Just thought I'd post this "Caution", as it may prevent an accident. The hose shown in photo below is not held on by any type of clamp (no production cars did). The hose can come off if you load the front compartment up with items that may be near it. When the hose comes off, you will have nearly no braking power at all. I would recommend putting a clamp on this hose to prevent this from happening.
I am speaking from experience as I had this happen to me last summer, and was truly surprised/terrified at the same time when the brakes failed to work. Fortunately for me quick thinking and grabbing park brake got to me side of road where I discovered a carry bag had worked the hose off the brake booster.
If that pops off the idle will jump to about 4000 rpm's. I'm pretty sure it wouldn't go unnoticed.
You will still have brakes. They'll just be unassisted.
Idle didn't jump on mine, but it's a engine conversion with newer computer. I don't know if "unassisted" is a good word, in my experience I thought I was going to bend the brake pedal or bust something and it made little difference. My point is that if you are driving normal behind somebody when this happens, you're probably going to rear end them.
A .23 cent hose clamp removes this concern.
[This message has been edited by California Kid (edited 02-22-2014).]
Yeah without the booster, you lose a substantial amount of caliper pressure. These readings were taken with a 1 1/2" cylinder (multiply PSI by 1.77 to get lbs of pedal force) and show the vacuum assist gain in caliper pressure.
code:
Caliper Pressure Readings for Stock 88 Booster:
Input Air Pedal Force Engine Off Engine On Vacuum Assist (psi) (lbs) Caliper (psi) Caliper (psi) (psi)
Originally posted by California Kid: Idle didn't jump on mine, but it's a engine conversion with newer computer. I don't know if "unassisted" is a good word, in my experience I thought I was going to bend the brake pedal or bust something and it made little difference. My point is that if you are driving normal behind somebody when this happens, you're probably going to rear end them.
1. Something is wrong with that. Booster Vac should cause a huge vac leaks. Many engines have a hard time starting or won't start when booster line is off. If started, idle should be way high and may cause Codes from ECM.
If car has booster filter in engine bay, could be plugged.
2. If you use a clamp then be careful. A little over tight can do damage to Plastic valve on booster.
------------------ 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)
1. Something is wrong with that. Booster Vac should cause a huge vac leaks. Many engines have a hard time starting or won't start when booster line is off. If started, idle should be way high and may cause Codes from ECM.
If car has booster filter in engine bay, could be plugged.
2. If you use a clamp then be careful. A little over tight can do damage to Plastic valve on booster.
I wouldn't say something is wrong in my case, car runs great. I think it's more related to Hilborn Injection System on how the vacuum system is plumbed, and they may have installed a check valve/s so Brake System is independent from engine management (FAST ECU fully programmable computer).
I understand your concern regarding on over tighten of clamp, and those doing this should take care, it doesn't require must pressure to keep hose attached.
The main reason I posted this as a Caution item, it that the hose on mine came off booster while traveling down the road (not when placing bag in compartment, so bag shifted while out on road). Maybe I just drive my car too hard.
[This message has been edited by California Kid (edited 02-23-2014).]
What about a stronger brake booster as a fix for a desired lower pedal effort on fully functioning stock brakes?
Just my opinion, but the 12 inch Corvette Rotors w Caliper relocation plate makes a huge difference without the added pressure to the calipers. I was amazed at the difference when I switched over to the Corvette Rotors, while I know some have added a stronger booster with them, I don't see the need for it (feel it would be too much of an increase).
Just thought I'd post this "Caution", as it may prevent an accident. The hose shown in photo below is not held on by any type of clamp (no production cars did). The hose can come off if you load the front compartment up with items that may be near it. When the hose comes off, you will have nearly no braking power at all. I would recommend putting a clamp on this hose to prevent this from happening.
I am speaking from experience as I had this happen to me last summer, and was truly surprised/terrified at the same time when the brakes failed to work. Fortunately for me quick thinking and grabbing park brake got to me side of road where I discovered a carry bag had worked the hose off the brake booster.
Original point taken (especially on 30 yo hoses). Thank you.
Idle didn't jump on mine, but it's a engine conversion with newer computer. I don't know if "unassisted" is a good word, in my experience I thought I was going to bend the brake pedal or bust something and it made little difference. My point is that if you are driving normal behind somebody when this happens, you're probably going to rear end them.
A .23 cent hose clamp removes this concern.
I don't know how you're system is. But on a stock system(or any system I would have) there's a valve on the brake booster vacuum. If you pulled the vacuum hose off where you want to put the clamp, you would have an open hose to the intake that's approx. 5/8" in diameter. That's a HUGE vacuum leak. I'm curious how your system isn't affected by a vacuum like that. I didn't hook up my vacuum hose when installing my engine a couple months ago. When I started it, I had an idle at about 4500 rpms. I didn't take me long to find that leak.
That valve is there so the booster holds vacuum in the event of an engine stall. This allows a few pumps at the brake pedal to have power brakes until the car comes to a safe stop.
