I went joyriding today in my new '86 GT automatic. I was on a road that I wasn't too familiar with, looking for a house I lived in as a child. It is a country two-lane that takes over 30 minutes to drive from end to end. Anyway, I was surprised twice and had to hit my brakes hard. Not really panic stops but hard. Both times locked up the front wheels. The rears did not lock up.

This car has spent most of it's life in a garage. I doubt the parking brake has been used very often. It only has 62K on it now. I have been thinking that I need to change the brake fluid since the brakes seem "weak". After today, I'm wondering if maybe the rears aren't engaging the way they should because of a lack of on-going adjustment from non-use of the e-brake.

(1) If the system is working correctly, should I expect the regular use of the e-brake to improve the overall balance and performance of the braking system?

(2) How long would it take to achieve optimum adjustment?

(3) Should I go through this process before the fluid change?

Thanks,

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Jonathan
23K mile '85 notchie - Still under construction
https://www.fiero.nl/forum/Forum2/HTML/121056.html
I'm not a mechanic but I play one in my garage - me
Power tends to corrupt, and absolute power corrupts absolutely - Lord Acton
Those who hammer their guns into plows will plow for those who do not - Thomas Jefferson
The tree of liberty must be refreshed from time to time, with the blood of patriots and tyrants - Thomas Jefferson

cars built before ABS became the norm are not designed to have the rear brakes lock up .having the rear wheels always turning keeps the car going in a straight line and allows you to steer in a normal fashion .most of your braking is done with the front wheels . this does not mean the rear wheels are not still helping with the braking of the car , it just is not as noticeable .as far as the fiero ebrake goes , it is only good at getting stuck and having the annoying dingy thing going off for 10 miles or so .

Rear shouldn't lock in many cases.

Using E brake for adjustment is a Myth. If/when does work then rear piston(s) have problems or soon will be.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

I wish I could lock my fronts haha... Seriously

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86 Fiero GTX project now tearing up the street, My build thread! 3800sc, interior, wheels, suspension and more! https://www.fiero.nl/forum/Forum1/HTML/089483.html

quote Originally posted by wftb: ... having the rear wheels always turning keeps the car going in a straight line and allows you to steer in a normal fashion ... .

Yes, I agree that cars without ABS were designed to lock the front wheels first, and that such a car will tend to keep going straight ahead when the front wheels are locked. But that will not allow you to maintain steering control, normally or in any other fashion. Locked wheels will not provide any directional control, period, while rolling wheels will tend to go in the direction they're pointed.

Consider also that "the engineers" have to design a given vehicle for every possible combination of vehicle loading and road conditions that it is likely to encounter in service. In more precise terms, for braking stability you always want to have the center of gravity ahead of the center of traction.

[This message has been edited by Marvin McInnis (edited 12-13-2012).]

Semi-tractor trailer combo's jackknife because of a lack of traction on the back. Stop the front end of anything and let the rear end go and see what happens. I live in Iowa near the Missississippi where snow, frost, sleet, rain, hail are a way of life, not some "theory". In the months from December (early), to around the middle of April, I put my best traction on the BACK of any vehicle I've ever owned. I give myself a huge edge by using studded tires on all four wheels, if possible, or the REAR only if it's a matter of choice. My last of 7 children is a high school senior and this has served us well. Think about it, Tap your brakes and with less quality traction you go into an immediate spin when the the back of the thing passes you by. Ditches are full of cars here that pull straight because of front wheel drive (so people have a false sense of security with 10-15 mph too much speed) and all hell breaks loose when the dynamics change when they hit the brakes. If you have rear emergencies you can try to modulate them but that should never become an issue. Keep damn good rubber on the rear and with properly adjusted stuff you should be ok. I know the game is easier on great roads, but come drive on I-80 or I-27 with just a touch of the slippery on them and you'll quickly find yourself in prayer that those back wheels are more than (trailer) wheels just trying to roll along for some phantom steering purpose. I want my back wheels, emergency or regular brakes, to do more than rolling along not helping much. While you need more braking POWER under normal conditions under the normally heavier front end, all bets are off when roads aren't good.

[This message has been edited by weaselbeak (edited 12-13-2012).]

i live in the snow belt area of ontario canada .when we get big storms we get big snow and white outs .i know all about putting the best rubber on the back .and if your rear tires lock up before your fronts , you are still going to go for a loop .and you can still steer with the front wheels locked up .not much , but sometimes enough to get away from trouble .buy a street stocker and go racing at your local oval track .you get to try all this stuff out first hand .

My front and rear tires are different. The fronts are well worn and the rears are fairly new. I did this because of several people posting that the rears wear faster. There is some life left in the fronts so I will use it up and change them when they hit the wear bars. I have another set of tires just like them that were on the rear. I'll put them on next and use them up.

