I just realized that my brakes are horribly biased to the front as I hit some ice today. I realize Fieros are always going to lock up the fronts first, but it was like the rears weren't even operating. I can pull my e brake handle almost vertical, and it will hold the car, but it doesn't stop it from a roll. I've pulled on the handle about 200 times while alternating holding the brake pedal and pumping it. I also tightened up the adjustment nut on the cable junction. Any ideas? Doe sthis mean my rear brakes need new pads or do I need stupid calipers? I hate buying calipers.

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1984 Fiero SE, White, first love, sold...
1986 Fiero SE 2M6, gold, sold... sniff...
1988 Fiero 2M4, the Fox
1987 Fiero GT, Blue, 3.4/4T60
Still looking for that perfect CJB 88 GT...

Ya this would be good to know, the whole Idea sounds fishy to me, but everyone says thats how you adjust your rear brakes to keep them tight.

Annoying. Some things about fieros bug the crap out of me.

I just found out about the rear brake article in The Ogre's Cave. If you have a low brake pedal and have to pull up high on the e-brake to engage the rears, you may have to manually adjust them by cranking on the lever at the calipers. It worked great on my two cars. Take a look at the article.

There's a helical shaft that goes into a receiver that's clutched to the inside of the piston:



When the lever is pulled it rotates this helix and pushes the piston away from the back of the caliper, pressing the brake pad into the rotor. That's why you have to either remove the lever (so the shaft can spin) or use a tool to turn, or "screw", the piston back down the helix when installing new, thicker pads. When you apply the brakes the piston is pushed against the pad and away from the back of the caliper by brake fluid, this causes the receiver inside the piston to adjust the slack out of the helix. If you never use the parking brake the receiver gums up and stops adjusting, and then the piston is held away from the pad more than it should be, causing the rear brakes to have problems. At least, that's how it looks to me.

JazzMan

[This message has been edited by JazzMan (edited 12-17-2007).]

Good explanation, though I only get it in theory. My ebrake cables are no good, so I need good ones first.

The hand brake DOES NOT adjust the brakes. The hand brake thing was/is a result of GM trying to avoid having to completely redesign and recall every vehicle that uses this piston design.

When they work correctly, this piston does not need the hand brake to adjust. The problem is that the inner and outer piston get trash and corrosion in the void between them that keeps them from moving the way the are supposed to. The threads of the hand brake screw can also crap up but that seems to be less of a factor. Using the hand brake sometimes helps to dislodge the crud but don't count on that working.

A completely disassembled piston and how it is supposed to work is in my cave. See the rear brake article and the link at the beginning of it.

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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 of every forum page...)

OK so it wasn't designed to need to be adjusted but it does need it because of road grime/corrosion.

This brake design is supposed to self adjust but it sometimes doesn’t:



The same information can be found in the Chevrolet Camaro TSB 88-275-5 that is part of the brake recall documents contained in RC-91V055-NN at NHTSA shown below:

[This message has been edited by spark1 (edited 12-29-2007).]

If the hand brake does not adjust the rear brakes then why was it that when I worked as a District Sales Manager for Pontiac Motor Division in St. Louis & Portland Zones during the 80's was told by Central Office and Zone Sales & Service Departments to educate the dealers, their sales & service personel and customers of the need to use the ebrake periodically as it was the only way to adjust the rear brakes as the pads wear down?

if the rear calipers do not work, could the e-brake function be removed in some way (removing the actuating rod thing and somehow sealing the hole that's left), using it as it is and adding an aftermarket wire-actuated caliper for the e-brake?

On the '88 you could simply use front calipers on the rear, other than the emergency brake function they're identical. Don't know about previous years.

JazzMan

quote Originally posted by Mike Murphy: If the hand brake does not adjust the rear brakes then why was it that when I worked as a District Sales Manager for Pontiac Motor Division in St. Louis & Portland Zones during the 80's was told by Central Office and Zone Sales & Service Departments to educate the dealers, their sales & service personel and customers of the need to use the ebrake periodically as it was the only way to adjust the rear brakes as the pads wear down?

Because GM was trying to avoid an even more massive recall than they already had on all vehicles using this piston design. Another recall on them would likely have forced them to completely redesign and replace the entire caliper on all vehicles. The previous recall was addressed with very minor changes to the piston assembly only, which in the scheme of things is fairly cheap to do. "Educating the consumer" is an easy way to shift blame from poor design. NHTSA has a long history of letting car makers do half assed fixes to critical systems and while there are plenty of recalls, little of the actual repairs that do go out are ever made.

As it was the recall was only offered for the manual transmission cars... because among the other issues, the bearing in the piston assembly would fail under regular use and kill the hand brake system as well as auto adjustment. The only reason this did not happen in automatic trans cars much is because AT drivers hardly ever use the hand brake. The bearing problem was really there in all cars but just didn't show up so NHTSA let GM get off only fixing the manual trans cars.

theogre: looked at your website. very informative. but, I don't recall seeing any info on how to test whether the piston is functional or not. is there a way? Don't want to put the caliper back on (I'm in the process of examining, cleaning and painting my calipers) only to discover that the piston needs to be replaced.

