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Author Topic:   Hydraulic Brake Repair In a Pinch

jimh posted 11-25-2014 10:41 AM ET (US)
Last year I gave an account of a big problem that developed with the hydraulic brake system on my GMC truck while on vacation. See
http://continuouswave.com/sail-logs/irnp2013/index.html
for details. The short version of the story: the hydraulic hose on the left rear wheel developed a leak, and the brake system failed by this loss of pressure. We had a scary drive home with crippled brakes.
It just occurred to me, as a result of a conversation I was having with an acquaintance of mine on a tangental subject, that the cure for my hydraulic brake problem was at hand, and, when in a pinch like this, I could have made an emergency repair that would have resulted in a restoration of brake service, at least temporarily. Looking back at the situation, I just did not see this solution, but it seems quite obvious, once you have heard of it.
Since the problem with my brake system was a loss of fluid down stream of the master cylinder and only affecting one wheel, I could have made a temporary repair by just shutting off flow of brake fluid to that wheel. A very simple way to do that is by using a pair of ViceGrips or similar locking pliers, and pinching closed the metal brake tubing that runs to that wheel. If I had thought of this, I perhaps could have restored partial brake operation by getting to a hardware store and buying two small ViceGrip pliers. I think I would have needed two, because it would be best to shut off both brakes on one axle. I do not think one-wheel braking on an axle will be good.
To shut off the brake line, I would have have to figure out which steel line was running to which wheel, and then pinch it closed with the ViceGrip pliers. I think this would have worked well in my case, because my leak was on the rear axle. The front brakes tend to do more of the braking on most vehicles.
You would use this same method on a boat trailer brake system. It will be very easy to identify which hose goes to which wheel, too.
The only drawback to pinching off the steel brake tubing will be that you will need to replace it when a complete repair is made. That might add to the repair cost. In my particular situation with the GMC truck, I ended up replacing all the steel brake lines on the vehicle, as they were all getting rather suspect with age.
Certainly this is a very temporary fix, but it might be useful in a situation of travel with a boat trailer in a remote spot when a brake problem develops--a solution for when you are in a pinch, so to speak.
russellbailey posted 11-25-2014 12:53 PM ET (US)
jimh, I think you have a good idea, but I don't know how successful a pinch of the line would be given the high pressure in the line and the low viscosity of the braking fluid - it might work great. However, something similar is you can screw a plug fitting into the end of the line to block off one caliper. This preserves the brake system for after the caliper repair.
I keep such a plug in my on-road repair kit for the trailer. If a caliper malfunctions (which essentially means sticks shut and does not release), I can unscrew the hose to that wheel, screw the plug in, and keep good braking on the other wheels. The plug is two pieces - a union fitting and a screw in plug.
[Since I went to all stainless calipers I've not had to do that, but I did one time before I went with all stainless, and as part of the update added the plug piece to the repair kit]
Jefecinco posted 11-25-2014 05:46 PM ET (US)
Jim,
We call those kinds of repairs "field expedient repairs" and many are taught in military service schools.
With steel brakes lines it could be pretty difficult to close off a line well with a pair of vice grips. The lines are very strong and quite resistant to malformation. I doubt my hands have the strength to close off a steel brake line with a vice grip plier. The most elegant solution would be to have the appropriately sized cap for the male fitting at the end of the line. Of course you could carry one of those around for so long that by the time you'd need it you'd forget you have it.
Anyway it's good to discusses these kinds of repairs. You could almost make a thread on the subject to hear of other field expedient solutions. It could even be appropriate for a reference article.
Butch
jimh posted 11-25-2014 06:06 PM ET (US)
Installing a cap at some connection in the path of the brake line is a more elegant solution. It also avoids having to damage what might be a perfectly good steel brake line by pinching it. It seems like the best place to shut off a bad brake line hose would be by disconnecting it at the master cylinder. Here I am speaking about a vehicle with four-wheel brakes that has a separate line from the master cylinder to each wheel. On a boat trailer, there is usually just a single line from the brake actuator and it is distributed to the four wheels by T-junction joints. Also, if you only have two-wheel brakes you can stop thinking about fixing them by this method. I don't think it would be a good idea to have brakes on only one wheel of a boat trailer.
fno posted 11-26-2014 09:29 AM ET (US)
If you have motion activated brakes on your trailer, you can disable them as well by installing a medium sized C-clamp on the trailer tongue brake assembly. This prevents any rearward movement and thus no brake pressure is applied. I keep a clamp in my road side trailer repair kit.
