No Brakes - how hard to replace master cylinder plus lines?, looking for some guidance before I dig into my manuals... Options

[potomacmidget]

Merry Christmas everyone,

So, my brakes have been really soft, and I figured they were due a bleeding so I bought a pressure bleeder (watched Ian Karr video) and put my car on jackstands and removed all the wheels. Topped off the reservoir with fluid, then when I inspected the master cylinder and observed it was visibly "wet" with what I could only suspect was fresh fluid. First thought was "ok, not good, that must be my pedal problem" then I reached in there with an open end wrench to see if I could snug the connection, and the tubing (vertical) was not even connected to the MC, it just swung away when I touched it, then all the fluid poured out. I guess the threaded part of the tubing rotted away in the MC?

Regardless - looks like I need a new MC, and will have to inspect/replace sketchy lines, etc., and all that comes with that project.

Prior to diving into my collection of service manuals, any guidance on the challenges of this job? Do's and Dont's? It looks a bit nightmarish to access the MC, and since my simple job turned a lot harder, I will wait until my garage is warmer than 30F. All advice appreciated...

thanks,
Reg

[mepstein]

It’s a pita but easily done by someone without much mechanical knowledge (me) and just takes basic tools. Patience is the most importance part of the repair. Replace your caliper soft lines if it’s been more than a couple years. Again, a bit of a pita but they swell shut and make the brakes inoperative.

[r_towle]

If you have decided to replace all the hard lines, reach out to PMB performance and ask if he has pre-bent lines.
It will make your life easier.
Still a challenge, but pre bent lines get you closer

[emerygt350]

If you are going in, you might as well replace MC but it may be fine, you just need new reservoir lines. I am always a little conservative about replacing old parts that are still good. Build quality hasn't exactly improved on most things in the past 50 years. The MC might be a worthy exception to my rule...

[mepstein]

I had an MC give out on me just as I pulled into my garage. Managed to stop with my e-brake but it was a close call. So now I’m in the - replace if questionable - camp.

[Craigers17]

If you’re going to replace the MC, just be aware that once you start the process, you will likely open up a can of worms where, “while you’re in there”, you’ll want to assess the condition of your pedal cluster and possibly want to refurbish. Which if/when you remove the cluster, you will be tempted to replace the accelerator and clutch cables…so on and so forth.

Also, while maybe not necessary, the MC and reservoir lines are more easily accessed by at least partially lifting the gas tank. While you have that raised, you’ll likely be tempted to replace the under-tank fuel lines, which will in turn tempt you to replace the fuel sock filter in the tank, which will require you to replace the gaskets that go between the tank and the fuel line fittings. Just saying…

[technicalninja]

It sounds like the feed tubes came out of the master.
There is pair of grommets that can rot and are difficult to install the metal lines in.
These can also be damaged by poor installation.

https://pmbperformance.com/products/master-...porsche-911-912

Below the grommets inside where their recess is a steel "stop" washer. These are critical to not lose and re-install below the grommets. There is a chance yours could be missing.

The original master was 17mm, parts are NLA.

What replaces it is an early 911 master. 1974 works for look up.

https://pmbperformance.com/products/19mm-at...che-914-4-914-6

Which can be had "clone" brand URO 9113550120 for less than $100. Rock Auto was $80.

There used to be "kits" to make the first 6" of steel line remote from the main tubes to ease installation. I couldn't find one.

Getting the tubes into the grommets is the bitchy thing here. After you do it once you'll get better. That first time can be (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif)

Pulling the gas tank will help and probably needs to be done for afore mentioned PMs.

If the master is fresh (less than 5 years old) it might be someone screwed up on the line install and you MIGHT just need the grommets.

If the system is OLD (more than 20) then you and PMB are going to become friends as ANYTHING made from rubber should be replaced. These include master cylinder, rubber lines, calipers/caliper kits, and the rear pressure valve.

[potomacmidget]

Dear All -

I really appreciate all of the responses, thanks so much. I surfed the PMB website, and although I received a great car from a fellow forum member, (over 10 years ago) I think it is time to go through all the components and replace the lines and MC too... I may be reaching out for more help, once I start digging in. Well, I always need a project...and now I have got one...

Best,

Reg

[DC_neun_vierzehn]

If you’re going to replace the MC, just be aware that once you start the process, you will likely open up a can of worms where, “while you’re in there”, you’ll want to assess the condition of your pedal cluster and possibly want to refurbish. Which if/when you remove the cluster, you will be tempted to replace the accelerator and clutch cables…so on and so forth.

Also, while maybe not necessary, the MC and reservoir lines are more easily accessed by at least partially lifting the gas tank. While you have that raised, you’ll likely be tempted to replace the under-tank fuel lines, which will in turn tempt you to replace the fuel sock filter in the tank, which will require you to replace the gaskets that go between the tank and the fuel line fittings. Just saying…

This is really, really good advice, be prepared to also do X, Y, Z “while you’re in there.”

