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#1
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Brake pedal goes half-way to the floor, only the first time
Brake pedal goes half-way to the floor, only the first time.
Finally driving my car again after it was laid up for 2 months. I don't think it was like this 3 months ago. When I first press the brake pedal, it goes half-way, but certainly not all the way, to the floor, and at t hat point it stops the car very well. If I press the pedal again within 2 or 3 minutes, it moves very little before it's stopping the car. If I wait maybe 15?? minutes, it's like the first sentence in the previous paragraph. What's the problem? Bad master cylinder? |
#2
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Brake pedal goes half-way to the floor, only the first time
micky wrote:
Brake pedal goes half-way to the floor, only the first time. Finally driving my car again after it was laid up for 2 months. I don't think it was like this 3 months ago. When I first press the brake pedal, it goes half-way, but certainly not all the way, to the floor, and at t hat point it stops the car very well. If I press the pedal again within 2 or 3 minutes, it moves very little before it's stopping the car. If I wait maybe 15?? minutes, it's like the first sentence in the previous paragraph. What's the problem? Bad master cylinder? If you disconnected the caliper while you were working on the front end the system probably needs bleeding - even if you didn't it probably does . Some cars require bleeding both front and rear systems to maintain balance in the valving system . Your repair manual should have the procedure . -- Snag |
#3
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Brake pedal goes half-way to the floor, only the first time
On Wed, 29 Oct 2014 09:48:47 -0500, "Terry Coombs"
wrote: micky wrote: Brake pedal goes half-way to the floor, only the first time. Finally driving my car again after it was laid up for 2 months. I don't think it was like this 3 months ago. When I first press the brake pedal, it goes half-way, but certainly not all the way, to the floor, and at t hat point it stops the car very well. If I press the pedal again within 2 or 3 minutes, it moves very little before it's stopping the car. If I wait maybe 15?? minutes, it's like the first sentence in the previous paragraph. What's the problem? Bad master cylinder? If you disconnected the caliper while you were working on the front end the system probably needs bleeding No, I didn't. (For others planning to do this: At first I did what I usually do, I hung the caliper from other parts using a bent wire hanger, but later I had a loop of fairly heavy stranded electrical wire and that worked better.) - even if you didn't it probably does . Some cars require bleeding both front and rear systems to maintain balance in the valving system . Your repair manual should have the procedure . Is the symptom I have really caused by needing bleeding? I had spongy brakes once after doing something to the brakes, and every time I pushed the pedal it was the same, spongy, like stepping on a sponge. Now it's never spongy. When the pedal is going down the first time, there is almost no resistance (only what comes from the spring) until there is normal resistance. |
#4
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I would check the brake fluid level in the master cylinder first. If that seems to be OK, then I agree with Terry that bleeding any air out of the brake lines and cylinders should correct the problem.
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#5
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Brake pedal goes half-way to the floor, only the first time
On 10/29/2014 10:56 AM, nestork wrote:
I would check the brake fluid level in the master cylinder first. If that seems to be OK, then I agree with Terry that bleeding any air out of the brake lines and cylinders should correct the problem. Ditto and I'd do it ASAP! |
#6
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Brake pedal goes half-way to the floor, only the first time
On 10/29/14, 10:27 AM, micky wrote:
Brake pedal goes half-way to the floor, only the first time. Finally driving my car again after it was laid up for 2 months. I don't think it was like this 3 months ago. When I first press the brake pedal, it goes half-way, but certainly not all the way, to the floor, and at t hat point it stops the car very well. If I press the pedal again within 2 or 3 minutes, it moves very little before it's stopping the car. If I wait maybe 15?? minutes, it's like the first sentence in the previous paragraph. What's the problem? Bad master cylinder? I'm foggy, but I think it could be a brake opening up mechanically, more than normal, as you drive, gradually pushing fluid back into the master cylinder. If you have drums in the rear, one or both may need adjustment. Sometimes pulling up the slack with the parking brake will act as a temporary adjustment. If a rotor is warped, it could move the caliper back and forth as you drive, gradually opening it. |
#7
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Brake pedal goes half-way to the floor, only the first time Stomp
micky posted for all of us...