Just how I do it. Remove cables and arm, use an open end wrench that fits the screw, put the wrench on with nut on top of it, no nut and screw will thread into the caliper and turn "opposite of lock". It should turn free and smooth. If the caliper is off car you will need the pads in so the d pins will keep the outer piston from turning.
Also if I take my time and keep turning the screw I can get the arm back on very close to the stop and have maybe 6 clicks on the E-Brake arm and have the rotors locked and a good high brake pedal because the rear pads are close to the rotor where they should be.

[This message has been edited by RWF (edited 12-21-2007).]

so, if I have the piston out (which I do), I should be able to do pretty much the same: with the screw all the way in and the outer piston somehow stopped from turning, the inner piston should rotate when I turn the screw in the "un-lock" direction (counter-clockwise for the left-hand caliper piston). correct? again, if the piston is not working, the less time I waste on it, the better

Yes

I was not addressing the recall. We were informed of the usage of the ebrake as early as the fall of 83 when the car was introduced to adjust the rear brakes as the pad wear increased over time. I did not dream it even though I am over 50.

quote Originally posted by Mike Murphy: If the hand brake does not adjust the rear brakes then why was it that when I worked as a District Sales Manager for Pontiac Motor Division in St. Louis & Portland Zones during the 80's was told by Central Office and Zone Sales & Service Departments to educate the dealers, their sales & service personel and customers of the need to use the ebrake periodically as it was the only way to adjust the rear brakes as the pads wear down?

Of course I can't be sure why they told you this, but I can tell you that it's wrong. If the rear pistons are working properly, then the use of the parking brake is not necessary to adjust the rear calipers.

I suspect they told you this because either:

a) they were trying to band-aid the caliper design problems before they got forced into a recall, or
b) they didn't understand how their own design worked.

Neither answer is very comforting from the perspective of a customer.

I secured the actuation screw in a vise and tried to rotate the cylinder by hand, grabbing it with both hands and giving it my best shot. no movement at all. guess I'll give it another try using the pad for slightly increased leverage, but it seems I should start saving up for parts...

I don't know if the test mentioned above works or it's an accurate indicator.

If you are trying it on a bench... If you are bottoming out the screw, you are probably forcing the pistons together. The pistons have a cone seat that is likely to make them lock tight with little effort.

What Bruce said about them leaking... It's pretty common. The vent hole was hidden behind the dust boot on later ones and if the hole manages to be near the top, can hold allot of fluid before it leaks out where you can see it. Also if you aren't careful testing them, you could cause them to leak. The trash that is common inside the pistons may get loose and work that seal.

I'm buying a pair of Raybestos rebuilds. I am hoping they tested the mechanism. The guts are the unknown.

What a PITA stupid design. I've never been a Ford man, but I like the way they do their rear disc park brake, just a mini drum brake, cable operated, completely independent of the hydraulic system. Wonder if there's a way to convert to that? :sheesh:

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1984 Fiero SE, White, first love, sold...
1986 Fiero SE 2M6, gold, sold... sniff...
1988 Fiero 2M4, the Fox
1987 Fiero GT, Blue, 3.4/4T60
Still looking for that perfect CJB 88 GT...

I thought about that too but there doesn't seem to be enough room around the hub assembly. I do however look in the junkyards from time to time to watch for very small rear drum setups. Something might pop up.

TK

Because of the hub space problem I'm more inclined to go with a separate small caliper instead. I've seen those set up and they look elegantly simple.

JazzMan

The mini drum is used on allot of things with bigger wheels. My SUV has that drum in the rotor setup and it's 4wd.

While this OE park brake design does blow... anything you do to replace it has to meet FMVSS or legally the car is not street ready. Fortunately the tests for the parking brake are fairly easy to accomplish. Park nose up x% grade car can't move, park nose down same grade(s) car can't move. In fact the FMVSS test is good for determining if the OE system of any car is working properly. You'd be amazed how many don't.

Ogre, have you been keeping up with which rebuilt rear calipers seem to be the higher quality?

And Merry Christmas to you sir for everything you do for this forum!

Terry

Anyone know who makes a spot caliper (mechanically actuated) so you can use standard front calipers on the rear? I figure I'd have to create a mounting bracket but I think it would be worth it.

quote Originally posted by jsantini: Anyone know who makes a spot caliper (mechanically actuated) so you can use standard front calipers on the rear? I figure I'd have to create a mounting bracket but I think it would be worth it.

Jegs has quite a few from Wilwood. I imagine Summit has them too. Also, someone mentioned JC Whitney had a mechanical parking brake caliper. Not sure how it works.

I don't know if this has been addressed yet in this thread, but MANY cars back in the day needed to have their brakes adjusted using the hand brake.

