Time to write a how-to to FIX your E-brake. <----Edited, edit in green I have used the Orge's method for years, but knew there had to be a better way, so I went OCD on it and figured one out. The Orge's method is sound but doesn't always work, you need a shim, and doesn't always work, when it does its great. But I have figured out a way that will always work on the first try. Well this is more of a way to unfreeze a stuck seal in the piston, Ideally you pull the e-brake handle a few times and it adjusts fine. Even more ideal it should self adjust with no user intervention. This is most of the time not the case as Fieros are getting old and alot of people don't use the e-brake so it gets stuck, especially people with autos as they don't think they need it as they just put it in park and call it good. But you must use your e-brake to keep it adjusted right. Ideally, you don't but it helps ALOT. I know you might be thinking what does the cable part of the brake have to do with the hydraulic part of it, well keeping the e-brake adjusted keeps the pads close to the rotor and gives you a good firm, high pedal. Thus better brakes. And this is where the bigger booster I sell really shines. As you want a good firm pedal and high up so you don't run out of pedal.
**CAUTION theoretically this could tear the seal inside but if it does it mean the caliper is junk anyway and needed to be replaced, IE so frozen it wont move and bonded to the inner wall**
To start lets talk about how it works, the Orge's cave says it ratchets, not so much, it acts like it, but no ratchet mechanism inside the piston. I cut one open and with much debate with my friend on how it works, (good debate) we figured it out. But first lets look inside.
The parts inside as you can see here it looks like a ratchet mechanism but it never comes out of the groves when together, it has the gear and the groves so it can move freely when you step on the brake, at first it looked like it came out and just moved to the next slot, this is not the case.
Here is how it is assembled, not much help now but it will make sense.
Now here is a side view of how it all fits together the part in the center of the pic goes into the piston and has a seal on it, this is the seal that gets stuck, the fluid pushes this part down, and the e-brake has coarse threads on it and also pushes this part down, this is why the rear calipers have the vent hole in the middle to allow air to escape, as fluid does not push on the piston itself but the inner piston. Now the way the e-brake works, the "ratchet part" is it will spin the inner piston inside the outer piston shell. IE: you pull the handle and it pushes down, when you let up it moves just far enough away to release the brakes and then spins the inner piston and that is what takes up the slack, when it is stuck it doesn't spin and it pulls it way back, thus a low pedal. I hope you are still with me. Lets get on to the adjustment/FIX procedure.
The easiest time is when putting on new pads, as most of this has to be done anyway. This will be step by step
The e-brake lever assembled. I always use a zip tie or wire to hold the cable end in place.
Cut the zip tie and move the end of the cable behind the lever.
Then use a screwdriver to pop off the spring.
Use a 13mm wrench to unhook the brake cable from the strut, gives you more room to work.
now since you have the 13mm in you hand slide the box end over the cable and the cable locks and the cable will pull right out.
Now use an 11/16 wrench to unhook the e-brake lever, without moving the e-brake lever, hold it when you take off the nut, this part is easier while it is still bolted to the car.
now unbolt the caliper, pop off the pads and you end up with this.
open the master cylinder cap.
Now you need to compress the piston, and BOTTOM it out, there are two ways to do this. A C clamp and a big socket over the stud sticking out. You want the stud to be able to spin as you compress the caliper.
or with a "brake spreader" tool
once the piston is bottomed out, you HAVE TO bottom it out for this to work, make sure the e-brake stud is at it's highest point, IE slight turns and you will see it move in and out, make sure it is all the way out. Then put the e-brake lever back on as far away from the stop as you can.
Put some vise grips on the lever.
and move the lever to the stop, this is the hard part and this is where you will break the stuck seal free. It may take alot of effort to break it free, but this is what has to be done. Then you can take the lever off and spin the bolt a few more times, with a wrench in the same direction to make sure it is free.
Now that is has broke free, you should be able to work the lever back and forth to move the pads to the rotor. (When you move it one way it will move the piston out, when you move the lever back the piston should stay)
Now to reassemble, put the cable back through the hole and put on the spring make sure the cable extends past the lever.
