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Soft brake pedal


Forrest Gump 9

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Hello all

 

I’ve picked up a 99 4runner as a winter beater. The brake would go soft when you press the pedal. If you pump it a second time then it’s perfect. So far I’ve replaced the front pads and master cyclinder and didn’t help. No leak any where, the brake lines are fine. What else could cause that?

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Its a pretty common toyota complaint. Some upgrade to Tundra stuff as supposedly the master is much larger.

 

Did you change the fluid? Might help.

 

Yes, the fluid was changed.

 

I had two other 4runner, both 2000, and upgraded to the tundra rotors and calipers and never had any problem with those.

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id put $20 bux on this

 

 

jack up and support

remove the front wheels

using screwdrivers push back each side caliper pistons 1 side at a time i.e. rf inner pistons, (have someone push the brake pedal and watch for sticking pistons), rf outer pistons, (have someone push the brake pedal and watch for sticking pistons), lf inner, lf outer.

 

i'd bet you have one of the pistons sticking in the caliper and it needs replaced.

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id put $20 bux on this

 

 

jack up and support

remove the front wheels

using screwdrivers push back each side caliper pistons 1 side at a time i.e. rf inner pistons, (have someone push the brake pedal and watch for sticking pistons), rf outer pistons, (have someone push the brake pedal and watch for sticking pistons), lf inner, lf outer.

 

i'd bet you have one of the pistons sticking in the caliper and it needs replaced.

 

Good for not assuming , I automatically assumed when he replaced that pads he ruled out a bad piston/ caliper

 

Def check those bad boys

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id put $20 bux on this

 

 

jack up and support

remove the front wheels

using screwdrivers push back each side caliper pistons 1 side at a time i.e. rf inner pistons, (have someone push the brake pedal and watch for sticking pistons), rf outer pistons, (have someone push the brake pedal and watch for sticking pistons), lf inner, lf outer.

 

i'd bet you have one of the pistons sticking in the caliper and it needs replaced.

 

The front calipers are four pistons. So a sticking caliper can cause air in the system? If changing out the calipers cure this I’ll PayPal you $20. I have four calipers sitting in my back yard.

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Wont cause air in the system, but will cause terrible brake feel. May also not retract right away, and cause pads to drag a little and hurt the pad life and mileage.

 

If you are using back yard calipers, check those and make sure the pistons move freely....seems like theyd seize up quicker if they are just yard ornaments lol

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id put $20 bux on this

 

 

jack up and support

remove the front wheels

using screwdrivers push back each side caliper pistons 1 side at a time i.e. rf inner pistons, (have someone push the brake pedal and watch for sticking pistons), rf outer pistons, (have someone push the brake pedal and watch for sticking pistons), lf inner, lf outer.

 

i'd bet you have one of the pistons sticking in the caliper and it needs replaced.

 

This

 

second bet is air in the lines

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Air in the abs pump?

 

If you got any air in the abs pump while bleeding the lines you may not be able to get it out without activating the system. Go out to a gravel parking lot and slam on the brakes a couple times to make the abs work then try bleeding again. If you get air out do it a couple more times until the pedal feels right. Before doing that though, there were other good suggestions. Check your calipers and make sure they aren't sticking first.

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The front calipers are four pistons. So a sticking caliper can cause air in the system? If changing out the calipers cure this I’ll PayPal you $20. I have four calipers sitting in my back yard.

 

yeah i know theyre 4 pistons, i was trying to make my instructions detailed enough that it would show i knew that. they don't put air in the system but give a very similar feeling. As someone else said be a little leary of backyard calipers if they haven't been protected from the elements. and lastly i dont need $20. lol

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Also make sure that bleeder screw is on top of replacing calipers or you will never get the air out . I’ve seen to many times they put the calipers on the wrong sides and can’t figure out what the issue is so just double check
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Also make sure that bleeder screw is on top of replacing calipers or you will never get the air out . I’ve seen to many times they put the calipers on the wrong sides and can’t figure out what the issue is so just double check

also don't work on your own car if this is even possibly an issue, hahahah

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