Brake pedal goes half-way to the floor, only the first time. Finally driving my car again after it was laid up for 2 months. I don't think it was like this 3 months ago. When I first press the brake pedal, it goes half-way, but certainly not all the way, to the floor, and at t hat point it stops the car very well. If I press the pedal again within 2 or 3 minutes, it moves very little before it's stopping the car. If I wait maybe 15?? minutes, it's like the first sentence in the previous paragraph. What's the problem? Bad master cylinder? Is this the same car you did the suspension work on? If so you may have introduced air into the system through cracks in the hose or bulging. The first step is to top off the master cylinder then bleed the brakes properly, per manufacturers instructions. If that doesn't work it is probably the master cylinder, diagnose and repair per manufacturers instructions. If it has power brakes it may be the booster but IDK your set up. I have a faulty memory on this subject. -- Tekkie |
#8
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Brake pedal goes half-way to the floor, only the first time
I've had that happen with a couple of vehicles after I changed the brake shoes or pads and didn't bleed their cylinders. Bleeding always stopped the pedal from sinking. After I bleed brakes, I close all the bleeder screws and pump the pedal hard a few times. Then I open each screw, and usually no fluid comes out right away, indicating there was still some air inside. |
#9
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Brake pedal goes half-way to the floor, only the first time
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#10
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Brake pedal goes half-way to the floor, only the first time
wrote in message ...
I've had that happen with a couple of vehicles after I changed the brake shoes or pads and didn't bleed their cylinders. Bleeding always stopped the pedal from sinking. After I bleed brakes, I close all the bleeder screws and pump the pedal hard a few times. Then I open each screw, and usually no fluid comes out right away, indicating there was still some air inside. If you bleed them, bleed the nearest one to the master cylinder first and then the next nearest, etc. |
#11
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Brake pedal goes half-way to the floor, only the first time
On Thursday, October 30, 2014 5:50:57 PM UTC-4, wrote:
On Thu, 30 Oct 2014 01:25:39 -0700 (PDT), wrote: I've had that happen with a couple of vehicles after I changed the brake shoes or pads and didn't bleed their cylinders. Bleeding always stopped the pedal from sinking. After I bleed brakes, I close all the bleeder screws and pump the pedal hard a few times. Then I open each screw, and usually no fluid comes out right away, indicating there was still some air inside. Badly adjusted brakes will have a low pedal on first push, and come up and be firm on second. Poorly bled brakes will come up a bit on each succuessive push but will never be "firm" Adjusted? I haven't owned a car with brake shoes in my lifetime. I doubt Micky's import has shoes. And never seen a disc brake that you could adjust. |
#12
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Brake pedal goes half-way to the floor, only the first time
On 10/31/14, 8:25 AM, trader_4 wrote:
Adjusted? I haven't owned a car with brake shoes in my lifetime. I doubt Micky's import has shoes. And never seen a disc brake that you could adjust. Have four-wheel disks taken over? Well call me Rip Van Winkle! How do you guys go parking without rolling into the lake? The 1949 Chrysler Crown Imperial had four-wheel disks, but owners hated them. The 1950 Crosley Hot Shot had them. Owners paid to have them changed to drums. The 1962 Studebaker Avanti established the standard of disks on the front and drums on the rear. If Micky has no drums, I believe brake mechanics could still be the problem. Typically, runout is specified at less than .05mm. If it's greater, and the cause is uneven transfer from the pads, resulting in uneven disk thickness, the driver will feel pedal pulsing. If that's not the case, and the measurement varies once per revolution, the problem could be contamination between the disk and the hub face. Otherwise, it could be a warped disk, which can happen putting lug nuts on. If a disk wiggles ever so slightly as the car runs down the road, the caliper will wiggle. I can't speak from experience, but I imagine this wiggling could open the caliper ever so slightly, causing a long push the first time the brake pedal is pushed. |
#13
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Brake pedal goes half-way to the floor, only the first time
On Fri, 31 Oct 2014 16:10:17 -0400, J Burns