Now use your hands to push the spring back into place, (I have tried all kinds of brake tools for this, your hands work best)
Then flip the cable around into position and secure it with a zip tie or wire.
Put the master cylinder cap back on and pump the brakes use the e-brake lever a few times to bring the pistons back into position.
Now the adjuster nut under the back of the car, (88s are in the front part of the cradle) is just to take up the slack in the cable.
adjust it until one of the E-brake cable just comes off the stop as seen in the pic below.
Pull the handle a few times and readjust the the adjuster so as above one of the levers just comes off the stop.
That's it, now your e-brake should work and your pedal should be high and firm, if the pedal is not high and firm, air may have entered the system at some point and bleed the brakes.
To explain what happened when the piston is bottomed out it has no where to go and has to spin inside and thus it breaks free of it being stuck.
Just to show the old way, you needed a shim.
and you had to hold the piston tight against the rotor and shim with a screwdriver.
but it would always slip off and the piston would tend to move back and forth, and it took alot of trys to maybe get it to unstick, a real PITA, now with my method the piston has no where to go and has to spin, it has no choice. Now there is no shim needed and it works every time.
Nice write up but I have a tool I bet you didn't use and that is a spring compressor, not really a brake tool, made more for the door springs and one handy little tool as well as probably the cheapest tool you will ever but except for a screwdriver. They sell them at all the parts store for around 10 bucks and I have used them on the door springs and ebrake springs, just about any spring it will fit on. The beauty of it is you put it one to squeeze the spring to remove it, leave the spring in it and then it is all set to fit right back in when it comes time to put it all back together. A life/eye saver when you are removing the door springs that can and do come flying off to parts unknown in the garage or outside never to be found again. one other thing you might want to pickup when you buy that tool is a ratcheting wrench the right size, I thinks its 1/2" although I think 13mm works as well, it makes the compressing and releasing of the spring so much quicker.
I have always fought with the e-brakes over the years. I really appreciate you taking the time and effort to post the details and pic's of your solution, great job! A+ to you! ------------------ "Because in a split second, It's gone"
Ayrton Senna
[This message has been edited by Ponnari (edited 11-13-2014).]
I have always fought with the e-brakes over the years. I really appreciate you taking the time and effort to post the details and pic's of your solution, great job!
Thank you, I have always fought with it too, some just wouldn't adjust, thus a better way was needed other than just replacing the caliper.
I'm going to be doing this procedure this weekend, dumb question probably, sorry, when using the vise gripes on the lever to break the inside seal free how do you know that or when it has broke free?
------------------ "Because in a split second, It's gone" Ayrton Senna
I knew there had to be a better way, once I found it and it worked, I took pics of the next one I did. No more " I hope this one adjusts" as now you can force it to work.
Using Ebrake for Fiero and many, Many, others only saves times between major brake work. (Some readers remember Drum brakes and rust frozen adjusters. Is a similar issue.)
If rear brakes work... The brakes Will self adjust Without Driver using E brakes as FMVSS requires.
If you have to repeatedly use my or any other method to adjust them then likely the pistons are junk.
Adjusting parking brake cables correctly is good but won't help a lot of people because Many need to replace both wheel cables at a minimum. Bad cables are very common, worse in rust belt states, and new cables can freeze in Winter. I lived up north and seen both problem even on car 2-5 years old.
A big Problem is many pistons look like above, Especially where the Pistons meet in that airspace in front of the inner piston seal, and won't move as design.
I have the "recall" piston kit and so far works without using Ebrake handle for ~4 years now. Before that I had to adjust rear brakes 1-2 years max. GM made changes to updated piston design, including moving vent hole to side behind piston dust boot and black coating on the piston. (The recall kits are gone from GM.)
The "ratchet" function... Correct that the function is not tooth ratchet like most wrenches. Not a bearing type either like many Auto trans uses (example Lo Roller Clutch in TH125c.) or "New" Sears ratchet in TV ads. The "ratchet" is more complicated than just where the two pistons meet. It is a balancing act of the all the Springs inside the caliper, where the shape of the two pistons meet and others. Even the pitch of the threads of the parking brake screw matters here.
The faces where metal of two pistons meet are cone/taper clutch.
