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87 4Runner Brakes very spongy

I have an 87 4Runner that I knew had bad rear brakes, but the vehicle still did well at stopping quickly. After removing the drums, I decided to replace the rear cylinders, one brake line, pads and drums. After everything was back together, I went through and snugged up the lines, adjusted the emergency brake until it was tight and bled the brakes starting with the furthest from the Master Cylinder (which is also new within the past 5 months) and ending with the drivers front brake cylinder. THe brakes still seemed very spongy and I was unable to lock the brakes up onmy gravel driveway and the vehicle took a greater distance to come to a stop than it should have, so I went ahead repeated the bleeding process after making sure that there were no leaks and the lines were nice and tight. Needless to say I have bled the brakes a total of 6 times and there is still no luck. The front brakes and calipers are around a year old with maybe 10,000 miles on them. It doesn't make much sense that the brakes worked better before the new rear brakes than they do after all new rear components. Anyone out there have any ideas? Any help would be greatly appreciated.

Reply to
gus.natale
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According to this site:

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There is aLSPV (Load Sensing Proportioning Valve) that should be bled last. Itchanges the amount of fluid pressure to the rear brakes according to theweight.

In the past I have experienced some sponginess of the brakes until everything gets seated in. Did you run the rear shoes out until they are just in contact with the drums? The article says within .5 mm.

Reply to
OldPhart

This will sound stupid but it might just work. Try bleeding with the rear of the truck jacked up as high as possible. Then try bleeding with the front jacked up. If there is air in some hard to reach place that might move it to where you can expel it. This technique is really for bleeding cooling systems and not hydraulic systems but you've tried everything else. Just a thought. Good luck. Al

Reply to
al

site:

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There is a> LSPV (Load Sensing Proportioning Valve) that should be bled last. It> changes the amount of fluid pressure to the rear brakes according to the> weight.

Yikes, that LSVP looks pretty ugly. I don't know if I will even be able to get the bleeder screw open. I have heard of by-passing it from others, but what confuses me is that there are two lines coming from the front of the vehicle and one going out to the junction on the rear axle. I will try these suggestions. Thanks!

Reply to
gusdog

site:

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is a> > LSPV (Load Sensing Proportioning Valve) that should be bled last. It> > changes the amount of fluid pressure to the rear brakes according to the> > weight.

I think I have found the problem. There seemed to be a very small leak (small enough to let air in but no fluid out) at the LPSV, so I have removed it and am putting in a brake line T and a manual adjusting proportion valve.

Reply to
gusdog

| I think I have found the problem. There seemed to be a very small | leak (small enough to let air in but no fluid out) at the LPSV, so I | have removed it and am putting in a brake line T and a manual | adjusting proportion valve. |

Hope that takes care of it. Manual non-adjustable valves were all we had for years and years.

Reply to
OldPhart

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