Master brake cylinder went poop

L

Lafayette Bruce

Daily Driver
Bummer! My master brake cylinder dripped on my shoes last night. Got a look at it this morning and looks like it is coming from around the push rod that drives the cylinder. It is about 3 years old and has less than 6K miles. Are there any bullet proof cylinders out there that will not betray me in the future?
I really dread getting in there and changing it because of all the stuff that needs to be moved to keep the fluid from eating things up. Not to mention the hassle of bleeding afterwards. Oh well, I've done it before and guess I can do it again. Just need a couple days to get used to the idea.
BB
 
Brake Cylinder Hassles

I've had to do the hydraulics thing too many times myself .. and I have the task staring me in the face again.

I think I've bought at least two brake MCs from VIcks ...

I'm considering a non-DOT3 effort this time ... I read through a recent thread discussing this, and I'll be rehashing all that info again as I get into it.

AND ... this time I have the Motive pressure bleeder for that task.

Jeff
 
If somebody would make ....

....a GOOD master cylinder, they would sell many! I have gone through several new ones before finding ones that would hold up for only a year or two, for both X's AND my Jaguar. I don't get why they cannot design something that is of a more consistent and durable quality. Does anyone know if the domestic US cars have this issue? Maybe that's how they make their $$$, though...knowing we will have to keep buying over and over.:2c:
 
Has anyone modified their MC?

I have considered boring mine out and putting in larger seals/cups to push more fluid.

I have also thought about hoaning it out and having it chrome plated.

Has anyone retrofitted a larger MC into their stock peddle box? I am sure it could be done with the appropriate MC.
 
Have you used them?

Have you had them re-sleeve a master for you? How much was it? I see some prices on their site but not sure what category the X fell into. What about seals? Were you able to get a rebuild seal kit?
BB
 
NEW master cylinder available

I have a brand new Altecna brand (original supplier to FIAT) still in it's red/white box. If you'd like to get it email me.

pizza-store*hotmail.com

Best Wishes,

Ed
 
Seal kits are reasonably available thru the usual parts vendors and eBay.

Some members of the Wash DC Fiats Club have posted here extolling the virtues of a local company that resIeeves masters.

You would have to contact the company to get specific prices.

The prevailing theory seems to be that master cylinders fail from the seals being damaged by abrasion over pits in the bores of the master, pits that have developed from moisture in the brake fluid reacting with presumably inferior cast iron of the current crop of cheap masters.

Resleeving using a non-corroding material (stainless steel, brass, etc) would seem to address this problem.

Using a brake fluid that is not hygroscopic would also theoretically address the problem, but I don't know of any.
 
Went through many attempts..

the ones from IAP were no good. I ended up towing the car to a shop and they were able to get a new one from Raybestos. May want to look into that?

**EDIT Per Raybestos.com, part number MC39268, for 74-77 X's, MC39136 for 78-83...
 
Thank you

Thank you for your kind offer but for now I am going to pursue the sleeving option as I want to make it so I never have to do it again. (Or at least for a very long time.) If I run into roadblocks like getting outrageously expensive, I may be back.
Thanks
BB
 
Dot 5 Silicone

Does not abzorb moisture and I have changed my 79 to Dot 5 about 14 years ago. Still the orginal Master on the car that I purchased new.

Many of you complain about failures but the OEM equipment is getting dated these cars don't get driven as much as my daily driver. Case in point. My Dodge 2003 Ram I purchased new, it has 115000KM on it in 6 years. My 79 X I purchase new it has 84,000KM on it in 30 years.

I would suggest using Dot 5 silicone just for the reason that we don't drive the car much and it doesn't abzorb moisture. Change the master cylinder, remove all the bleeders from the calipers, then turn them upside down and drain the calipers. Then purge with Dot 5, remount the calipers and bleed the system. This has worked for me, some say Dot 5 is spongy, maybe a little, but then I still have brakes working on a 30 year old car. I did the same with the clutch master and slave and currently have 14 years on them with Dot 5 on my 79 X. The 87 X I have I changed the Master and slave for the clutch and the master for the brakes, currently I have 5 years on them no problems yet.

TonyK.

Grimsby Ontario Canada.
 
etownsley said:
I have considered boring mine out and putting in larger seals/cups to push more fluid.
Click to expand...

