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9 members (jmoore, KEVINSKI, Bucker, 55shaker, 3B, papas52, 2-Ton, Joe H, GMCJammer51),
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Mod | | | Forums66 Topics128,157 Posts1,056,894 Members48,458 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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For helping keep this great
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| | | | Joined: Mar 2015 Posts: 15 New Guy | | New Guy Joined: Mar 2015 Posts: 15 | I am rebuilding my rear brake cylinders on my '40 Chevy panel. I took them apart and was a bonehead and did pay attention to which direction the pistons were facing. I thought one was with the cup out and was with the cup in, but that doesn't make any sense to me. Any help would be appreciated. | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 |
Denny G
Sandwich, IL
| | | | | Joined: Mar 2015 Posts: 15 New Guy | | New Guy Joined: Mar 2015 Posts: 15 | So, if I'm reading this right, both of the pistons have the flat part in. Right?? | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | The flat side of the cups goes against the pistons. As the
pressure in the cylinder it pushes the open side of the cup,
forcing it out against the cylinder sealing it tighter the
more the pressure is increased.
dg
Denny G
Sandwich, IL
| | | | | Joined: Mar 2015 Posts: 15 New Guy | | New Guy Joined: Mar 2015 Posts: 15 | Thanks, I think I got it. I think I had one of the pistons backwards and it was leaking pretty bad. | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | We all have to learn these things.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
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