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Brakes - sanity check?

bkaushansky

Member
Joined
Jun 13, 2021
?88 245 with RX7 front calipers and stock rears. OEM master cylinder.

My brand new Volvo OEM brake junction block crapped out and is leaking at the switch. Don?t need the switch so I was planning on using a M12x1.0 plug and copper washer. BUT? if fluid is leaking past the internal o-rings (slowly) should I be concerned?

I?m thinking, no since assuming I remove all air bubbles the pressures will equalize. I would still maintain 2 separate circuits just in case.

Then there?s the other option of pulling the internals of the junction block completely out. This creates a single circuit utilizing the stock rear proportioning valves to create pressure differential (front to rear). This would eliminate any possibility of a fail safe.

Thoughts?

B.
 
Fluid should not pass between the two halves of the junction block, you can easily remove the center pin and other parts to replace the o rings inside of the junction block.
 
:nod:

I just bought the correct sized ball hone from ebay and the o-rings from Volvo to rebuild an original Volvo junction block.

Fluid should not pass between the two halves of the junction block, you can easily remove the center pin and other parts to replace the o rings inside of the junction block.
 
If the fluid is leaking past the o-rings then it can also potentially leak between the circuits. In the UK at least 1990+ models came with a junction block that had no switch (instead relying on a mc level sensor). That would be a better option.
 
If you don't want to rebuild the warning light valve. I would contact plantman or hiperfauto and see if they have any of their junction block eliminators left.
 
If you don't want to rebuild the warning light valve. I would contact plantman or hiperfauto and see if they have any of their junction block eliminators left.

Unfortunately, the supply of new junction blocks without a warning switch has been exhausted.

So I'm looking into rebuilding the original junctions with warning switches and that's why I bought the o-rings from Volvo and a suitable sized ball hone to clean up the passage a couple.
 
If the fluid is leaking past the o-rings then it can also potentially leak between the circuits. In the UK at least 1990+ models came with a junction block that had no switch (instead relying on a mc level sensor). That would be a better option.

1991 in the US, then in 92 they went to ABS and eliminated the junction
 
Got a solution!!

For those with single line front caliper upgrades, I replaced the junction box completely with 2 Tee fitting. This maintained 2 independent circuits. The fluid sensor is now in the cap and it just so happens the wiring is plenty long enough to reach, almost as if intended to go there. The Tee fitting I used were Empi 10mmx1.0 bubble flair for a VW Bug. Made a ?U? bracket out of steel to hold the tee fitting in same location.

B.
 
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