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

[mepstein]

I’m no brake expert (for sure) but we like to stick to the stock style parts, even on high performance builds, so the car can be worked on down the road and parts easily obtained in the future. If that’s not a concern for you and it’s typical in the industry, I don’t see why not.

[technicalninja]

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.

I'd stay away from custom stuff unless it was a REQUIREMENT.

And if I had a "driver quality" E30 M3 I'd be doing the HAPPY dance!

Wouldn't make major changes to that at all...

I DO have a very nice 98 E36 M3 and it's appreciated so much in the last 10 years that it will stay "basically" stock configuration.

I was going to LS6/T56 it. Now, I'll just add a snail to the stock engine...

[gereed75]

Hawk, I get your perspective but I don’t see any reason that the possibility of being in “a bad accident involving brake issues” goes up with a -3AN system. From an engineering perspective it should go down. The AN system has substantially fewer connections than the stock system - like four as opposed to maybe a dozen. Seems better to me.

Any recent examples of this technology being used in OEM applications?

Not at all looking forward to having to drop the rear subframe to replace with stock.

[Superhawk996]

Hawk, I get your perspective but I don’t see any reason that the possibility of being in “a bad accident involving brake issues” goes up with a -3AN system. From an engineering perspective it should go down. The AN system has substantially fewer connections than the stock system - like four as opposed to maybe a dozen. Seems better to me.

Any recent examples of this technology being used in OEM applications?

Are we talking the same AN fittings as shown below?

No OEM is ever going to AN fittings. Cost is one thing. The multitude of failure points within the fittings is another. As far as I’m aware there are no DOT approved AN fittings. No OEM is going to use Non DOT parts.

Now I get the argument that AN derives from mil-spec parts. Despite what marketing may say, are you getting Mil-spec parts in retail? Not likely.

I have also personally used AN extensively in racing. Again, that’s another story where equipment is constantly being maintained and inspected. In the rare event of a failure, all activity is on closed course with willing participants that have signed waivers acknowledging the danger of the activity. Completely different than street use.

[iankarr]

I made a few videos on installing a new MC and bleeding...

MC bleeding in the car:
https://youtu.be/OOSer774NqM?si=Pz_J5OTd2xuHq8z6

Bleediing the system:
https://youtu.be/ymHHD6uKhfc?si=5aatSHLVVJZLtZqk

You can do it...

[bkrantz]

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.

With SS lines be ready to really crank on a flare nut wrench (don't use a regular open-end wrench). The SS flares are indeed much harder. When I installed the PMB SS line kit I had to tighten fittings much more than I ever did on brake lines before, and I still had some drips.

All this made me question the need for SS lines. Maybe if you drove in salt water?

[technicalninja]

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

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif)
Actually, with EVERYTHING he said!

Including the CN brake lines!
If you have to DIY it's the ONLY thing to use. I prefer it to the stainless and the CN doesn't rust/corrode either.
Bunch "softer" which not only helps sealing it makes fabrication easier...
It's not stupid expensive either!

I see ZERO downsides to CN for any hard lines in the car, not just brake lines!

And I've already purchased 90% of my brake parts (5 lug conversion) at PMB.

[gereed75]

These lines are kitted with factory made fittins and use Teflon lines with braid and then PVC cover, not a DIY AN fitting. They do terminate to the brake system with an adapter fitting.

https://www.chasebays.com/cdn/shop/files/Ch...ng?v=1698182168

Looks pretty robust and way fewer connections than multiple steel lines with a rubber hose termination to the caliper

[Superhawk996]

These lines are kitted with factory made fittings . . .

Yeah - misunderstood what you were planning. That’s better than DIY. Presumably there is some pressure testing and quality control going on there. I didn’t look to see if those particular lines are DOT compliant. There are some stainless flex lines that are. Not sure about these with the AN flare.

Here’s the thing. Controlling a long flex line is not as simple as it seems.

The flex line has to be kept from contacting other parts as wheel cycles from full jounce to full rebound and lock to lock steering. I’ve personally seen instances where the line was too short and was getting pulled under tension at full rebound. Likewise I’ve seen instances where the flex line contacts the tire; the stainless braid quickly acts like a saw.

The flex line has to be kept from resonating and whipping around in the wind, otherwise the line will fatigue and break (eventually). Seems simple to tie wrap it to something . . . Now go back and check to see that you still have full wheel travel and no contact. Usually not as simple in practice as it seems.

Teflon lines require larger minimum bend radius than OEM style rubber flex hose. Trying to not bend lines too tightly while avoiding the other rubbing and resonance issues results in long(er) flex lines.

There are advantages to the way the OEM lines are routed. Steel lines will always have less expansion than teflon/stainless braid flex lines and is going to be better brake feel and performance.

Modern low expansion rubber flex lines are much closer to the expansion of teflon / stainless steel braided lines than they were back in the 80s.

All things to consider.

[gereed75]

Thanks Hawk. All important considerations.and I appreciate your sharing your knowledge in an effort to keep a brother safe.

When these sets are kitted for a particular chassis they typically include tubing bent fittings where small radius bends are needed.

No known set for the 914 AFAIK.