Jefecinco posted 11-26-2014 10:54 AM ET (US)
fno,
Have you tested the clamp solution? I assume you're clamping the sliding part of the tongue just forward of where it enters the fixed part of the tongue. If so, I'd be concerned that the force applied when the tow vehicle brakes are applied with some effort would simply make the clamp slide forward rendering it ineffective.
I seem to recall a lockout mechanism on some surge brakes. Perhaps it is used for backing.
Butch
Don SSDD posted 11-26-2014 12:55 PM ET (US)
I think you can easily pinch brake lines with Vise Grips. Just see where the leak is and do this upstream of the leak. You'll be replacing the line anyway, if that is where the leak is.
Some people have other solutions. I bought a 1962 Chev from a fellow, he said it would be safe to drive home, even though it hadn't been on the road in 10 years. I decided not to take a chance and had a deck truck bring it home. When later bleeding the brakes, I found a leak- the electric tape put over a leaky in the line had let go.
Don
jimh posted 11-26-2014 01:23 PM ET (US)
Re Don's electrical tape repair story: early this Spring I drove my truck a few miles, and when I stopped a cloud of smoke came out from under the hood. There was a leak in a power steering hose. On a straight road, there was very lille fluid lead. When I started to maneuver to back up to the boat trailer, I was using a lot of power steering boost. The fluid squirted out and hit the exhaust manifold, making a lot of smoke. I taped over the leak in the hose with electrical tape so I could drive the car to a repair shop nearby to get the hose assembly replaced. The tape held for a few miles of mostly straight highway driving to get to the repair shop.
I don't think the steel brake line could be so rigid it would resist deformation by ViceGrip pliers. The steel is flexible and can be bent by hand. I think it would be bent under the force and leverage of the pliers, too.
Jefecinco posted 11-26-2014 05:33 PM ET (US)
If the steel line can be bent by hand I imagine it could be squeezed shut with vise grips. The best course could be to bend it double and squeeze it shut at the bend.
Butch
andygere posted 11-27-2014 03:22 PM ET (US)
Most modern cars and trucks have dual circuit master cylinders. This means that the reservoir is divided in to two chambers, one controlling the front brakes, and the other the rear. When your rear brake hose developed a leak, it compromised the hydraulic system for both rear brakes. After some time the rear fluid reservoir would empty out, and both rear wheels would be without hydraulic brakes. The front brakes would continue to function normally. A simple field repair to get you to the next auto parts store would be to simply cut the failed hose, and pump the brakes until the fluid in the rear system was exhausted. At that point, you would only have front braking, and whatever stopping power that might be provided by the trailer brakes.
A better bit to keep in the spares box for a long trip would be a replacement brake hose and a bottle of brake fluid. After replacing the hose, the system could be bled well enough to get you home safely. A can of brakeClean is a good idea in case any fluid gets on your drums or rotors. I once made this repair on my '63 Impala in an auto parts store parking lot. That car had a single circuit system, and fortunately for me I discovered the minor fluid weep before the hose failed completely and left me with no hydraulic brakes at all.
jimh posted 11-28-2014 05:50 PM ET (US)
Andy--your comments are very interesting. In the case of my (1995) vehicle, the brake system had an early implementation of anti-lock brakes. Can you comment on how that might have affected the way the brakes would work with a leaking brake line to a rear wheel.
jimh posted 11-29-2014 11:13 AM ET (US)
I looked at the master cylinder of the brake system on my 1995 GMC truck. There are two outlet hoses from the cylinder. These connect to the anti-lock brake distributor mechanism. Since the master cylinder has two outputs, can I assume it has the dual brake system as described by Andy?
Ridge Runner posted 11-29-2014 02:50 PM ET (US)
In 1976 FMVSS Standard 105, came into effect in the United States and was required by law, but has been used on cars since the late 1960's.
