My "68 E-type has been having break release issues periodically for a while. I had the brake master cylinder and brake booster replaced initially and then just the master/slave cylinder replaced a couple of times. These resolves the issues for 5000 miles or so, but then it reared it’s ugly head again. The last master replacement was 6/28/19, and the problem is back again, with only 2000 miles driven. At this point have have to think that other variables in the breaking system are the culprit. I welcome and look forward to your thoughts, speculation, suggestions. Thanks. George, Brooklyn, NY
I don’t know why it would be time dependent but I would change out flexible hoses at the front wheels and the one to the IRS. If possible, if you can recreate the situation with the car up on jack stands, knowing if one or all wheels are locking is valuable input. If it occurs in traffic, that isn’t an option but some importanat data might be obtained if you could pull over and get an infrared reading on the 4 brake discs. One or two that are much hotter than the others might mean something to the diagnosis.
The classic scenario that locks all 4 wheels is the little piston at the end of the brake master cylinder, which activates the reaction valve. Sounds like you have circled around those components several times.
I could see that a “sticky” wheel cylinder might occur randomly but if you have been able to fix the problem by replacing master and slave cylinders, then that doesn’t really line up diagnostically.
What have you done to get the brakes to release, when it occurs?
BTW, I am impressed that you are putting 5000 miles chunks of drive time on a Brooklyn car. Sounds like you head out to the scenic areas a lot 
Very possibly a vacuum issue. Sticky reaction valve my guess.
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No limit, WE feel your pain…seems across the board, THE REPRO BRAKE parts are not good UNLESS you go after market as I have…
More to come, but its junk out there.
Im going all out, looking into electric brakes and all.
Its all on the table.
gtjoey1314
Joey, there may indeed be a problem with parts but I think a major cause of Etype brake issues is simply that the cars don’t get driven enough. Mechanical parts, especially brakes, do better when exercised on a regular basis. Although in this case, it sounds like the OP is indeed putting some miles on the car. A very good thing!
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Could be but…The parts overall are junk. No better no worse.
Im driving ALOT and getting issues.
All my upgraded NON STOCK parts are fine. Its my repro originalish that are a problem.
Ive got 3 friends with etypes all brakes done over the last 4 years, OVER and OVER again…
P.S. To stop the pain Ive gone, ZEUS one piece vented front calipers, rear stainless zues pistons, braided flex lines all round.
This cured ALOT of small issues.
But the master, booster and vac tank are a complete cluster.
Help is hopefully on the way…
Ok, so in comparative terms…I also have a '68 car. I also replaced the master and slave cylinders. I also chased my butt around trying to fix sticking brakes.
It all boiled down to a sticking reaction valve. After these parts are assembled they typically or possibly sit on the shelf for some time. Assembly grease is used during the assy process and that grease goes “hard” resulting in a slow release of said valve.
My suggestion is to carefully remove the cover and internals, including and especially the small piston, and clean and relube and replace. 99% sure this will fix your problem.
You might lose some fluid doing this so be prepared with rags etc.
Do you have the correct heat shields (plural) correctly installed? Not just the bottles but the servo need to be protected.
As for our Italian American friend, he is a Giant amongst car cognoscenti and has excellent taste , but does get rather apocalyptic at times…
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I struggled with this problem for a while, and ended up doing a comprehensive teardown to locate the failing component. You can read about what I did here:
The bottom line, since you don’t really want to read two hundred posts, is that the problem was resolved by rebuilding ore replacing literally everything, which isn’t a helpful solution. The key takeaways: there’s only one vacuum hose that can cause brakes to lock, so for three bucks of vacuum hose, get it out of the way first. I agree with the idea that brake grease may have something to do with it: I cleaned all the old grease out of the reaction valve, and reassembled dry. You want to check the little piston at the front of the master. On rebuilding the booster, a few points: There’s a little spring supplied with the repair kits that’s shorter than stock, so reuse the original. When assembling the master and servo, I used brake fluid for lubricant rather than grease. And the only other oddball thing I did was to run a thin bead of silicone grease around the parting seam of the servo, to prevent air leakage around the edges of the diaphagm. And that’s all I did that differed from the books. When everything was back together, it worked fine and continues to work. I sould add, that all this work was done on a relatively new servo. This diagram may help:
Zeus brakes are a wild goose chase, they fix no problem you have. And if Joey has a magic fix for the servo problem, we’ll probably get it when he tells us about his magic solution to the five speed problem.
