Caliper "lip seals"?

[GTR1999]

I dunno guys, I never used anything but lip seals in my vettes the past 35 years. In that time, I had one caliper lock up because the BF was mudd, my son had a rebuilt SS caliper leak last year, we rebuilt it with stock lip seals and that was it. Get the rotor runout and bearing endplay dialed in and bleed the brakes once a year( I haven't done that now for 4 years!!:amazed and you should be ok as long as the bores are still good.
I know some of the O ring coversions had issue when they came out, pistons cocking in the bores, but that might/should have been addressed by now.

 

[turtlevette]

Why bother, the simple O ring conversions seem to work flawlessly.

they lasted two practice sessions on my car....I went back to my trusty J-56 pistons with lip seals.

If you compare apples to apples, the o-ring pistons would need to have insulators as well.

O-rings with insulators will out perform stock seals with insulators.

A square cut seal or quad seal would out perform an o-ring.

no, the problem was not heat. the problem with the o-ring is it makes a poor seal compared to a lip seal and the insulator had nothing to do with it, it was two pumps at every corner starting with the first corner.

The stock system follows the surface of the rotor better and does not have the piston knock back problem. A blessing and a curse at the same time because of air pumping.

Do you think you'll ever be on a road course again?

 

[mrvette]

I dunno guys, I never used anything but lip seals in my vettes the past 35 years. In that time, I had one caliper lock up because the BF was mudd, my son had a rebuilt SS caliper leak last year, we rebuilt it with stock lip seals and that was it. Get the rotor runout and bearing endplay dialed in and bleed the brakes once a year( I haven't done that now for 4 years!!:amazed and you should be ok as long as the bores are still good.
I know some of the O ring coversions had issue when they came out, pistons cocking in the bores, but that might/should have been addressed by now.

Gary, interesting you mention that, trigggered a old memory....

and I stil have the old rotors sitting around....on the rear, I had some odd click noise for some reason, it was in the days of the lip seals, and so ran the car with the rotors secure with the wheel adapters....up in the air, to observe WTF was that annoying clicking sound....

so what happened was due to the rotors having been turned, there was a spiral like a old phono record in the surface, that grabbed the pads and the pistons I heard the clicking sound from the pads forced in/out of the circumference against the lock pins.....they go in/out of the radius when jacked up with no loading...just at idle in 1st gear....

that action on the pads, caused the pistons to be cocked in the SS bores....

had to replace the rotors with NEW....because so it seems reground rotors are done like a phonograph record, and so the pads follow that pattern and click UP/OUT to repeat the pattern....

so I came to the conclusion to never refinish any rotors, just replace them....

 

[Grampy]

One of the failure modes we observed in pneumatic actuators was the rolling of the "o"ring piston seal. We think this was induced by sticktion in the bore. We eliminated the problem by changing to the quad-ring. I don't think "o"-ring torsion failure would be a worry in the brake application as the piston stroke is (should be) very short. Gene was spot on when he described the lip seal. All these seal cross sections are standard industrial variants. They all have their uses. The lip seals are perhaps a carry over from drum brake wheel cylinder seals of the time. Remember this is a first generation design. The difference is the drum brakes could have much longer strokes if not properly adjusted. Elastomers have a property called compression set where they will retain a certain amount of deformation. The geometry of the lip seal makes it a little more prone to a compression set induced leak if it sits for extended periods.

Grampy

 

[BBShark]

So, has anyone ever used a quad seal in a Corvette?

 

[MYBAD79]

So, has anyone ever used a quad seal in a Corvette?

I would bet money the answer is no, unless maybe with aftermarket calipers. Machining/modifying the stock caliper and piston would be so expensive that it's cheaper to simply buy a Wilwood setup.
Some more food for thoughts: The 93+ F-body brakes are pretty good and inexpensive, I wonder if anybody has used those on a C3. It's a single piston floating caliper and I believe those calipers use a quad seal ring and the groove is in the bore....

 

[Twin_Turbo]

The GM calipers, being it delco morain or PBR all use a square o ring, I have never seen a quad ring in any of them.

 

[BBShark]

So, has anyone ever used a quad seal in a Corvette?

I would bet money the answer is no, unless maybe with aftermarket calipers. Machining/modifying the stock caliper and piston would be so expensive that it's cheaper to simply buy a Wilwood setup.
Some more food for thoughts: The 93+ F-body brakes are pretty good and inexpensive, I wonder if anybody has used those on a C3. It's a single piston floating caliper and I believe those calipers use a quad seal ring and the groove is in the bore....