As shown in my cave Rear Piston notes When you have enough pressure when two pistons meet, they work as one piece. Below design pressure, inside piston can move.
The inner piston, the nut/sleeve (item 3 in bottom picture) and the small spring can rotate around the screw to adjust pad clearance. Is why the bearing at top of inner spring is there. (edit to fix cave links. Same for others in this thread.) ------------------ 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)
Good writeup! I always do my brakes pretty much exactly the same way.
quote
Originally posted by theogre:
If rear brakes work... The brakes Will self adjust Without Driver using E brakes as FMVSS requires.
...
When you have enough pressure when two pistons meet, they work as one piece.
This is a contradictory statement. The E-brakes self adjust feature is disabled by the two pistons locking together under the brake pedal operation. They will never take up the slack unless you operate the E-brake lever, or do what Sardonyx outlined.
Ogre's absolutely right about the two pistons acting as one when you apply brake pedal pressure, and that they are a friction ratchet, they don't click, they slip. And, that if the internal piston's seal binds up in any way (Rust, or contamination) the pistons will not be able to rotate independantly of one another like they should, and will not adjust beyond what you can initially do, unless you remove the handle and increment it when needed.
There is one thing that is SUPER FREAKING IMPORTANT.
NEVER, EVER try to apply or bleed the brakes hydraulically BEFORE you run in your E-brake adjustment.
Why?
Everytime you hydraulically apply the brakes, it compresses the stiff little spring inside the piston whatever distance the pad actually moves.
Normally the big spring pushing the piston out is pressing against the retainer on the piston one way, and the smaller spring inside the piston pushes back, and the balance of the two keep the stresses on the retainer pretty low, it's held in by friction only.
However, when the piston has to go a long way hydraulically, it will compress the internal spring a whole lot more than it is supposed to, while also relieving a little of the pressure on the bigger spring behind the piston. This imbalance will blow the spring retainer right out of the back of the piston, and the brake pad will have a tendancy to drag, and the E-brake will no longer function.
So, always install the brake, Adjust the E-brake, THEN you can use the brake pedal, or bleed the brakes. It's not just optional, its required for them to work correctly, and safely.
Originally posted by Fierobsessed: >Originally posted by theogre: >If rear brakes work... The brakes Will self adjust Without Driver using E brakes as FMVSS requires. >... >When you have enough pressure when two pistons meet, they work as one piece.
This is a contradictory statement. The E-brakes self adjust feature is disabled by the two pistons locking together under the brake pedal operation. They will never take up the slack unless you operate the E-brake lever, or do what Sardonyx outlined.
No... You stop short...
I said: When you have enough pressure when two pistons meet, they work as one piece. Below design pressure, inside piston can move.
Self adjust happens when pistons sees low hydraulic pressure... Caliper have low hydraulic pressure in the space when pads close clearance but not to stop the rotors.
Taper angle is the key here. This taper isn't like tapers used BJ, Tie rod ends, or even tapers in drill press or milling machines because of angle. You need more pressure here to keep them lock because of angle two piston meet. BJ etc will lock and stay locked w/ little effort. The BJ nut is to make sure the tapper can't vibrate loose and fail. Drill press and mills using tapper to attach bits doesn't need the nut. A tap on narrow end and bits fall out.
I said: When you have enough pressure when two pistons meet, they work as one piece. Below design pressure, inside piston can move.
Self adjust happens when pistons sees low hydraulic pressure... Caliper have low hydraulic pressure in the space when pads close clearance but not to stop the rotors.
Taper angle is the key here. This taper isn't like tapers used BJ, Tie rod ends, or even tapers in drill press or milling machines because of angle. You need more pressure here to keep them lock because of angle two piston meet. BJ etc will lock and stay locked w/ little effort. The BJ nut is to make sure the tapper can't vibrate loose and fail. Drill press and mills using tapper to attach bits doesn't need the nut. A tap on narrow end and bits fall out.