This standard requires that the master cylinder is divided internally into two sections, each of which pressurizes a separate hydraulic circuit. Passenger vehicles typically have either a front/rear split brake system or a diagonal split brake system.
A front/rear split system uses one master cylinder section to pressurize the front caliper pistons and the other section to pressurize the rear caliper pistons.
In a diagonal split system the right front and left rear are served by one actuating piston while the left front and the right rear are served, exclusively, by a second actuating piston. If either circuit fails, the other, with at least one front wheel braking remains intact to stop the vehicle. This system was developed with front wheel drive cars suspension design to maintain better control and stability during a system failure.

jimh posted 11-29-2014 03:58 PM ET (US)
Going back to my brake problem with the hose leaking from the left rear wheel, does the dual master cylinder system mean that if I had kept operating the brakes until I lost all the fluid in the one segment, I would have restored the brakes in the other segment? That sounds like a good outcome, better than my solution of limping home trying to never use the brakes.
Ridge Runner posted 11-29-2014 07:31 PM ET (US)
Yes, dual chamber master cylinders make the brakes less prone to failure. Each chamber of the master cylinder operates the brakes to one set of wheels either in a front/rear split or diagonal split system.
If the brake line going to one set of wheels is broken or the brake fluid is lost through other means, the other set of brakes will still work properly.
Binkster posted 11-29-2014 11:13 PM ET (US)
jimh's comment (my solution of limping home trying to never use the brakes.) reminds me of a brake problem I had way back in the day. I was probably 18/19 at the time, and on summer vacations I drove a cab for a cab company owned by my aunts father. It was in a residential town with a railroad station running through the middle of it and most fares were either going or coming from the station. The cabs were a fleet of a half dozen '52 Chrysler 4 dr sedans, big lumbering beasts near the end of their life.
Well, I get a call to pick up a fare, a woman, and bring her to the railroad station about 2 miles away. On the way to pick her up the brakes just failed. The pedal would go to the floor and the car would just drift to a stop, pumping didn't help. So of course I kept going and picked her up. I didn't mention the brake problem to her, no sense in alarming her. I kept off the main roads and only drove through residential streets all the way to the station. When I would come to a stop sign, I rubbed the right front wheel against the curb to come to a full stop. We made it and she never knew there was a problem.
So much for being young.
rich
andygere posted 11-30-2014 02:16 AM ET (US)
jimh, the antilock brake system (ABS)would operate independently on each braking circuit. The ABS system is a fantastic safety innovation, which builds on the earlier safety innovation of dual circuit hydraulic brakes. The ABS system uses speed sensors on each wheel to detect rapid decelleration, which happens just before the wheel locks up in hard braking situations. The ABS controller reduces braking pressure until accelleration is detected, then increases pressure until rapid decelleration starts to occur. It does this very rapidly, so as to pulse the braking pressure for each wheel in order to get the maximum stopping power without locking up any of the wheels. Since the ABS system operates independently on each wheel (or in some rear wheel drive vehicles on each axle), it allows dual circuit systems to operate as they would in a non ABS equipped vehicle.
BQUICK posted 12-02-2014 02:50 PM ET (US)
I would just pinch the brake hose with the vise grips. You have rear disc brakes on a 1995?
jimh posted 12-03-2014 01:15 AM ET (US)
I don't think I have mentioned what type of brakes are on a 1995 GMC truck in this discussion. As far as I know, the rear brakes are drum brakes. Actually, I don't think anyone has mentioned "disc brakes" in the discussion. How did that come up?
jimh posted 12-03-2014 01:16 AM ET (US)
I think my c.1995 ABS only has three circuits. It works the rear brakes as one circuit, and the front brakes as two separate circuits
andygere posted 12-06-2014 03:11 PM ET (US)
Jimh, the three circuit system you have was pretty common on rear wheel drive trucks of that era.
endus posted 12-11-2014 12:01 PM ET (US)
Good idea. Duct tape and a hose clamp might also work and allow you to maintain some functionality in the affected corner. If you had a piece of appropriately sized hose or a piece of rubber that might even be better.
On SS lines I wonder whether you could get a good enough seal to make that work, though. Probably not. Air in the line might also be a problem.

