Help - Brake Distribution Block Leaks at Switch Port

65-Fstbk

Active Member
May 20, 2007
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39
Vancouver, B.C. Canada
Hey All,

I am having issues with the brake distribution block leaking at the switch when bleeding the brakes.
I did a front drum to disc conversion, switched to a dual bowl master and did the plumbing.

I started with a Circa 1970 original distribution block - leaked at switch port when bleeding
I heard that placing a pin-stopper in the switch port prevents the piston from moving when bleeding so I tried that
Still leaked at switch port (fluid should not get to this area)
So I bought a rebuild kit and rebuilt the block - still leaked at switch port
Took it apart, checked everything and remounted it 3 times and 3 times it still leaked at switch port
I also confirmed with the company that sells the rebuild kit that my gaskets etc were all in the correct orientation
Finally gave up on that and ordered a new distribution block - leaked at switch port (with pin-stopper in)
Company I bought it from sent me a new one - installed that - leaked at switch port

There has got to be a solution for this. I am now thinking of scrapping the block and going with an adjustable proportioning valve that takes both lines from the Master but allows you to dial back pressure to the rear drums once the system is bled. Has that worked for anyone?

Other solutions?

Thanks Guys
 
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65-Fstbk

Active Member
May 20, 2007
309
19
39
Vancouver, B.C. Canada
Damaged threads on the actual switch itself?
Thanks but can't be that b/c the new blocks came with new switch. The thing is, brake fluid should not get to that area, it should be staying dry even if the internal piston shifts to one side under a pressure loss situation. This seems to be a pretty common problem but no-one seems to have a concrete solution.
 

2Blue2

will be trying this sex one when I can find it
Mar 5, 2019
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My 2 cents

Leaks at the plastic right?
70 P-block

Lower Right corner picture switch slides to the fitting and stops.
Wrong fitting then switch slides to far and leaks


brake-pressure-differential-switch.jpg
 

2Blue2

will be trying this sex one when I can find it
Mar 5, 2019
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You got fluid coming out all 4 bleeders?
Just a guess, but for so many attempts to fail, there must be rubbish/ rust in the old lines thats damaging the o rings?
But with the pin stopper you would think the o-rings are not rubbing yet...

If they sent a new one without getting old one back makes you think they have had this problem before.
Just maybe you got a damaged original followed by a couple pf crappy replacements?

This is your second thread on this right?
Other than that I aint got nothing.
 

65-Fstbk

Active Member
May 20, 2007
309
19
39
Vancouver, B.C. Canada
You got fluid coming out all 4 bleeders?
Just a guess, but for so many attempts to fail, there must be rubbish/ rust in the old lines thats damaging the o rings?
But with the pin stopper you would think the o-rings are not rubbing yet...

If they sent a new one without getting old one back makes you think they have had this problem before.
Just maybe you got a damaged original followed by a couple pf crappy replacements?

This is your second thread on this right?
Other than that I aint got nothing.
All the lines are new.
It has me perplexed and it seems this problem is not that unusual.
I have tried and original 1970 era block and that leaked,
I rebuilt it 3 times and had the rebuild guy confirm my seal placement was correct - leaked 3x
I bought a new block - leaked
I installed a replacement new block - leaked
If this new block leaks you may see the car on Craigslist. LOL
 

wicked93gs

10 Year Member
Sep 30, 2006
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Nashville TN
Hmmmm, I haven't checked that. Wouldn't think anything surprising b/c it's just a manual disc/drum setup with a new dual bowl master.

I ask because its remotely possible that for some reason the pressure is higher that what the o-rings are able to stop. I couldn't say why that would be...but its the only thing I can really think of...unless the o-rings are simply too small or you have had a run of bad brake switch blocks
 

65-Fstbk

Active Member
May 20, 2007
309
19
39
Vancouver, B.C. Canada
Over the weekend I purchased an adjustable proportioning valve that accepts both front and rear lines. I had to do some replumbing of the lines and fab a homemade bracket but got it in. So far no leaks.

BTW - If anyone needs to run double flares on brake lines I would highly recommend the Titan tool. I have no financial incentive, no freebies etc but the tool worked way better than those typical flare kits. If anyone wants me to post a pic of it let me know. Nice to use a tool that works nicely.
 
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