I would be shocked if the O-rings used in C3's are a special size. The sizes for O-rings were standardized a long time ago. I would also be shocked if the quad rings were made to a different standard. I could be wrong but I think they are interchangable with standard o-rings.

 

[redvetracr]

[/QUOTE]

I would be shocked if the O-rings used in C3's are a special size. The sizes for O-rings were standardized a long time ago. I would also be shocked if the quad rings were made to a different standard. I could be wrong but I think they are interchangable with standard o-rings.[/QUOTE]

the o-rings are a standard size but the trick is knowing what material they should be made of and what the hardness (durometer number) should be...

 

[BBShark]

the o-rings are a standard size but the trick is knowing what material they should be made of and what the hardness (durometer number) should be...

SBR, Butyl, EP are all very common materials that are compatable with brake fluid.

Does anyone know the size?

 

[MYBAD79]

The GM calipers, being it delco morain or PBR all use a square o ring, I have never seen a quad ring in any of them.

misunderstanding.... I thought a quad ring is a square O-ring (refers to the four sides of the square profile).... apparently a quad seal is the X profile seal ring....
and no, you're correct, I have never seen a X profile seal ring in any caliper.

When retrofitting these X-rings, will they fit in the stock piston groove? If I haven't thrown them in the garbage I have a few old pistons on the shelf and could measure the groove....

 

[damoroso]

I've been following this thread because as luck would have it, I'm gathering parts for a brake system upgrade now. A friend had two front calipers on a front axle he's using for his Model A hot rod and he doesn't want them, they happen to be SS sleeved C3 calipers. $25. I looked at the Wilwood D8 series, both the D8-6 and 4. The 6 series is $330 clear, $417 powder coated ea. The 4 series is $260 clear, and $330 powder coated ea. I think I'll look for a set of rear SS sleeved cores and rebuild them too.

I'll use a kit from Mike in Dallas, but from Grampy's post, it sounds like the quad ring is the way to go, it makes sense. Question is, since kits come with the typical O ring, what quad ring fits and where do you get them??

 

[Twin_Turbo]

the quad ring only fits a square cut groove, I think the o ring pistons are machined with a round groove right? I haven't looked at one of those in a long time. I went back to lip seals and tight runout & bearing play on the 77. Never a problem, brakes just fine. I do use GM seals though, not some chinese junk. Only the delco bags.

 

[Grampy]

It's been a while but I think quad rings and "o"rings use the same groove. That is you can retrofit a quad ring into an "o" ring groove.

The groove is basically square. Slightly tapered walls <5* permitted. The corners of the groove should have a small radius. Do to the very short stroke of any given braking event the seal can be considered static.

The lip seal groove is also basically square.

"o"-rings are indeed standardized but since the caliper was originally designed for the lip seal the bore might not be an "o"ring standard. The seal bore tolerance is pretty tight. Looking at standards there are a few choices for a 1.875 front caliper bore. The choices are because of different standard "o"ring cross sections diameters for that bore. IIRC the VB&P ring looks about a .210 std. The replacement for that would be a 2-325 "O"ring. The quad ring equivilent is 4-325.

The elastomers used for brake systems are also one of the standards as brake fluid is a common usage (caliper half cross port seal).

Of course none of this is tested and it could be that a custon seal is used as a compomise between the semi-static and semi-dynamic environment.

Grampy

 

[turtlevette]

those lip seals seal better under pressure than an o ring. the problem is the piston pumping and letting air in.

I'm not sure that's entirely true. If you notice on those zero tolerance pistons i sent you years ago, the piston is machined to wedge the o-ring tighter against the bore as the piston moves out. So as the pressure increases the o-ring gets a bit tighter.

My problem with them is the o-ring seat in the piston needs to be just a little bit bigger in diameter to get a tighter static fit. You can push them in with your fingers. Typical OEM stuff needs a C clamp the seal is so tight.

 

[MYBAD79]

I think I'll look for a set of rear SS sleeved cores and rebuild them too.

I happen to have a set of freshly rebuilt SS sleeved calipers (still in the plastic wrap they came in), if you're interested.....

 

[010752]

those lip seals seal better under pressure than an o ring. the problem is the piston pumping and letting air in.

I'm not sure that's entirely true. If you notice on those zero tolerance pistons i sent you years ago, the piston is machined to wedge the o-ring tighter against the bore as the piston moves out. So as the pressure increases the o-ring gets a bit tighter.

