Your low on fluid & fix the leak. It ain't gonna stop, only get worse. Bill
Master Clinder
Thread Starter
Drifting
Joined: Aug 2010
Posts: 1,797
Likes: 304
From: Charlotte Area North Carolina
Master Clinder
I have a '66 that has been in storage for a few months. I've noticed a very, very slow leak from the passenger side rear brake and a spot of brake fluid on the garage floor about the size of the end of a Q-Tip.
I have added 70 R3 brake fluid.
Could you tell me how full the master cylinder should be kept. Picture attached. Wondering if this is plenty or should I add more. Still working on fixing the leak so I don't have to keep adding brake fluid. Brakes work just fine.
I have added 70 R3 brake fluid.
Could you tell me how full the master cylinder should be kept. Picture attached. Wondering if this is plenty or should I add more. Still working on fixing the leak so I don't have to keep adding brake fluid. Brakes work just fine.
Thread Starter
Drifting
Joined: Aug 2010
Posts: 1,797
Likes: 304
From: Charlotte Area North Carolina
Thank you for the reply.
Master cylinder cap is stamped "use only SAE 70 R3 brake fluid" on the top of the cadmium dichromate lid so that is what I asked for at Auto Zone. He looked up the information I gave him and made the recommendation.
Checked the stamp number of the bottom of the master cylinder and it does not appear to be numbers matching for a '66. Should be #2225032 and mine looks like #2539039 and some of the numbers are very hard to make out so I might be off a little - I was using a mirror.
Any help is appreciated.
Master cylinder cap is stamped "use only SAE 70 R3 brake fluid" on the top of the cadmium dichromate lid so that is what I asked for at Auto Zone. He looked up the information I gave him and made the recommendation.
Checked the stamp number of the bottom of the master cylinder and it does not appear to be numbers matching for a '66. Should be #2225032 and mine looks like #2539039 and some of the numbers are very hard to make out so I might be off a little - I was using a mirror.
Any help is appreciated.
Burning Brakes
Joined: Mar 2005
Posts: 1,231
Likes: 34
From: Ontario
Fix The Leak !
I would fix the leak . If you are using ordinary brake fluid and the leaked fluid finds its way to your paint you will be sorry.
Also with a single master cyl system you don't want to take any chances .
Bill Purdy
Also with a single master cyl system you don't want to take any chances .
Bill Purdy
Last edited by 63split63; Jan 31, 2011 at 09:46 PM.
Safety Car
Joined: Mar 2009
Posts: 4,191
Likes: 951
From: Corpus Christi, TX
The leak you're describing is very common for C2s and C3s that sit for a while with the brakes not used. After some time, the cup seals in the calipers relax and let fluid leak. They'll hold pressure just fine, but when they're unpressurized gravity pulls the fluid past the relaxed seals.
If you store yours for long intervals, make it a point to go out and stomp on the brakes every week or so and hold em for a few seconds. This tends to keep the seals from relaxing to the leak point. Corvette Doctor did this for me while my car was in his shop for 19 months while I got my motor issues worked out. Haven't needed to reseal the calipers.
If you store yours for long intervals, make it a point to go out and stomp on the brakes every week or so and hold em for a few seconds. This tends to keep the seals from relaxing to the leak point. Corvette Doctor did this for me while my car was in his shop for 19 months while I got my motor issues worked out. Haven't needed to reseal the calipers.
Le Mans Master
Joined: Aug 2005
Posts: 6,541
Likes: 1,975
From: Temple Terrace Florida
Brakes
Time for a rebuild. I would rebuild the calipers with an O-ring kit. If the car sits for any length of time, the O-rings are more forgiving. At the very least, I would pull the pads out to make sure that brake fluid has not leaked on them. If I drive the car, brakes and steering are areas I never put off fixing. Jerry
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Burning Brakes
Joined: Mar 2005
Posts: 1,231
Likes: 34
From: Ontario
O Ring Seals
Before you use o ring pistons in your calipers take the time to reserch the pros & cons . There is lots of info on this forum .
I just rebult my callipers and I chose not to use the O ring seals after doing a lot of reading .
Bill Purdy
I just rebult my callipers and I chose not to use the O ring seals after doing a lot of reading .