wrote: On 10/31/14, 8:25 AM, trader_4 wrote: Adjusted? I haven't owned a car with brake shoes in my lifetime. I doubt Micky's import has shoes. And never seen a disc brake that you could adjust. Have four-wheel disks taken over? Well call me Rip Van Winkle! How do you guys go parking without rolling into the lake? The 1949 Chrysler Crown Imperial had four-wheel disks, but owners hated them. The 1950 Crosley Hot Shot had them. Owners paid to have them changed to drums. The 1962 Studebaker Avanti established the standard of disks on the front and drums on the rear. If Micky has no drums, I believe brake mechanics could still be the problem. Typically, runout is specified at less than .05mm. If it's greater, and the cause is uneven transfer from the pads, resulting in uneven disk thickness, the driver will feel pedal pulsing. If that's not the case, and the measurement varies once per revolution, the problem could be contamination between the disk and the hub face. Otherwise, it could be a warped disk, which can happen putting lug nuts on. If a disk wiggles ever so slightly as the car runs down the road, the caliper will wiggle. I can't speak from experience, but I imagine this wiggling could open the caliper ever so slightly, causing a long push the first time the brake pedal is pushed. What kind of vehicle are we talking about? Was it ever stated? Both of my cars still have drum rear brakes, with self adjusters which by their very design have a tendancy to fail to adjust the brakes - particularly on cars with automatic transmissions where the driver seldom if ever uses the parking brake - which adjusts the brakes when it is applied. |
#15
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Brake pedal goes half-way to the floor, only the first time
On Friday, October 31, 2014 4:10:22 PM UTC-4, J Burns wrote:
On 10/31/14, 8:25 AM, trader_4 wrote: Adjusted? I haven't owned a car with brake shoes in my lifetime. I doubt Micky's import has shoes. And never seen a disc brake that you could adjust. Have four-wheel disks taken over? Well call me Rip Van Winkle! How do you guys go parking without rolling into the lake? We're talking about Micky and the service brake, not parking brakes. The 1949 Chrysler Crown Imperial had four-wheel disks, but owners hated them. The 1950 Crosley Hot Shot had them. Owners paid to have them changed to drums. The 1962 Studebaker Avanti established the standard of disks on the front and drums on the rear. If Micky has no drums, I believe brake mechanics could still be the problem. Typically, runout is specified at less than .05mm. Never said brake mechanics couldn't be the involved. The issue was that Clare brought in "adjustment". Disc brakes don't have an adjustment. And I'll bet Micky's brakes on that care are disc. If it's greater, and the cause is uneven transfer from the pads, resulting in uneven disk thickness, the driver will feel pedal pulsing. If that's not the case, and the measurement varies once per revolution, the problem could be contamination between the disk and the hub face. Otherwise, it could be a warped disk, which can happen putting lug nuts on. If a disk wiggles ever so slightly as the car runs down the road, the caliper will wiggle. I can't speak from experience, but I imagine this wiggling could open the caliper ever so slightly, causing a long push the first time the brake pedal is pushed. I would agree that sounds possible. But it would seem it would have to be quite a bit of wiggle to result in the pedal going half-way to the floor. |
#16
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Brake pedal goes half-way to the floor, only the first time
On Sat, 01 Nov 2014 02:54:20 -0400, J Burns
wrote: On 10/31/14, 9:18 PM, wrote: What kind of vehicle are we talking about? Was it ever stated? Both of my cars still have drum rear brakes, with self adjusters which by their very design have a tendancy to fail to adjust the brakes - particularly on cars with automatic transmissions where the driver seldom if ever uses the parking brake - which adjusts the brakes when it is applied. I wondered, too. Found it (September 30): "I hit a curb with my car and broke in half the right half-axle, broke a big chunk out of the RF rim and a piece the size of a tea-cup saucer from the tire too, cracked my lower suspension arm, and severed the right ball joint (2000 Toyota Solara, only has a lower ball joint. I'm not sure how many cars this story covers. " That car seems to have disks all around. After gazing into my crystal ball, I'll vote for runout. It could come from damage to the disk or hub, or it could be a little rust from all the time it sat disassembled. http://www.motorsforum.com/tech/disc...out-46368-.htm It may take thousands of miles of wear before the pedal starts to pulse. Micky may have caught it quickly enough to fix it without buying parts... if it's rust or dirt. Well, runout on a disc WILL cause the problem if it pushes the pistons back - effectively "backing off the adjustment" |
#17
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Brake pedal goes half-way to the floor, only the first time
micky wrote:
Brake pedal goes half-way to the floor, only the first time. ...... What's the problem? Bad master cylinder? that is indeed, the text-book symptom of a bad master cylinder. GW |
#18
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Brake pedal goes half-way to the floor, only the first time
On 11/1/14, 11:32 AM, wrote:
