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| Brake Bleeding help - 74 Swinger https://slantsix.org/forum/viewtopic.php?t=42018 |
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| Author: | Eatkinson [ Wed Sep 22, 2010 11:23 pm ] |
| Post subject: | Brake Bleeding help - 74 Swinger |
So for the first time I've ever bled brakes, I'm bleeding my '74 Swinger's Power brakes. But I'm not getting a high and hard pedal result and I can't figure out why. What am I missing? 1. The car's brake pedal has been going close to the floor, enough so that the brake warning light on the car is going on. 2. I take off the master cylinder brake fluid cap. The reservoirs are both empty. First I put fluid in the one chamber that (according to the cap) says "Fluid Side", but when I watch a brake bleeding How-To video, they state to fill the reservoir on both sides. 3. The car seems to get a higher and harder brake pedal, without me doing anything, but I'm not convinced that there's not air in the lines. 4. With a pedal-pushing partner, I check each bleeder valve in sequence: RR, LR, RF, LF. Each time my partner pumps the brakes, while holding it down, I open each wheel's bleeder valve until the fluid coming out looks clear (no bubbles), tightening the valve before he lets up on the pedal. I check the Master Cylinder as we go to make sure there's adequate fluid in the reservoir. But as I proceed in sequence, the pedal is becoming softer again. 5. By the time I finish the last wheel, the brake pedal is better than when I started and the brake warning light doesn't come on, but it's nowhere near where I'd like it. Can someone tell me why I'm not getting a high, hard brake pedal from doing this? I expected bleeding the brakes and getting that specific pedal feeling went hand in hand. Am I missing a step? Thanks in advance for your thoughts. |
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| Author: | wjajr [ Thu Sep 23, 2010 7:52 am ] |
| Post subject: | |
Power brakes are mushy feeling when the engine is not running, and tend to have a lower peddle than non assisted brakes. One pushes the brake peddle down to overcome the vacuum diaphragm, and than engages the master cylinder. It all feels rather disconnected. Pumping will raise the peddle until the pumping stops and peddle is released, and than the vacuum diaphragm repositions at which point the mush is back. Both fluid reservoirs have to be filled before any bleeding, the master cylinder has to be bench bleed first, than installed before bleeding the wheel cylinders. The reservoirs have to have fluid covering their bottoms at all times, or air will be reintroduced back into the system. The drum brakes have to be properly adjusted, or you will have a low brake peddle. Front disk brakes, if equipped, have no adjustment, both disk & front drum’s are supplied by the larger reservoir. |
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| Author: | Eatkinson [ Thu Sep 23, 2010 9:04 am ] |
| Post subject: | |
Thanks for the information. What else can I do to solve my mushy brakes? The master cylinder is not a new install, therefore I didn't expect to have to bleed the master, nor do I know how to do it. If people think I should do that before bleeding each wheel, please let me know (and how). The fluid reservoirs were nearly dry and empty when I started. So, I filled the fluid reservoirs on both sides of the dual cylinder, and bled each tire. The pedal is better than when I started, but still feels lower than it should be. I want it high and firm. What else am I missing? When I bled each tire, I gave about four-five cycles on each bleeder: the fluid coming out wasn't exactly "clean" per-se but it was solid fluid, no bubbles. |
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| Author: | wjajr [ Thu Sep 23, 2010 12:57 pm ] |
| Post subject: | |
Adjust up the drum brakes. If the shoes have to move extra distance (too much clearance in other words) before contacting the drum; the peddle has to be depressed further to deliver additional fluid to move the wheel cylinder pistons out to cause the shoes to make contact with the drums. Hence lower peddle… If the drums & shoes, and disk brake pads & rotors are near worn out, you will also get a low peddle. Quote: I gave about four-five cycles on each bleeder: the fluid coming out wasn't exactly "clean" per-se but it was solid fluid, no bubbles.
Keep bleeding until you get fresh brake fluid out of each bleeder. By doing this you will remove moisture, and contamination from the system. It will take about a pint and a half to accomplish a good flush.Bench bleeding of master cylinder is only necessary when you get a new unit. A master cylinder that has been in service has to have enough fluid in it to purge, and not expose the floor of the reservoir during a bleed cycle. Keep checking and topping off fluid as needed during the bleed process. |
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| Author: | slantfin [ Fri Sep 24, 2010 9:02 am ] |
| Post subject: | |
It may be that you have introduced some air into the master cylinder by having the fluid get too low. If that is the case you have to bleed the master cylinder. You can get a set-up to do that, consisting of 1/2" and 9/16" fittings with barbed connectors that will fit inside a short length of tubing. The tubing is directed back into the reservoirs to purge the air in the plunger area. The old-school trick is to have an assistant pump up the pedal and then keep pressure on it while you loosen the MC fittings. Once the pedal goes to the floor, have him keep the pedal down until you tighten the fitting again. This should displace any air in the plunger area. Catch any brake fluid in a rag or old towel. It will take off paint if you spill it on the car. Incidentally, the "fluid side" on the gasket refers to the orientation of the gasket, rather than indicating which reservoir to fill. Fill both sides. MC Bleeder Good name for a rapper. |
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| Author: | KBB_of_TMC [ Sat Sep 25, 2010 6:59 am ] |
| Post subject: | |
A soft flex hose can also cause a very soft pedal - just FYI |
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| Author: | wjajr [ Sat Sep 25, 2010 12:10 pm ] |
| Post subject: | |
KBB_of_TMC: Quote: A soft flex hose can also cause a very soft pedal - just FYI
Never thought of rubber hose probelm. Yes, yes, check all three hoses, if cracked, hard, or soft, replace them. Don’t mess around with degraded brake parts. |
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| Author: | 2 Darts [ Tue Sep 28, 2010 8:43 am ] |
| Post subject: | |
I recall a problem like this back in the dim recesses of my addled brain. The solution involved connecting a vacuum cleaner as a source for the PB vacuum. Problems I have had with bleeding brakes have included crushed metal lines as well as weak soft lines. Also have run across bleeder valves that were full of dried mud. When I converted the 73 to BBP disks, the bleeder valve wound up lower than the brake hose. I found it necessary to remove the caliper, clamp the piston into it, and raise the caliper so that the bleeder was on the high side. That moved an air bubble that formed in the caliper to escape. Once I got a solid stream of clean fluid, shut off the bleeder, and re-installed the caliper. No problems since. |
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