So I was talking to the mechanic who fixed my "other" problem and he mentioned that the brakes are really grabby. Meaning that (especially the driver rear) with catch hard with a slight brake tap. And said that most likely the lines were collapsing and needed to be replaced. Also said it could be the cylinder in the rear leaking a bit and causing the grip.

So question is, how tough is it to replace the lines? I have done a ton of brake jobs just not a full line replacement...

Any other suggestion as to what it could be?

 

You can buy kits with pre bent tubes. You can get them in standard or stainless as well. I ended up going to the autoparts store and bought a roll of regular tubing and bent my own lines. Also bought the fitting and rented the double flare tool. Double flaring is actually pretty easy. For bending the lines just be careful when you remove the old ones and match it up to the them.

 

Was it really that much cheaper to bend your own?

 

I think so. I think you can get them from inlinetube.com if my memory serves me right. I also wanted the extra line because I needed to run new vent lines for the fuel tanks too.

 

Makes sense, I'll check around.

 

one other note. i replaced all of my brake lines (well except for the lines running along the rear axle to each wheel because they were in ok enough shape). but i digress, around the master cylinder and also some parts along the frame up front there is coil spring around the brake line. i definitely ordered the coil spring (i think from inlinetube --- you can get it by the foot) but got the actual brake line from autozone. if you do make your lines from scratch yourself be sure you can get the fittings or reuse the current ones before you start the project. A couple I had to reuse and the others I had to go around to a few different autoparts stores for all of the fittings.

 

The only reason you need to replace the hard steel lines is if they are really crusty with rust. They will not cause braking problems unless they burst. When they need replacing, I just go to the local store and use the universal lines.

The rear cylinder leaking could be a legitimate cause for grabby rear brakes. It will get fluid on the linings and make them grab. If this was the case though, you would find yourself putting fluid in the master cylinder once in awhile because of the leak.

If they are actually grabbing, the most common cause is sticking parking brake cables.

 

Would it do it only when I hit the brakes? Have to check that out. Thanks!

 

I agree with Franklin2, there is no need to be replacing brake lines - steel or rubber -in an
attempt to cure symptoms like these.

In my case, the problem was resolved by bleeding the brake system including the
combination proportioning/metering/differential valve.

 

Got a leak from the rear of the MC, so it's time to change the booster/MC assembly again. This will be #3 in 29+years. Also gonna replace the rubber lines while the system is down. The 'new' MC looks like it's been rust-proofed with a paint of some sort.

 

I checked it out last night in detail and the e-brake seems to be in perfect order. It is only happening on the driver's side rear which has the symptoms of the e-brake. Maybe I'm missing something looking at it... What's the best way to diagnose it?

Seems like a pretty easy fix, I'll bleed it out tonight and see what I get.

 

that's interesting. brake fluid seems like the most corrosive fluid on earth. i'd be curious to know how it holds up over time.

 

Quote:

Originally Posted by ospreyguy

Seems like a pretty easy fix, I'll bleed it out tonight and see what I get.

Remember about the proportioning valve, it's got a pin that needs to be pulled
or pushed (depending on model of truck).

The following may help although there have been no real answers, at least not
yet....

https://www.ford-trucks.com/forums/1...ing-valve.html

 

The other thing I would check would be to make sure the caliper isnt freezing up on the rotor and making the brakes grabby. Lines are easy especially if they are the front. Prebent are not worth the price in my book.

 

I think there is a disconnect between you and your mechanic. I *think* he misspoke and was really talking about the rubber hoses.

The rubber hoses (which some folks call brakes "lines") are not one layer. They are multilayer and CAN collapse internally and will NOT show a sign on the outside. Front wheel drive General Motors cars were notorious for this ... I have not seen a Ford truck do it ... but it don't mean that it couldn't.

YES ... this will give you a "grabby" brake ... mostly because when the rubber hose collapses it will not allow all of the pressure to normalize at that wheel when the brake pedal is released ... therefore, that wheel already has pressure in it before you hit the brake pedal.

Steel lines CANNOT collapse internally ... BUT ... if a steel brake line is partially crushed the same thing can happen ... pressure will NOT fully release and will stay up at the closest wheel when you lift you foot off the pedal. I used to see this a lot on MGB rear brakes.

Wheel cylinders and Disc brakes calipers can do the same thing if the piston is starting to seize in the bore. The master cylinder can make pressure sufficie3nt to PUSH the [piston out ... but there is not enough force to push the pistons back IN ... even if they stick *just a little bit* they can cause a grab or pull.