On Sat, 01 Nov 2014 02:54:20 -0400, J Burns wrote: On 10/31/14, 9:18 PM, wrote: What kind of vehicle are we talking about? Was it ever stated? Both of my cars still have drum rear brakes, with self adjusters which by their very design have a tendancy to fail to adjust the brakes - particularly on cars with automatic transmissions where the driver seldom if ever uses the parking brake - which adjusts the brakes when it is applied. I wondered, too. Found it (September 30): "I hit a curb with my car and broke in half the right half-axle, broke a big chunk out of the RF rim and a piece the size of a tea-cup saucer from the tire too, cracked my lower suspension arm, and severed the right ball joint (2000 Toyota Solara, only has a lower ball joint. I'm not sure how many cars this story covers. " That car seems to have disks all around. After gazing into my crystal ball, I'll vote for runout. It could come from damage to the disk or hub, or it could be a little rust from all the time it sat disassembled. http://www.motorsforum.com/tech/disc...out-46368-.htm It may take thousands of miles of wear before the pedal starts to pulse. Micky may have caught it quickly enough to fix it without buying parts... if it's rust or dirt. Well, runout on a disc WILL cause the problem if it pushes the pistons back - effectively "backing off the adjustment" I've been too optimistic. How could the hub transmit enough force to break an axle, crack a suspension arm, and sever a ball joint, without being damaged? Hub runout should show that a new hub and bearing is needed. An optimist could hope the disk is OK. |
#19
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Brake pedal goes half-way to the floor, only the first time
On Sat, 01 Nov 2014 11:04:59 -1000, Geoff Welsh
wrote: micky wrote: Brake pedal goes half-way to the floor, only the first time. ...... What's the problem? Bad master cylinder? that is indeed, the text-book symptom of a bad master cylinder. GW Given the recent history of the vehicle -IE- it's damage history, I'd be looking at the brake on the damaged axle first. Clamp off the brake flex hose to that wheel. Is the pedal highand firm? If not, look elsewhere. If so, you know where to look. Brake hose clamps are available at Harbor frioeght and many auto parts/tool suppliers at reasonable cost. Some are little screw clamps, others are a vice-grips with round rod jaws. Make your own by brazing a 1/4 inch long 1/4 or 5/16" diameter steerl rods to a 6 or 8 inch cheap vice grips. |
#20
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Brake pedal goes half-way to the floor, only the first time
Supposedly these are one of the few things that Sears sells that are still worth it... apparently the same as S-K, Blue Point etc.
http://www.sears.com/craftsman-hose-...ktRedirec t=y Or, the plastic ones from Harbor Freight work fine. Lots of guys just use flat jaw vice grips but I don't like doing that. nate |
#21
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Brake pedal goes half-way to the floor, only the first time
On Sunday, November 2, 2014 8:11:31 AM UTC-5, N8N wrote:
Supposedly these are one of the few things that Sears sells that are still worth it... apparently the same as S-K, Blue Point etc. http://www.sears.com/craftsman-hose-...ktRedirec t=y Or, the plastic ones from Harbor Freight work fine. Lots of guys just use flat jaw vice grips but I don't like doing that. nate I'd like to see opinions from auto manufacturers one using these on brake hoses. My concern would be that you run the risk of damaging the hose, possibly resulting in later failure. And even if you did use them to pinch the hoses, I would think they would cut off the fluid while you changed a caliper. I tend to doubt they are going to hold pressure enough to test the brakes with pedal pressure for functionality. |
#22
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Brake pedal goes half-way to the floor, only the first time
On Sunday, November 2, 2014 9:07:35 AM UTC-5, trader_4 wrote:
On Sunday, November 2, 2014 8:11:31 AM UTC-5, N8N wrote: Supposedly these are one of the few things that Sears sells that are still worth it... apparently the same as S-K, Blue Point etc. http://www.sears.com/craftsman-hose-...ktRedirec t=y Or, the plastic ones from Harbor Freight work fine. Lots of guys just use flat jaw vice grips but I don't like doing that. nate I'd like to see opinions from auto manufacturers one using these on brake hoses. My concern would be that you run the risk of damaging the hose, possibly resulting in later failure. And even if you did use them to pinch the hoses, I would think they would cut off the fluid while you changed a caliper. I tend to doubt they are going to hold pressure enough to test the brakes with pedal pressure for functionality. I actually agree with you; I have used them but would prefer to use a pedal jack to e.g. change a caliper. It's good to have them but I only use them when nothing else will do what I need it to do. I don't know about the plastic ones but the metal ones should hold pressure in the situation the OP describes. nate |
#23
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Brake pedal goes half-way to the floor, only the first time
On Sun, 2 Nov 2014 06:40:48 -0800 (PST), N8N
wrote: On Sunday, November 2, 2014 9:07:35 AM UTC-5, trader_4 wrote: On Sunday, November 2, 2014 8:11:31 AM UTC-5, N8N wrote: Supposedly these are one of the few things that Sears sells that are still worth it... apparently the same as S-K, Blue Point etc. http://www.sears.com/craftsman-hose-...ktRedirec t=y Or, the plastic ones from Harbor Freight work fine. Lots of guys just use flat jaw vice grips but I don't like doing that. nate I'd like to see opinions from auto manufacturers one using these on brake hoses. My concern would be that you run the risk of damaging the hose, possibly resulting in later failure. And even if you did use them to pinch the hoses, I would think they would cut off the fluid while you changed a caliper. I tend to doubt they are going to hold pressure enough to test the brakes with pedal pressure for functionality. I actually