Last spring I pulled my corroded gas tank to swap in a new Dansk tank … and “while I was in there” I saw all of the access I had to fuel lines, fuel pump, fuel filter, fresh air box motor, seals, and tubes, wiper rack/motor/isolator, seals, and all kinds of other stuff.

A one day project turned into a multi-month project (partly due to figment issues with a couple of parts that needed to be returned). Glad I tackled all of it and great peace of mind, but I sure wish I knew the can of worms it was going to open in advance!

[rhodyguy]

While shopping at PMB, get 4 speed bleeders. Source about 8’ of clear plastic line that fits the speed bleeders.

[fiacra]

Since you plan to do all of the lines, including the supply lines from the reservoir, I would install the lines and rubber plugs on to the MC first and feed them up to the MC reservoir. You do need to move the gas tank to do this, but you don't have to disconnect any lines or take it all the way out if you are not doing anything on the tank. Just prop it out of the way. Still, as already mentioned now is a good time to replace the lines under the tank, filter, sock, etc. Trying to seat the metal lines/plugs on the MC with it installed is probably the most frustrating part of the job so it is nice to be able to do it before installing the MC.

A few other things that randomly come to mind:

- Truly getting all the air out of the lines is a lot of work. I use a Motiv pressure bleeder. It is invaluable for this job, and has been a real help on my other vehicles. Lightly tapping the brake pressure regulator with a mallet can help free air bubbles. Bench bleed the MC before installing. I have gone through three quarts of brake fluid before being satisfied that all the air is out. You may not need as much, but they are brakes, the things that stop your car and (hopefully) keep you from getting killed or injured, so be sure.

- Don't forget you may need to replace the grommet above the MC that the metal lines go through.

- Make sure you have new copper washers for the banjo fitting. You can anneal the old ones, but new is better in my opinion.

- When replacing the rear soft lines the forward clip that holds them to the bracket looks near impossible to get off. There is a notch in the back of the bracket that you can't see that you can get a screwdriver behind to lever the clip forward so you can then more easily get it off. A Porsche mechanic I know puts vice grips on them and levers them off that way. Either way works, or come up with your own. I stared at them for a while before I figured it out.

- Finally, spend the extra money and get the ATE MC. I got my first one from a popular supplier on this board, and it turned out to be defective. Nothing fun about eating the cost of a part and then having to do this job all over again. Not trying to disrespect that supplier, I have lots of other quality parts from them on my cars, but that experience left a bad taste in my mouth. It was a poorly seated casting plug that leaked. And yes, I did contact them to let them know about the defective MC. I had the part for a few years before putting it in so I didn't expect a refund. They met my expectations there (IMG:style_emoticons/default/biggrin.gif) .

- You have already discovered that PMB is your friend in this process. High quality parts, responsive, and willing to answer questions. They get my money every time if I have a choice in suppliers.

- If you have a 17mm MC that you are replacing with a 19mm MC (which you should do) don't forget that it will feel different. You will need more force on the brake pedal. Don't be freaked out by that. You'll get used to it.

Good luck!

[technicalninja]

(IMG:style_emoticons/default/agree.gif) Well done Fiacra.

That tapping trick works on the master as well. Fill it, lightly tap the master till no more bubbles in reservoir, I loosen line fittings at master till they drip, tighten. Tap master again, loosen line fitting and watch when bubbles stop. Tighten fitting.

I HAVEN'T bench bled a master in 2 decades. I can do the above with a cloth dish towel to catch the fluid and not get any on the car. You don't have to drip very much if you get it right.

Now, most of the time I'm in the engine compartment of an appliance car and the master access is better but you can be super clean under a 914 too.

I can change a master cylinder on a Honda Accord, and get it perfectly bleed, without ever touching the bleeders at the wheels doing it this way.

One thing I've decided to add to 914 bleeding is a "stomp" procedure to clear the air out of the rear control valve. It has a section similar to an accumulator and the only way to clear an accumulator is to fill and release it.

Bleed master and front brakes. Open feed fitting at rear control valve until it drips, connect and tighten. Bleed rear brakes until you think you are good, tighten bleeders.

At this point you should have a hard pedal. Stomp it hard 4-5 times. This should operate the rear valve which has to reach 525+psi before it does its thing.
Re-bleed rear brakes, you should get a few more bubbles.
Lather, rinse, repeat...
The 19mm master should do two things, harder to push (not bad, many prefer) and raise the pedal height.
You should be HIGH and HARD when complete.

That rear control valve always gets overlooked, never gets serviced and I'd bet money yours is original. PMB is the only source for me there.
If I was re-doing "hydraulics" that would be the second item on the MUST replace list after the master.
They can rebuild yours; they may have completed units done for "swaps" which you would do a core return of your old one after you completed the job.

A pressure bleeder such as Fiacra suggests makes the above process quicker and easier (and maybe messier too). My method will work with gravity.
Personally, I use a "Vacula" and suck the fluid through the lines/bleeders.
It's really the same either way. Using a pressure differential to move the fluid.


Do look at your pedal assembly. If it needs redo, I'd go Bruce Stone and I can do that myself...

