Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

[Patrick B.]

[Owen L.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

Thank you for this important follow up.

I'm now curious why LS does not use EPDM to be assured of fluid compatibility no matter what the customer decides to use. By using components that are not universally compatible they set themselves up to automatically distrust customers when claims come back.

[Leif A.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

Patrick,
Thank you, once again, for your persistence and perseverance on this matter...it is truly important. As I stated in one of your other posts regarding this issue, it boggles the mind that Lone Star Caliper hasn't, either, heard about this issue or done anything about it. It certainly isn't a money issue for them but it is certainly tainting what use to be a terrific reputation...and, it's damn dangerous.
With your permission, I would like to forward all your testing information to Lone Star Caliper and see if Ken wants to fix this issue. Please let me know if your OK with this.

[Patrick B.]

[Gary B.]

[Joe L.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

Patrick,

Superb work again. Prior to this past year or so, there was lots of speculation and not much data. Now the data are there for all to see. I would love to hear Ken’s reply.

Gary

Gary and Patrick------


I TOTALLY agree. The brake fluid/brake seals conundrum has finally been definitively put to rest after numerous discussions, speculation, and opinions (including my own) over many years.

[Thomas N.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

Patrick
Great job on this! Do you happen to know the id, od and width (which is the actual diameter of the o-ring material) or part number from the oring store that people should buy for their o-ring calipers? That way someone could buy the o-rings ahead of time without tearing their calipers apart? It might help people to plan a job ahead before tackling.

[Patrick B.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

Patrick
Great job on this! Do you happen to know the id, od and width (which is the actual diameter of the o-ring material) or part number from the oring store that people should buy for their o-ring calipers? That way someone could buy the o-rings ahead of time without tearing their calipers apart? It might help people to plan a job ahead before tackling.

The o-rings sizes we need are standardized in a series called AS568 Standard Inch O-Rings. The front o-rings are size AS568-325 (nominal 1-1/2 ID x 1-7/8 OD x 3/16 CS) and the rear o-rings are size AS568-318 (nominal 1" ID x 1-3/8 OD x 3/16 CS). Use the AS568 sizes because the actual sizes differ from the nominal. For example, the section size is about 0.210" actual but 3/16" nominal.

These are the sizes of the Lone Star o-rings I have measured. I measured a front CSSB o-ring and it was identical, so I assume the rears are also identical. In all probability there is only one manufacturer of the special brake pistons used for o-ring calipers, so the o-ring sizes would be common among retail brands.

The premium brake seal material is peroxide cured EPDM. If you go to the effort of getting EPDM o-rings, pay the extra for the peroxide cured formulation. It is still only about $1.67 per o-ring.

[Leif A.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

Leif— It is certainly ok with me if you want to talk to LS about this. I would think they prefer to give their customers the most useful product they can. The solution to the DOT 5 issue is so simple, and they can gain a competitive advantage over CSSB by using the right o-rings.

Patrick,
I just forwarded to Ken @ Lone Star Caliper all the threads over the last several months regarding your investigative work and the results using peroxide cured EDPM o-rings. I, also, shared our concern for the safety of his current product, as well as, our support of his company and what he does for the classic car community...we just need them to be safe. I will let the community know when I hear back from him.

[Patrick H.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

How about the tiny o-ring that goes between the caliper halves?

[Gary B.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

How about the tiny o-ring that goes between the caliper halves?

theoringstore.com

[Patrick B.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

theoringstore.com

The measurements are from an old Delco o-ring. The one I suggested is size AS568-011 in the AS system, but I have never tried one for fit on a caliper

[Mark L.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

This information seems to put the nail in the coffin. To be sure I would like to have a lab analysis of the two materials done to confirm the material and also to have more evidence to present to LS. If someone would send me one EPDM o-ring I will remove an o-ring from a recently rebuilt caliper and get them tested. My address is on the second page of the Restorer.

[Gary B.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

This information seems to put the nail in the coffin. To be sure I would like to have a lab analysis of the two materials done to confirm the material and also to have more evidence to present to LS. If someone would send me one EPDM o-ring I will remove an o-ring from a recently rebuilt caliper and get them tested. My address is on the second page of the Restorer.

Mark,

The test you suggest is exactly what is needed to wrap up the testing of various O-rings. If these is a cost for the testing you suggest, count me in for a contribution.

Gary

[Thomas N.]

Re: Testing Lone Star Caliper O-rings in DOT 4 Brake Fluid

The o-rings sizes we need are standardized in a series called AS568 Standard Inch O-Rings. The front o-rings are size AS568-325 (nominal 1-1/2 ID x 1-7/8 OD x 3/16 CS) and the rear o-rings are size AS568-318 (nominal 1" ID x 1-3/8 OD x 3/16 CS). Use the AS568 sizes because the actual sizes differ from the nominal. For example, the section size is about 0.210" actual but 3/16" nominal.

These are the sizes of the Lone Star o-rings I have measured. I measured a front CSSB o-ring and it was identical, so I assume the rears are also identical. In all probability there is only one manufacturer of the special brake pistons used for o-ring calipers, so the o-ring sizes would be common among retail brands.

The premium brake seal material is peroxide cured EPDM. If you go to the effort of getting EPDM o-rings, pay the extra for the peroxide cured formulation. It is still only about $1.67 per o-ring.

Patrick
Thanks for the clear and concise part numbers for the o-rings. This will help others out greatly!