PFF - Pennock's Fiero Forum, PDA Edition

Brakes went to the floor driving home tonight. (Page 2/3)

Patrick

DEC 08, 08:16 PM

quote

Originally posted by RotrexFiero:

My Fiero is garage kept and has low miles.

Didn't really address my question. If the MC failed due to the "cold", then I'd think it would've failed on the way to work after sitting all night.

quote

Originally posted by Patrick:

I'm curious. In regards to the "cold temp" theory... was your car sitting overnight (before driving to work) in a garage that was warmer inside than the temperature was outside?

[This message has been edited by Patrick (edited 12-08-2021).]

RotrexFiero

DEC 09, 06:26 AM

I left for work at noon. It was not as cold at that time.

You'd have to do an analysis of why parts wear out and fail. This could entail many things.

I guess you could be superficial and say parts fail because they just wear out.

But, extraneous factors can create accelerated, or more robust conditions for failure. If the part was doomed for failure, because of age, and it was old, then maybe the excessive cold night pushed it further.

But, I heard what TheOrge was saying. The brake fluid was old. Perhaps it had high water content.

Larryinkc

DEC 09, 08:52 AM

I had a similar issue on a 1962 Corvette many years ago. Before I bought it it had not been driven on a regular basis for many years. I drove it every day, after a few months of driving it I pulled in my driveway and the brake pedal went to the floor as I was pulling up to my garage door. In a panic moment I let the pedal up really stomped it hard. The brakes held that time and I stopped before I hit the door. I took the master cylinder apart and the seals were hard as a rock. I rebuilt the master cylinder and never had another problem with the brakes.

Dennis LaGrua

DEC 09, 11:09 AM

Most unusual problem. Pedal went to the floor and then became hard again? I'd go with moisture in the master cylinder that froze or maybe in the lines to the booster. If you have verified that you have no leaks then it becomes hard to determine the cause.
I've never been real fond of the Fiero braking system so when it came time for a brake job I just replaced all the wheel calipers/rotors the master cylinder and the brake booster. Now I can lock the brakes by pressing the pedal hard. It may have been a waste but I just didn't trust critical 34 year old parts.
I replaced the MC earlier this year with an AC Delco unit and it said "Made in USA" on it.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Skybax

DEC 09, 12:56 PM

My money is on the master cylinder... old, dry, shrunken seals combined with cold metal contraction.

I would replace it regardless with a quality unit, then I would disassemble the old one to investigate.

[This message has been edited by Skybax (edited 12-09-2021).]

Steel

DEC 09, 04:59 PM

Had this before and thought I had it fixed with new rubbers hoses, a fluid change and a professional bleed job. Came back about a month later, thankfully I didn't hit anything. Replaced the master cylinder with a brand new one after a bench bleed and have not had a single issue since and almost 65k miles later.

Mike in Sydney

DEC 09, 05:07 PM

quote

Originally posted by Dennis LaGrua:

I've never been real fond of the Fiero braking system so when it came time for a brake job I just replaced all the wheel calipers/rotors the master cylinder and the brake booster. Now I can lock the brakes by pressing the pedal hard. It may have been a waste but I just didn't trust critical 34 year old parts.

Dennis, What caliper / rotor setup did you use for your replacement?

Dennis LaGrua

DEC 09, 05:56 PM

quote

Originally posted by Mike in Sydney:

Dennis, What caliper / rotor setup did you use for your replacement?

I used Centric Rotors, rebuilt Cardone Calipers and Wagner "ThermoQuiet" pads.. All OEM replacements. I won't fool with the brake system as a possible mismatch could occur but I do use the S-10 Brake Booster as that only multiples the pedal force. It would be nice if we had a direct bolt in Wilwood caliper set but nothing like that exists.

RotrexFiero

DEC 09, 06:35 PM

Appreciate all the feedback...This certainly brings to light the need for proper brake maintenance and being proactive in replacing these parts.

I'm going to get a brake bleeder and replace the MC.

Dennis LaGrua

DEC 09, 08:22 PM

quote

Originally posted by RotrexFiero:

Appreciate all the feedback...This certainly brings to light the need for proper brake maintenance and being proactive in replacing these parts.

I'm going to get a brake bleeder and replace the MC.

You could also get the job done with Russell speed bleeders that replace the bleeder screw with a one way valve. Have not had luck with the pressure bleeders sealing on the plastic MC reservoir but the vacuum bleeders seem to work OK.