#1  
Old 09-28-2020, 10:16 AM
Skip Fix's Avatar
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Default Baffling brake problem

Last outing this spring in the IA/Camaro second convertor was still to tight so ordered one from Lenny at Ultimate. Car has sat since those runs. Last weekend get in it to move it to the lift to swap convertors and brake pedal has a LOT of travel and is only making 800 psi at the floor front and back. But would hold that pressure not bleed down. Line Lock would hold pressure. Was making 1100 before . 1.03" Mopar MC . Hurst Line lock acting as my T for the front lines. SS flex line to Wilwood Dynalites 4 piston 1.75" on the front. Adjustable prop valve in the rear line. Rear is 79-81 TA brackets and rotors and 2.5""metric" caliper on it. Can't find a leak anywhere.

This weekend it is down to 600 psi at the floor and by hand I could push the pedal 2" before any pressure is made. Took the lines off at the MC and plugged it and pedal barely can move 1/8" like a well bled MC. Still no leaks. RF wheel is pretty tight to turn by hand, a lot more than left. Rear seem to move OK but spinning rear end/trans would make it a little harder.

Any thoughts? Stuck piston in the Wilwood?

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Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
  #2  
Old 10-12-2020, 01:39 PM
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Update-the past two weekends bled the crap out of it since it I unhooked lines at MC. I could pump it up. Right front I could barely spin by hand left intermittently the same. I could pump it now and get 1000psi but then get crappy pedal. Pumped up then using line lok on front it kept a good pedal so seemed like that localized it to front. Plugged lines at the calipers.First one better, second one almost normal. Even releasing pressure did not free up the calipers on the rotor. So they are not releasing. I even had to use a pry bar to slide the right off the rotor and the left was easier but would not pull off easily. Pulling the pads off the outer pistons are 0.080 more out of the caliper on the right than the inner,and 0.060 on the left. Thinking we got some sticking pistons.

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Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
  #3  
Old 10-12-2020, 03:42 PM
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77 TRASHCAN 77 TRASHCAN is offline
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Default

Are pistons plastic or stainless?

Plastic pistons can be problems

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1977 Black Trans Am 180 HP Auto, essentially base model T/A.
I'm the original owner, purchased May 7, 1977.

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  #4  
Old 10-12-2020, 04:28 PM
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Metal not sure if SS or other metal.

I had a full sized Bronco that used the plastic pistons that stuck.

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Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
  #5  
Old 10-12-2020, 04:32 PM
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Scott Stoneburg Scott Stoneburg is online now
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Default

Wilwoods have a lot of drag. In my experience it gets worse as the pads wear down some. Also the caliper has to be exactly centered over the rotor. They have to be shimmer correctly. I had 1 that was a little off and it made a big difference.on pad wear.

  #6  
Old 10-12-2020, 07:22 PM
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Scott when I first put them on centered it pretty good. This whole thing is kind of weird since when I pulled it off the trailer from the track it was working great, then no pedal. I do get a lot of condensation in the shop and there is a little surface rust when pistons hit the pad backing so maybe some corosion on the pistons. They used to spin fairly freely.

Got some ne calipers on the way that will hopefully resolve it. Need to teat the new convertor out! But I do want to stop at the end of the track!!

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Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
  #7  
Old 10-12-2020, 09:10 PM
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lust4speed lust4speed is offline
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Soft spot in a brake hose ballooning out?

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1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress.
  #8  
Old 10-13-2020, 09:33 AM
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Teflon/SS hoses and they were still on when I plugged it at the calipers and got a good pedal again. You could see them slight get bigger at 1200psi.

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Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
  #9  
Old 10-15-2020, 09:18 AM
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Two new calipers and pressure and pedal back to normal.

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Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
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