By sheer dumb luck, I've had the better traction tires in the rear.

Jonathan

quote Originally posted by wftb: i live in the snow belt area of ontario canada .when we get big storms we get big snow and white outs .I know all about putting the best rubber on the back .and if your rear tires lock up before your fronts , you are still going to go for a loop .and you can still steer with the front wheels locked up .not much , but sometimes enough to get away from trouble .buy a street stocker and go racing at your local oval track .you get to try all this stuff out first hand .

What fantasyland do you live in? Is Canadian ice and snow chemically superior? How many people go to the track and "learn how to drive properly?. I know of not a single soccer mom in history who's done that with her minivan. Sliding wheels, front or rear, have pretty much zero control with steering without some measure of traction. I choose the back for my best rubber because a spinning vehicle is OUT OF CONTROL. My odds are with a vehicle when the rear stays in the rear.

[This message has been edited by weaselbeak (edited 12-13-2012).]

On the Fiero you do NOT want the rear brakes to lock. the fiero is A$$ heavy. the back QUICKLY wants to become the front when the rear loses traction. (trust me, I kow!)

Does the car stop in a reasonable amount of time / distance? that's all that matters.

Cheers!

just how Fieros are.
and - it gets much worse if you do Grand Am brakes up front, and leave the rears stock.
good luck getting any significant braking force out of the hand brake. especially while trying to drive.

quote Originally posted by Pyrthian: just how Fieros are. and - it gets much worse if you do Grand Am brakes up front, and leave the rears stock. good luck getting any significant braking force out of the hand brake. especially while trying to drive.

Since you brought it up, what would you do for rear brakes on an 88 cradle swap car if you wanted e-brake? If you kept stock 88 brakes on the rear, won't they be stronger than stock 85-87 front brakes? If so, do you upgrade the fronts? To what? Do you upgrade fronts and rears so everything works together? To what?

Jonathan

quote Originally posted by Boostdreamer: Since you brought it up, what would you do for rear brakes on an 88 cradle swap car if you wanted e-brake? If you kept stock 88 brakes on the rear, won't they be stronger than stock 85-87 front brakes? If so, do you upgrade the fronts? To what? Do you upgrade fronts and rears so everything works together? To what? Jonathan

I just did an 88 cradle swap to my 84 and for brakes in the front I adapted the 88 front calipers to my 84 spindles using 12" Vette rotors. I machined some custom adapters to hold the calipers onto the spindles. I also switched to the 88 MC and Booster. It stops like it has a rope tied to the rear bumper...lol. I plan on adding the 12" Vette rotors to the rear as soon as I get some time to make the bracket to move the calipers outward. Right now, the car seems a little bit biased to the front brakes more than 88's I have driven but I really don't mind it too much. It may have something to do with the difference in diameter of the front rotors.

quote Originally posted by Boostdreamer: Since you brought it up, what would you do for rear brakes on an 88 cradle swap car if you wanted e-brake? If you kept stock 88 brakes on the rear, won't they be stronger than stock 85-87 front brakes? If so, do you upgrade the fronts? To what? Do you upgrade fronts and rears so everything works together? To what? Jonathan

hard to answer with an 88 cradle - not sure what options you actually have?
on my 85, I have Grand Ams up front & Cadillac on the back. I had just the Grand Ams up front for a bit - but they were WAY overpowering vs the rears.

perhaps a proportioning valve?

Its my personal opinion that GM used a proportioning valve designed for a front engine car and it actually supplies too much braking to the front of the car, especially if you have larger rear tires.

When my rear brakes started to give me issues on my Automatic 85GT I swapped in Grand Am Calipers and pads, while leaving good stock front brakes. I personally loved it. The rear brakes finally had enough bite to make it feel like you dropped an anchor out behind the car. If I would have had a standard trans I would not have tried it, but now, all my cars have Grand Am rear brakes, (well except my 88GT)

I do miss the park brake and I have the Cadillac caliper adapters here. I plan on running Grand Am up front and Cadillac on the rear of my 87 V8 Fiero. The better braking has saved my butt more times than an E-Brake has, so I really feel it was the better choice for me. Once I have the Cadillac calipers on the back I'll have the best of both worlds. If you run the stock 14" wheels and tires and drive the car in town or city driving you will be fine with stock brakes, if you have the 15" wheels the brakes are just barley fine, but if you move to 16" or 17" you will quickly find out how poor the brakes are and I drove a Fiero that had stock Brakes and 20" wheels once, only once, that car was so unsafe that even the owner agreed and took the 20" wheels off until he could get new bigger brakes for the car.