I don't quite understand why you would want to do that. Bigger bore in the master cylinder would mean more force needed on the pedal for the same stopping power.
 
Lafayette Bruce said:
Bummer! My master brake cylinder dripped on my shoes last night. Got a look at it this morning and looks like it is coming from around the push rod that drives the cylinder. It is about 3 years old and has less than 6K miles. Are there any bullet proof cylinders out there that will not betray me in the future?
I really dread getting in there and changing it because of all the stuff that needs to be moved to keep the fluid from eating things up. Not to mention the hassle of bleeding afterwards. Oh well, I've done it before and guess I can do it again. Just need a couple days to get used to the idea.
BB
Click to expand...

There are no bullit proof master cylinders. If the manufacuters made them, they would never sell them again!

That being said, there are not many companies making them for this application any longer, and many of the different brands you see today are usually all from the same place, just reboxed. The brand I sell seems to be real good if proper care is used.

Most master cylinders, or any hydralic part, fails because of moisture or dirt. I don't get many returned to me as defective, but if I do the first thing I do is disasemble them to see what the problem is before I ship them back to the manufacture in Italy. EVERY SINGLE ONE comes back with dirt in the internals! This fouls the rubber seals, and often all the rest is still OK.

Lesson, clean everything!

Things that will lead to hydralic component failure:
1. Dirty fluid. Clean the resevour and keep it clean before you bleed your system again. When the system is apart clean all the pressure lines on the inside.
2. Deteriorating hoses. I can't begin to tell you how many cars come in without brake fluid compatible hose on the feed line. And the pressure hoses also fail with time. When the fronts start to crack on the inside, replace them all.
3. No lubrication on moving parts. I keep a big tube of silicone grease on my work table, and every hydralic part gets disasembled & lubricated with the stuff. And I pack the boot to help keep moisture out of the working area.
4. Bad fluid. Everyone has their opinion. As I have stated before, I use DOT 4 fluid and change it every 2 years no matter how many miles. I use a suction bleeder to assist me when bleeding, no wife around here any more!

I own cars with more miles on replacement hydralic parts than the originals made it. With simple care, you can also.
 
What Dan and Chris said

We have saved all of the used master cylinders that we pulled from salvage cars, me being convinced someday supply is just going to dry up and we'll need to remanufacture them.

Of the pile of 50 or so brake and clutch masters, I went through every one to see which were still moving and felt functional. I then selected five of each and tore them down.

In every case, looking through them with a wet bore, they looked pristine. It was not until you gun-rod clean them with a cloth and look again that EVERY ONE had pits in the bore where the seals sat. Every one.

In my opinion, it is completely pointless to try to rebuild a master cylinder as you'll find this problem consistently. The only solution to save a pitted body is to bore and resleeve it. Very expensive, but a lot of vintage guys have no other option, and we'll be there someday too.

Double agree with Chris that debris is the biggest culprit of problem new cylinders.

-Matt
 
Excellent write-up.

I'm also a DOT 4 fan as well. Clean fluid makes all the difference in the world.

Now Chris, you could use any friend or associate to pump that pedal up/down for ya. Come on now! :)
 
Great info

Thank you very much for the solid input Matt & Chris. I probably have not been as diligent as I could be about cleanliness of the fluid. I sent my old cylinder off today for a sleeve job and they have a 10 year warranty. Feed lines are in great shape and I will look into using DOT 4
Thanks again
Bruce
 
bbrown said:
I'm also a DOT 4 fan as well. Clean fluid makes all the difference in the world.

Now Chris, you could use any friend or associate to pump that pedal up/down for ya. Come on now! :)
Click to expand...

With the Vacula system, I connect it to shop air, slide it on the bleeder nipple, and after confirming the resevour is full of clean fluid, open the bleeder nipple. (For the left front I pump the pedal five times, right ten, pick one rear twenty, the other five.) Then I close the bleeder & move onto the next wheel.

Friends never seem to be hanging around when I need them, and associates all need to be paid. I run a one man shop, everything is me so I know it's the way I want it done.

Keep in mind I lost my wife six years ago (according to my daughter) next month, and even then she was so busy with our kids & writing it was easier to just do it myself, and I had been for years at that point.

I occasionally do need a second person, and I am the first to get help when I need it.
 
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