The Fiero is NOT one of these vehicles because of the design. But the 82-92 Camaro (as mentioned in that TSB) did use such a design.

Pretty much, it's every vehicle from the 80s that had DRUM rear brakes.

It's been at least 4 years since I've had to change out the pads (shoes) on a drum brake car, so I totally forget exactly what's happening, but in a drum brake configuration, you have two shoes that, when the brakes are applied, push outwards towards the inside of the brake drum. This causes friction and the car stops. There is a "wheel cyl" which has two small pistons on it. This sits at the top of the brake setup between the two shoes. These pistons push outwards and cause the shoes to open up, thus causing the braking action.

The shoes need to pivot on something, so the bottom "fulcrum" for lack of a better word, is a spring loaded "rotator" assembly. This assembly is used to take up the slack between the shoes and the drum, and allow for pivoting of the shoes to the drums. There is a "star" gear located in the center of this rotator assembly which is held in place by a little arm. Now this is where it gets a little fuzzy for me. This arm is attached to the emergency brake mechanism. By pulling up on the hand brake, you are effectively adjusting this star wheel which permenantly reduces the slack between the shoes and the drum. If the tension is above a certain amount, the arm will slip off of it and not adjust it further until there is sufficient slack to allow it to adjust it.

This is roughly how I've seen it in the 4 cars I've owned that had drum brakes. I imagine that it's fairly similar on most other GM vehicles that have drum brakes.


As far as the Fiero's emergency brake goes, I've never had to adjust it, but I'd always assumed that this was done by adjusting that "nut" that goes on the linkage that connects the two cables to the primary emergency brake cable.

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Todd,
2006 Pontiac Solstice
2004 Volkswagen Beetle Convertible (Wife's Car)
2002 Ford Crown Victoria LX
1987 Pontiac Fiero SE / V6 (3.2) 5-Speed
1984 Porsche 944 5-Speed
1981 Pontiac TransAm (Olds 455BB)
1973 Volkswagen Type-2 Transporter

In places where salt is used on the roads in winter, the advise on use of the park brake is “use it or lose it”. If the park brake isn’t used frequently it may not work at all when needed due to corrosion.

The Fiero parking brake should also be used frequently for the same reason and because it is supposed to self adjust when applied. If pad wear is great enough (between uses) that the park brake mechanism fails to engage, it cannot self adjust so it is inoperable.

If you have an 84-86 Fiero with an automatic transmission, GM doesn’t believe you need a functioning parking brake so don’t worry about it working correctly. Just tell your State inspector that NHTSA signed off on that logic. Same goes if you have an 82-86 Firebird or Camaro with rear disc brakes.

The Cadillac/Buick rear calipers of the same vintage were not recalled, probably cause none had manual transmissions. Those are commonly used to “upgrade” older drum brake systems to disc. The vendors selling those kits always include a warning to use the parking brake frequently to keep them adjusted.

Check these babies out. Think those would hold tight enough to pass inspection for a fiero e-brake? Course, you'd have to figure out where and how to mount em... hmm
http://www.jegs.com/webapp/...0002_829936_-1_11755
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1984 Fiero SE, White, first love, sold...
1986 Fiero SE 2M6, gold, sold... sniff...
1988 Fiero 2M4, the Fox
1987 Fiero GT, Blue, 3.4/4T60
Still looking for that perfect CJB 88 GT...

[This message has been edited by fierodeletre (edited 12-26-2007).]

Is it hydraulically or mechanically actuated? I can't tell. I'm blind aren't I.....

The more I look the smaller they get. .7CU pad.....Is that for a slot car?

[This message has been edited by TK (edited 12-27-2007).]

I resurrected this topic rather than start a new one, because I think I have stumbled on to some significant data....

I replaced both rear calipers, because the e-brake function was not working - piston and e-brake lever were binding and tough to move, pistons were all chewed up due to somebody using channel-lock pliers on them, boots were gone, etc. I got two "bolt and go" set-ups from the local auto parts store. These are ready to go on the car - pads installed, new bolts and seals, even set to the right gap to slide on over the rotor.

WHAT I LEARNED ... Before I did all this, I read Ogre's excellent write-up on how to adjust the rear brake to minimize the gap (and pedal travel). The part about using a screwdriver to hold the piston out while manually moving the e-brake lever got me thinking: I understand that the reason you do this is so that when you cycle the e-brake lever forward the e-brake screw will wind back out, but the THE PISTON STAYS UP TO THE ROTOR, kind of like using a ratchet. But instead of using a screwdriver to keep the piston from moving back out, why not just use the hydraulic action of the brakes themselves?

WHAT I DID.. I adjusted the rear calipers like this:
Sitting in the drivers seat...
1. Set the e-brake (at least as far as you can).
2. Step firmly on the brake pedal and HOLD.
3. Release the e-brake.
4. Release the brake pedal.

I did this three times, and got a nice firm, high pedal.

Maybe this is what the GM engineers had in mind when they designed this e-brake system.