My problem with them is the o-ring seat in the piston needs to be just a little bit bigger in diameter to get a tighter static fit. You can push them in with your fingers. Typical OEM stuff needs a C clamp the seal is so tight.

Don't know what problems you had with your zero tolerance pistons, but the incorrect piston groove dia and not enough "squeeze" on the oring probably was a cause of failure. The oring in a caliper application really is static even though over time and with pad wear the oring will travel in the bore. During breaking operations the oring just distorts, not moves, and the memory in the rubber along with the angle of the bottom of the groove acts a return spring to lessen pad drag. That is why they recommend not using the springs on conversions.

On how oring and lip seals compare depends on the amount of squeeze designed into the oring.
Generally lips seals or cup seals are generally a low pressure seal (less than 2500psi) and more than enough for brake systems, whereas orings can be good up to 5000psi.
The sealing confusion is probably the "ucup" seals which are usually made from hard urethane and are far superior to the best oring setup for pressure.

The quad rings, despite the hype and from what I have heard have a higher failure rate under static usage than the oring in the same applications. The groove ideally is a little more narrow, but can be put in an oring spec groove. I think where they excell is in dynamic situations.

Here is a oring handbook by parker.
Drill down and you will find the machining spec charts for high pressures static and dynamic. Note there are all different types of installs, some with backer rings etc.
http://www.parker.com/literature/ORD 5700 Parker_O-Ring_Handbook.pdf

A year or so ago I fooled around with master sizes etc and ended up trying front ss calipers with cup seals and without the springs, but using a 1-1/4" mastr to make up for any pedal loss. So far, so good.
I wonder how the cup seals would hold up with an oring tensioner under them?
If GM had to do it all over agian, they would have probably come up with the D8 design back in 65.

Anyway Merry Christmass to all. :bounce:

 

[MYBAD79]

If GM had to do it all over agian, they would have probably come up with the D8 design back in 65.

Anyway Merry Christmass to all. :bounce:

I wonder why they designed the C3 caliper the way they did ?? What advantage did they see by having the seal ring in a groove on the piston ?

 

[mrvette]

If GM had to do it all over agian, they would have probably come up with the D8 design back in 65.

Anyway Merry Christmass to all. :bounce:

I wonder why they designed the C3 caliper the way they did ?? What advantage did they see by having the seal ring in a groove on the piston ?

Maybe I not taken enough calipers apart, but I never seen one with the seal on the caliper body, always on the piston.....

:skeptic:

 

[turtlevette]

Don't know what problems you had with your zero tolerance pistons, but the incorrect piston groove dia and not enough "squeeze" on the oring probably was a cause of failure. The oring in a caliper application really is static even though over time and with pad wear the oring will travel in the bore. During breaking operations the oring just distorts, not moves, and the memory in the rubber along with the angle of the bottom of the groove acts a return spring to lessen pad drag. That is why they recommend not using the springs on conversions.

A year or so ago I fooled around with master sizes etc and ended up trying front ss calipers with cup seals and without the springs, but using a 1-1/4" mastr to make up for any pedal loss. So far, so good.
I wonder how the cup seals would hold up with an oring tensioner under them?
If GM had to do it all over agian, they would have probably come up with the D8 design back in 65.

:

Its nice to banter with someone who is mechanically astute. The Zero tolerance setup will leak eventually. It would be more robust with a bit tigher interference fit on the o-ring. I'm going to disagree with you that the seal is static, otherwise how would you explain piston knock back? The Zero tolerance pistons are still a rather slopy fit in the bore, i would think because of the large expansion coefficent of the aluminum. Stainless or titanium could be fitted a little tighter. The loose fit allows the pistons to move laterally in the bore. My old SS retrofitted cores are actually worn in the bore because of this effect. Most low mileage cars will never see that. I see a lot of failure modes most don't because of the amount of miles i put on my car.

What you explain above is good theory wise but even with bearings set up with no play the spindle is going to move just a bit during hard cornering or a shock loading event such as hitting a pothole which is going to force the pistons back in the bore. The o-ring seals could really use some force to push them back against the pad and rotor. I've found the wilwood 2 pound inline residual pressure valve makes for a firmer pedal. I believe any fixed caliper setup would need these. I use them with my wilwood calipers.

Do you get any decent modulation with the big 1.25 master?

The wilwood setup has made a world of difference. I don't waste track time letting the brakes cool anymore.