[67drake]

I occasionally read threads here about old rubber brake lines causing brakes to drag. I’ve never run into this, and was slightly skeptical till now.
2 weeks ago I fired up my GTO after it had sat for 3 years or so. I wanted to burn the old gas off, and it was a beautiful day out here in the boondocks, so I started driving a big 50 mile loop around my home town.
About 2-3 miles from home, on the way back, I noticed a slight brake drag. Took it home and pulled all 4 wheels, adjusted and cleaned the brakes, freed up the emergency brake cables. Everything seemed great.
Took another ride taking the same route and the same thing happens in almost the identical spot, but now a little worse. None of the wheels seems locked up both times I jacked the wheels up, after each trip.
I ordered new rubber brake hoses, based on what some members here had mentioned, and new wheel cylinder rebuild kits. The first wheel cylinder I rebuilt wasn’t too bad. Then on to the rubber line. When I got it off I couldn’t even get a hint of air through that line with my air nozzle at 125 PSI.
OK, I believe you guys now!
Curious how the other side turns out when I have time to do it.

[Scott65]

It's a real thing for sure. Went through this not too long ago on my Dad's GTO. Unbeknownst to me he still had all the original rubber lines. That thing was terrifying to drive. I changed all 3 flex lines and it was a pleasure to drive after that.

[77 TRASHCAN]

You are doing the proper repair.

Although I'm sure you are working on an all drum car, the same can happen to a factory disc car also (captain. Obvious).

Thankfully GM used stainless caliper pistons. Most times a caliper can be easily rebuilt.

If you own one of the off brands ( Ford dodge) they generally use plastic pistons. Forget about bringing one of those calipers back with a kit.

[MatthewKlein]

Originally Posted by 67drake

I occasionally read threads here about old rubber brake lines causing brakes to drag. I’ve never run into this, and was slightly skeptical till now.
2 weeks ago I fired up my GTO after it had sat for 3 years or so. I wanted to burn the old gas off, and it was a beautiful day out here in the boondocks, so I started driving a big 50 mile loop around my home town.
About 2-3 miles from home, on the way back, I noticed a slight brake drag. Took it home and pulled all 4 wheels, adjusted and cleaned the brakes, freed up the emergency brake cables. Everything seemed great.
Took another ride taking the same route and the same thing happens in almost the identical spot, but now a little worse. None of the wheels seems locked up both times I jacked the wheels up, after each trip.
I ordered new rubber brake hoses, based on what some members here had mentioned, and new wheel cylinder rebuild kits. The first wheel cylinder I rebuilt wasn’t too bad. Then on to the rubber line. When I got it off I couldn’t even get a hint of air through that line with my air nozzle at 125 PSI.
OK, I believe you guys now!
Curious how the other side turns out when I have time to do it.

If there is a bracket on the hose rust can build up inside the bracket causing the hose to act like a check valve. Master cylinder pressure is enough to overcome the restriction but there is nothing to force the oil back to the master cyl.

[mgarblik]

There is an almost sure fire way to diagnose these collapsed hoses. You do need to be careful though. After your test drive with the brakes dragging, pull the wheels. Go to the wheel and brake drum that seem to be the hottest. Then carefully, crack open each bleeder at the caliper or wheel cylinder. If the fluid dribbles out as normal, the hose associated with that component is still OK. If the fluid shoots out under pressure, you found the collapsed hose. The fluid will be VERY hot. So wear gloves and be careful. But this will isolate the problem hose. Best practice is to replace all 3 or 4, depending on design every 10 years or so. Glad you found the issue.

[rohrt]

Its like bigfoot. You don't believe it until you see it first hand.

[72projectbird]

Cut the old hose open. You'll be amazed at how small the opening is on a collapsed hose. It's a wonder it even did anything in the first place.

[Keith Seymore]

Originally Posted by Scott65

It's a real thing for sure. Went through this not too long ago on my Dad's GTO. Unbeknownst to me he still had all the original rubber lines. That thing was terrifying to drive. I changed all 3 flex lines and it was a pleasure to drive after that.

Agree. We see this all the time in the vintage truck world.

K

[67drake]

Originally Posted by mgarblik

There is an almost sure fire way to diagnose these collapsed hoses. You do need to be careful though. After your test drive with the brakes dragging, pull the wheels. Go to the wheel and brake drum that seem to be the hottest. Then carefully, crack open each bleeder at the caliper or wheel cylinder. If the fluid dribbles out as normal, the hose associated with that component is still OK. If the fluid shoots out under pressure, you found the collapsed hose. The fluid will be VERY hot. So wear gloves and be careful. But this will isolate the problem hose. Best practice is to replace all 3 or 4, depending on design every 10 years or so. Glad you found the issue.

Good idea.
I did check by feel the temperature of each rim, after the second trip. Both front rims hot, but not hot enough where I couldn’t keep my hand on them. Back rims were warm. Anyway, both front rims being about the same temperature, I expect to find the rubber line on the other side is in similar condition. The rubber hose in the back of the car I replaced new about 7-8 years ago.

[Scott65]

Replace them all and be done with it. And you'll have the benefit of knowing exactly how old all are and when to expect to do it again, etc.

[Goatracer1]

It doesn't have to be that old a car either. It happened on my Chevy Crew cab when it was only about 10 years old. First one side in the front and then the other.

[Schurkey]

I've personally owned three brake hoses that were totally blocked, prevented brake application on that wheel.

I've owned at least one brake hose that was restricted, so that brake application was slow/weak.

I've never owned nor seen a brake hose that acts like a check-valve, where the brake applies but won't release.

[Scott65]

Dad's rear behaved that way (applied, but didn't wanna release, though it would just in a delayed fashion), oddly was much worse on one side.

[Schurkey]

Originally Posted by Scott65

Dad's rear behaved that way (applied, but didn't wanna release, though it would just in a delayed fashion), oddly was much worse on one side.

Entirely possible based on one side having weaker shoe return springs, a more-seized wheel cylinder, or a damaged (dented, crimped) brake tube between the hose and wheel cylinder.

NOT possible based on a restricted brake hose, since one hose services both rear brakes.

[Scott65]

It was strange for sure. But the problem side had a new wheel cylinder installed previously... Go figure. Thankfully the new brake lines put everything back right with the world again in the braking department.

[67drake]

Finally got back out in the shop tonight. Yup, drivers side rubber hose clogged solid too. It ought to stop like a new car after this.