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 Posted: 07-14-2019 10:56 pm
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redracer

 

Joined: 09-10-2012
Location: BROOKHAVEN, Georgia USA
Posts: 617
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cjw: here's a post I did a few years ago(use the "SEARCH" box at top). Read some of the other comments as well
Hope this helps:
Brakes > Pressure Differential Warning Actuator (8 replies - 4015 views) 08-29-2017
Dealing with a North American Safety device, the Pressure Differential Warning Actuator. Just finished the car and the brake fail light stays on ...

posted: 08-30-2017 10:04 am
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redracer
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I wrote about this over 25 years ago and had it published in the White Lady, our now defunct mag. for all Jensen owners.I believe I had it entitled "Another one of Nadir's stupid safety ideas"(or something to that effect). Our dual master cylinders had one side do front brakes and the other the rears, unlike modern cars which do diagonal pressure, i.e. left front with right rear, etc.. You can live and drive easily without the rears(I have), but not the fronts, and you will NOT need a light to tell you so. Plus, bleeding the brakes has sometimes "locked" the pins on one side or the other causing the light to always be on.
The "fix" is fairly simple and requires you(or friend) to have the small 1/8" pipe tap(27 threads/inch and NOT the British pipe of 28 threads/inch, which is what the oil pressure line fittings are). Remove both ends of the switch, remove the 2 sliding plugs and the small steel ball, then turn the tap 12-13 complete turns in each end(no drilling is necessary as the holes are the correct size to begin with!!). Using 2 brass allen plugs(takes a 3/16" allen wrench), wrap a little teflon tape on the "starting" ends of each plug and install, being sure none of the teflon is exposed in the chambers(snip extra off).
(if you can't find the brass plugs, I still have plenty)