Caliper O-Ring Conversion

[Michael C.]

I've decided to convert the calipers on my 69 to O-rings. My infrequent driving has left me victim to the leaking lip seals. Most parts sellers appear to sell kits without springs. Does this imply that springs don't normally need replacing? I've replaced the lip seals many times, but never the springs. Anything I should expect in a kit besides the pistons, seals and O-rings (large and small)?

The calipers are Delco Moraine, and are several years old, but not original. Is it safe to assume they are stainless steel sleeved? How can I tell for sure once I open the caliper? At least on parts seller stated their kit is for sleeved calipers only.

Any tips regarding the conversion process?

Thanks, Mike.

[Bob W.]

Re: Caliper O-Ring Conversion

Mike, Give Ken at Lonestar Caliper Co. a call as he will answer all your questions. Post back as to what you find out, the phone # is (903) 829-8400.

[Joe L.]

Re: Caliper O-Ring Conversion

I've decided to convert the calipers on my 69 to O-rings. My infrequent driving has left me victim to the leaking lip seals. Most parts sellers appear to sell kits without springs. Does this imply that springs don't normally need replacing? I've replaced the lip seals many times, but never the springs. Anything I should expect in a kit besides the pistons, seals and O-rings (large and small)?

The calipers are Delco Moraine, and are several years old, but not original. Is it safe to assume they are stainless steel sleeved? How can I tell for sure once I open the caliper? At least on parts seller stated their kit is for sleeved calipers only.

Any tips regarding the conversion process?

Thanks, Mike.

Mike-----

Some of the o-ring caliper conversions use piston springs and some do not. Usually, if they are required for a particular conversion, they are supplied with the kit.

If the calipers have been replaced, the liklihood is that they have been previously sleeved. You may even find a rebuilders stamp on them somewhere. However, not all stainless steel sleeved calipers are created equal. Some of the "cheapies" on the market use cheap decorative stainless steel sleeves, often with poor machine work. These are the "budget" type sold at some automotive parts stores. The best calipers use 316 stainless for the sleeves. I believe all of the major rebuilders (Lonestar, Vette Brakes, SSBC, etc.) use this type. Unfortunately, it's hard to distinguish the "cheapies" from the good ones on visual inspection. However, if you find any corrosion, pitting, or other flaws on the piston bores, then they were either unsleeved or they are the inferior sleeves. Most rebuilders will not re-sleeve a caliper that's been previously sleeved.

There are two easy ways to discern a caliper bore that's been sleeved if you can't tell the difference between a cast iron and stainless steel bore. First, simply look at the dust seal groove. If the bore has been sleeved, you'll easily be able to see the end of the sleeve. Second, the caliper bores are usually not machined out for their full length-----only the piston seal contact surface. So, if you look toward the rear of the bores, you will see the parting line between sleeve and original bore.

By the way, I'm not a fan of o-ring calipers. O-ring calipers are nothing new. They were used in disc brakes of other auto makers way back in the day. However, GM chose not to use that technology for Corvettes. They must have had good reasons. It will be interesting to see what Ken says, though. If you talk to him, please report back here.

[William F.]

Re: Caliper O-Ring Conversion

Yes, but since the pistons which have o ring seals don't continually contact rotor, which may have excess runout , it's said that in many cases O ring type will solve the air pumping that occurs with excess lateral rotor runout in combination with the lip seal type that keeps pistions in contant in and out contact with a rotor with excess lateral runout. Right?

[Joe L.]

Re: Caliper O-Ring Conversion

Yes, but since the pistons which have o ring seals don't continually contact rotor, which may have excess runout , it's said that in many cases O ring type will solve the air pumping that occurs with excess lateral rotor runout in combination with the lip seal type that keeps pistions in contant in and out contact with a rotor with excess lateral runout. Right?

William------


Yes, that's right. However, that capability would have been a big plus for GM when they designed the Corvette disc brake system. They did not take advantage of it, though. I figure they had good reason for this. We just don't know what the reasons were. Of course, if one uses o-ring seals, one might find out some of the reasons.

[William F.]

Re: Caliper O-Ring Conversion

Joe,
With all respect, a lot of these O ring sealed calipers are being used. I've used 2 with no leaks or other problems. If anybody knows any real disadvantages, I'd like to hear from them and tell what problems, if any, the've encountered.

[Joe L.]

Re: Caliper O-Ring Conversion

Joe,
With all respect, a lot of these O ring sealed calipers are being used. I've used 2 with no leaks or other problems. If anybody knows any real disadvantages, I'd like to hear from them and tell what problems, if any, the've encountered.

William------


I'd like to hear from others that have used them, too.

