Are there any "approved" adjustable proportioning valves?
I used one on a truck with disc front and rear, and it worked fine but technically was for "race only" or something like that, wasn't supposed to be legal on the road. Actually once I got it adjusted the first time I never had a need or desire to play with it...
I've also used a "junkyard proportioning valve", a GM one from a vehicle with the same disc brakes front and rear as I have, again no problems, and I'd do it again without a second thought.
And the first time I re-did/upgraded a brake system I used a "generic" proportioning valve that looked just like a GM one, and also worked just fine but cost more that I think it is worth.
What is the great advantage to an adjustable one over the proper factory one or a suitable one form a junk yard?
Grigg