DOT 5 had a different feeling when cold and required more effort to stop my C3. I flushed the system and went back to a high quality brake fluid (German) and have not had any leaks or problems in years and years.

When I rebuilt the calipers I took them down to bare parts and made sure the machine surfaces were still in good shape. Then I cleaned and polished the bores before re-assembling the caliper halves. With a great surface the pistons seal well.

The car was made to use DOT 3 so I will continue to use DOT 3 just the like the manufacturer suggested. It works great for me and both of my Corvettes.

Getting ALL the air out of the brake system is easy with the right tool. I use a Phoenix Reverse Bleeding Pump and Push the air UP and OUT of the brake system. Why defy gravity and try to push air down?

On my C3 the brake system is the most important sub-system as it alone slows the car down. Going fast is easier than slowing down fast. After many runs on a drag strip my brakes were still perfect with no fading. I won't go FAST until I can slow the car down even faster. No backup brake system and I don't drive it. My Parking brake is great, I put them on 34 years ago and they are still working.

Merry Christmas to you all!

Chris

 

I am about to do my periodic 3-5 year brake flush.

I am going to try the Phoenix Reverse Bleeding Pump method because, intuitively, it just makes more sense than the traditional bleed method. Thanks for the reminder!

 

I agree completely. I've owned my 77 for 40 years and had to put it in storage for a while. Everything went to hell. Brakes, front engine seal, carburetor, electric window motors, the list goes on. Now I drive it virtually every weekend and zero issues for 5 years.

 

SSBC wrote the book on Corvette calipers and DOT-5 silicone fluid and here it is.


Circa 1985




This was the former owner. They were a big promoter of DOT-5. He has passed and a new private equity group has purchased and reopened the company about 5 years ago.

EDIT - CSSB is a different company from SSBC that wrote this book. SSBC was an early Corvette SS caliper producer. The newly reorganized company does not sell any Corvette brakes.

 

Thanks for that tip on the book.
There are a few on E Bay!

 

That is Terrific information^^^^^^^^^^!!!!

Back in 1986 when I put on my 4 SS VBP LIP seal calipers, no one was offering O ring seal SS calipers which was a much later design change.

I wonder now, not knowing all the details in that book about the calipers, if using O ring seals instead of the OEM DESIGNED LIP SEALS like I still have today in my calipers that are 40 years old is such a grand idea, especially if the pistons and brake pads are suppose to be in constant contact? I have always been very skeptical of the O ring concept, especially since my lip seals have performed flawlessly over the last 40 years..........

 

I have that catalog somewhere in my files. They were good, I bought SS calipers from them 40-45 years ago. I didn't know they reopened and I don't believe they are the same co as the one in FL. Never had an issue with their work. I can't say that for some of those selling today.

 

Gary,
This company was close to me back when I lived in Buffalo, NY. They were great. Not so sure now.

 

This is very interesting information. Thank you for sharing. As I understand it, CSSB contracts out the seals and rubber parts. For there O ring caliper conversions they wanted a O ring that doesn't have a parting seam on the outer edge. As some inexpensive O rings do. So they have a overseas manufacturer making special O rings with a offset seam. If you look at them you can see this.
Obviously they wanted the parts for a price. A higher quality rubber that is safe with both types of fluid would simply cost more. So, they just warn against using quality brake fluid.
Cheaper for them.
I've had DOT 5 in my Corvette for decades. My seals don't leak. My brakes are excellent cold or hot. I'm NOT changing.

 

Just to clarify....I typed the letters wrong, my apologies. It's easy to confuse the 2 companies.

"CSSB" is "Corvette Stainless Steel Brakes" company in Florida.

There is a different company "Stainless Steel Brakes Corporation" that is in Buffalo NY. (Clarence NY originally and now in Elma NY) . The Buffalo company wrote the book and did sleeve Corvette calipers etc. They are now reorganized as "SSBC-USA". They have branched away from doing Corvette brakes. Simple, right?

 

I've had my '68 for 25 years. Within the first 2/3 years I experienced the leaking caliper syndrome. Fortunately a previous owner had installed stainless sleeved calipers......but with lip seals.
The PO used a garage to keep the car that was certainly unheated, unventilated and probably damp during the autumn/winter months.
I bought new performance pads to replace the cheapo ones installed and a set of 'O' ring caliper pistons. The stainless inserts wre obviously in good condition but had marking/discolouration on the operating surfaces from the lip seals and rust discolouration suspended in the brake fluid from corrosion on the inner surfaces of the remaining cast iron components in the braking system (so master cylinder and caliper internals). I flushed the braking system 2/3 times........but not before almost surgically cleaning the stainless caliper inserts, initially with fine wire wool and then the finest Crocus paper (in a similar pattern to honing cylinder bores). 20 plus year later - one brake flush many years ago and I haven't needed to tough the system.
Fortunately my garage, although unheated is attached to the house and always above outside temperature which is the main reason for the longevity of the system.

Brake fluids.
Its a 'given' that any earlier Corvette used and stored in damp, perhaps colder enviroments will potentially struggle with braking systems due to brake fluid deteroration caused by ingress of condensation and its consequent absorbsion caused by hygroscopic action of mineral brake fluid and the water content potentially boiling-off under heavy continued braking, creating brake fade. Sure later non-hygroscopic brade fluids will still have moisture entering in to the system but still likely to 'boil-off' under continued heavy braking?

 

Thanks, I have to say I got the two names mixed as well.

 

This is exactly why I would never consider trying DOT 5.0 (not to mention how difficult it is to convert back).

Looking out my window, I just saw a vehicle that benefits greatly from DOT 5.0. The Grumman LLV. I bet Hagerty's example has 20 year old DOT 5.0 in it.

