Braking issue

mavisky · Sep 18, 2013

Ok so I've been fighting this for a while now and I'm turning to the internet for the next round of help.

Situation: First inch or so of travel is soft and doesn't seem to accomplish anything, the next 1/2" does some braking, then the pedal gets very hard and braking doesn't really increase. The brakes slow the car down fine, but under panic braking they don't seem to be giving me full braking force. I can assure you that no matter how hard i stand on them it won't kick the ABS in.

Setup:
New master cylinder properly bench bled.
stock 95 gt calipers with properly greased slide pins
stock 18 year old rubber lines and brake lines

Remedies:
I've bled the brakes with an assistant, bled them with a vacuum, bled them with the car idling (in case that affected the abs system), and I tested to make sure the depressed further when the vacuum booster had a vacuum pulled on it. I also did everything i could to eliminate vacuum leak issues including all new rubber lines, and a new upper intake manifold gasket.

I'm about 3 steps from putting the thing up on jackstands and ripping the entire braking system off the car, buying some new parts and going through them with a fine toothed comb.

Possible solutions:
- Brake booster possibly damaged and not providing full assistance
- pads glazed and unable to brake effectively
- rubber lines expanding too much causing a reduction in force at the caliper
- still not properly bled somehow (thought I'd read somewhere about the Ford dealer using a tool to bleed through the abs unit)
- vacuum pump (hard to believe a TS1 with 1.7's would be too big though)

RichV · Sep 18, 2013

What pads do you have? What fluid do you use? Is the fluid new, or off the garage shelf?

Was it the same with the old MC?

The booster is the easy culprit, you can check it for a leak. Just hook up a vac pump to it and see if it holds. There is some adjustment to the pedal/booster into the MC that may need checked. But I've always just kept the settings out of the box and never had issue.

Does it feel better right after a bleeding? If you have a faulty caliper that lets in air after a timeframe. The soft lines would only make the brakes seem spongy.

I had a set of EBC yellows on my race car once to give them a try, and I hated the pedal. It felt like you were stepping into a wall, the brakes were there, but there was zero pedal modulation.

mavisky · Sep 19, 2013

I think I'm going to replace the booster after some discussion in other threads and then take each caliper off individually and make sure the slide pins are functioning correctly.

mavisky · Oct 4, 2013

Stainless braided brake lines are in hand. Hoping to maybe get these all installed this weekend. Will report back with information.

MustangChris · Oct 6, 2013

let us know how it goes with the new lines.

ReplicaR · Oct 7, 2013

Here is a quick question. I see that you have a HCI combo. Did the braking problem start after the HCI swap? Is the motor making enough vacuum to make the brakes work?

mavisky · Oct 10, 2013

Braking problem seemed to start at some point down here in GA. I think the master developed a leak (evidenced by rust and missing paint on vacuum booster under master) and that led to air getting into the ABS block. I'm wrapping up the brake line install tonight hopefully and then bleeding it manually so that it's drivable to Ford and then letting them bleed the ABS block on it. My only option after that is that the cheap ass pads i have on the front combined with the tiny 95 gt calipers are just sucking it up big time compared to the 275's I have on the front.

mavisky · Oct 16, 2013

Stainless lines installed and bled. Pedal feels great when the car is off, but the pedal travel is really long still. Typical Atlanta traffic today meant that there weren't any opportunities for me to get it up to speed and do a true panic braking maneuver safely. I don't know if there's air in the ABS block, but I'm tempted to just delete the damned ABS and be done with it. Anyone know someone who makes a replacement ABS distribution block? Otherwise it's off to Ford for an alignment and brake bleed when i get back from vacation.

mavisky · Oct 17, 2013

BTW, I also nailed it in 2nd around a corner and the thing totally spun just one of the tires. Looks like I'll be doing a Trac-loc rebuild over the winter. At this point the car is getting nothing else done to it as I think I'm going to plan for a Factory Five build in a couple years. We'll just enjoy this while I have it and keep the base parts that will transfer in good shape and say to hell with the rest that doesn't.