Weak Rear Brake Stopping Power
 

so i was driving around on the ice/snow the other day and noticed that my rear brakes never lock up when i put the pedal on. the front do obiously, but you would think that the back would as well even though they are obviously weaker. so i'm wondering, when can i see my rear anti-lock lock in action?

The axle has a linkage to a brake proportioner valve, it's a curved rod running to the unit bolted to the frame. If it's bad, or you tweaked the rod off-roading, this will not allow enough of the hydraulic pressure from your brake booster to reach your rear brake drums/pads. Adjustment requires having the rod be barely (fully closing) touching the valve closure, while the vehicle is at rest on a level surface. The valves purpose is to provide less pressure to the rear brakes, when the vehicle pitches forward during braking. This helps rear wheel lock-up, fully preventing it sometimes.

well i thought i did everything properly when i went to the downey hd kit. I think i know what your talking about though. it's the little reservoir for the brake fluid right above the rear axle right? (i believe it's called the LPSV; not sure what it's actual name is) the downey hd kit came with an modification to make sure that this part works properly. It makes it so when your axle goes up and down, you still have braking power. anyone know how to fix it so it works period?

Here's some pics so you can see the downey mod parts.

the new bracket to raise the LPSV bar height:
http://i69.photobucket.com/albums/i4...ediumSmall.jpg

LPSV reservoir and rear brake assembly:
http://i69.photobucket.com/albums/i4...ediumSmall.jpg

another angle:
http://i69.photobucket.com/albums/i4...ediumSmall.jpg

Your rear brakes probably just need to be tightened up. I tighten mine twice a year.

found out what LPSV is. Load Proportioning Sensing Valve. You might be right. how exactly would i do that with the rear drums?

With the lift, the LSPV "sees" that as a very lightly loaded rear end of the 4Runner and cuts the rear brake bias accordingly. See:
- http://www.4crawler.com/4x4/4R_suspe...ortioningValve
- http://www.4crawler.com/4x4/ForSale/...l#LSPV_Bracket

good stuff. well now i know how exactly the LPBV works and it makes much more sense now. i think i'll have to get some of my buddies in the back to see how well this thing works.

4crawler - where in the bay are you from?

Santa Clara, near the SJ Airport.

oh geez your close by. i'm up in los altos (next to mt. view) off 85

mmm university chicken (formerly cluck-u)....best damn wings in the south bay