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mavisky

Braking issue making me crazy

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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)

Edited by mavisky
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You definitely do not need a vacuum pump, there's no way a TF1 cam is causing you to lose brake pressure.

Maybe one (or more) of your calipers is shot and needs rebuilt? (would be a good excuse to do a Cobra front brake setup if it turned out to be a front caliper needing rebuilt ;) )

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first thought was original rubber lines. Would not hurt to replace those with stock replacements or stainless lines.

He said he replaced them with new rubber lines... don't worry though, I missed that part the first time I read it too lol.

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He said he replaced them with new rubber lines... don't worry though, I missed that part the first time I read it too lol.

ugh, thats like 5 times ive done that this past week. lol I need a vaca..

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No the lines are truly original and 18 years old. I've just been hesitant to update them as I didn't want to have to buy braided lines again if they didn't work for a pbr or cobra brake setup down the road.

I guess maybe a rebuild/replacement of the front brakes is a good starting point.

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No the lines are truly original and 18 years old. I've just been hesitant to update them as I didn't want to have to buy braided lines again if they didn't work for a pbr or cobra brake setup down the road.

I guess maybe a rebuild/replacement of the front brakes is a good starting point.

The line below is really confusing then, lol

I also did everything i could to eliminate vacuum leak issues including all new rubber lines, and a new upper intake manifold gasket.

I would say look into the piston seals in the calipers, maybe one is leaking? I had my stock cobra front passenger side caliper blow a seal and spray down the inside of my wheel with brake fluid along with giving me a spongy pedal. It wasn't enough of a leak for the pedal to go to the floor thankfully, but it was enough that my brakes sucked until I got my 10th anniv. front calipers on the car.

Have you looked over the rubber brake lines really well to inspect for dry rotting or cracks? Don't forget there is also a flex line above the center of the rear axle to check also.

Edited by 95riosnake
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Rio - I meant rubber vacuum lines, should have clarified there.

The wheels are still spotless and there's no signs of a leak anywhere.

I just replaced the master cylinder and bled it during install so it should be off the table.

At this point I'm thinking it's either the lines or the booster or a combination. It's just frustrating that my tiny little Honda (which still weights 2800lbs) wearing 195's would probably outbreak this thing at this point in time.

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you mentioned you have ABS, have you bled the ABS block?

I have not, aside from bleeding the car with it idling on jackstands. I've never seen a procedure for doing that. I wouldn't be terribly opposed to getting rid of the system, but i don't see a reason to go out of my way to do it.

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well if the abs has air in it you'll need to take it to the dealer, they have specialty equip to evacuate the air. if you can't get the abs to kick in there's definitely an issue with the abs...

It's not that the ABS isn't functional, I think it probably is. The problem is that a full panic stop won't induce enough grab to actually lock up the wheels thus negating the need for ABS at this point even.

If it was mine I would change the rubber lines and do a full brake fluid exchange (just keep bleeding out every wheel until new fluid comes out making sure to keep master full)

It's got all brand new fluid after the master cylinder change, but the rubber lines are still there.

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I believe the booster is not adjusted properly to the master. That rod is threaded and screws out with a hex 5.5mm I believe and a pair of plyers to hold it.

On going project, 94 cobra, r block, tfsr225, hp efi, vortech ys

Instagram [MENTION=584]Rolocut[/MENTION]

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I guess it's possible but this is the stock booster. I noticed some paint had flaked off of it below the master cylinder (which is what caused me to replace the master as it was obviously leaking) so maybe some got inside the booster and is keeping it from working 100%?

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I guess it's possible but this is the stock booster. I noticed some paint had flaked off of it below the master cylinder (which is what caused me to replace the master as it was obviously leaking) so maybe some got inside the booster and is keeping it from working 100%?

my money is on the brake booster. If there are no vac leaks, it could be the diaphragm inside the booster. you said you used the stock master cylinder right? if yes, there should be no need to adjust the brake rod inside the booster. If the pedal is rock solid and you're not locking up the brakes, I would be 99% sure it is the booster.

I had that happen on a 91 of mine, and I could actually hear a hissing noise from the booster when I stomped on the brakes real hard. its not a chore to swap that out, and I think you can just move the master out of the way without having to disconnect the brake lines.

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Thanks for all of your inputs. Here's my current plan of attack.

1. Replace brake booster

2. verify all brake calipers are functioning correctly including a replacement and re-greasing of all slide pins.

3. take vehicle to local Ford dealer for proper bleeding and evacuation of any air in abs block.

I will report back at the conclusion of these steps. If step 2 is bad enough I may upgrade to either PBR or 03/04 cobra setup.

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Thanks for all of your inputs. Here's my current plan of attack.

1. Replace brake booster

2. verify all brake calipers are functioning correctly including a replacement and re-greasing of all slide pins.

