Automotive Brake Caliper Leak Rate Standards and Tests

Question

Automotive Brake Caliper Leak Rate Standards and Tests

umatrix (Mechanical)

(OP)

27 Jan 20 21:30

I am seeking standards for standards/ documentation pertaining to brake caliper leak testing, both air/vacuum and or fluid tests.

I've found some documents that suggest some values for automotive brakes (page 6 of link), but I am looking for something more official.
https://www.cincinnati-test.com/images/AB120%20Set...

BrianPetersen (Mechanical) · Answer 1 · 2020-01-27 21:51:51

What is the purpose of your leak testing?

Is it on a production line as a sanity-check that the component has been assembled correctly, or something else?

umatrix (Mechanical) · Answer 2 · 2020-01-27 21:57:06

Exactly a production line as a sanity-check that the component has been assembled correctly.

Tmoose (Mechanical) · Answer 3 · 2020-01-27 22:14:12

The linked document says this -
"1.477 sccm (This is equivalent to 100 bubbles with a diameter of 1/8” in one minute in a dunk tank).

Brake System (brake fluid) at 5-200 psig ---1 - 20 sccm"

==============

DANG ! More than a 1/8" bubble per second ?!
I guess that is tested with air, so maybe with brake fluid it would seal a LOT tighter, but that seems like a defective caliper to me.

IRstuff (Aerospace) · Answer 4 · 2020-01-28 00:20:34

Seems awfully high to me. Nevertheless, we can apply a use-case: no more than 1-inch drop in a 3-in diameter reservoir over 1 yr, for example. This would equate to 3.7E-6 cc/s fluid loss; so, no detectable leakage, period. It would take a 3.8-hr test to detect one drop of fluid loss.

TTFN (ta ta for now)
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BrianPetersen (Mechanical) · Answer 5 · 2020-01-28 02:38:12

Since this is for a production-line sanity check ... the usual methods of production-line leak-testing are only going to be able to apply pressure for a short period of time (a few seconds). If there is any leakage detected at all using normal leak-testing apparatus (not something exotic) ... you have a problem.

If it needs to be defined any more precisely than that, then the question is best asked of your customer who is buying these parts. Perhaps whoever will be paying for the leak-testing apparatus may have an interest in this, too.

dgallup (Automotive) · Answer 6 · 2020-01-28 16:20:39

SAE J1118 Hydraulic Valves for Motor Vehicle Brake Systems Test Procedure gives test procedure but not pass/fail values.
SAE J1137 Hydraulic Valves for Motor Vehicle Brake Systems—Performance Requirements does give some allowable leakage values.

SAE J1693 REMANUFACTURED HYDRAULIC MASTER CYLINDER FOR MOTOR VEHICLE BRAKES—GENERAL CHARACTERISTICS AND TEST PROCEDURE seems pretty general.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

IRstuff (Aerospace) · Answer 7 · 2020-01-28 17:34:32

Getting back to the OP's original citation, on the previous page, they note that air will flow 53 times more volume than water through an pinhole, and water is probably a factor of 3 worse flow than brake fluid, so that means that a bubble test should therefore have no more than 2 such bubbles per minute.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

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Automotive Brake Caliper Leak Rate Standards and Tests