agree with you; I have used them but would prefer to use a pedal jack to e.g. change a caliper. It's good to have them but I only use them when nothing else will do what I need it to do. I don't know about the plastic ones but the metal ones should hold pressure in the situation the OP describes. nate I not only think they will, I KNOW they will. I've done it hundreds of times. I've even used them to drive a car back to the shop after it blew a fles hose (rear - body to axle) several times. (several different vehicles) It was a very quick and accurate way to determine where a low pedal problem came from. Block off the rear flex, pedal comes up, rear brake problem, no use looking for the trouble in the rear. Pedal doesn't come up? go to right front. Pedal doesn't come up? go to left front. Still doesn't come up? look into the master. |
#24
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Brake pedal goes half-way to the floor, only the first time
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#25
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Brake pedal goes half-way to the floor, only the first time
On Sun, 02 Nov 2014 20:53:15 -0500, J Burns
wrote: On 11/2/14, 4:52 PM, wrote: On Sun, 2 Nov 2014 06:40:48 -0800 (PST), N8N wrote: On Sunday, November 2, 2014 9:07:35 AM UTC-5, trader_4 wrote: I'd like to see opinions from auto manufacturers one using these on brake hoses. My concern would be that you run the risk of damaging the hose, possibly resulting in later failure. And even if you did use them to pinch the hoses, I would think they would cut off the fluid while you changed a caliper. I tend to doubt they are going to hold pressure enough to test the brakes with pedal pressure for functionality. I actually agree with you; I have used them but would prefer to use a pedal jack to e.g. change a caliper. It's good to have them but I only use them when nothing else will do what I need it to do. I don't know about the plastic ones but the metal ones should hold pressure in the situation the OP describes. nate I not only think they will, I KNOW they will. I've done it hundreds of times. I've even used them to drive a car back to the shop after it blew a fles hose (rear - body to axle) several times. (several different vehicles) It was a very quick and accurate way to determine where a low pedal problem came from. Block off the rear flex, pedal comes up, rear brake problem, no use looking for the trouble in the rear. Pedal doesn't come up? go to right front. Pedal doesn't come up? go to left front. Still doesn't come up? look into the master. Trader 4 sounds right to me. I'd be scared to clamp a line made for 3,000 PSI. I remember a car that came in smelling like burning brakes. I jacked up the hot wheel and couldn't get the disk brake to release except by loosening the bleeder. When I tried a stop on the road, the car pulled to the other side, showing that the problem brake wasn't getting full pressure. When I parked, I had to loosen the bleeder to release the brake. It was as if something had kinked the line. I replaced it. Not long afterward, the same thing happened to the other side. I suppose normal braking pressure might be 1,000 PSI. It would take a tight clamp to stop it. If I clamped it tight, I'd be afraid that down the road I'd have a "kink" or a leak. In view of the great damage from hitting the curb, the hub might have so much runout that it might not require a gauge to detect it. Just a ruler on a stable surface, held down by a weight, with the end pressed against the hub. And some feeler gauges. Your collapsed lined had nothing to do with clamping. Lines fail - and the failure you mention is COMMON.. Clamping the lines WORKS, and if done with the proper clamp it will not damage a good hose. Might damage one that is already failing - which needs replacement regardless. |
#26
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Brake pedal goes half-way to the floor, only the first time
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#27
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Brake pedal goes half-way to the floor, only the first time
On Sun, 02 Nov 2014 22:55:46 -0500, J Burns
wrote: On 11/2/14, 10:13 PM, wrote: Your collapsed lined had nothing to do with clamping. Lines fail - and the failure you mention is COMMON.. Clamping the lines WORKS, and if done with the proper clamp it will not damage a good hose. Might damage one that is already failing - which needs replacement regardless. I wish I understood what happened with that car. At first, I assumed that the piston was jammed with dirt or corrosion. If the line had collapsed, I would have expected pressure from the brake pedal to open it so I'd get full braking on that wheel. As I haven't seen it on any other vehicle, might those lines (just the front) have been manufactured differently from most lines? The other explanation is that something had been done to those lines that isn't done to most lines. For example, I have read that if you remove the caliper, you should be careful not to turn it 360 degrees (1 turn in the line) when you refasten it; a twist could cause the line to burst later on. Several things can happen. THe "lining" of the hose can separate from the structural part of the hose and cause a "flap" that allows fluid out to the caliper, but does not allow the caliper to return. In this case, the brake initially drags, causing a pull to that side while driving, and