Bleeding Brakes
Thread Starter
Melting Slicks
Joined: May 2003
Posts: 2,078
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From: Dyersburg TN
Bleeding Brakes
I am about to replace the rubber brake hoses on my 92. Do I have to start the bleed process at the ASR unit, or can I just do each wheel as I change the line?
Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
Re: Bleeding Brakes (dburgjohn)
If you're just doing hoses, then that is all you need to bleed. Whenever you are downstream of ABS controllers you can ignore them in bleeding.
So, throw on the hoses and bleed at the calipers. DO NOT forget to keep an eye on the fluid level in the reservoir!!!
If you have a vacuum pump (hand help jobber like from Craftsman) now may be a good time to remove as much fluid as you can from the reservoir, clean it, (leave a little fluid in the bottom) and refill with clean fluid. Go ahead and buy the big jar of fluid. When you bleed, keep pulling fluid until the new stuff reaches the caliper. Again, do not let the reservoir go empty. :cheers:
[Modified by RainDelay, 10:41 AM 4/23/2004]
So, throw on the hoses and bleed at the calipers. DO NOT forget to keep an eye on the fluid level in the reservoir!!!
If you have a vacuum pump (hand help jobber like from Craftsman) now may be a good time to remove as much fluid as you can from the reservoir, clean it, (leave a little fluid in the bottom) and refill with clean fluid. Go ahead and buy the big jar of fluid. When you bleed, keep pulling fluid until the new stuff reaches the caliper. Again, do not let the reservoir go empty. :cheers:
[Modified by RainDelay, 10:41 AM 4/23/2004]
Cruising
Joined: Jan 2004
Posts: 14
Likes: 0
From: Lenexa Kansas
Re: Bleeding Brakes (RainDelay)
I've used a MityVac pump for several years now to quickly / easily / cleanly bleed the ABS & Calipers on my '94.
Tonight however, a different result.
I replaced all the rubber hoses with SS. I also replaced my J55 front calipers with GS.
The rears bled fine / normally.
The fronts appear to be sucking air - possibly through the bleeder screw threads.
Anyone else ever experienced this?
I've got a friend coming over tomorrow to help me bleed them the "old-fashioned" way.
I knew it was time to call it a night tonight when I almost went and asked my wife if she'd mind getting out of the bathtub for a few minutes to help me in the garage! :nono:
Tonight however, a different result.
I replaced all the rubber hoses with SS. I also replaced my J55 front calipers with GS.
The rears bled fine / normally.
The fronts appear to be sucking air - possibly through the bleeder screw threads.
Anyone else ever experienced this?
I've got a friend coming over tomorrow to help me bleed them the "old-fashioned" way.
I knew it was time to call it a night tonight when I almost went and asked my wife if she'd mind getting out of the bathtub for a few minutes to help me in the garage! :nono:
Pro
Joined: Mar 2002
Posts: 732
Likes: 138
From: Allen (DFW) Texas
Re: Bleeding Brakes (MaxAlex)
I would assume the answer is yes, but just in case - did you replace the crush washers on each side of the caliper end of the new brake hoses with new ones? If not, that would likely cause both air ingestion and fluid leaks. And of course torqued the through bolt to proper specs?
Cruising
Joined: Jan 2004
Posts: 14
Likes: 0
From: Lenexa Kansas
Re: Bleeding Brakes (rhneff)
Yep - New crush washers on both sides - properly torqued.
Just to check for leaks, I slowly pressed the brake pedal all the way to the floor - about three times before it built pressure & held.
I checked it again an hour or so later - still solid pedal - no leaks. That makes me think more likely to be bleed screw leaks. I did try putting some anti-seize on the bleeder screw threads - that seemed to lessen the air leakage, but it still exists.
Just to check for leaks, I slowly pressed the brake pedal all the way to the floor - about three times before it built pressure & held.
I checked it again an hour or so later - still solid pedal - no leaks. That makes me think more likely to be bleed screw leaks. I did try putting some anti-seize on the bleeder screw threads - that seemed to lessen the air leakage, but it still exists.
Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
Re: Bleeding Brakes (MaxAlex)
I just brought new GS calipers. hope I don't have that problem.
