Weak brakes after sitting up for years

[PaleoMan]

My '79 911 sat in the garage for several years. Now it's up & running, but the breaks are weak. Up on the lift, the front wheels don't turn easily, as if the calipers don't retract fully?

What to do? Change fluid, I assume, but then disassemble and clean calipers? or just drive it and hope they free up?

thanks in advance!

[wolds]

I wouldn't drive it the way it is. You might want to flush the system with fresh fluid. After you have done this step, pull the pads out of the calipers. Then, one caliper at a time open the bleeder and see if you can get each piston to retract into the caliper body. Once you have done that go through the bleed process again starting at the right rear caliper, left rear, right front and finally left front. At this point you know that the pistons are free and that you have fresh fluid throughout the system. If this works and you now have a firm brake pedal you would be good to go for awhile. While doing this inspect your rubber lines running to each caliper for signs of wear or cracking. Ultimately it might be time for a caliper rebuild which if you don't want to do yourself, Eric of PMB Performance can. Warren

[ClickClickBoom]

Drive it, get the brakes hot, had a sticky brake on my Carrera, dragged a little, the car had been sitting prior to me buying it, been driving it like it was stolen from a troll in the Santa Cruz mountains, gotta go I think he is after me again!

[PaleoMan]

I'll at least refresh the fluid. I don't have any help at the moment, and I know there are some gadgets that pump the fluid out so that you don't have to have somebody pumping the break pedal.. any recommendations for these pumps?

thanks very much for the helpful replies!

[wolds]

our host has a power bleeder which is what I use, others have used the gravity method in which case all you need is some tubing and a container to catch the old fluid as it's running out. Same sequence applies. RR,LR,RF,LF. Warren

[chrismorse]

When working with anything older than about 10 years, I would not recommend manual bleeding, that is with foot power. (particularly if the system wasn't flushed on at least a bi-annual basis)

Over the years, crud develops in the system and each pedal push scrapes "stuff" down the bore, Then, you end up with a pile of trash at the end of a "normal" pedal stroke in the bore of the MC.

The "UP" and "Down" of the manual bleeding pushes the piston & seal way past its "Normal" range, right over that pile of trash in the bore.

While I was a service manager/writer, I probably saw almost as many master cylinder failures right after a brake job/bleed, (with foot), as with normal wear and tear.

I am giving the ATE blue a try, just to make sure I can tell when I have "all" of the old stuff out. Perhaps I'll go with Motul next time.

I like the Mighty Vac but use just a little vacuum, so I don't pull air past the caliper seals.

If you see any signs of leakage, torn/deteriorated dust boots, or notice stuck pistons during the bleed, it might be time for some caliper overhauling.

If you just try the caliper bleed & exercise, pay particular attention to brake pedal travel or pulling in the weeks going forward. I had a stuck piston in the 911 and a seized slider in my work truck.

chris

[PaleoMan]

Good tips, Chris & Warren! I like gravity bleed idea, and will use blue fluid to tell when all the old stuff is out. Before today, I never knew it came in blue, what a good way to tell.
Thanks!

[crustychief]

The flexible lines that go to the calipers will swell inside as to make it difficult for the fluid to transfer back after braking. They probably need replaced.

[PaleoMan]

Well crap. The front wheels bled fine, but I could not get hardly any fluid out of the rear wheels. Might as well just pull them all and have them rebuilt?

I used a MightyVac, it held good vacuum but just couldn't suck the fluid out of the rear. Oddly, the instructions specify to start at the front, closest to the reservoir, then work to the back.

[RWebb]

replace the flex hoses with new rubber as previously advised

then see if the rears work

or... take the rears apart & examine the bores/pistons while you have the old flex hoses off

[ivangene]

trapped water for a 10 year period will rust

you have to find what is rusted and free it up
might just be the bleeders - pull them all the way out and look at them - Ive seen them plugged before - replace as needed

if the pistons are stuck that should NOT cause the fluid to not flow - its a blockage in the line or the bleeder

[PaleoMan]

I actually took the bleeders completely and blew through them easily, so they were clear.

I'll change out the rubber lines. before taking off the calipers.

thanks!

[PaleoMan]

I'm searching around for parts, ran across Automotion web site. Prices seem great -- all 4 hoses for $30 total, and the master cylinder is only $80 (says "was $195"). I figured I may as well do all the hoses and master cylinder.

Anything else that I should do while I'm at it? Still looking at possible caliper rebuilds, I realize, but may as well get these items done first.

Thoughts?

[PaleoMan]

I see from the tech articles that I need a 'flare-nut' wrench. The one illustrated is 11mm. Can I assume that my brake lines will all use this size?

Interestingly, my bleeder valves were different sizes, front vs. rear.

[RWebb]

Originally Posted by PaleoMan

Anything else that I should do while I'm at it?

inspect the calipers - bores, pistons & seals

if pitted or rusted then you might need to replace the hard lines

I'm not sure what P AG used when but some hard lines may be rust-prone steel

There is a guy in Sandy Utah (Eric?) who can restore calipers and make them very pretty

[r_towle]

PMB Performance in Utah (Eric) does a great job on calper rebuilds.

I might suggest you replace the soft rubber lines at each wheel first.
They get clogged with age and the pedal wont come back, calipers get tight etc.

When you remove them, cut them in half and look at the inside, you will see it.
Its like clogged arteries.

After that much time, those lines should be replaced anyways, and they are the cheapest part of the system, so get those done first, flush out all the old fluid and bleed the whole system.

rich

[PaleoMan]

I've ordered stainless lines from Pelican, and talked to Eric's shop. Will wait on the caliper rebuilds until after I try the new lines.

I'll also take a caliper off and see if I can do a quickie on it myself. Have nothing to lose, if I can't do it, then it goes to Eric.

They quoted me a price of about $560 for all 4 calipers. Not bad, I suppose, but sure would be nice to be able to do those myself with just a kit.

Thanks for all the help!

[PaleoMan]

Originally Posted by r_towle

PMB Performance in Utah (Eric) does a great job on calper rebuilds.

When you remove them, cut them in half and look at the inside, you will see it.
Its like clogged arteries.

rich

Clogged arteries indeed! In the picture you can see light through what's left of the opening of my old brake lines. I don't know how big the opening should be, but I'm guessing much bigger than this!

I put Simvistatin in the gas tank to see if that would open them up. Actually I did replace all brake lines with the stainless from Pelican, and now brakes work great. I figured I'd need a caliper rebuild, but may have dodged that bullet.