Bill Purdy
Drifting
Joined: Dec 2002
Posts: 1,946
Likes: 28
From: Long Beach CA
I recently had a caliper that wasn't leaking, but it was sucking air in. Rebuilt it with a standard lip-seal kit from NAPA. Those work just fine.....if your calipers are stainless steel sleeved. If not, get some that are.......
Thread Starter
Drifting
Joined: Aug 2010
Posts: 1,797
Likes: 304
From: Charlotte Area North Carolina
Follow-up: SAE 70 R3 is the same as today's Super Heavy-Duty DOT 3 for manual drum and disc brakes found at local auto parts stores, according to my car guy at Auto Zone.
Good advice on fix the leak. Especially like the idea of just going out in the garage and mashing on the brakes to keep the seals active and pressurized. Like the idea of sitting in the car for a little while, pressurizing the brakes, and dreaming for warmer weather.
Thank all, will proceed to rebuild and stop the leak. Will have to investigate the O-Ring and stainless sleeve options.
Kevin
Good advice on fix the leak. Especially like the idea of just going out in the garage and mashing on the brakes to keep the seals active and pressurized. Like the idea of sitting in the car for a little while, pressurizing the brakes, and dreaming for warmer weather.
Thank all, will proceed to rebuild and stop the leak. Will have to investigate the O-Ring and stainless sleeve options.
Kevin
Le Mans Master
Joined: Dec 2007
Posts: 8,000
Likes: 659
From: Puget Sound
Jim
Last edited by 1snake; Feb 1, 2011 at 06:45 PM.
Thread Starter
Drifting
Joined: Aug 2010
Posts: 1,797
Likes: 304
From: Charlotte Area North Carolina
Hello All,
Have ordered the lip seal rebuild kit. Also ordered the DOT 5 synthetic brake fluid from CC and I'll go ahead and rebuild all 4 breaks and change to the synthetic at the same time. Will be nice to fix the leak and not have to worry about getting the DOT 3 on the paint.
Have no specifics to share on stainless sleeves versus o-rings versus lip seal. Just decided to go with the lip seal for $25.90 (all 4 brakes) plus shipping and handling + the synthetic brake fluid.
Thanks everyone
Kevin
Have ordered the lip seal rebuild kit. Also ordered the DOT 5 synthetic brake fluid from CC and I'll go ahead and rebuild all 4 breaks and change to the synthetic at the same time. Will be nice to fix the leak and not have to worry about getting the DOT 3 on the paint.
Have no specifics to share on stainless sleeves versus o-rings versus lip seal. Just decided to go with the lip seal for $25.90 (all 4 brakes) plus shipping and handling + the synthetic brake fluid.
Thanks everyone
Kevin
Burning Brakes
Joined: Mar 2010
Posts: 1,016
Likes: 250
Hello All,
Have ordered the lip seal rebuild kit. Also ordered the DOT 5 synthetic brake fluid from CC and I'll go ahead and rebuild all 4 breaks and change to the synthetic at the same time. Will be nice to fix the leak and not have to worry about getting the DOT 3 on the paint.
Have no specifics to share on stainless sleeves versus o-rings versus lip seal. Just decided to go with the lip seal for $25.90 (all 4 brakes) plus shipping and handling + the synthetic brake fluid.
Thanks everyone
Kevin
Have ordered the lip seal rebuild kit. Also ordered the DOT 5 synthetic brake fluid from CC and I'll go ahead and rebuild all 4 breaks and change to the synthetic at the same time. Will be nice to fix the leak and not have to worry about getting the DOT 3 on the paint.
Have no specifics to share on stainless sleeves versus o-rings versus lip seal. Just decided to go with the lip seal for $25.90 (all 4 brakes) plus shipping and handling + the synthetic brake fluid.
Thanks everyone
Kevin
When you change over the fluid, make sure you thoroughly purge all remaining DOT 3/4 fluid from the Master Cylinder and brake lines.
I've seen many folks recommend disassembling the MC and calipers (even if all new parts), cleaning out the brake fluid (which is usually DOT 3/4) that was used in the assembly process for lubrication and applying a film of DOT 5, and flushing the brake lines assuming you're not replacing the brake lines (replacing brake lines with the body on is do-able but not the easiest job).
Or just use DOT 4 but change it every couple of years, like you should (but most folks never do).