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Author	Topic: Hydraulic Brake Repair In a Pinch
jimh	posted 11-25-2014 10:41 AM ET (US) Last year I gave an account of a big problem that developed with the hydraulic brake system on my GMC truck while on vacation. See http://continuouswave.com/sail-logs/irnp2013/index.html for details. The short version of the story: the hydraulic hose on the left rear wheel developed a leak, and the brake system failed by this loss of pressure. We had a scary drive home with crippled brakes. It just occurred to me, as a result of a conversation I was having with an acquaintance of mine on a tangental subject, that the cure for my hydraulic brake problem was at hand, and, when in a pinch like this, I could have made an emergency repair that would have resulted in a restoration of brake service, at least temporarily. Looking back at the situation, I just did not see this solution, but it seems quite obvious, once you have heard of it. Since the problem with my brake system was a loss of fluid down stream of the master cylinder and only affecting one wheel, I could have made a temporary repair by just shutting off flow of brake fluid to that wheel. A very simple way to do that is by using a pair of ViceGrips or similar locking pliers, and pinching closed the metal brake tubing that runs to that wheel. If I had thought of this, I perhaps could have restored partial brake operation by getting to a hardware store and buying two small ViceGrip pliers. I think I would have needed two, because it would be best to shut off both brakes on one axle. I do not think one-wheel braking on an axle will be good. To shut off the brake line, I would have have to figure out which steel line was running to which wheel, and then pinch it closed with the ViceGrip pliers. I think this would have worked well in my case, because my leak was on the rear axle. The front brakes tend to do more of the braking on most vehicles. You would use this same method on a boat trailer brake system. It will be very easy to identify which hose goes to which wheel, too. The only drawback to pinching off the steel brake tubing will be that you will need to replace it when a complete repair is made. That might add to the repair cost. In my particular situation with the GMC truck, I ended up replacing all the steel brake lines on the vehicle, as they were all getting rather suspect with age. Certainly this is a very temporary fix, but it might be useful in a situation of travel with a boat trailer in a remote spot when a brake problem develops--a solution for when you are in a pinch, so to speak.
russellbailey	posted 11-25-2014 12:53 PM ET (US) jimh, I think you have a good idea, but I don't know how successful a pinch of the line would be given the high pressure in the line and the low viscosity of the braking fluid - it might work great. However, something similar is you can screw a plug fitting into the end of the line to block off one caliper. This preserves the brake system for after the caliper repair. I keep such a plug in my on-road repair kit for the trailer. If a caliper malfunctions (which essentially means sticks shut and does not release), I can unscrew the hose to that wheel, screw the plug in, and keep good braking on the other wheels. The plug is two pieces - a union fitting and a screw in plug. [Since I went to all stainless calipers I've not had to do that, but I did one time before I went with all stainless, and as part of the update added the plug piece to the repair kit]
Jefecinco	posted 11-25-2014 05:46 PM ET (US) Jim, We call those kinds of repairs "field expedient repairs" and many are taught in military service schools. With steel brakes lines it could be pretty difficult to close off a line well with a pair of vice grips. The lines are very strong and quite resistant to malformation. I doubt my hands have the strength to close off a steel brake line with a vice grip plier. The most elegant solution would be to have the appropriately sized cap for the male fitting at the end of the line. Of course you could carry one of those around for so long that by the time you'd need it you'd forget you have it. Anyway it's good to discusses these kinds of repairs. You could almost make a thread on the subject to hear of other field expedient solutions. It could even be appropriate for a reference article. Butch
jimh	posted 11-25-2014 06:06 PM ET (US) Installing a cap at some connection in the path of the brake line is a more elegant solution. It also avoids having to damage what might be a perfectly good steel brake line by pinching it. It seems like the best place to shut off a bad brake line hose would be by disconnecting it at the master cylinder. Here I am speaking about a vehicle with four-wheel brakes that has a separate line from the master cylinder to each wheel. On a boat trailer, there is usually just a single line from the brake actuator and it is distributed to the four wheels by T-junction joints. Also, if you only have two-wheel brakes you can stop thinking about fixing them by this method. I don't think it would be a good idea to have brakes on only one wheel of a boat trailer.
fno	posted 11-26-2014 09:29 AM ET (US) If you have motion activated brakes on your trailer, you can disable them as well by installing a medium sized C-clamp on the trailer tongue brake assembly. This prevents any rearward movement and thus no brake pressure is applied. I keep a clamp in my road side trailer repair kit.
