Changing Master/booster & prop valve from 87 down to 88-91

[WagonMan]

A customer of mine has an 86 Grand Marquis and can't find a new/used distribution/prop valve that bolts just below the booster on the frame. Is it possible to switch to the 88-91 booster/master and change the brake lines eliminating the valve? WagonMan

[Tiggie]

Don't have a direct answer for you but...

Found some discussion on this from years ago http://www.grandmarq.net/vb/showthre...=Proportioning

Also they sell rebuild kits for Mustangs, may be the same on the 86. At $9 you aren't out of much. https://www.musclecarresearch.com/valve-kit-kh-E7ZC

[gadget73]

No reason you can't. I do believe the later master cylinder uses bubble flares vs the early one with double flares, so you'll need the proper tool there. The wiring for the switch is different. On the older one it was a shuttle valve in the prop valve assembly, not honestly sure what the later one used. Level switch in the lid maybe? Should just be a matter of moving the wiring from the old to the new. The old block had some more parts in it that I suppose were deemed excess. Later ones were a more straightforward pressure reducer to the back without all the extra metering and crap. Possible you'll get a slight improvement in braking with the later valve. A working one is definitely better than a non-working one though.

Holy crap old post, back when I researched things. Also shame on me for never actually doing followup on that. Years ago now my master cylinder, prop valve, and booster were changed to 98-02 non-abs parts and it made a considerable improvement in pedal feel and stopping ability. It wasn't bad before, but its definitely better now.