iancshafer Posted May 7, 2016 Report Share Posted May 7, 2016 Setup:Stock 510 front discs and rear drumsSymptom:After driving and not using breaks for a bit, will lose pressure in the breaks and need to pump once to get it back.Here is what I have done so far:1) Replaced master break cylinder with OEM. inspected the master cylinder, noted there were air bubbles in the front reservoir and assumed the seals in the piston were shot.2) bled the breaks using vacuum suction in follow order. Rear passenger, rear driver, front passenger, front driver.3) gravity bled all breaks at the same time, while keeping reservoir filled4) checked for leaks, found none.Still needs one good pump to regain full pressure. Thoughts? Quote Link to comment
mklotz70 Posted May 7, 2016 Report Share Posted May 7, 2016 If you have a solid, firm pedal when it pumps up, then your shoes are having to travel too much. Adjust the shoes closer to the drum to lessen the travel. If you have to, have the drums turned. If you can find a place that can grind the shoes for you, they can true them up to match the inside of the drums perfectly. Then they can be adjusted a lot closer and you'll have great brakes on the first push. Matching the shoes to the drums is something that used to be very common when everyone had drum brakes. Hard find that service now. 2 Quote Link to comment
datzenmike Posted May 7, 2016 Report Share Posted May 7, 2016 The front most reservoir is actually for the rear brakes. Look on the master and it should have F at the back and R at the front cast into it. Quote Link to comment
mklotz70 Posted May 7, 2016 Report Share Posted May 7, 2016 I didn't even notice it was for a 510. Thought it was a truck. lol Probably wouldn't have posted if I'd have noticed that. lol 3 Quote Link to comment
datzenmike Posted May 7, 2016 Report Share Posted May 7, 2016 They have rear drums too Mike and having them properly adjusted is very much a good idea. 1 Quote Link to comment
Doctor510 Posted May 7, 2016 Report Share Posted May 7, 2016 Setup: Stock 510 front discs and rear drums Symptom: After driving and not using breaks for a bit, will lose pressure in the breaks and need to pump once to get it back. Here is what I have done so far: 1) Replaced master break cylinder with OEM. inspected the master cylinder, noted there were air bubbles in the front reservoir and assumed the seals in the piston were shot. 2) bled the breaks using vacuum suction in follow order. Rear passenger, rear driver, front passenger, front driver. 3) gravity bled all breaks at the same time, while keeping reservoir filled 4) checked for leaks, found none. Still needs one good pump to regain full pressure. Thoughts? Bleed the brake master cylinder ! 2 Quote Link to comment
mklotz70 Posted May 7, 2016 Report Share Posted May 7, 2016 They have rear drums too Mike and having them properly adjusted is very much a good idea. Yep....it's still definitely the problem.....I just don't typically chime in on the 510 stuff....:) Bleed the brake master cylinder ! Definitely a good thing to do, but I don't think that's causing his particular issue. If his pedal is spongy, there's air in the system. If it's good and firm when it pumps up, it's simply taking too much fluid to engage all the brakes, typically due to loose shoe adjustment on the drum brakes. 1 Quote Link to comment
banzai510(hainz) Posted May 7, 2016 Report Share Posted May 7, 2016 510brakes are not self adjusting in the rear when tey wear the pedal will go closer to the ground the rear brakes the backing plate will be a 7mm square post. turn this in 1/4 turns till is sluightly dragging. Just be carefull no to round the squarepost off. If its hard it needs to be cleaned from the inside by the shoes. One could always weld a 12mm or 14mm nut on there to make this ezer. 1 Quote Link to comment
MikeRL411 Posted May 9, 2016 Report Share Posted May 9, 2016 510brakes are not self adjusting in the rear when tey wear the pedal will go closer to the ground the rear brakes the backing plate will be a 7mm square post. turn this in 1/4 turns till is sluightly dragging. Just be carefull no to round the squarepost off. If its hard it needs to be cleaned from the inside by the shoes. One could always weld a 12mm or 14mm nut on there to make this ezer. It's actually a 1/4 inch square stud! Not a 7 mm one. Depends on the year which the original poster "forgot" to mention. No info, no real meaningful response [or a stripped rear brake adjusting stud]. Quote Link to comment
DanielC Posted May 9, 2016 Report Share Posted May 9, 2016 I do not know about 510 wheel cylinders, but 521 wheel only have one port for brake fluid to go in and out. If you pressure bleed the system, or vacuum bleed the system, air can stay in the wheel cylinders. You need to bleed the old fashioned way, by pushing down on the pedal, and then opening the bleeder. Wait until the fluid flow stops, because then the brake shoe springs have retracted the shoes, and pushed any air in the wheel cylinder back out to the bleeder valve, 1 Quote Link to comment
mklotz70 Posted May 9, 2016 Report Share Posted May 9, 2016 That's a very good point about waiting for the springs to collapse the wheel cylinder for proper bleeding! :) 1 Quote Link to comment
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