more on initial braking. When the brake heats up and fades, the pull can move to the other side on braking. Can really throw a beginner mechanic for a loop!!! Sometimes the problem is rust in the metal crimp fittings expanding and squeezing the hose, restricting fluid flow. This can have the same results, or it can just cause the one brake to apply more slowly, causing a pull to the opposite side on initial application. The hose can also bulge, causing a soft pedal. Then, of course, the hose can split/leak. Other brake problems include calipers sticking due to corrosion or fluid contamination, brake caliper sliders sticking, drum brake cyls seizing, adjusters seizing or breaking, and caliprs or cyls leaking . Leaking cyls can cause the brake to grab, or to loose friction. Leaking grease seals can contaminate brake surfaces as well - causing either a grab or loss of friction. In other words, leaking cyls, calipers, or grease seals can cause a pull in either direction. Disabling brakes one wheel at a time can quickly isolate where the problem is by elimination. |
#28
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Brake pedal goes half-way to the floor, only the first time
On 11/2/14, 11:15 PM, wrote:
On Sun, 02 Nov 2014 22:55:46 -0500, J Burns wrote: On 11/2/14, 10:13 PM, wrote: Your collapsed lined had nothing to do with clamping. Lines fail - and the failure you mention is COMMON.. Clamping the lines WORKS, and if done with the proper clamp it will not damage a good hose. Might damage one that is already failing - which needs replacement regardless. I wish I understood what happened with that car. At first, I assumed that the piston was jammed with dirt or corrosion. If the line had collapsed, I would have expected pressure from the brake pedal to open it so I'd get full braking on that wheel. As I haven't seen it on any other vehicle, might those lines (just the front) have been manufactured differently from most lines? The other explanation is that something had been done to those lines that isn't done to most lines. For example, I have read that if you remove the caliper, you should be careful not to turn it 360 degrees (1 turn in the line) when you refasten it; a twist could cause the line to burst later on. Several things can happen. THe "lining" of the hose can separate from the structural part of the hose and cause a "flap" that allows fluid out to the caliper, but does not allow the caliper to return. In this case, the brake initially drags, causing a pull to that side while driving, and more on initial braking. When the brake heats up and fades, the pull can move to the other side on braking. Can really throw a beginner mechanic for a loop!!! Sometimes the problem is rust in the metal crimp fittings expanding and squeezing the hose, restricting fluid flow. This can have the same results, or it can just cause the one brake to apply more slowly, causing a pull to the opposite side on initial application. The hose can also bulge, causing a soft pedal. Then, of course, the hose can split/leak. Other brake problems include calipers sticking due to corrosion or fluid contamination, brake caliper sliders sticking, drum brake cyls seizing, adjusters seizing or breaking, and caliprs or cyls leaking . Leaking cyls can cause the brake to grab, or to loose friction. Leaking grease seals can contaminate brake surfaces as well - causing either a grab or loss of friction. In other words, leaking cyls, calipers, or grease seals can cause a pull in either direction. Disabling brakes one wheel at a time can quickly isolate where the problem is by elimination. Those two blocked lines are the only failures I remember. It was a European car from the early 1970s. I may have found the cause: corrosion at a fitting gradually squeezed the rubber lining together. (Maybe the rear lines used a different kind of fitting.) http://ecomodder.com/forum/showthread.php/internal-flexible-brake-line-failure-finally-happened-me-21019.html Shop manuals always seem to say to hang a caliper by a wire so its weight isn't on the line, but I've read that mechanics often let calipers dangle on brake lines. Who's right? |
#29
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Brake pedal goes half-way to the floor, only the first time
On 11/3/2014 12:36 AM, J Burns wrote:
Disabling brakes one wheel at a time can quickly isolate where the problem is by elimination. Those two blocked lines are the only failures I remember. It was a European car from the early 1970s. I may have found the cause: corrosion at a fitting gradually squeezed the rubber lining together. (Maybe the rear lines used a different kind of fitting.) http://ecomodder.com/forum/showthread.php/internal-flexible-brake-line-failure-finally-happened-me-21019.html Shop manuals always seem to say to hang a caliper by a wire so its weight isn't on the line, but I've read that mechanics often let calipers dangle on brake lines. Who's right? Manual is right, mechanics are wrong. That may be common practice, but that doesn't make it right. - .. Christopher A. Young Learn about Jesus www.lds.org .. |
#30
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Brake pedal goes half-way to the floor, only the first time
On Mon, 03 Nov 2014 00:36:50 -0500, J Burns