Jefecinco	posted 11-26-2014 10:54 AM ET (US) fno, Have you tested the clamp solution? I assume you're clamping the sliding part of the tongue just forward of where it enters the fixed part of the tongue. If so, I'd be concerned that the force applied when the tow vehicle brakes are applied with some effort would simply make the clamp slide forward rendering it ineffective. I seem to recall a lockout mechanism on some surge brakes. Perhaps it is used for backing. Butch
Don SSDD	posted 11-26-2014 12:55 PM ET (US) I think you can easily pinch brake lines with Vise Grips. Just see where the leak is and do this upstream of the leak. You'll be replacing the line anyway, if that is where the leak is. Some people have other solutions. I bought a 1962 Chev from a fellow, he said it would be safe to drive home, even though it hadn't been on the road in 10 years. I decided not to take a chance and had a deck truck bring it home. When later bleeding the brakes, I found a leak- the electric tape put over a leaky in the line had let go. Don
jimh	posted 11-26-2014 01:23 PM ET (US) Re Don's electrical tape repair story: early this Spring I drove my truck a few miles, and when I stopped a cloud of smoke came out from under the hood. There was a leak in a power steering hose. On a straight road, there was very lille fluid lead. When I started to maneuver to back up to the boat trailer, I was using a lot of power steering boost. The fluid squirted out and hit the exhaust manifold, making a lot of smoke. I taped over the leak in the hose with electrical tape so I could drive the car to a repair shop nearby to get the hose assembly replaced. The tape held for a few miles of mostly straight highway driving to get to the repair shop. I don't think the steel brake line could be so rigid it would resist deformation by ViceGrip pliers. The steel is flexible and can be bent by hand. I think it would be bent under the force and leverage of the pliers, too.
Jefecinco	posted 11-26-2014 05:33 PM ET (US) If the steel line can be bent by hand I imagine it could be squeezed shut with vise grips. The best course could be to bend it double and squeeze it shut at the bend. Butch
andygere	posted 11-27-2014 03:22 PM ET (US) Most modern cars and trucks have dual circuit master cylinders. This means that the reservoir is divided in to two chambers, one controlling the front brakes, and the other the rear. When your rear brake hose developed a leak, it compromised the hydraulic system for both rear brakes. After some time the rear fluid reservoir would empty out, and both rear wheels would be without hydraulic brakes. The front brakes would continue to function normally. A simple field repair to get you to the next auto parts store would be to simply cut the failed hose, and pump the brakes until the fluid in the rear system was exhausted. At that point, you would only have front braking, and whatever stopping power that might be provided by the trailer brakes. A better bit to keep in the spares box for a long trip would be a replacement brake hose and a bottle of brake fluid. After replacing the hose, the system could be bled well enough to get you home safely. A can of brakeClean is a good idea in case any fluid gets on your drums or rotors. I once made this repair on my '63 Impala in an auto parts store parking lot. That car had a single circuit system, and fortunately for me I discovered the minor fluid weep before the hose failed completely and left me with no hydraulic brakes at all.
jimh	posted 11-28-2014 05:50 PM ET (US) Andy--your comments are very interesting. In the case of my (1995) vehicle, the brake system had an early implementation of anti-lock brakes. Can you comment on how that might have affected the way the brakes would work with a leaking brake line to a rear wheel.
jimh	posted 11-29-2014 11:13 AM ET (US) I looked at the master cylinder of the brake system on my 1995 GMC truck. There are two outlet hoses from the cylinder. These connect to the anti-lock brake distributor mechanism. Since the master cylinder has two outputs, can I assume it has the dual brake system as described by Andy?
