Bleeding Brake Problem

[joeV]

Just changed all four brake calipers, new ss brake lines and new master cylinder. Was able to bleed the rear brakes with out a problem, but not able to bleed the fronts. Don't see any leaks anywhere. Is it possible that the proportional valve is bad? If so, is there a replacement for it or a rebuild kit?

Joe

[stockman1]

Just changed all four brake calipers, new ss brake lines and new master cylinder. Was able to bleed the rear brakes with out a problem, but not able to bleed the fronts. Don't see any leaks anywhere. Is it possible that the proportional valve is bad? If so, is there a replacement for it or a rebuild kit?

Joedo the front calipers compress when you step on the pedal?

[MikeFleming]

Is it possible that the proportional valve is bad? If so, is there a replacement for it or a rebuild kit? Possible? Yes. More likely it's just crudded up with dried, hard old brake fluid due to poor maintenance. Which I guess makes it bad.

No, there are no replacements available (it was specific to the SVO) but you could probably use one from GT of that era - the tube sizes should be the same, while the front/rear balance will be off. Maybe swap springs?

You can take apart the one you have and clean it but i doubt you'll find any repalcement seals for it. So be very careful on disassembly.

I have pictures of a NOS one somewhere.

[TheSVOTrust]

If you want a kit for our cars - I can have Scott consider it ! https://www.musclecarresearch.com/E7ZC-2B091-BA-autopsy Will take info from you guys on seal sizes , drawings and or cross reference numbers. I will look at the project sheets from 1982 and see if I can find specs when I get back from AZ Mark

[joeV]

I figured it might be full of crud since it has been sitting for 5 years. Are there any manuals you know about that will show how to disassemble?

[fastsvo]

If you want a kit for our cars - I can have Scott consider it ! https://www.musclecarresearch.com/E7ZC-2B091-BA-autopsy Will take info from you guys on seal sizes , drawings and or cross reference numbers. I will look at the project sheets from 1982 and see if I can find specs when I get back from AZ Mark

Please count me in!

-eric

[Chalky]

try cracking the lines from the MC to the PV and see if you get fluid going from the MC to the PV. That'd tell you if it's blocked.

[Ford Builder]

Some times you can give the block a quick crack with a hammer it shocks the valve , they stick in one direction on occasion front or back or vise versa.

[joeV]

Thanks for all the suggestions. Hopefully I will try them out this weekend and sees what happens.

[k98dave]

The Dist valve for the 93 Cobra may work, I know NPD has those.

[Chalky]

The SVO uses SAE threads and apparently 87-93 used metric threads.


http://home.comcast.net/~mjbobbitt/mustang/page11.html

[rodster]

During my 84 'refresh' I flushed the brake fluid by using a vacuum pump at the calipers and it seemed to pull air bubbles through all the time. Never had this issue on other cars before, thinking the air is coming through the bleeder threads while cracked open. Can't remember if that happened when I replaced the rear calipers or not.

As soon as I get a 'helper' I'll use the old pump/hold/bleed method to help flush things out a bit more.

All 4 act the same so I don't think there is any problem w/ the prop valve but a kit for it would be great! :Like1:

[MikeFleming]

I've been using a vac bleeder for over a decade on many different cars. It's very common for bubbles to come past the bleeder-to-caliper body thread gap when using a vac bleeder. I wrap several laps of teflon tape on the bleeder screws to help it seal against the caliper body and most of the bubbles go away. Also make sure the nipple attachment on the bleeder hose is air tight or it will suck air (bubbles) there also.

[rodster]

Thanks for the tip, I'll give that a try. I know the hose is tight so it must be the threads. Do you just leave the tape on when you are done?

[MikeFleming]

Do you just leave the tape on when you are done? Yep.

[rodster]

Worked much better. :cool:

Don't recall have this problem before on the old cars I worked on. :confused:

Ban me for not coming up with the solution myself. ;)

[MikeFleming]

Ban me for not coming up with the solution myself. ;) So wait!

You went to the interwebs and asked how friends & others do things instead of staying all closed in your garage with some quality time with your SVO while fiddling with stuff until a solution came to mind?

You are SOOO banned.

[rodster]

Yea, but it was soooooo cold I wasn't thinking straight (no heated garage) and my car is red. Pleeeease don't ban me. :)

I promise to spend more time in the garage and less time on the interwebs.....unless there is cool stuff going on here! :cool:

[MikeFleming]

There is a lot to be said for adding heating [and cooling] capabilities to the shop. I hear that's a good way to dispose of old oil.