wrote: On 11/2/14, 11:15 PM, wrote: On Sun, 02 Nov 2014 22:55:46 -0500, J Burns wrote: On 11/2/14, 10:13 PM, wrote: Your collapsed lined had nothing to do with clamping. Lines fail - and the failure you mention is COMMON.. Clamping the lines WORKS, and if done with the proper clamp it will not damage a good hose. Might damage one that is already failing - which needs replacement regardless. I wish I understood what happened with that car. At first, I assumed that the piston was jammed with dirt or corrosion. If the line had collapsed, I would have expected pressure from the brake pedal to open it so I'd get full braking on that wheel. As I haven't seen it on any other vehicle, might those lines (just the front) have been manufactured differently from most lines? The other explanation is that something had been done to those lines that isn't done to most lines. For example, I have read that if you remove the caliper, you should be careful not to turn it 360 degrees (1 turn in the line) when you refasten it; a twist could cause the line to burst later on. Several things can happen. THe "lining" of the hose can separate from the structural part of the hose and cause a "flap" that allows fluid out to the caliper, but does not allow the caliper to return. In this case, the brake initially drags, causing a pull to that side while driving, and more on initial braking. When the brake heats up and fades, the pull can move to the other side on braking. Can really throw a beginner mechanic for a loop!!! Sometimes the problem is rust in the metal crimp fittings expanding and squeezing the hose, restricting fluid flow. This can have the same results, or it can just cause the one brake to apply more slowly, causing a pull to the opposite side on initial application. The hose can also bulge, causing a soft pedal. Then, of course, the hose can split/leak. Other brake problems include calipers sticking due to corrosion or fluid contamination, brake caliper sliders sticking, drum brake cyls seizing, adjusters seizing or breaking, and caliprs or cyls leaking . Leaking cyls can cause the brake to grab, or to loose friction. Leaking grease seals can contaminate brake surfaces as well - causing either a grab or loss of friction. In other words, leaking cyls, calipers, or grease seals can cause a pull in either direction. Disabling brakes one wheel at a time can quickly isolate where the problem is by elimination. Those two blocked lines are the only failures I remember. It was a European car from the early 1970s. I may have found the cause: corrosion at a fitting gradually squeezed the rubber lining together. (Maybe the rear lines used a different kind of fitting.) http://ecomodder.com/forum/showthread.php/internal-flexible-brake-line-failure-finally-happened-me-21019.html Shop manuals always seem to say to hang a caliper by a wire so its weight isn't on the line, but I've read that mechanics often let calipers dangle on brake lines. Who's right? Corrosion in the fittings is, as I noted, a major cause of the problem. Grease monkeys let calipers hang - real mechanics hang the caliper and give the hoses some respect. They also use the right tool to clamp the line to avoid dripping brake fluid everywhere when they remove the caliper - and use the same clamp for trouble shooting. |
#31
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Brake pedal goes half-way to the floor, only the first time
On Monday, November 3, 2014 12:36:55 AM UTC-5, J Burns wrote:
On 11/2/14, 11:15 PM, wrote: On Sun, 02 Nov 2014 22:55:46 -0500, J Burns wrote: On 11/2/14, 10:13 PM, wrote: Your collapsed lined had nothing to do with clamping. Lines fail - and the failure you mention is COMMON.. Clamping the lines WORKS, and if done with the proper clamp it will not damage a good hose. Might damage one that is already failing - which needs replacement regardless. I wish I understood what happened with that car. At first, I assumed that the piston was jammed with dirt or corrosion. If the line had collapsed, I would have expected pressure from the brake pedal to open it so I'd get full braking on that wheel. As I haven't seen it on any other vehicle, might those lines (just the front) have been manufactured differently from most lines? The other explanation is that something had been done to those lines that isn't done to most lines. For example, I have read that if you remove the caliper, you should be careful not to turn it 360 degrees (1 turn in the line) when you refasten it; a twist could cause the line to burst later on. Several things can happen. THe "lining" of the hose can separate from the structural part of the hose and cause a "flap" that allows fluid out to the caliper, but does not allow the caliper to return. In this case, the brake initially drags, causing a pull to that side while driving, and more on initial braking. When the brake heats up and fades, the pull can move to the other side on braking. Can really throw a beginner mechanic for a loop!!! Sometimes the problem is rust in the metal crimp fittings expanding and squeezing the hose, restricting fluid flow. This can have the same results, or it can just cause the one brake to apply more slowly, causing a pull to the opposite side on initial application. The hose can also bulge, causing a soft pedal. Then, of course, the hose can split/leak. Other brake problems include calipers sticking due to corrosion or fluid contamination, brake caliper sliders sticking, drum brake cyls seizing, adjusters seizing or breaking, and caliprs or cyls leaking . Leaking cyls can cause the brake to grab, or to loose friction. Leaking grease seals can contaminate brake