Write up on bleeding brakes and clutch?

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PHENDERSON

Well-Known Member
There is a lot of info in many different locations on several different ways to bleed the system, for those of us new to the process (me included) it's a little confusing.

I'm wondering if there is a step by step write up on the process of filling/bleeding the brake and clutch system. If not, does anyone with experience want to create one? It seems like there are enough questions on the topic that it would help a lot of us.
 
TravMac

TravMac

Well-Known Member
To echo Sluggonaut: Bench bleeding really should be done with any master cylinder after taking everything apart like this. It's the only way i got my master cylinder to pump to the rear. Was nearly thinking I'd need new parts until I realized it hadn't been done before bolting it up to the car. Good thing it's easy access to take on/off!
 
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Gtstorey

Goblin Guru
A lot of the procedure depends on what tools and help you have available. I prefer pressure bleeding, but you have to have the tools to do that. It does make it a simple 1 person procedure.
I've had motorcycles that the only way I could get air purged was to push fluid in from the calipers.
I've never had much luck with vacuum bleeding, but that is the way a lot of people prefer. Most of my use of vacuum was on motorcycles though and probably the worst possible case for vacuum bleeding with nothing but a vertical run to the caliper.
Nothing wrong with the old fashion 2 person press, hold, bleed, release method, but it can be slow and you need patience and help.
 
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Chubbs

Well-Known Member
Pressure bleeding was the only way I could make the goblin work. I'm not sure why, I almost always vacuum bleed. But I tried and tried with my vacuum and I could never get the pedal to firm up.

I don't have a pressure bleeder. I went to the autoparts store and bought a new master cylinder cap. Like this:

Amazon.com: Genuine GM 22688449 Brake Master Cylinder Reservoir Cap : Automotive

Buy Genuine GM 22688449 Brake Master Cylinder Reservoir Cap: Master Cylinders - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com

I drilled a hole in it, then threaded a quick disconnect air fitting into the top. Hook up compressed air. Then you have a $10 pressure bleeder. It worked great. It leaks, it's fragile, and it's not exactly "professional"...but it worked, and it worked quickly.
 
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Gtstorey

Goblin Guru
Just be careful with how much pressure you apply. I probably got a little overzealous with pressure as I tried to replicate a clutch leaking issue, but not much if any higher that "normal" pressure for pressure bleeding. I ended up with a leaking reservoir, but it could have just been a cheap, crappy reservoir to start with.
 
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PHENDERSON

Well-Known Member
I plan on pressure bleeding, seems to be the way to go especially for a 1 man job. With this process do you fill the reservoir, open 1 of the bleeder nipples and then pressurize the system, topping off the res as needed and wait for fluid to start flowing out?
 
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Gtstorey

Goblin Guru
If you are purchasing a pressure bleeder system like the motive it will have instructions, but in general you add brake fluid into a tank that you attach to the reservoir. Pressurize the tank and it will supply pressurized fluid to the reservoir. Typically you start at the wheel the farthest from the master cylinder and just open the bleeder until you get fluid without bubbles, then move to the next farthest wheel.

Make sure when doing the clutch that you hold the pedal up before you start pressurizing. The pressure can hold the pedal down and not allow fluid into the system.
 
Rauq

Rauq

Goblin Guru
I won't ever discourage someone from using a strategy they think is better, but...

If I have the car in the air, on jackstands, with no wheels attached, I can bleed all the brakes in 5 minutes. It does have to be done twice on an initial build, first to add fluid to all the lines, then second to remove air from all the lines. Bleeding the line from the front to the clutch bleeder is also quick and easy.

I don't think the slave cylinder itself can be bled by any method other than the 2-person pump and release, down-open-close-up method. As the bleeder is before the slave cylinder, you have to pressurize the system with the pedal (actuation-high pressure, not pressure bleeder pressure), and then let the clutch springs push the air in the slave cylinder out of the bleeder.
 
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PHENDERSON

Well-Known Member
Okay well now I'm second guessing myself.

Everything on the brake side seems straight forward except for bleeding the master cylinder. Do you bleed the lines then the cylinder or other way around?

On the clutch side do you vacuum bleed from the bleeder on top of the transmission first and then do the slave cylinder or other way around.

