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-   -   No rear brakes on 1st pump (

lmsport 12-21-2018 07:39 AM

the mid-eighties to about 90 model f-bodies were campaigned for bad calipers....people with auto trans never use their e-brake which means the ratchet mechanism in the rear calipers never gets exercised which is how the calipers adjust themselves as the pads wear. GM replaced the calipers with units that had coated parts in the ratchet.

johnsongrass1 12-21-2018 09:14 AM


Originally Posted by 64nailhead (Post 4643777)
I think it's fixed. The issue appears to be a simple problem that I have never encountered for the mere reason that everytime we, son and I, jump into a new project we always put new brake hydraulics on every wheel end and I change every brake line, hard and soft. This GTA is not mine nor my son's, and it's a rust free unit which is unlike most all of the rust belt beauties that we usually build/work on. So I ***/u/me that there wouldn't be a corrosion issue.

I pulled off the rear calipers and found the sliding sleeves that ride on the o-ring were rusted and not sliding. The passenger side was not moving at all and the driver side was better, but not moving properly. The result is that the pads were too far from the rotor after the brakes were released causing an excess amount of fluid needed to have them engage the rotor. This caused the brake light from the combination valve switch and no rear brakes on the 1st pump. A couple of minutes with a scotch roloc disc and a little caliper grease was needed.

Tony's post about panic pushing of the pedal and Olnolan's video put me onto it. And lmsport's last post describing the excessive bias was what got me thinking. When I was 'panic stop' pushing the pedal with no light and good rear brakes the light bulb went off in my head. Only took me a week or so - hehe.

Thanks for the help everyone - it was entertaining, educational and interesting - at least to me lol.

Tomorrow it's supposed to rain in monsoon fashion - 3" or so - and be in the 50-60 degree range. Which should do it for a temporary cleaning of the salt off the roads. Perhaps I can get in a couple more burnouts and brake tests.

Thanks - Jim

Hey! where the credit for post #22? Oh it's like that huh? bahaha! Just teasing! It's good to hear it's working for ya.

64nailhead 12-21-2018 11:53 AM


Originally Posted by johnsongrass1 (Post 4643853)
Hey! where the credit for post #22? Oh it's like that huh? bahaha! Just teasing! It's good to hear it's working for ya.

I forgot to mention that I did that and it worked - pedal was rock hard. It was an eay way to confirm the master cylinder was good. Too bad I didn't do that before I gutted the original.

johnsongrass1 12-21-2018 11:57 AM

I take stuff apart all the time just to see how it works. Usually learn something like I shouldn't have cause it won't go back together.

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