Front brakes and the LQ-2

[Brewster64]

Front brake limiting valves have been around a long time, they just changed a bit in 1975 with 121 brakes. Gone are the days of your dash switch shutting off the front brakes. They are gone now with the advent of ABS. In a nutshell, your 89 Pete with a dry/ slippery road switch will cut brake pressure to front brakes by 50 percent but only up to about 30 psi, by a 60 psi application the ratio will be up to 100 percent application to front brakes as this is deemed an emergency application. Alot of trucks actually had an automatic limiting valve that was basically always in slippery mode. To look at it, you would think it's a T with a QR in the bottom, but it actually had a function. These were in place to keep trucks from skidding steer tires mostly in town, going around tight corners, into driveways, etc to maintain steering control. Your original valve was was probably just stuck so your front brakes never worked at all, good thing the QR finally started to leak. Don't bother even thinking about ABS on that ol truck. Way less hassles without it.