3. take vehicle to local Ford dealer for proper bleeding and evacuation of any air in abs block.

I will report back at the conclusion of these steps. If step 2 is bad enough I may upgrade to either PBR or 03/04 cobra setup.

I got an 03-04 cobra front and rear brake set up with fresh rotors cut maradaza.jpgy8a8uta7.jpgyqasute2.jpg

On going project, 94 cobra, r block, tfsr225, hp efi, vortech ys

Instagram [MENTION=584]Rolocut[/MENTION]

Sent from my iPhone using Tapatalk

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So one my car I had the same issue and it turned out to be the little rubber gasket/ suction ring under the brake fluid reservoir cap was gone. I put a new one there and it was replaced and it work great. But I then just did my cobra brake swap and it was a world of difference!

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Picking up the brake booster on the way home from work tonight. Here's hoping i have enough wiggle room in the master cylinder lines to get it out easily. Something is telling me i won't given the size of this thing.

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Well after an hour or two of wrestling in the footwell of the car the booster has been swapped with no major improvement. It feels a little bit better, but that's about it. Brake pedal is still very soft. Going to order up the braided lines from americanmuscle.com and go from there.

http://www.americanmuscle.com/russell-brake-kit-9495gt.html

While installing those I'll be giving the sliding pins a once over and everything as well. If they don't fix the problem the thing is going to Ford to be bled and diagnosed. I need an alignment anyway so may as well get it in there.

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It's probably just a bad master cylinder. Those are cheap enough. I always disconnect the battery when I bleed the brakes. If that ABS so much as has a little fart when you bleed the brakes, it's going to get air in it, and need the computer bleed procedure. With the battery disconnected, there is no chance of that.

Kurt

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Nope. Top half of pedal is still squish and then the bottom of the pedal gets harder and i still can't brake half as well as my little honda CRZ.

The master definitely had a leak as it had bubbled the paint on the vacuum booster below the mounting flange indicating a leak out of the primary seal. Current master cylinder is bone dry and bench bled perfectly. Install went easy and the brake fluid has never gone too low on it since install. I'm really about certain there is air in the ABS block or somewhere else, but since these rubber lines are 18 years old now I figure I'll replace them with new braided lines and then let Ford flush and fill the brake fluid. If they find another issue in the process I'm sure they'll let me know.

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I had this same issue on my 94 GT when I swapped to the 99+ PBR calipers. At the same time I also installed SS braided lines in the front and the single one in the back. new hawk HPS pads all around, and Centric posi quiet rotors that were cross drilled and slotted. I bled the system thoroughly. took the car out to bed the brakes and i was sincerely disappointed.

What i eventually found out was that the stock master cylinder was wrong for that setup (its actually too big). I had to install the 93 Cobra master cylinder, and the problem was solved.

you mentioned that you have the stock calipers though - so that shouldnt be a problem with the stock master. i'm still scratching my head about your issue, and I'm pretty good with brake systems.... I had money on the booster (sounds like that was bad anyway though).

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I had this same issue on my 94 GT when I swapped to the 99+ PBR calipers. At the same time I also installed SS braided lines in the front and the single one in the back. new hawk HPS pads all around, and Centric posi quiet rotors that were cross drilled and slotted. I bled the system thoroughly. took the car out to bed the brakes and i was sincerely disappointed.

What i eventually found out was that the stock master cylinder was wrong for that setup (its actually too big). I had to install the 93 Cobra master cylinder, and the problem was solved.

you mentioned that you have the stock calipers though - so that shouldnt be a problem with the stock master. i'm still scratching my head about your issue, and I'm pretty good with brake systems.... I had money on the booster (sounds like that was bad anyway though).

Damn, I was hoping to put off getting a new master cylinder and proportioning valve. Guess not.

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I had this same issue on my 94 GT when I swapped to the 99+ PBR calipers. At the same time I also installed SS braided lines in the front and the single one in the back. new hawk HPS pads all around, and Centric posi quiet rotors that were cross drilled and slotted. I bled the system thoroughly. took the car out to bed the brakes and i was sincerely disappointed.

What i eventually found out was that the stock master cylinder was wrong for that setup (its actually too big). I had to install the 93 Cobra master cylinder, and the problem was solved.

you mentioned that you have the stock calipers though - so that shouldnt be a problem with the stock master. i'm still scratching my head about your issue, and I'm pretty good with brake systems.... I had money on the booster (sounds like that was bad anyway though).

Yea that's what's confusing me so much. Stainless braided brake lines are in hand. Hoping to maybe get these all installed this weekend. Will report back with information. I am a little bummed though that if I do step up in brake size eventually I will have to probably replace the master again. I'd rather have them too powerful than not powerful enough though. I think I'm going to eventually have Ford take a look at if the new lines don't solve it. At that point the master, booster, lines will all be new.

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