ProwlerGT's 3000GT Revival Thread - Start Up

[Nihil]

Originally Posted by ProwlerGT

Yeap, I'm gonna have to call TANGINA (Poltergeist psychic/medium) and have her exercise the demons. They got her narrating those "chillingham castle" ghost shows now all spokey like. lol

Good ideas on the bleeding technique. I usually have a partner to help me with that so I'm not too worried about it. I do have speed bleeders which I'd rather use, but 1 of the bleeders wouldn't thread into the caliper so I opted not to install them cause on the back my rears are different thread sizes too. I didn't wanna mix it up.

I was wondering if the popping was the brake pedal itself as well, but that would seem odd. The popping happens when I get the pedal all the way down and then it gives (goes down) just a tiny tiny bit and makes the popping sound very subtle like. I know its not the booster cause I replaced that. I guess I could go down there and try to jostle the pedal at its bushing and see if it moves much. If so then buy a bushing kit for it.

1. What do you/ya'll think of emptying the brake fluid completely and running compressed air through the system with 1 caliper (or line just before the caliper) open at a time?

2. What about spraying brake parts cleaner in the lines and then forcing it through with slow compressed air. Let sit and then high compressed air it out LIBERALLY? I know I've seen several warnings about not putting anything near brake parts unless its brake fluid, but we all know this stuff dries up very well and i'd be immediately forcing it out of the system with lots of 50 - 60psi compressed air. My hunch is that there is junk caught at the junction metering valve that simply won't come out with regular flushes.

They actually make tools to flush brake systems, one end hooks up to the bleeder, the other to the reservior, it circulates the entire system through. I don't know how much they cost, for something like that, I'd find a reputable brake specialist shop and have them check your brakes......which, if after you replace that valve, it's no different, I'd recommend taking somewhere. Brakes are the one thing, that MUST be working properly or serious injury can occur....

[cbatters]

Originally Posted by ProwlerGT

Yeap, I'm gonna have to call TANGINA (Poltergeist psychic/medium) and have her exercise the demons. They got her narrating those "chillingham castle" ghost shows now all spokey like. lol

Good ideas on the bleeding technique. I usually have a partner to help me with that so I'm not too worried about it. I do have speed bleeders which I'd rather use, but 1 of the bleeders wouldn't thread into the caliper so I opted not to install them cause on the back my rears are different thread sizes too. I didn't wanna mix it up.

I was wondering if the popping was the brake pedal itself as well, but that would seem odd. The popping happens when I get the pedal all the way down and then it gives (goes down) just a tiny tiny bit and makes the popping sound very subtle like. I know its not the booster cause I replaced that. I guess I could go down there and try to jostle the pedal at its bushing and see if it moves much. If so then buy a bushing kit for it.

1. What do you/ya'll think of emptying the brake fluid completely and running compressed air through the system with 1 caliper (or line just before the caliper) open at a time?

2. What about spraying brake parts cleaner in the lines and then forcing it through with slow compressed air. Let sit and then high compressed air it out LIBERALLY? I know I've seen several warnings about not putting anything near brake parts unless its brake fluid, but we all know this stuff dries up very well and i'd be immediately forcing it out of the system with lots of 50 - 60psi compressed air. My hunch is that there is junk caught at the junction metering valve that simply won't come out with regular flushes.

How about just runnning a couple pints of brake fluid through until each wheel comes out clear into a glass jar (using either a commercial one-man-bleeder or the clever 360 degree loop of tubing with zip tie mentioned earlier.



Clint

[ProwlerGT]

Maybe I haven't said it, but I thought I did. The fluid is clear and bubble free and has been for quite some time now hence the "puzzling" lack of brake power.

I suggested the air blow out method cause i think junk is stuck in the prop valve though after reviewing the specs for the springs to activate in the prop valve you have to have a panic stop of like over 700psi maybe the air blow out method won't do shit.

[ProwlerGT]

Drivability test 3 - Took the car out for its first "real-life" event since Katrina. Went to the grocery store for some regular driving. Brakes seemed the same (stopping power not good), but I could stop when I wanted to this time without seeming like they were fading. I still religiously hear the brake pads scrapping the discs though. Gonna jack the car up tomorrow and see which wheel(s) is/are doing it.

Wondering now about booster push-rod to master cylinder clearance. Using my hand and a small ruler it seems as if the push-rod is not engaging the master cylinder until the pedal is pushed 3/8" downward. Adjusting pedal height will not resolve this. I think if I check the specs and its off (which I think it must be cause 3/8" seems too much) I'm gonna have to pop the MC off to adjust it I do believe.

[ProwlerGT]

AH HA!!

LITTLE TEST: With my sister's help I had an idea for a new test to see if the push rod clearance is good. I had her watch the brake fluid reservoir with the top OFF of it. Brake fluid at max line. Use a flashlight. I went in the car and gently gently gently with both hands for "control of the push" pushed the brake pedal down slowly slowly slowly .... merrily merrily merrily life is but a dream.. oopps i trailed off sorry.... I noticed an initial bump when pushing the pedal accounting for brake pedal play and then noticed a second bump as if the push rod was engaging late.