Ridge Runner	posted 11-29-2014 02:50 PM ET (US) In 1976 FMVSS Standard 105, came into effect in the United States and was required by law, but has been used on cars since the late 1960's. This standard requires that the master cylinder is divided internally into two sections, each of which pressurizes a separate hydraulic circuit. Passenger vehicles typically have either a front/rear split brake system or a diagonal split brake system. A front/rear split system uses one master cylinder section to pressurize the front caliper pistons and the other section to pressurize the rear caliper pistons. In a diagonal split system the right front and left rear are served by one actuating piston while the left front and the right rear are served, exclusively, by a second actuating piston. If either circuit fails, the other, with at least one front wheel braking remains intact to stop the vehicle. This system was developed with front wheel drive cars suspension design to maintain better control and stability during a system failure.
jimh	posted 11-29-2014 03:58 PM ET (US) Going back to my brake problem with the hose leaking from the left rear wheel, does the dual master cylinder system mean that if I had kept operating the brakes until I lost all the fluid in the one segment, I would have restored the brakes in the other segment? That sounds like a good outcome, better than my solution of limping home trying to never use the brakes.
Ridge Runner	posted 11-29-2014 07:31 PM ET (US) Yes, dual chamber master cylinders make the brakes less prone to failure. Each chamber of the master cylinder operates the brakes to one set of wheels either in a front/rear split or diagonal split system. If the brake line going to one set of wheels is broken or the brake fluid is lost through other means, the other set of brakes will still work properly.
Binkster	posted 11-29-2014 11:13 PM ET (US) jimh's comment (my solution of limping home trying to never use the brakes.) reminds me of a brake problem I had way back in the day. I was probably 18/19 at the time, and on summer vacations I drove a cab for a cab company owned by my aunts father. It was in a residential town with a railroad station running through the middle of it and most fares were either going or coming from the station. The cabs were a fleet of a half dozen '52 Chrysler 4 dr sedans, big lumbering beasts near the end of their life. Well, I get a call to pick up a fare, a woman, and bring her to the railroad station about 2 miles away. On the way to pick her up the brakes just failed. The pedal would go to the floor and the car would just drift to a stop, pumping didn't help. So of course I kept going and picked her up. I didn't mention the brake problem to her, no sense in alarming her. I kept off the main roads and only drove through residential streets all the way to the station. When I would come to a stop sign, I rubbed the right front wheel against the curb to come to a full stop. We made it and she never knew there was a problem. So much for being young. rich
andygere	posted 11-30-2014 02:16 AM ET (US) jimh, the antilock brake system (ABS)would operate independently on each braking circuit. The ABS system is a fantastic safety innovation, which builds on the earlier safety innovation of dual circuit hydraulic brakes. The ABS system uses speed sensors on each wheel to detect rapid decelleration, which happens just before the wheel locks up in hard braking situations. The ABS controller reduces braking pressure until accelleration is detected, then increases pressure until rapid decelleration starts to occur. It does this very rapidly, so as to pulse the braking pressure for each wheel in order to get the maximum stopping power without locking up any of the wheels. Since the ABS system operates independently on each wheel (or in some rear wheel drive vehicles on each axle), it allows dual circuit systems to operate as they would in a non ABS equipped vehicle.
BQUICK	posted 12-02-2014 02:50 PM ET (US) I would just pinch the brake hose with the vise grips. You have rear disc brakes on a 1995?
jimh	posted 12-03-2014 01:15 AM ET (US) I don't think I have mentioned what type of brakes are on a 1995 GMC truck in this discussion. As far as I know, the rear brakes are drum brakes. Actually, I don't think anyone has mentioned "disc brakes" in the discussion. How did that come up?
jimh	posted 12-03-2014 01:16 AM ET (US) I think my c.1995 ABS only has three circuits. It works the rear brakes as one circuit, and the front brakes as two separate circuits
andygere	posted 12-06-2014 03:11 PM ET (US) Jimh, the three circuit system you have was pretty common on rear wheel drive trucks of that era.
endus	posted 12-11-2014 12:01 PM ET (US) Good idea. Duct tape and a hose clamp might also work and allow you to maintain some functionality in the affected corner. If you had a piece of appropriately sized hose or a piece of rubber that might even be better. On SS lines I wonder whether you could get a good enough seal to make that work, though. Probably not. Air in the line might also be a problem.