86 GT Brake Question (Page 1/1)
thejinx13 JAN 13, 12:25 AM
I recently purchased an 86 GT, and to say the brakes were soft would be a huge understatement. I suspect that someone tried to do the rears at some point and messed up the Ebrake auto adjuster. What I read online, that I can find, seems to indicate the excessive pedal travel could be caused by that. I'm not sure I understand though because shouldn't most of the stopping power be coming from the front and not be impacted by the parking brake? Just trying to get an idea on where to start. I initially thought it was the booster but a lot of people seem to be relaying symptoms close to what I am experiencing after rear brake work.

Thanks for any help you can provide!

Chris
Mike in Sydney JAN 13, 06:28 AM
Start by bleeding the brakes. Bleed in the following order: LR, RR, RF, LF. If that doesn't raise the pedal, try manually adjusting the rear brakes using the procedure shown in Ogre's Cave. If that doesn't work, you may be looking at replacing or rebuilding the rear calipers. BTW, with a 34-year old car, you should think about changing out the flexible brake lines. Some people replace with braided stainless lines but unless you are racing or have a high horse power engine, I think that braided lines are overkill.

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Mike in Sydney

[This message has been edited by Mike in Sydney (edited 01-13-2021).]

Mike in Sydney JAN 13, 06:31 AM
Start by bleeding the brakes. Bleed in the following order: LR, RR, RF, LF. If that doesn't raise the pedal, try manually adjusting the rear brakes using the procedure shown in Ogre's Cave. If that doesn't work, you may be looking at replacing or rebuilding the rear caliber. BTW, with a 34-year old car, you should think about changing out the flexible brake lines. Some people replace with braided stainless lines but unless you are racing or have a high horse power engine, I think that braided lines are overkill.

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Mike in Sydney

theogre JAN 13, 11:01 AM
Booster and vacuum Will Not cause Low Pedal and related problems. Only thing they cause is Hard to Very Hard Pedal when have vacuum problems or booster is dying/dead. Push pedal a few times w/ engine off and that is best example of "dead" booster.

Only time a booster can cause low pedal or brake hydro problems is when some moron replace it and never bother to adjust the output push rod that hits the MC. If has OE booster then won't happen. (Many replacement are correct out of box but not all and need tools to adjust. low pedal means output rod is short. hydro then rod is too long and MC can't return to rest.)

Manually adjust P-brake might help short term but if does rears are "dead" and need replacement and sooner then later.
See my Cave, Rear Brakes and rest of brake section.

Hoses...
SS Hoses are Hype BS product even if labeled as "DOT Approved." As soon as you add support for middle of them the DOT cert and often Warranty is Void but most buyers won't bother w/ either issue until have problems.
see rubber brake lines vs stainless steel http://www.fiero.nl/forum/Forum2/HTML/129208.html

Get New OE Type hoses meets SAE J1401 often sold as "pro grade" hoses. This Hose "Rubber" is labeled as DOT106 and SAE J1401.

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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

[This message has been edited by theogre (edited 01-13-2021).]

thejinx13 JAN 13, 02:42 PM
That was super helpful, thank you. This forum is great.
thejinx13 JAN 24, 08:23 PM
Whelp, I bled the brakes today and there was no air, and didn't help the problem. The fluid however was very dark, it looks more like dirty diff fluid than brake fluid. I ordered new brake lines as well, since as someone else said, they are north of 30 years old. No signs of leaking so I am hoping new lines and fluid fix the problem. The car has 52,000 miles and I'm all but sure the fluid is original.

Thr car has almost no stopping power so if the fluid solves it I will be the poster child for the necessity of fluid changes. Haha
hobbywrench FEB 19, 12:24 PM
You never know what was done previously. Some people think petroleum based solvents are ok- NEVER. If you plan to keep the car I would suspect everything. The front calipers are easy to dismantle and repair parts are still available, including pins, pin seals, boots. The rear calipers are all rebuilds and the pool is suspect according to reports. Some owners buy several hoping to get a good one. Lots of damage can be done on the rears achieving a proper lever arm setting, and proper pad insertion. Brake cables rust and drag. Recently bought a new master from NAPA with steel body (Mexico) expecting problems-working well and good price. Good unit bleed instructions included prior to install.

Run several bottles of fresh fluid through. Patience required in bleeding. Google and find lots on gravity as well as vacuum, pressure, and pumping bleed techniques.