From the moment I pushed the pedal to the moment of the 2nd bump the brake fluid reservoir level did not move up or down AT ALL! What's this mean? It means that the push-rod to master cylinder clearance is WAAAAAY off in terms. From the pedal to the brake pads should be like the same type of response you get from a limb on your body. This space between the rod and the MC (about 3/8") accounts for not only not being able to use all the power in your brakes, but for late braking (milliseconds to seconds which count a great deal on the road) and for YOU GUESSED IT ... DRAGGING BRAKE PADS!

Check it out:


Don't have time tonight, but tomorrow the first thing I'll be doing is popping the MC off and adjusting that clearance. I bet you this nabs the damn brake demons and that I ended up ordering that Prop valve for nothing!

The specified space shown on the graphic accounts for what can be described in English as maybe the width of a sharpened pencil tip. This is damn near touching the MC back plate which is how it should be.

For adjustment, it would seem that you should get the push-rod out enough to where it touches the MC back plate lifting it barely off the booster mounting surface and then successively back the rod off in 1/4 turns till you have it right.

This also explains why I had thought that my 1st stock booster was bad and why the 2nd used OEM booster did the same exact thing cause this means my original booster push-rod and the 2nd used less mileage booster I bought were BOTH incorrectly adjusted too far back. Unfortunately and GOOD to know at the same time this may mean that all NA booster push rod's over time back themselves off from extended usage. This should be checked by everyone at least with an NA car.

I'm soooo excited.... and I just can't hide it.... I know I know I know I know....I want brakes... I want brakes ! YEAH! cheese cheese cheese... lol

[ProwlerGT]

The proportioning valve is on national backorder so my order was canceled. Dunno if they plan to make more. I guess this is another one of those parts we can all add to the "no longer made" list.

So I hope when I get around to the push-rod adjustment that it fixes my issue otherwise I gotta do a hunt for a low miles used one.

[Nihil]

Originally Posted by ProwlerGT

Otherwise I gotta do a hunt for a low miles used one.

No......not low miles used.......new and upgraded better than stock......

You gotta change yer thinkin my friend!

[ProwlerGT]

And this is how it happens. Most people when they get excited about an idea to jump out there and do it. Me.... I get excited about the idea and then I think past it to what as my dad says, "What out in left field is going to go wrong next?" and it discourages me from going through with the idea. I know the push-rod has to be it, but its like I can't get myself to try to fix it because its too easy, afraid it will end up being something else, and unbelievably enough it will feel ODD after all this time to have finally nixed this damn problem. Its like a "parting with it" if you will. Strange. Could be because I'm up for 15 hours now and my sleep schedule is the furthest from normal that there is. Here I am at 9:17 AM and never went to sleep yet cause 1 friggin overnight plunge in the garage threw me off for weeks to follow. Yes, this post was just to moan and groan.

[ProwlerGT]

Working in this one tonight:
Brake booster push rod

[ProwlerGT]

Well for future readers here's some interesting detail on the push-rod:

The summary:
It may be wise to readjust your power booster push-rod cap nut +/- every 50k miles depending on driving habits. It may also be a good practice to put a 7mm nut behind the cap nut so that it does not move in the future thereby eliminating the need for future adjustment after much use.

The details:
That 3/8" I wrote about ... well I believe I've figured out where I lost it. The little cap nut that is the tip of the push-rod that pushes the master cylinder is almost exactly 3/8" long. It is actually about 6.5/16 long which comes to 3.25/8" long.

Whats this mean? Before the fluid in the reservoir moves (top of reservoir off pushing pedal ever so slowly) the pedal travels 3/8" down. The cap nut is adjusted or I should say PUSHED BACK OVER TIME DUE TO USE 3/8" back and thus the delay of braking and loss of ability to use fully available brake power.

Each successive push of the brake pedal moves the cap nut EVER EVER EVER EVER EVER so slightly backwards in a clockwise motion due to sheer forward pushing force. Over many thousands of miles; probably over 60k the cap nut gets far enough back to where it affects the braking performance.

I found this stuff out I went to adjust the cap nut on my old OEM booster which is off the car. The cap nut would not budge at all. It was jammed all the way back and I had to use the vice grip pliers to hold the rear grip portion in place while i turned the cap nut counter-clockwise.

The only thing that bothers me though is if the cap nut is 3/8" long and the brake pedal engages the fluid movement at 3/8" push down then this would mean adjusting the cap nut outward nearly its full length, which I believe would damn near push it right off the end of the push-rod threads. Though on the car vs using the spare I had to work on may make a difference since its all connected up to the pedal etc.. Though I also have to see the back of the master cylinder push plate too and see if it is worn inward though that would've been taken care of during the mc rebuild I do believe.

Idea: A 7mm nut behind the push-rod cap nut tightened good against it may eliminate the need for future adjustment.

I haven't been able to will myself to work on the car yet cause I don't want to set myself up for further disappointment even though I'm confident about this fix, but now having done this on the spare booster I've got some reference experience for doing it on the car.