It IMO is all about the thread pitch of the e-brake screw, as it would rather spin than retract, (working right) And I don't see how it would ever self adjust with out useing the E-brake, it's just not going to happen, I cut the piston open, thus the pics, you can use your brakes all you want and the internal piston is not going to spin without the E-brake. IE: The gear looking part is so it can move in and out with fluid, it wont spin ever with out the screw turning, (I played with the cut open one alot)
On a side note this really should be titled "How to get your frozen(non-working) e-brake to work again" as all the adjustment is automatic once the seal is broke free.
I played with the cut open one some more today, there is a taper, but it is more so the internal piston can push on the sides of the external piston rather than the center, the taper does not act like a one way clutch, I can push on it and spin it either direction, not the same pressure as when you hit the brakes, but I feel the point is valid.
Note for external spring over cable... If you have spring tool for doors then can use same tool for this. It will compress enough so easy to get back on the level.
Adjusting cables... Short version. Both levers at stops on caliper body, the handle should move 5-8 click after finish adjusting. Source: 87 FSM
Again, When parts work... Self-adjust feature happen every time you stop. Doesn't matter if people bought GM/NHTSA blaming owners for not using parking brakes. They wrote that BS to save GM money before FMVSS got publish on the internet. This rear brake setup would Fail FMVSS rules if GM made them to use Pbrake to adjust. NHTSA gave GM a huge bone to save money and more bad PR to blame owner and only applies the recall to manual trans cars. Brake Recalls for this issue applies to several car lines, not just Fiero.
If adjusting cables then using p-brake helps, sorry but most people are on just fooling themselves. If you forget to use them, the pistons can blow out the back sheet metal. That's happen then you need new parts fast or the pads can drag. Pad drag is a big problem. Can warp a rotor or even catch fire.
A CHECK for this problem is to retract the piston. the piston face is under 5mm from caliper body. Over 5mm means trouble. See my Cave, Clamp Method notes
quote
Originally posted by sardonyx247: I played with the cut open one some more today, there is a taper, but it is more so the internal piston can push on the sides of the external piston rather than the center, the taper does not act like a one way clutch, I can push on it and spin it either direction, not the same pressure as when you hit the brakes, but I feel the point is valid.
Funny... You finger generates maybe a few inch-pound of torque and few pounds of pressure. System should have very Low fluid pressure to close pad clearance. That is when the inner piston can move. After hitting the rotors the pressure will climb and both pistons will move as one part.
Brake pressure is 0 - 1500+ PSI. piston area (~2.8 in² ) x Brake PSI =... (<- Edit to remove the smily) 2.8x100=280 pounds generated by the piston set. 2.8x500=1400 2.8x1200=3360
Outside piston does little to make actual brake force because of air vent. Most of brake force generated at inner piston then transmit that thru cone shape faces and outer piston.
You cut the piston and other parts wrong way. That looses important details and Will confuse most people. That inner/small spring have a bearing at top for a reason. When you hydraulically push out the piston at low pressure and generate enough force on small spring, the pitch of screw will force enough torque so the small spring, nut and inner piston to rotate and take up pad clearance.
[This message has been edited by theogre (edited 01-06-2016).]
Note for external spring over cable... If you have spring tool for doors then can use same tool for this. It will compress enough so easy to get back on the level.
Adjusting cables... Short version. Both levers at stops on caliper body, the handle should move 5-8 click after finish adjusting. Source: 87 FSM
That's happen then you need new parts fast or the pads can drag. Pad drag is a big problem. Can warp a rotor or even catch fire.
A CHECK for this problem is to retract the piston. the piston face is under 5mm from caliper body. Over 5mm means trouble. See my Cave, [URL=http://home.comcast.net/%7Efierocave/brakes6.htm]Clamp Method notes
I think this picture must illustrate what went wrong with my 88 rebuilt passengers side caliper, I had just purchased from the Fiero Store. I rotated the caliper piston the correct direction per 88SM, to get the pads to easily slip on the rotor, but as soon as I Bleed the brakes it would have excessive drag. The drivers side worked fine, anyway I was happy with the service I got from the Fiero Store when they warrantied it.
Thank You theorge, The Cave is a great source of information.
Even the piston on the left looks like it may be a little suspect. The retaining cage shouldn't be quite that far in, if they are pressed all the way in, it will hit the internal piston causing it to bind and not be unable to self adjust.