One other thing to keep in mind: the Corvette disc brake system was used for 18 model years. Some changes were made over the years but they were relatively minor. At any point in that long period GM could have rather easily converted to o-ring type pistons and seals. This would have possibly resulted in alleviating some of the apparent problems associated with the lip seal pistons and seals. I'm sure that GM had more than a few warranty and service problems over the period related to the brakes. But, they never changed the piston or seal design (yes, I know that the piston design changed for 65-E67 versus later but seal design was not part of it).

[Domenic T.]

Re: Caliper O-Ring Conversion

A bit off Corvette, but aircraft used O-ring seals as far back as I can remember. As I remember the hydraulic system went right to the O-ring design. Mechanical linkage was prior.

Dom

[John M.]

https://www.restore-an-old-car.com/lip-seal-vs-o-ring.html

with lip seals the sealing area incresaes with applied pressure. Low pressure or vacuum allows them to leak if they take a set as in sitting for a long period

[Michael C.]

Re: Caliper O-Ring Conversion

I just completed a phone call with Ken at Lonestar. Very gracious of him to spend several minutes with someone on a "cold call." Joe's description above on how to identify a sleeved caliper helped me answer that question, so I didn't bother Ken with that. Yes, they're sleeved. Appear to be high quality sleeves, but I can see and barely feel a "minor" scratch in one sleeve. Ken gave me some info on what I might try with that issue. He even offered to polish it out for free if I think it's worth the two-way freight cost. He stated that lip seals are more forgiving of "minor" sleeve imperfections because of the greater surface area of the lip. Maybe this is one reason GM stuck with lip seals for so long???

He concurred with some of the comments above and in other threads - O-rings are great for infrequently driven cars (like mine). He has had O-rings on one of his cars for around 10 years with no signs of leaks.

Although he caters to the wholesale market, he will sell retail. I'll be sending him my wishlist to get prices. Hope I can afford him.

Thanks everyone for your thoughts.

[Bob W.]

Re: Caliper O-Ring Conversion

Mike, Ken is a great guy he has been always fair with his pricing to me, as I buy something from him a every Carlisle event I attend. I have a list ready for spring Carlisle

Bob

[Greg H.]

Re: Caliper O-Ring Conversion

Hi Michael,
I replaced the lip seals in my 67 roadster with O rings back in 2012 after years of trying to stop the lip seals on this car from leaking. Now, not a drop has appeared and I still have a grate brake pedal for a non-power brake car. I installed the O-ring seals from Stainless Steel Brakes.

My fight with lip seals began back in 1984 when I bought a 67 coupe to use as my daily driver, 200 plus miles per day. I had to re-work all 4 wheels at least twice a year. My fix was to hone the caliper bores as an attempt to improve the sealing probability of the lip seals. That process improved and extended the sealing capabilities but the standard leaking would eventually start again. Because of these leaking lip seals, I am an expert brake bleeder. I have pressure bleeder that will allow me to do a full bleeding in record time.

About 1987, stainless steel sleeved calipers were the new brake product and I thought they would help solve my caliper leaks so I purchased a set and continued my daily drives. Some improvement but the lip seals still leaked. No honing allowed here, just total disassembly, cleaning and re-assembly with new factory seals. The pressure bleeding continued until I replaced the lip seals with O-rings and the leaks stopped.

About a year ago, I rebuilt my AC system on the coupe and I replaced all of the old O rings with new O-rings and I wondered why the factory did not use lip seals to seal the AC system?

You will be happy with your new O rings.
Greg

[Jeffrey S.]

Re: Caliper O-Ring Conversion

I rebuilt the sleeved calipers on my '69 about 15 years ago with o-rings due to air pumping. I was constantly bleeding the rears to get a firm pedal. I know that the correct way is to true up the rotors to eliminate the wobble but I wanted to try this as an easy way out. I have not had a leak or a soft pedal since. I would not hesitate to recommend this to anyone that needs a rebuild.
Jeff

[William F.]

Re: Caliper O-Ring Conversion

Joe,
I went back some of the "similar threads" listed below and saw one of yours which said something to this effect:" I (Joe) was skeptical of o ring system originally, but now think they're OK." You haven't changed your mind again on this, have you?

[Dennis D.]

Re: Caliper O-Ring Conversion

I installed the original developer ZTI ( zero tolerence) orings and pistons around 1994. The air pumping was so bad I couldn't go around the block. Work flawlessly. No sleeves no springs. Just cleaned up my original caliper bores. BTW,The rumout will cause the lip seal to collapse and pump air in no time. Remember an article in a 1980 vette mag describing this.