What's the secret to master cylinders?

[Bergretter]

Alright, I've had my 40 for 14 years now, and I have not figured out the secret to enjoying a leak free master cylinder for brake or clutch. I have replaced with aftermarket, I have replaced with OEM, I've honed many times in between, and I've bled the systems regularly. What is the magic answer? Is there a place to get real quality cylinders? Is there a specific fluid that will inhibit the rust on the bottom of the cylinders? Please, share secrets! I've resorted to trays under my dash to keep the floor paint from getting the bubbles.

 

[Pin_Head]

You have either unusually bad luck or bad brake fluid.

Ever win anything in the lottery?

 

[Poser]

Welcome.



I have not had any issues with new OEM components in almost 20 years of working on these vehicles.

 

[mr_manny]

I did get a sketchy rebuild MC once...other then that, zero issues with OEM.

 

[DSRTRDR]

I second OEM, but CDan tells me they are no longer available for my vintage

BTW mountainrescue: black font does not show too well on this background

 

[dirtcurt]

Do you let it sit for long periods? My 74 get mad at me for letting it sit for long periods. If I drive it to work every day, those things don't happen as much or at all. Cold winters seem to be rough on the brake system especially if it gets no use. No tech here but just what I've found with my cruiser.

 

[lostmarbles]

Maintenance might be the answer

I've owned my BJ40 since 1981. Yet I've changed the clutch and brake mastercylinders only once in that time. And I'm about to put the originals back on again - (Just repainted and with new kits fitted.)

I bought the vehicle in Western Australia and it is on its third time around the clock.

The only reason I bought and fitted replacements was "peace of mind" due to the age of the originals.

I've also changed the clutch slave cylinder once but all brake wheel cylinders are still original and leak-free. (They have had new seals and boots fitted by me though.)

There are some signs of wear on the original master cylinder bores but nothing that would cause leakage. (The damage only affects the inner seals - not the final outer ones!)

My brakes are fine and they are checked 6 monthly (as required by law here in NZ) by a very fussy vehicle testing station that I use.

In fact the only leaks I've ever had are:

• With the original clutch master cylinder (understandable since I always "double de-clutch"). This was repaired at the time simply with a seal kit).
• With the after-market PBR-brand replacement brake master cylinder. This unit leaked IMMEDIATELY FROM NEW with a very slight "weep" from the base of one of the two fluid reservoirs. (Just enough to blister the paint there but not enough to become wet or to drip which is why I've never fixed it.)

I put my good fortune down to the fact that I have always flushed fresh fluid through both systems every 2 years or so. I also buy fluid in sealed containers and NEVER buy it in bulk or in unsealed containers where it is likely to be pre-contaminated with moisture.

 

[lostmarbles]

Maintenance might be the answer

I've owned my BJ40 since 1981. Yet I've changed the clutch and brake mastercylinders only once in that time. And I'm about to put the originals back on again - (Just repainted and with new kits fitted.)

I bought the vehicle in Western Australia and it is on its third time around the clock.

The only reason I bought and fitted replacements was "peace of mind" due to the age of the originals.

I've also changed the clutch slave cylinder once but all brake wheel cylinders are still original and leak-free. (They have had new seals and boots fitted by me though.)

There are some signs of wear on the original master cylinder bores but nothing that would cause leakage. (The damage only affects the inner seals - not the final outer ones!)

My brakes are fine and they are checked 6 monthly (as required by law here in NZ) by a very fussy vehicle testing station that I use.

In fact the only leaks I've ever had are:

• With the original clutch master cylinder (understandable since I always "double de-clutch"). This was repaired at the time simply with a seal kit).
• With the after-market PBR-brand replacement brake master cylinder. This unit leaked IMMEDIATELY FROM NEW with a very slight "weep" from the base of one of the two fluid reservoirs. (Just enough to blister the paint there but not enough to become wet or to drip which is why I've never fixed it.)

I put my good fortune down to the fact that I have always flushed fresh fluid through both systems every 2 years or so. I also buy fluid in sealed containers and NEVER buy it in bulk or in unsealed containers where it is likely to be pre-contaminated with moisture.

 

[lostmarbles]

Senile

Now you know why I'm called "Lostmarbles". Can't even post a reply without it popping up twice!

 

[Bergretter]

Man DSRTRDR, in one reply you exposed my secret identity and found my signature jacked! You're good. Hopefully the black text has now disapeared from my sig, thanks. I agree that OEM is the superior product but finding these masters for my '68 is almost impossible now. I wonder if it is the cold/humid locations I have had this truck in (AK and WA) that causes regular pitting on the bottom of the cylinders? I do drive the 40 at least 3 times a week. Anyone recomment one brake fluid over another?

 

[OswaldtheBold]

Man DSRTRDR, in one reply you exposed my secret identity and found my signature jacked! You're good. Hopefully the black text has now disapeared from my sig, thanks. I agree that OEM is the superior product but finding these masters for my '68 is almost impossible now. I wonder if it is the cold/humid locations I have had this truck in (AK and WA) that causes regular pitting on the bottom of the cylinders? I do drive the 40 at least 3 times a week. Anyone recomment one brake fluid over another?

I just got a new OEM brake master cyl for my '68 from Cruiser Dan last week. The only problem was he did not have a parts book for the '68 to confirm the part was the same as later ones. A quick check of SOR's website catalog confirmed it was the same up through 7/70. (Thanks Dan!) Price was less than $100 including shipping.

 

[DSRTRDR]

Man DSRTRDR, in one reply you exposed my secret identity and found my signature jacked! You're good.

;p

if CDan still has the earlier cylinders - way to go

 

[IDave]

;p

if CDan still has the earlier cylinders - way to go

The earlier master cylinders are singles, as opposed to your duelie '72, which is what is gone, I guess.

 

[DSRTRDR]

The earlier master cylinders are singles, as opposed to your duelie '72, which is what is gone, I guess.

yup

 

[Coolerman]

Another option to help with the rusting in the cylinders both master and slaves/wheel cylinders is to send them off to have stainless steel or brass liners pressed into the bores. Then you never have to worry about that issue again.
A bit expensive but may solve your problem.

http://www.brakecylinder.com/sleeve1.htm
http://www.applehydraulics.com/brakes.htm
http://www.resleeve.com/sleeving.htm