The middle one is far too loose obviously,
The helical nut should be flush, or just peak out of the retaining cage a little.
One problem that I have run into with rebuilt pistons is that they replace the internal seal with a new one that is thicker than the OEM seal, and just won't allow the internal piston to rotate. Just far too much friction.
If you have a piston and you wonder if its good, run the E-brake screw into it with the lever and nut on it attached, and pull the screw out without rotating the piston. If the nut in the piston rotates and allows you to pull the screw out, its in working order. If the nut pulls out a little without spining, the piston is shot. (the internal piston is not rotating, jammed, rotted in) If the whole thing falls apart, well you know your answer there too. If fluid leaks past the little seal in the face of the piston, that also means its toast.
The unfortunate fact is that these parts are becoming scarce. Rebuilders are rebuilding the pistons, and using sub-par seals, or using defective replacement pistons. Last I checked, GM doesn't supply them anymore either. So, if your piston doesn't work. You can get a rebuilt caliper and it might not work.
Pretty crappy, but thats what happens when your car turns 30.
Originally posted by Fierobsessed: Even the piston on the left looks like it may be a little suspect. The retaining cage shouldn't be quite that far in, if they are pressed all the way in, it will hit the internal piston causing it to bind and not be unable to self adjust.
Maybe. I took the picture and "good" piston look about same as "rebuid kit" pistons. I don't have a picture of piston kit parts. I don't know if PFF archives have picture of kit... Search for 18019027 but didn't find any pictures.
Originally posted by Jims88: I rotated the caliper piston the correct direction per 88SM, to get the pads to easily slip on the rotor, but as soon as I Bleed the brakes it would have excessive drag. The drivers side worked fine, anyway I was happy with the service I got from the Fiero Store when they warrantied it.
Thank You theorge, The Cave is a great source of information.
Pad clearance won't close "to spec" after pushing brake pedal 1 - several times then yes, likely have iffy rebuild parts. Good pistons will self-adjust no matter what pad clearance. Just push pedal slowly if closing big clearance after brake work.
Originally posted by Fierobsessed: If you have a piston and you wonder if its good, run the E-brake screw into it with the lever and nut on it attached, and pull the screw out without rotating the piston. If the nut in the piston rotates and allows you to pull the screw out, its in working order. If the nut pulls out a little without spining, the piston is shot. (the internal piston is not rotating, jammed, rotted in) If the whole thing falls apart, well you know your answer there too. If fluid leaks past the little seal in the face of the piston, that also means its toast.
And that right there is exactly how the piston self adjusts without using the E-brake.
That spring inside the piston can get compressed two ways... a) When you release the parking brake, and b) when you hit the brake pedal. But no matter HOW it's compressed, the end result is that the internal nut wants to walk down the actuator lead screw. And if the spring force is great enough to overcome the sum of all the friction forces (leadscrew threads, tapered face contact, and internal seal), the nut screws itself down the leadscrew, the internal piston spins, and the slack is taken up.
Bottom line is that it doesn't matter HOW the internal spring gets compressed. It only matters that it does.
Of course, that's assuming that they are working properly. Which is very rare...
Now here is a side view of how it all fits together the part in the center of the pic goes into the piston and has a seal on it, this is the seal that gets stuck, the fluid pushes this part down, and the e-brake has coarse threads on it and also pushes this part down, this is why the rear calipers have the vent hole in the middle to allow air to escape, as fluid does not push on the piston itself but the inner piston.
I'm confused. How does the piston come apart to reveal the inner and outer pistons as seen here?
I disassembled an '88 rear caliper and wound up with a coarse-threaded E-brake screw, a big spring and a couple nuts and washers. The Piston clearly still has its internal piston inside it and it does not come out, or turn or anything. Is it stuck? Its a surplus caliper but like you I was trying to figure out how it works. Once I had it apart I still wasn't sure; your thread helped but I am confused why mine didn't come all the way apart.
Maybe the '88s are different. My piston looks more like the ones in Ogre's picture.
Originally posted by css9450: I'm confused. How does the piston come apart to reveal the inner and outer pistons as seen here?