Most important tip: DON'T GET ANY ON YOU!!!
Brake fluid absorbs easily via skin, the liver can process it, but the kidneys cannot, it stays forever, and is cumulative. Water is the solvent.

I only use DOT4, I NEVER use DOT5 (True silicone) but am fine with DOT5.1
Street cars don't really need 5.1 IMO.

Check/Set master cylinder free play properly.

[VaccaRabite]

I just did this on my car. After 15ish years of service the master cylinder failed. I took that as a sign to replace everything except the hard lines which were still in tip top shape.

Call PMB. Owned by Eric Shea. They specialize in brakes and they have everything you need. They are who Porsche goes to to rebuild classic brake systems. Eric got his start with 914s. He's an Admin here and owns the 914world FB page. He's also about the most honest person you will ever deal with, and will tell you what's up whatever the issue is. I buy everything through PMB these days.

For hard lines, don't use steel or stainless. Get rolls of copper nickel tube and the right sized ferrules. Easier to bend and shape. Won't ever rust. More kink resistant. This is the one single component that I might not buy from PMB. I bet Eric has pre-bent lines though, which sure makes this step easier.

For the soft lines, use the PMB stainless soft lines.

Do not replace the the prop valve on the firewall with a T. Really. Seriously. If you are thinking about it, STOP. You do not ever want your rear brakes locking up before your front brakes. There are some old guys that advocate doing this. They are wrong. Period.

Rebuild your brake calipers. You know where I'm going to tell you to go. Yup. PMB. There are sets on the shelf ready to go for the 914, and he wants your cores.

Pads and rotors? PMB. Do you have to? No. But you should. Again, call and talk to them. Tell them what kind of driving you do and they will tell you what you want for that kind of driving.

I don't work there. I'm not family. But I've known Eric for decades and watched his business go from a home garage to the powerhouse it is today. He remembers his roots and builds pretty loyal customers.

Zach

[potomacmidget]

Hi Zach, technicalninja, Fiacra, Rhodyguy, ,DC neun vierzehn

thanks again for all the help, I really appreciate it. I already have an order into PMB, and I too am of the opinion that I would rather get the new lines on the MC, and then push the lines up to the reservoir, so looks like I will probably pull the tank and find more projects (I still have my original plastic fuel lines, and I KNOW those need to go too) - perhaps lots to do between now and warm weather.

I am sure I will be asking for more guidance...

and I think I need to change my screen name.. prior to buying the 914, I had an MG midget, and I live near the potomac river, and I had to pick a screen name for the MG, but that car is long gone now...but now Potomacmidget just sounds weird....

Again, really appreciate the help. Will keep you informed of my progress.

Best,
Reg

[technicalninja]

Midget to 914...

Awesome trade! (IMG:style_emoticons/default/first.gif)

You are one of a few!

Most folks find the 914 tiny!

You KNOW what small means...

My very first project car (only drove it once) was a 1964 Austin Healy Sprite.

All the bad stuff that a "Bug Eye" had but not the eyes!
Glad I never went back...

914Mac
914midget
Poto914

Welcome to the World!
We're slightly "on the spectrum" but that's common for car guys anyway!

(IMG:style_emoticons/default/welcome.png)

[thomasotten]

If you do replace with stainless steel, be sure to check them for leaks a day later and retighten as necessary. Stainless steel is harder and doesn’t compress in the flare as easily as normal steel.

[Craigers17]

Here's a link to my virgin experience in this process a few years back. You might find some tidbits that are helpful. Hopefully my ignorance, combined with the experienced insights of more informed members, might make your life a little easier.

http://www.914world.com/bbs2/index.php?sho...=348755&hl=

[Jamie]

Midget to 914...

Awesome trade! (IMG:style_emoticons/default/first.gif)

You are one of a few!

Most folks find the 914 tiny!

You KNOW what small means...

My very first project car (only drove it once) was a 1964 Austin Healy Sprite.

All the bad stuff that a "Bug Eye" had but not the eyes!
Glad I never went back...

914Mac
914midget
Poto914

Welcome to the World!
We're slightly "on the spectrum" but that's common for car guys anyway!

My dear old "Bugeye" and you demean it! Was my only car for first 15 yrs. of driving starting in 1960, and I would love to have it back now. But when the passenger door mounts rusted out and door about fell off I knew the end was now, not near. Rebuilt the 948cc engine in my dorm room in about a week, and was a most reliable travel companion since I kept it going for so long. (IMG:style_emoticons/default/aktion035.gif)
(IMG:style_emoticons/default/welcome.png)

[gereed75]

Great advice for the OP. I have used several premade PMB lines and they are great

Ok, so now for the thread drift - what is the consensus of the world on using -3 AN lines and fittings on a car that you are not worried about originality on. Pretty common in the race car world and in many cases much easier and can eliminate the need to remove suspension components to access fittings/hangars. Can often eliminate couplers and other fittings also minimizing leak points

I am about to install a -3AN kit on my driver quality E30 M3.

[Superhawk996]

I am about to install a -3AN kit on my driver quality E30 M3.

Really bad idea. If you have a bad accident involving brake issues - you better lawyer up.