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Agreed. I had the same sticking problem and solved with this procedure.
That’s “jello” for you, “jelly” for him, lol!
This alludes to an earlier thread about brakes, but after having my system rebuilt 35 years ago, I’ve been running silicon fluid and have had zero problems. I even have a 35 year old jug of fluid in the cupboard that I haven’t needed. I’ve never had to top off the reservoirs even once. No drips, no leaks, no failed components. Same with the clutch.
So if you find you have to tear everything down, you may wish to consider going with silicon. Note that all tubes, hoses and components need to have all traces of the old dot 3 fluid and gunk removed first.
I suspect Peter is correct; it’s heat related.
It is worth checking the reaction valve drive piston in the master cylinder and maybe you could look at the vacuum hoses and valve but I wouldn’t go throwing the baby out with the bathwater just yet.
so make note of what Michael Frank said…but…in agreement kinda with Peter and Andrew…heat may be the culprit…do you have brake pedal free play at the time you have the no release…? If not…check free play. Is your system using DOT 4…are you CERTAIN? And…I’d flush the fluid anyway…moisture (water) expands, steams far lower temp than DOT 4. this pushes the brakes on…been there done that, a combination of old fluid that had collected moisture (it will do it more in a humid environment…but it will…no matter) and not correct pedal setting. Do the Easy stuff first…
Nick
Oh I agree on the heat but it’s the design and American set up that makes it worse
Rhd have bottles on the firewall and opposite side of the headers!
More to come
Gtjoey
Geez Louise, this system has worked reliably for a lot of people for many decades. There’s a chance that this specific problem may be related to fluid quality, but it’s not related to the heat shields or the location of the bottles. The engine isn’t suddenly producing more heat, and today’s brake fluids have more thermal tolerance. Remember, the problem goes away for a time after they play with the hardware.
Of the things I did when struggling with my locking problem, the one thing that I think made a difference was greasing the edge of the servo diaphragm. I wish I had taken the time to do a close examination of the parting surface, I’m sure the answer was there.
Joey has another toy.
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Is that a brake cylinder for a trailer?
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There have been a couple of instances Mike (at least on the UK forum) where 4.2 owners failed to fit the lower heat shield and had lazy brake release in traffic.
When the heat shields were fitted (required regardless of LHD/RHD or 4.2/5.3) the dragging stopped.
It sounds logical to me and the LHS lower shield wasn’t there for driver comfort on RHD models. I think one of the cases (David Jones) had long headers on his car at the time, but don’t recall the other. Obviously, if the OP has all shields present and correct, it’s not the cause in his case but it might help another reader to avoid the same mistake.
First of all, many thanks to all of you who responded to my malfunctioning break dilemma issues, it certainly gives me a more focused starting point to finding a solution. I will certainly start with the easier to address solutions first, as many have suggested.
Although I enjoy living in NYC, the major disadvantage for a car guy, is not have a garage where you can work on your car for as long as need year round:(:(
I can only imagine the knowledge I would have acquired by now… I will let you know the outcome of this adventure.
Notes: - The brake fluid I’m using is Ate Original Bremsflussigkeit Typ 200 New Racing Quality Dot 4 (which will be flushed during this process.
-Wilwood Breaks (at least 12 + yrs old) and steel(?) messed break lines
- When the break stick initially, they release in 5 seconds or so. As I us them more in stop and go traffic (like the Holland Tunnel) it take longer and longer to release. Occasionally, when traffic starts moving and they are still stuck I have to use the engine in 1st gear to push through to lock up:(
I don’t know which wheels are sticking (front/rear, one or two) but when I,ve had the master cylinder changed, everything goes away until it starts again 4 to 5K later. Also my mechanic added an extra hear shield to protect the top (master) cylinder when it was last installed, to no avail. This is a relatively recent issue (20K miles) in my ownership of the car.
Finally, this will give you and idea how the car is driven, plus four trip to Florida.
Turning Heads for 38 Years - The New York Times
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