Now, If the whole valve came out of the booster, then I could understand not having brakes. But for most(stock or modified) applications you would still have a noticeable jump in RPM's at idle.
In my experience, those vacuum hoses don't come off all that easily unless contaminated. But I have replaced them that have split or cracked.
I'm not in anyway saying a clamp is a bad idea. But I'm curious how the hillborn system is working. Do you have a separate vacuum pump?
Personally, I'm going to add a clamp to mine now, because this thread got me thinking. While It most likely won't be an issue, this situation is made worse if you are running a significant amount of boost (20+PSI), like I plan to be, so, better safe then sorry.
What about a stronger brake booster as a fix for a desired lower pedal effort on fully functioning stock brakes?
In my opinion, the stock brakes on 84-87 Fieros were never fully functioning, which is why I have Grand Am brakes on the front of my 86 SE, and Seville brakes on the rear (with a parking brake that can actually hold the car). And I'd be able to stop if I lost boost.
I'm not in anyway saying a clamp is a bad idea. But I'm curious how the hillborn system is working. Do you have a separate vacuum pump?
If it wasn't so damn cold in this stinking winter I'd give you a better answer, but I'll give it a shot. No I do not have a separate vacuum pump, the Hilborn System is plumbed to take vacuum off each of the 8 ports below the throttle blades. Those tubes are connected to one main tube which goes to a "T" section, one lines goes to brake booster, the other goes to an electronic senor block that feeds info to FAST computer. Engine Idle speed is set/held by just one simple screw and lock nut - nothing else in system to regulate idle. Near as I can figure the Hilborn Throttle Position Sensor information going to computer over rules Vac reading sent to the FAST ECU unit (as I said earlier - engine ran fine with brake booster hose off). Note with the "Old Hilborn" mechanical system you would have to run a separate vacuum pump.
The Hilborn System does not have "any" throttle step up device, such as cams, or vacuum assist connected throttle blade shaft/s. You could fabricate something up to accomplish this in order to use Cruise Control or Air Conditioning, but I haven't done so, as I don't use either of these on my car.
I still believe this item is a valid concern for any Fiero Owner, let alone at least checking to ge sure that the rubber hose is in excellent condition. Not related to this thread, but it scares me to think about how many people are still running their Fiero's with Production rubber brake hoses.
[This message has been edited by California Kid (edited 02-24-2014).]
Ironically, I too had my brakes fail big time but from a different cause: failing to use thread locker (maybe 3-4 bucks) on the caliper bolts. Believe me, I went from hero to zero, champ to chump in about 2-3 seconds . Kit
I went from oh yeah to oh sh!t in two seconds flat. When my turbo hit 10psi for the first time it popped that same hose but on the intake manifold side, I guess the tension clamp didn't do its job to well. I was doing about 70 and headed for a stop sign, It took both feet to stop just in time, from there I slowly continued home to change my shorts and add hose clamps to all vacuum lines in the engine bay.
[This message has been edited by JCircs (edited 02-25-2014).]
Just thought I'd post this "Caution", as it may prevent an accident. The hose shown in photo below is not held on by any type of clamp (no production cars did). The hose can come off if you load the front compartment up with items that may be near it. When the hose comes off, you will have nearly no braking power at all. I would recommend putting a clamp on this hose to prevent this from happening.
I am speaking from experience as I had this happen to me last summer, and was truly surprised/terrified at the same time when the brakes failed to work. Fortunately for me quick thinking and grabbing park brake got to me side of road where I discovered a carry bag had worked the hose off the brake booster.
Now that I look closer.... That's my car in your picture, I better add a clamp there too.
Ironically, I too had my brakes fail big time but from a different cause: failing to use thread locker (maybe 3-4 bucks) on the caliper bolts. Believe me, I went from hero to zero, champ to chump in about 2-3 seconds . Kit
I joined that camp a long, long time back, had a caliper cut the wheel open like a can opener, took out wheel, tire, and brake hose. Luckily that's all that happened and I wasn't going fast when bolt decided to exit. There have been a couple threads in the past on this issue, but it certainly deserves another post.
Originally posted by TopNotch: In my opinion, the stock brakes on 84-87 Fieros were never fully functioning, which is why I have Grand Am brakes on the front of my 86 SE, and Seville brakes on the rear (with a parking brake that can actually hold the car). And I'd be able to stop if I lost boost.
Have you tried driving with failed booster? Any booster fail will double or more the car's stopping distance. For 1 is you need to compress very strong spring in the booster.
GA Front, Seville rear, Blazer MC and OE Fiero hydraulics are very close to same as far as caliper pistons to MC ratio and needs a good booster to work.
Seville Rear uses same iffy piston design as Fiero and gets same problems. Get rebuilt caliper? Rebuilt units has same problem cause by Rebuilders tries to reuse or rebuild rear pistons. If they work new/now... often many have problems soon after like dragging pads etc.
