. Someone recommended checking the rod to make sure it was long enough for the pedal throw. I guess I made it a bit too long and after I tuned the car the vaccuum went from 13" to 20" it must have made some difference to the booster. I shortend the rod back about an 1/8" and it all works great now.