There was a racer trick to removing the spring from the proportioning valve to equal out the pressure to both the front and rear brakes, and as much as people felt it would let the rears lock up way too soon, the actual result was an almost perfect 4 wheel lockup under panic conditions. However properly modulated the car would stop much quicker than in stock configuration. The choice is yours its Dangerous to do if you don't know how to modulate brakes, but much safer if you do.
Side note and I only mention it, because I don't know the answer for fact, however removing that spring MAY ALSO DISABLE the systems ability to block off a portion of the brakes in the event of a brake line failure. When operation correctly if you blow a brake line it kicks the valve over and blocks off that side of the brakes allowing you to stop the car. If that is disabled it may not function and if you pop a brake hose, your foot goes to the floor. I have lost a brake line in a Fiero that had a malfunctioning valve and I was able to get 3 pumps of the pedal before it went away completely. It was a V8 5spd and I was doing about 60mph in a street race and went to slow back to the limit quickly when it let go. I had to downshift and pump the brakes then pull into a gas station and kill the ignition in 1st gear to come to a complete stop. The previous owner had done Corvette brakes on the car and didn't tighten down the flares in the lines correctly.

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

quote Originally posted by Pyrthian: on my 85, I had just the Grand Ams up front for a bit - but they were WAY overpowering vs the rears.

Then maybe Grand Ams up front and stock 88 brakes in the rear on a cradle swap car?

Jonathan

Guys, a stock street car has built in proportioning often in the range of 60/40 F/R. If you are locking up the fronts, you are braking too hard - a sliding tire doesn't stop at all well. Sounds like you could use new (stickier) tires.

Everyone that said the rears shouldn't be locking up (ever) is dead right. On the race cars (road racing, not that straight line stuff) we set bias as low as 10% on the rear as they are there to keep the back end from passing the front end and don't contribute a whole lot to over all braking effort.

I had a rear line leak once on my race car in between race heats. I didn't have time to fix it so I just grabbed a spare bleed screw and stuck it in the rear brake T fitting and went out and ran with front brakes only. My lap times were within about 1/2 second of what they were with all brakes working.

While we hear about all sorts of modding exercises being carried out on poor hapless Fieros, one thing I don't think I've ever heard of, probably because it would be complicated and there isn't anything jazzy or chromed that you could point to later, is modern antilock brakes and if possible, also the modern ABS and ESC (electronic stability control) that new cars have. It's funny, but in the Solstice forum we see 'he-man' drivers that don't want any stinking 'nanny' controls on their cars, who turn that off and often end up parked against something unyielding (buildings, bridges...) as a result. It would be very, very interesting to drive a Fiero with these systems!

bump

[This message has been edited by wftb (edited 12-15-2012).]

Fiero brakes kind of suck, just nature of the beast. Check your tire pressures and tire tread condition, tires are an important part of braking.

quote Originally posted by Capt Fiero: Side note and I only mention it, because I don't know the answer for fact, however removing that spring MAY ALSO DISABLE the systems ability to block off a portion of the brakes in the event of a brake line failure. When operation correctly if you blow a brake line it kicks the valve over and blocks off that side of the brakes allowing you to stop the car. If that is disabled it may not function and if you pop a brake hose, your foot goes to the floor. I have lost a brake line in a Fiero that had a malfunctioning valve and I was able to get 3 pumps of the pedal before it went away completely. ... The previous owner had done Corvette brakes on the car and didn't tighten down the flares in the lines correctly.

Myth... CV will block failed circuit.
CV blocks nothing. CV Does bypass PV section when front brake fails from fluid leaks. The bypass give rears full pressure.
MC itself will use mechanical method to try to keep brakes working when one circuit is dead.
May/will not work is many "upgaded" brakes with mismatch MCs.
See How Master Cylinders and Combination Valves Work at howstuffworks

Blowing line after do brake work is mainly a result in bad flaring, wrong line material or old line w/ re-flaring. Old lines are Work Hard from being hammered by line pressure, have corrosion problems, etc.

A couple of years ago I replaced my rear brakes, only, on the '85gt with brakes from the Grand am. The difference and the balance has been wonderful, and its an easy bolt on conversion. I know it leaves me with no parking brake, that never gets used anyway, but the difference in the brakes that I do use has been fantastic. I went auto crossing with the car afterward and the brakes were flawless, no I'll affects. I have manual calipers for the ebrake that I need to build brackets for in the future.

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RickN
White 88GT 5spd (<10K miles)
White 85GT (SC3800 Series II w/ AOD)
White 99 F250SD 7.3PSD 6spd
1956 Ford 860 Tractor w/ Freeman Loader
20Ft H&H Tilt Bed Trailer (Remember - Gravity is not a tie-down)

[This message has been edited by RickN (edited 12-16-2012).]