This build has forced me to learn a lot of new things which is a nice bonus.
 
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Gtstorey

Goblin Guru
My thoughts on pressure bleeding the clutch is to add pressure and bleed off the initial air to get fluid up to the high point. I then let off the pressure to allow the clutch to push back the slave cylinder back and then bleed any air at the bleeder. Repeat this process a few times. It seemed to work for me. It might not be any better than two person bleeding, but I was able to do mine without any help.
 
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Gtstorey

Goblin Guru
PHENDERSON said:
Okay well now I'm second guessing myself.

Everything on the brake side seems straight forward except for bleeding the master cylinder. Do you bleed the lines then the cylinder or other way around?

On the clutch side do you vacuum bleed from the bleeder on top of the transmission first and then do the slave cylinder or other way around.

This build has forced me to learn a lot of new things which is a nice bonus.
Click to expand...
I pressure bled the entire system at once, without doing anything special for the brake master cylinder.

I think the only bleed point for the clutch is the bleeder on top of the transmission, other than cracking the lines loose. Rauq was saying to bleed the slave cylinder by cycling pressure on and off with the master cylinder. I guess the GM recommended method is vacuum bleeding at the transmission bleed point. I might would have tried it with vacuum first but my 25 year old mighty vac pump broke the first squeeze of the handle trying to suck the brake fluid out of the reservoir while disassembling the donor .
 
Rauq

Rauq

Goblin Guru
PHENDERSON said:
Okay well now I'm second guessing myself.

Everything on the brake side seems straight forward except for bleeding the master cylinder. Do you bleed the lines then the cylinder or other way around?

On the clutch side do you vacuum bleed from the bleeder on top of the transmission first and then do the slave cylinder or other way around.

This build has forced me to learn a lot of new things which is a nice bonus.
Click to expand...
I can't speak for other folks' experience, but I didn't have to do anything with the either the brake or clutch master cylinders. The pressure bleeder pushed fluid straight through both.

Vacuum bleeding should work for the brakes if you use it at the calipers. Cobalt/Ion folks report great results in putting vacuum on the shared fluid reservoir to bleed the clutch, and this is GM's recommended method, but while my lines from reservoir to master cylinders hold fluid and don't leak, they weren't vacuum tight, so putting vacuum on the reservoir just ended up pulling air into the system.

I never tried putting a vacuum bleeder on the clutch slave cylinder bleed valve, so I can't speculate as to whether that'd work. Neither have I tried Gtstorey's clutch bleed method, but I probably will try it now.
 
Sluggonaut

Sluggonaut

Goblin Guru
PHENDERSON said:
Everything on the brake side seems straight forward except for bleeding the master cylinder. Do you bleed the lines then the cylinder or other way around?
Click to expand...
If you need to bench bleed the MC, you don't have a choice but to do it first. The reason I did it was because I could not get fluid to come out at any of the bleeders at the wheels. Once I bench bled the MC, I was able to bleed the brakes normally.

If you are able to bleed the brakes, you may not need to bench bleed the MC. However, it only takes a few minutes and the kit is so cheap you might as well do it and know there is no air trapped in it anywhere.
 
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PHENDERSON

Well-Known Member
I think I understand the brakes.

Is there anything special about the clutch those of us who haven't done it should know?
 
Sluggonaut

Sluggonaut

Goblin Guru
I followed Lonny's instructions - it's like bleeding the brakes for the first part and then just cracking the bleeder with the pedal depressed to allow the slave cylinder to bleed back to the bleeder.
 
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PHENDERSON

Well-Known Member
Sluggonaut, are you talking about the bleeder on top of the trans? Or is there a bleeder on the slave cylinder? I took a look at the trans and I don't understand how that would work since the hydraulic line connects to that "T" thing that you have to remove to expose the bleeder. Seems like doing so would separate the trans from the hydraulic system. Or maybe there is a different location or I'm just totally confused.
 
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PHENDERSON

Well-Known Member
Is this the bleeder, pointing away in this pic on the "T" thing on top of the trans? I was thinking the "T" thing had to be removed to expose the bleeder but that didn't make sense. That's not going to be fun getting access to.
 

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