I also brought new GM hoses, not SS.
there are 2 types of banjo washers that I have seen. copper and aluminum. I'm not sure which type is correct.
I always bleed the old fashion way, ... my wife and 10yo son are certified pumpers :cool:
I also brought new GM hoses, not SS.
there are 2 types of banjo washers that I have seen. copper and aluminum. I'm not sure which type is correct.
I always bleed the old fashion way, ... my wife and 10yo son are certified pumpers :cool:
Pro
Joined: Mar 2002
Posts: 732
Likes: 138
From: Allen (DFW) Texas
Re: Bleeding Brakes (MaxAlex)
Are the calipers new, rebuilt, ?? Always possible there could be a leak in the calipers themselves, especially if they've been re-built and the cylinders weren't honed properly. Could also be related to the SS lines, I guess - I use the GM rubber ones, since the SS are illegal in the SCCA class I run, so I don't have any experience with those. The obvious culprits are things you've changed, lines or calipers. Good luck regardless - just put new GS calipers on my 96 and they look great!
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Cruising
Joined: Jan 2004
Posts: 14
Likes: 0
From: Lenexa Kansas
Re: Bleeding Brakes (rhneff)
I thought about maybe the calipers themselves leaking, but since I've pressurized the system with the pedal, I still do not have any leaks? Would it be safe to assume that the absence of leaks means I'm not getting air into the system?
Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
Re: Bleeding Brakes (MaxAlex)
Opening the bleeder too far or putting too strong of a vacuum will cause "false air". Too strong a vacuum wiil pull air between the bleed screw and the bleeder hose rubber fitting.
Pro
Joined: Mar 2002
Posts: 732
Likes: 138
From: Allen (DFW) Texas
Re: Bleeding Brakes (MaxAlex)
Absence of leaks would seem to indicate that. What is the symptom that makes you think you're getting air into the system? Spongy pedal? Air still purged when bleeder opened? Or ??? We've all been guessing without really knowing what your symptom is.
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
Re: Bleeding Brakes (rhneff)
Gordon Killebrew answered this question at a gathering we had here in Dover, DE last month.
He indicated that the best way to bleed a C4's brakes is to do it the old fashioned way... one person on a caliper, another on the brake pedal. Don't mess with anything fancy.
He indicated that the best way to bleed a C4's brakes is to do it the old fashioned way... one person on a caliper, another on the brake pedal. Don't mess with anything fancy.
Cruising
Joined: Jan 2004
Posts: 14
Likes: 0
From: Lenexa Kansas
Re: Bleeding Brakes (rhneff)
The symptom is - using a vacuum pump with clear hose - I can see what is coming out of the bleeder screw - I shoulld be getting a steady pull of fluid with a small amount of bubbles (if there is any air in the caliper).
What I am actually getting is a tiny bit of fluid and LOTS of bubbles. I'm going to try again tomorrow.
I may end up following the Killebrew method.
What I am actually getting is a tiny bit of fluid and LOTS of bubbles. I'm going to try again tomorrow.
I may end up following the Killebrew method.
Melting Slicks
Joined: Apr 2000
Posts: 3,198
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From: Northern CA
Re: Bleeding Brakes (MaxAlex)
I did try putting some anti-seize on the bleeder screw threads - that seemed to lessen the air leakage, but it still exists.
Team Owner
Joined: Sep 2003
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From: Freedom is never more than one generation away from extinction.
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Re: Bleeding Brakes (bogus)
Gordon Killebrew answered this question at a gathering we had here in Dover, DE last month. He indicated that the best way to bleed a C4's brakes is to do it the old fashioned way... one person on a caliper, another on the brake pedal. Don't mess with anything fancy.
Racer
Joined: Feb 2002
Posts: 390
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From: St. Louis MO
Re: Bleeding Brakes (BAM92)
I just purchased and used a Motive Products Power Bleeder ($49.95) and was very impressed with the efficiency and speed of using this unit. After replacing the brake lines with SS hardware it only took about 15 minutes to do all four calipers and I've never gotten the kind of brake response using a vacuum system. I'm really impressed with this unit - just wish I had some more brakes to bleed.
:thumbs:
:thumbs:
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Re: Bleeding Brakes (Topload)
Be sure to bleed in the right order RR-LR-RF-LF.