 

But DOT 5 does NOT have a different feel cold and hot. That guy is the only one I've ever seen say that. And I personally believe it to be nonsense.
I've converted 100s of vehicles over to DOT 5. My own amongst them. My Corvette will throw you through the windshield if your not buckled up!

 

As awesome as DOT 5 is, NASCAR, F1, and FIA must use it, right?

Grok, do any professional racing teams use DOT 5, and if not, why not?

 

I think trying to tie street use to racing use is apples and oranges. There are many products that do not cross over because the needs are substantially different. In a race car, just about everything is changed or rebuilt multiple times in a racing season. A street car just isn't afforded this level of service so products that offer wider ranges of use and greater longevity are used.

DOT 5's hydrophobic characteristics equate to extremely good long-term use and storage; it also will not harm painted surfaces. However, it's supposed to have a softer pedal feel – maybe it does – but it's nothing I've experienced as a compromise in stopping ability.

 

I have to agree with the above. Most C3 owners are not wishing to service the brake systems on their cars anywhere near the level of attention a race car receives.
We do have classic cars. Most of our cars get extended periods of storage. DOT 5 is the clear choice for classic cars that get little use and or extended storage intervals.
If there is a difference in the amount the fluid compresses. It's certainly not noticeable to me.

 

I purchased the CSSB booklet mentioned above.
It is an excellent read.
And a worthy purchase for any C3 owner.
Although long out of print, there are several on e-bay.

I would love to PDF the whole book and post it here, but that would likely land me in copyright infringement trouble.
I am not sure the new-born CSSB cares, or not.

So I decided to post several "teaser" shots here, since much of the book is exactly pertinent to this discussion.
And although dated 1977, much of this information has been lost to time.

The original owner of CSSB was a P.E., and did an excellent job of researching this, before writing this book, and obviously, starting up the CSSB company back then.

Forgotten FACT #1
The C3 brakes are indeed different in design than any other brake system in the world.
The pads were designed to be in CONSTANT CONTACT with the pistons.
This is the MAIN REASON you can not treat this system the same as any other disc brake system.


Fact #2
The seals do not move in normal operation.
They just flex .010"




Fact #3
The pistons tilt slightly under use, as the pads slide rearward under pressure.
This is not normal with other disc brake systems.
That is why the piston skirts are so short.


Fact #4
In 1972 and later the caliper material composition was changed, from ductile iron, to gray iron, and more prone to rear caliper breakage.




Fact #5
The primary corrosion site is the bore surface in between the two seals. Water from road splash, or even humidity, will penetrate the dust seal, and corrode this area. Until it compromises the hydraulic seal.


Fact #6
The aluminum pistons are anodized, but the coating wears away in as little as 3000 miles.
Then dissimilar metal corrosion begins. At both the pad/piston interface, and the piston / bore interface.
In both places, this coating wear is due to rubbing from slight movement of pads, or rocking of the pistons.


Fact #7
Stainless Steel Pistons used to be available.
These would help with lowering both corrosion and heat transfer.




Fact #8
GM Recommended rear wheel bearings be greased at 30k mile intervals.
Failure to do so may result in wheel bearing wear, rotor runout, and then braking issues.


Fact #9
Terrific graphic and explanation of air pumping.
The springs cause the pads to rest on the rotor surface, and it should not vary.
When there is rotor runout, the piston SPRINGS push the pistons toward the rotor, creating a VACUUM, sucking in AIR.
This is completely un-avoidable if the rotors have runout.
Several methods of reducing rotor runout are discussed. As they have been here.


Fact #10
Air and humidity leaks into the brake fluid thru the master cylinder VENTS.
Dot 3 or 4 absorbs water like a magnet.
In 12-18 months the water level in the fluid is high enough to need changing.
There is nothing you can do to slow this down.
Frequent fluid flushes are mandatory, if using DOT 3.


Fact #11
Using "normal" brake pad anti-squeek on this system, will cause fluid leaks.
The pads need to slide on the pistons, slightly.
Or they rock the pistons too much.


BUY THE BOOK!
There are many more helpful hints and service tips.

QUIZ TIME!
How many of those facts did you never know, or had just forgotten?

I will be the first to admit I flunked 8 out of 11.

 

This is awesome. Thanks for posting the information.

 

Wow..some great info!

Several points come to mind from your facts presented, Leigh:

1. Changing the brake fluid often is critical to maintaining an intact C3 brake system.

2. The corvette 4 piston fixed racing caliper brakes were decades ahead of brake systems, then and now, up to and including brake systems today, mostly which are floating caliper systems, utilizing 1-2 pistons applying direct rotor pressure on 1 side off the rotor. Not ideal.

3. Any 4 or 6 piston fixed brake caliper system since 1965 -82 brake systems, like the C2/C3's, is a constant contact brake caliper, not just the C2/C3 corvettes 4 piston brakes calipers.

4. Any OEM non SS sleeved C3 brake caliper system will eventually, and long gone by now, corrode with minimal usage.

5. When rebuilding a SS sleeved brake caliper, always utilize Stainless Steel pistons, not aluminum pistons, which will corrode with time.

6. The water/moisture penetration to the brake system comes from the master cylinder vents on the C3's.

7. The fact that the piston caliper seals don't actually move but only flex, reinforces my real world experience that lip seals in a properly operating brake system are extremely robust and reliable. I have never subscribed to the O-ring seals being a better caliper seal option than OEM lip seals.

8. GM's recommendation of greasing the rear wheel bearing every 30K miles will NOT prevent rear wheel bearing failure since the bearing tool needed for this procedure will not allow grease to penetrate the inner wheel bearing, only the outer bearing.