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Leaky brake valve  Rating:  Rating
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 Posted: 07-06-2012 04:20 am
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h2oman
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I have a 74 JH-5 and have several fluid leaks coming from the Brake pressure differential warning actuator (PDWA). One leak is out of the electrical switch, so my o-rings must be leaking on the sliding valve piece. Also it is leaking out of the front end. Is there a source for washers and o-rings? If not, has any one used an alternative?
I did take it apart and checked it for pitting, and it looks good. It was clean and rust free. The rest of my brake system is clean and recently rebuilt the wheel cylinders and replaced the GTLMA fluid. MC is in good condition and is clean.

Thanks,
Bob Waterman
74 JH-5 19695

Last edited on 07-06-2012 05:52 pm by h2oman

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 Posted: 07-07-2012 10:18 pm
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Sander
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Sorry that I'm not answering your question but I have some advice.  You might want to remove the electrical "switch", and then drill, tap and plug it.  I personally don't need a light to come on to know I have a leak.  The pedal sinking to the floor lets me know I have an issue.  Also, by putting in a plug you're separating and creating two separate brake systems ... front and rear.  If you loose a front brake line you'll still have rear brakes .... and visa versa.  And, no more leaks at the electric switch!  I've done this on all five of my cars.

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 Posted: 07-07-2012 10:20 pm
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Sander
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Sorry that I'm not answering your question but I have some advice.  You might want to remove the electrical "switch", and then drill, tap and plug it.  I personally don't need a light to come on to know I have a leak.  The pedal sinking to the floor lets me know I have an issue.  Also, by putting in a plug you're separating and creating two separate brake systems ... front and rear.  If you loose a front brake line you'll still have rear brakes .... and visa versa.  And, no more leaks at the electric switch!

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 Posted: 07-07-2012 10:31 pm
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h2oman
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Thanks for the response. I was just thinking about removing the PDWA and using a coupling and tee to replace it. Several people have done this on other british cars that had leakage issues. I saw a pic of a JH that had this setup which is apparently how they came stock in the UK.

I like your idea since it looks stock-ish, and no mods are needed to the brake lines, which are no longer leaking on my PDWA. Just the switch seems to still be leaking.

Do you have to re-tap the hole to put a plug in it? what size did you use?

Five Jensens! Wow you are a braver man than I!

Thanks,
Bob

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 Posted: 07-09-2012 07:07 pm
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Sander
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I'll have to check on the tap and plug sizes.  I did it years ago.  I'll send you a note with the information.

JH's - '73, '74 and '75 and 2 GT's.  I also "plugged" my '75 MGB.

(sorry for the double note)

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 Posted: 07-16-2012 11:39 am
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Jay
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I'm thinking if you have a leak from the hole where the switch mounts then you must have a leak from one or both sides of the shuttle valve. If that is the case, I'm not sure that you would indeed be creating two "separate" systems, front and rear. By plugging the hole, the same leak could still allow fluid to pass from front to rear or visa-versa.

My shuttle valve is still tripped either forward or back (i can't tell which way). Does anyone know of an easy way to get it centered again? When I remove the switch all that I see is the plunger that is moved by the shuttle. Has anyone removed this (what I'm calling) "plunger" to reveal the groove on the shuttle? If I could access the groove then maybe I could move the shuttle back to center.

Thanks.

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 Posted: 10-20-2012 03:22 pm
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redracer
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Jay, Bob: what Sander has done will not compromise your brake system. The 2 end caps are removed and tapped with a 1/8" tap, around 10-12 turns (this means no fluid from one side will get into the other side, we do not tap the electrical switch outlet--no need to); then we use a brass allen plug putting teflon tape ONLY on the upper threads to ensure no tape will "clog" the fluid lines. We have to retrofit the later switches( '75 and on) since only one end cap can be removed for tapping. I keep a couple of them ready-to-go.
bruce madden, red racer, atlanta, ga

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 Posted: 10-21-2012 03:04 pm
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h2oman
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Thanks for the response Bruce. When you say you tap the opening, are you talking about the end caps themselves, the end cap openings, or is it the passage between the 2 halves where the valve slides? I would like to modify this sometime in the future.

Do you sell modified units?

Bob

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 Posted: 10-21-2012 03:34 pm
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redracer
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Bob: you remove the 2 sliding shafts and the small ball that actuates the electrical switch. No predrilling is necessary as the 2 bore for the 2 shafts is perfectly sized for a 1/8" tap.
Yes, I do sell them etc., but this is a tech forum and is not (i would assume)a business site. This is Greg's website and I would need approval.

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