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#1
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1979 T/A how to get rear disc brake caliper pistons to retract back into bore?
I am working on my 1979 Trans AM SE with 4wheel disc and 4speed trying to change the rear disc brake pads and I cannot get the rear piston caliper to retract back into the bore with a C-Clamp. I have never had any problems doing this with brakes before. Is there some sort of trick with these type of calipers?
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#2
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You will need to take the parking brake lever off the rear of the caliper and unwind the caliper. When reinstalling leave a bit of clearance and use your parking brake to ratchet them tighter.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#3
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Yes those piston are turned and walked back in....pair of channel locks and rotate and push in rotate and push in etc .....if it doesn't rotate then u might have an issue...
There are special tools that make the job easier ....
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1973 Firebird Navajo Orange w/shaker,1973 400/461,1972 Intake SD CNC'd,1977 Q-Jet 800 CFM w/ Cliffs Kit,Tanks Inc PA4 255 Walbro intank pump ,-8an feed/return,RobbMc Regulator,RobbMc 40 micron filter,253 CFM 6x-8's w/H.S 1:5 Roller Rockers,SD Stump Puller H/R Cam 230/236 @.050 112 lobe separation 565/.570 lift,Crower Solid Rollers,28150 Hedman Headers,3" exhaust,full tailpipes,350 Turbo,9.5" 3200 Converter,3:42 gear,8.5 posi,C/E slide-alinks,Koni adj frt shocks,Best 12.18@110.55 Lookin for 11's |
#4
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Do I unwind something on the outside of the caliper or the piston? Which direction? I have the caliper off the car right now and on my bench top.
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#5
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You want to turn the shaft that the parking brake lever was on. It will either retract or push it out.
__________________
466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#6
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...
Last edited by Nitebird; 04-06-2019 at 11:23 AM. |
#7
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Quote:
OK i understand now. I will try that and see what happens. |
#8
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Don't turn the piston..look at the back of the caliper there is a shaft that the emergency brake lever attaches to that is what you turn. You should be able to turn it with a regular wrench..I think its a 1/2 or 7/16 been a while.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#9
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Go to Autozone and rent the tool. It's no cost if you bring it back. Other wise you may be in fora surprise.
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1979 Trans Am WS-6 .030 455 zero decked flat pistons 96 heads with SS valves 041 cam with Rhoads lifters 1.65 rockers RPM rods 800 Cliffs Q Jet on Holley Street Dominator ST-10 4 speed (3.42 first) w 2.73 rear gear __________________________________________________ _______________________________ 469th TFS Korat Thailand 1968-69 F-4E Muzzle 2 |
#10
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You can't push the piston back in fully like a regular caliper, they must be unwound.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#11
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OK i got the piston to retract by taking off the parking brake lever. I had to remove the parking brake lever and press the piston in using a brake tool for that purpose. With the lever attached it wasnt allowing the piston to rotate back into the bore. Do I need to install the big circular spring clips that comes with the calipers or are they just there for convenience in helping to stall the pads?
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#12
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The spring clips hold the inner pad to the caliper piston and provide positive engagement between the nub on the inner pad and the notch in the piston. This combination doesn't allow the piston to turn in normal operation. So when the parking brake is engaged, the lever turns the screw which pushes the piston out clamping the rotor mechanically. Great theory, unfortunately, they didn't work worth a damn in the real world. The only way to keep them working is to apply the parking brake at least once a month.
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#13
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This guys video helped me with the WS6 brakes even though his are Eldorado calipers.
https://www.youtube.com/watch?v=opjdu8DdVeA&t=250s |
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