I disassembled an '88 rear caliper and wound up with a coarse-threaded E-brake screw, a big spring and a couple nuts and washers. The Piston clearly still has its internal piston inside it and it does not come out, or turn or anything. Is it stuck? Its a surplus caliper but like you I was trying to figure out how it works. Once I had it apart I still wasn't sure; your thread helped but I am confused why mine didn't come all the way apart.
88 is same design.
He cut the whole thing in half... Outer piston, nut and small spring are cut. As said, that looses and confuses the details.
Sheet metal you can carefully pry that out w/o much damage. When I did mine, I had to use a punch in the vent hole to get inside piston out. That doesn't work if you have updated piston design w/ vent hole on side. Your piston could be so rusted than very hard to never get that out.
I see if I still have it and post some more pictures.
To see the whole thing in real world... Need someone to mill out parts. To start: Part of outer piston and a little bit of stamped metal part that keeps all pieces in place. Caliper side to show how all parts fit together. I would make one but no tools for this job. Is not really a job for Dremel and cut off wheels.
Even then most will have trouble to understand because need fluid pressure to self-adjust. Someone could animate the picture at bottom of cave page. Is allot of work to do that right.
Of course, that's assuming that they are working properly. Which is very rare...
That is(was) the point of this thread, it to get them to start working again. well post #1 anyway. Most of the time the e-brake doesn't work is because the inner seal is stuck to the outer piston, I am(was) posting how to break the seal free.
The thread is starting to stray, I know it is the topic of e-brakes, but saying how they "should self adjust" does nothing to help when they don't. The point of this thread is starting to get missed. Just saying.
And yes I cut the piston in half to see what was inside. I only cut the outer piston, the spring and nut are not cut, FYI.
[This message has been edited by sardonyx247 (edited 11-24-2014).]
Originally posted by Csjag: Thanks for your post, very informative. On my car the e-brake works but I have to pull it all the way up, does this mean stretched cables?
Caliper(s) problems, 1 or more bad cables or adjuster setup wrong. Most adjuster nuts should be in middle 1/3 of screw section.
Wheel cables break the jacket at the ends. etc.
[This message has been edited by theogre (edited 01-06-2016).]
I dont know anything about Fiero Ebrake, but dont they self adjust when you back up and apply the brakes like a lot of other cars ?
For myself, I havent used any emergency brake in 40 years in parking anything, stick or auto. Park works for auto and 1st/rev works in any stick. I dont know why they even call it an emergency brake. Ive had service brake go completely out and the 'emergency' brake didnt do anything at all over a few miles per hour...holding my hand out the window in the wind was just as effective.
I dont know anything about Fiero Ebrake, but dont they self adjust when you back up and apply the brakes like a lot of other cars ?
For myself, I havent used any emergency brake in 40 years in parking anything, stick or auto. Park works for auto and 1st/rev works in any stick. I dont know why they even call it an emergency brake. Ive had service brake go completely out and the 'emergency' brake didnt do anything at all over a few miles per hour...holding my hand out the window in the wind was just as effective.
Originally posted by rogergarrison: I dont know anything about Fiero Ebrake, but dont they self adjust when you back up and apply the brakes like a lot of other cars ?
For myself, I havent used any emergency brake in 40 years in parking anything, stick or auto. Park works for auto and 1st/rev works in any stick. I dont know why they even call it an emergency brake. Ive had service brake go completely out and the 'emergency' brake didnt do anything at all over a few miles per hour...holding my hand out the window in the wind was just as effective.
back up is for drum brakes. That only when adjuster works... Many have rust etc problem, worse when moron don't put adjuster hole plugs back after brake work. I've see many teeth and the pawl stripped when the screw is rust frozen.
USDOT/NHTSA's FMVSS doesn't call them that.... their called parking brakes and tested as such. Some States and OEM called E-brake and OEM listed stopping distance in owners book. 87 Fiero OM: 334' stopping distance [from 60mph] using emergency service brake with partially service break system failure. Total service brake fail could be longer still.
Originally posted by sardonyx247: Now to reassemble, put the cable back through the hole and put on the spring make sure the cable extends past the lever.
