Anyone have a list of what booster pumps my 88' 4runner is compatable with? I have a squishy brake and have replaced so far pads/shoes, wheel cylinders, drums, rotars and the MC. Have bled the brackes, and bench bled the MC. Picked up a booster pump out of a 92' 4runner today for 19 bucks.... looks the same but not sure. Any help would be greatly appreciated.

 

The brake booster from the 92 4Runner will work on your 88 4Runner, i have a brake booster and master cylinder on my 86 4Runner, its a direct swap.

 

the booster will work, but a bad booster will not cause squishy brakes, it will cause the opposite effect and hard brake pedal.

You sure the drums are adjusted correctly?

One other thing you haven't messed with and changed out is the LSPV which can create a squishy pedal if it's not sending te correct amount of pressure tot he brakes. You did bleed off the LSPV when bleeding the system right?

 

Have you bled the LSPV above the rear axle? Might want to check that too. Not sure a bad booster would give you squishy brakes. A hard pedal with reduced braking or an inconsistent feel would be more like a bad booster symptom.

 

no i have not bled the lspv, RBX suggested that to me yesterday, just havnt gotten to it yet. going to get into it sunday. Anyone able to tell me if the booster i got off the 92 is double diaphram or single? should i swap in since i have it on hand?

 

without a photo of the booster can't tell ya, but this is the difference between the two. BTW using a dual with a non 1" MC might result in a soft pedal.

dual:




single:

 

Bleeding these LSPV is very expensive I think I am about to just quit trying the last 4 2 bleeders snapped off the other 2 they came out but no brake fluid. I think that was about $600.00 for all four

The last one #5 is getting a adjustable valve

I would be willing to bet your back brakes are not adjusted tight enough

How does the emergency brake work??

 

ouch... i called Toyota and im kinda friends with the parts guy, he can get me the lspv for 200 bucks, normal is 270 something. I tend to check how much im looking at to replace something b4 i start messing with it..lol As far as having them adjusted right, they worked fine till about 2 weeks ago...just did ALOT of brake work about 6 months ago. Parking brake is set well, 4 - 5 clicks b4 tight, as suggested by toyotas service guys. no weeping/seeping from drum/calipers

 

M/C size alone shouldn't create a soft pedal. Go up in size and the stroke decreases resulting in a lower pressure per unit of force. Go down in size and the stroke increases resulting in a higher pressure per unit of force. Both will feel good with proper bleeding.

My guess is air in the LSPV...

 

that's funny because if you switch in a 1" master on a single diaphram booster the pedal gets harder. Figured it work the opposite.

 

Did anything change? I take it you used standard DOT 3 brake fluid. Brake fluid level change btwn the six months ago brake job and two weeks ago?

 

1" from 13/16" would give you a shorter stroke. Volume = Area x Stroke; Increase the area of the bore and you require less stroke to move the same amount of fluid. Less stroke is ofter perceived as a firmer pedal, but the system stiffness is the same.

 

hmmm well all I know is when i switched from my 7/8 bore mc to a 1" my pedal got harder meaning the brakes grabbed higher in the pedal. Much higher. Meaning the top half of the pedal got stiffer. Perception is reality. When I switched my single to dual the brakes catch almost where the old single and 7/8 grabbed.