Rust jacked brake hose
 

I'd heard of this but never had first hand experience.

Vehicle is off topic, a '91 Z28 but this could happen on any vehicle including our old trucks. It drove and stopped well, except hard braking at highway speeds it was all over the road.
Suspension and alignment was gone through and problem persisted.
Pressure bleeding brakes, one side spurted out, one just dribbled.

Removing that hose you could not blow through it, 125 PSI from compressor made fluid lethargically drip out.

On dissection the hose was rust jacked under the control arm mount.
This was not a rusty car by any means and both hoses looked Ok rust wise.
Attachment 2349310
Hose from other side for visual comparison, it is also partially occluded.

Attachment 2349311

Attachment 2349312
This is cut open with razor knife, no material was removed in cutting. Almost 100% closed off!

New front brake hoses and no other changes, now it stops straight at speed.

Something to think about.

Re: Rust jacked brake hose
 

what is "rust jacked" ?

Re: Rust jacked brake hose
 

oxide/rust expansion causing deformation

in this instance it did not take much expansion under the crimped area to force the hose closed

google truck frame rust jacking or concrete rust jacking for more common instances. it may go by other names as well

Re: Rust jacked brake hose
 

Very interesting. So the brake hose bracket was actually pinching the hose closed? due to rust on the bracket?

Re: Rust jacked brake hose
 

yes, rust between the swaged on bracket fitting and the hose

Re: Rust jacked brake hose
 

I've had it happen on a couple of squarebody trucks. Sometimes it will get worse as you drive and then finally locks up.

Never cut one apart but I'm sure it was the same problem.

Re: Rust jacked brake hose
 

My Iroc-Z had some rust starting on those same brackets but it wasn’t bad enough to pinch the hose yet. I changed all the brake hoses before I put it back on the road.

Re: Rust jacked brake hose
 

Great pics and explanation thank you! Most folks don't flush/replace brake fluid etc but imho it should be done every 50k at least.

Re: Rust jacked brake hose
 

we see that happen at the shop where I work, sometimes it will allow fluid to pass through the hose to the caliper but won't allow the caliper to release since no pressure going backwards. easy way to confirm if it's a caliper sticking or the hose not allowing it to release, just open the bleeder, if fluid squirts out and the rotor turns freely afterwards the hose is bad, if the rotor won't turn and no fluid squirted out the caliper is sticking. if you're still not sure replace both of them, better to be safe than sorry with the braking system.