CLICK FOR FULL SIZE
Now use your hands to push the spring back into place, (I have tried all kinds of brake tools for this, your hands work best)
CLICK FOR FULL SIZE
Use Door Spring compressor. Is easy installing the spring for one hand.
That and How to Decouple the cables are in my cave now. See my Cave, Rear Brakes
[This message has been edited by theogre (edited 01-06-2016).]
And that right there is exactly how the piston self adjusts without using the E-brake.
no matter HOW it's compressed, the end result is that the internal nut wants to walk down the actuator lead screw. And if the spring force is great enough to overcome the sum of all the friction forces (leadscrew threads, tapered face contact, and internal seal), the nut screws itself down the leadscrew, the internal piston spins, and the slack is taken up.
Bottom line is that it doesn't matter HOW the internal spring gets compressed. It only matters that it does.
The reason it doesn't adjust without the E-brake, is because fluid pressure acts something like 95% on the internal piston, and 5% on the main piston. So really, the internal piston is pressing against the main piston and applying the pad. And while brake pressure is present, the internal piston can't rotate (adjust). They did this to ensure that under normal (hydraulic) braking, the caliper doesn't slowly ratchet itself into a bound condition. Only using the parking brake, or some other means of rotating the screw will allow the E-brake to adjust.
Your example would be true if the little bleed hole in the center of the main piston was blocked, AND the internal piston had no seal. This would allow the E-brake to adjust hydraulically, but at the expense of the caliper slowly getting tighter and tighter each time it's used.
The reason the E-brake doesn't ratchet itself tight, is that it only rachets tighter after all pressure is off the pad, allowing the internal piston to slip inside the main piston.
sardonyx247 said only cut outside of piston... Your inner spring is allot short then 3 I have. Is why I said you just cut whole thing.
quote
Originally posted by sardonyx247: On a side note this really should be titled "How to get your frozen(non-working) e-brake to work again" as all the adjustment is automatic once the seal is broke free.
"Problem" is My cave, GM (PDF in cave) and Aftermarket TSBs aren't to fix "frozen" pistons... Can help some people but Doesn't help much when piston have any kind of problems. I stopped use my own method a few years ago when I installed a recall kit. I don't have pad clearance problems since.
Freeing "rust" frozen piston might help or not. If you get one free, is not hard to refreeze them again because of "dirt," pitting, etc, on inside cone area. Big issue is many pistons have water/moisture, worse salt/pollution from road salt etc, inside the vented area. GM idea the yellow "plug" valve to keep out dirt/water but in the real world is does very little. Is a big reason why you never drive thru deep water on the road even if you think safe. Do so can cause Brake and Electrical problems down the road in many models, not just Fiero.
I've added picture showing inside of outer piston. Is same unit in other picture on same page. I found it and time to light that to get a good picture. See my Cave, Rear Piston notes
[This message has been edited by theogre (edited 01-06-2016).]
For myself, I havent used any emergency brake in 40 years in parking anything, stick or auto. Park works for auto and 1st/rev works in any stick. I dont know why they even call it an emergency brake. Ive had service brake go completely out and the 'emergency' brake didnt do anything at all over a few miles per hour...holding my hand out the window in the wind was just as effective.
E brakes are great for manuals when you go to heat up your car during the winter. You can use first but if your on a hill your pretty much screwed. Could you wedge something behind the wheels? Sure, but an E brake is VERY necessary in Colorado when you live in the mountains. Plus, I always read on fiero ads "E brake doesn't work" which in turn makes your car more valuable (in a sense.)
It's like having a gen 1 headlight system work perfectly. I've been baffled when I watch those headlights work perfectly.
Use Door Spring compressor. Is easy installing the spring for one hand.
I guarantee useing your hands is easier than this. That takes too much time to crank down. hands = simple, dont over complicate things, just push it on, easy.
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Originally posted by zzzhuh:
It's like having a gen 1 headlight system work perfectly. I've been baffled when I watch those headlights work perfectly.
Every early year Fiero I have worked on the headlights, they work perfect, (150+ Fieros)
[This message has been edited by sardonyx247 (edited 02-16-2015).]
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