surfaces as well - causing either a grab or loss of friction. In other words, leaking cyls, calipers, or grease seals can cause a pull in either direction. Disabling brakes one wheel at a time can quickly isolate where the problem is by elimination. Those two blocked lines are the only failures I remember. It was a European car from the early 1970s. I may have found the cause: corrosion at a fitting gradually squeezed the rubber lining together. (Maybe the rear lines used a different kind of fitting.) http://ecomodder.com/forum/showthread.php/internal-flexible-brake-line-failure-finally-happened-me-21019.html Shop manuals always seem to say to hang a caliper by a wire so its weight isn't on the line, but I've read that mechanics often let calipers dangle on brake lines. Who's right? The shop manual. I know it's "common" to let 'em hang, but I don't like abusing hoses any more than I have to to get the job done. I had a '71 Porsche 914 once, was working on it circa 1996ish. Probably still had the original hoses. When I replaced them I cut one open out of curiosity, the inside was swollen almost shut, so it may be normal for this to happen over years 'n' years of use. Now my dad has a '73 chevy pickup that he still drives... I don't remember ever replacing the hoses on it... still drives fine, but were it mine I'd probably replace them and rebuild the hydraulics on principle. Just me... nate |
#32
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Brake pedal goes half-way to the floor, only the first time
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#33
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Brake pedal goes half-way to the floor, only the first time
On Mon, 03 Nov 2014 19:37:50 -0500, J Burns
wrote: On 11/3/14, 7:07 PM, wrote: Corrosion in the fittings is, as I noted, a major cause of the problem. I see you did. Sometimes I don't comprehend what's in writing in front of me! Grease monkeys let calipers hang - real mechanics hang the caliper and give the hoses some respect. They also use the right tool to clamp the line to avoid dripping brake fluid everywhere when they remove the caliper - and use the same clamp for trouble shooting. If I see a clamp for sale, how can I tell if it's the right tool for brake lines? The Lisle 22850 Hose Pincher looks like just the ticket, but how do I know for sure? The lisle unit is acceptable The SK 7600 series are better. AMPRO T70547 Hose Pinch is another option. Halfords in Brittain also sells a similar unit. The KC 08205 BRAKE HOSE CLAMP is also a good looking unit. Mine is like this irwin unit: http://www.wahardware.com.au/special...548000299.html I've had it for several decades (bought it in the early seventies) |
#34
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Brake pedal goes half-way to the floor, only the first time
On 11/3/14, 8:54 PM, wrote:
On Mon, 03 Nov 2014 19:37:50 -0500, J Burns wrote: On 11/3/14, 7:07 PM, wrote: Corrosion in the fittings is, as I noted, a major cause of the problem. I see you did. Sometimes I don't comprehend what's in writing in front of me! Grease monkeys let calipers hang - real mechanics hang the caliper and give the hoses some respect. They also use the right tool to clamp the line to avoid dripping brake fluid everywhere when they remove the caliper - and use the same clamp for trouble shooting. If I see a clamp for sale, how can I tell if it's the right tool for brake lines? The Lisle 22850 Hose Pincher looks like just the ticket, but how do I know for sure? The lisle unit is acceptable The SK 7600 series are better. AMPRO T70547 Hose Pinch is another option. Halfords in Brittain also sells a similar unit. The KC 08205 BRAKE HOSE CLAMP is also a good looking unit. Mine is like this irwin unit: http://www.wahardware.com.au/special...548000299.html I've had it for several decades (bought it in the early seventies) Amazon suggests the Lisle 22850 for brake lines, but Lisle's catalog says fuel lines, vacuum lines, etc. Amazon has 2 reviews for the AMPRO T7057. One said he used it to pinch a coolant line. It failed to seal, and he ended up with coolant running down his sleeve. The other liked it. He used it to pinch a brake line when he changed calipers, and it didn't damage the line, as happened every time he used Vise Grips. There's a guy who's not afraid to damage brake lines, again and again! (I believe if you put plastic food wrap over the top of a brake-fluid reservoir and screw the cap on, that will keep it from draining through an open line.) The Irwin pinch-off tool is a Vise Grip 7" RR. It weighs 13 ounces. Irwin says it's for tubing and opens to 1/4". I use 6" long-nose Vise Grips to work on gravity-fed gas lines. At the tip, the jaws are parallel when they come together and nearly parallel when 1/4" apart. It weighs only 6 ounces. I've seen no damage. With gravity-fed gas line, there's not much at stake. |
#35
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Brake pedal goes half-way to the floor, only the first time
On Sat, 01 Nov 2014 11:04:59 -1000, Geoff Welsh
wrote: micky wrote: Brake pedal goes half-way to the floor, only the first time. ...... What's the problem? Bad master cylinder? that is indeed, the text-book symptom of a bad master cylinder. GW You ruled out a leaking wheel brake cylinder, leaking caliper, brake line or connections? -- "Trust me, I'm from the government. I'm here to help." |
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