Thread: Brake Pull

Something that I almost tore my hair out tracking down was attempting to get my fully rebuilt Land Rover to brake in a straight line. The 350kg donk I had shoehorned in in place of the 350lb Rover V8 needed a tad more stopping power so I fitted discs. Took a week pulling everything to pieces to find out why it braked sort of straight with modest brake pressure, but lurched to the side doing an emergency stop. And bugger me when I was down to grasping at straws I used an air line to blow out all the hydraulic lines. One flexible hose made a screaming sound, so I inspected and blow me down, there's a small piece of rolled up swarf sitting inside the end fitting of a brand new brake hose

I’ve heard of a flaw inside a brake hose that was acting like a non return valve when under extreme pressure - just throwing it out there.

Yeah, partially blocked brake line on the left side creating a restriction. There's not that much force in the setup of a vacuum assisted brake system so any restriction really shows up. If you have a master cylinder in that with individual lines to the front disc's it could be in there even. I've had gunge getting caught up inside the connection to the caliper and making a restriction there, gritty crap. Not easy to find...

I dont see how anything could get inside the system if you havent had it apart.

sounds like caliper pistons aren't moving out evenly when fluid pressure rises.
suggest replacing seals around pistons or just free up/clean manually.

The rubber seals to swell over time, and eventually restrict piston movement.

Originally Posted by Finnwolf

I’ve heard of a flaw inside a brake hose that was acting like a non return valve when under extreme pressure - just throwing it out there.

had that problem quite a few times over the years.

Originally Posted by trapperjohn

sounds like caliper pistons aren't moving out evenly when fluid pressure rises.
suggest replacing seals around pistons or just free up/clean manually.

The rubber seals to swell over time, and eventually restrict piston movement.

Yeah what he said
And give everything a good dose of red rubber grease don't use any other lubricant.

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Originally Posted by trapperjohn

sounds like caliper pistons aren't moving out evenly when fluid pressure rises.
suggest replacing seals around pistons or just free up/clean manually.

The rubber seals to swell over time, and eventually restrict piston movement.

What also happens is you can get a band of rust in the caliper between the dust boot and the piston seal. You have to pull the piston out to see it sand it or we give it a fine bead blast. That binds the piston up

Update: I went to swapped around brake hoses to see if its a hose problem but fitting nuts are seized so I swapped around disc rotors. seems to make a difference when driving but the roads around where I live are not nice and flat. sometime it would pull to the right, sometimes to the left, but half the time it would stay straight. I'm gonna take it for another drive tomorrow for another test. If it continues to pull mostly to the right I'll try what @XR500 has done by blowing out the brake line and may buy a piston seal kit. If it starts to pull mostly to the left I'll know its the rotor and pick one up in a few days

Originally Posted by tac a1

I dont see how anything could get inside the system if you havent had it apart.

Corrosion from moisture getting absorbed into the fluid, particles break free and collect at restrictions is what it seems like.

I took the ute for another drive, 5km round trip. Under normal mind braking ute stays mostly straight but under heavy baking where the brakes lock up it still pulls to the right. I did another brake pressure test after swap around rotors and the left now has higher brake pressure whereas it was then other way round. I did replace all shocks two months ago so wondering if it needs a wheel alignment, also noticed torsion bars arent set the same height.

Originally Posted by Three O'Three

I took the ute for another drive, 5km round trip. Under normal mind braking ute stays mostly straight but under heavy baking where the brakes lock up it still pulls to the right. I did another brake pressure test after swap around rotors and the left now has higher brake pressure whereas it was then other way round. I did replace all shocks two months ago so wondering if it needs a wheel alignment, also noticed torsion bars arent set the same height.

Ah yep, get the suspension leveled, pop the shocks out and check/replace if needed, check the rear leaf springs, check the tyre tread depth pressures and then do the alignment.