Toyota Rear disc brakes issue
 

So I just put 4340 axles and rear disc brakes on my 94 4runner. I had to put a new booster on it and rebuild the front calipers. The problem I am having is the brake pedal feels like **** after I have blead the brakes. I dont have any leaks in the system. The rear brakes are sky-manufacturing rear disc set up with Chevy calipers and stainless lines running on the rear axle. I have a porportioning valve and 10lb residual valve comming off the master for the rear brakes. The only thing I can think of is I have a air pocket some where in the system and it has just not bleed out yet. Any thought or comments would be great.

Rob

to my knowledge a stock brake master cyl is big enough for the rear disk setup..i.e. it makes for a spongey pedal...we usually put a master cyl off a 93 yota t100 non abs on em and it works great...hope it helps...maybe someone else can help more??

sounds like air
that have a 1" bore master on it?
always bleed farthest corner to the nearest to the master.
bleed porportioning valve last. if it had one
sounds like u dont have anymore
fyi...these trucks r the hardest units i have ever had to bleed

yes has 1" master on it

Try a pressure bleeder if you can get access

I have power bleed the brakes on my 4runner. The only thing I can think of at this time is I am using my stock ABS master cylinder and the rear part of the master is to weak and I need to change it to a non ABS master.

So here is what I did today with the brakes. I have a 1" bore non ABS master cylinder on my 4runner. I have no proportioning valve and no 10lb residual valve on it at all. Took it all of to make sure it was not them. The runner had rear ABS and it is not hooked up at all. I have speed bleed the brakes and 2 person bleed the brakes and still have a ****ty pedal with the truck off and it goes to the floor when it is running. I am so fing pissed at this thng. I have also call sky and talk to someone there and he told me that everything I have done they would have done. So I am sunk any help would be great.

Rob

When you bled them, did you do the farthest away first (Left rear, right rear, right front, left front) to make sure you got the air out?

check your vaccum booster check valve (in the line) to the intake manifold. If you took it off and flipped it around, that might cause the sinking pedal when its running. it has a direction so that once manifold pulls a vaccum, the valve holds it. I've seen this problem on 2 different rigs that had poor brakes after the conversion.

Is this a new master cylinder? If not, the one you have may be bad.



Brakes are pretty simple...

The vaccum valve is fine I never took it off, it is holding vaccum. The master is new and yes I bleed the brakes the right way from passangers rear, drivers rear passangers front, and drivers front.

I have seen bad MC's even though they were new. Ask FlxRtd:o

I tried the master that was on my runner that was good. it was a ABS master and from what I have read that is not the master I need so i got a new master from Davez offroad performance. I really dont think it is the master.

Drivers Side Rear
Passenger Side Rear
Passenger Side Front
Drivers Side Front
the 1" master is plenty enuf for the brakes, this has been my experience anyway.

dumb question
is the calipers on the correct sides....bleeders at the top?
even if they are..i've had to unbolt caliper bracket and spin bleeder to tippity top then bleed....spin them back down and bolt them up after..

plenty of fluid coming out of each bleeder...no clog?
power bleeder?

only other thing i got is bench bleed the M/C

i feel for ya. i no exactly where you are comiing from on this. they freakin suck

i have cut my rusty frame out from the doors back and fabbed a new one in.. while all the time working around the calipers. refused to crack the lines .

im glad im not the only one that has made this mistake...lol..actually quite a few people have, its easy to do...

calipers have bleeders are on top, I have power bleed the brakes, I bench bleed the new master.

That what I found out today. The 1" bore toyota master is not pushing enough fluid causeing the low and spongy pedal in my 4runner. I am going to buy the rockstomper GM master and bracket to fix the issue.

I have been PMing ericb on pirate and have been reading his stuff for a few days now. I can fab it up right now I will have to let it sit because I have other things I need to work on at work.

i got some 1/4" plate if you need a piece...

:beers:

Great help I will be making this ASAP.

Are the factory studs on the booster not long enough to just use?

i got one of these with a master bolted to it somewhere
your welcome to come and check it out
if it will help

Stickman how soft was your pedal mine goes to the floor on the first pump. I was a little worried about just using the 1 1/8 GM master with that low of a pedal. I was thinking about using the 1 1/4 master instead. I have read ERICB page on the brake and was wonder what your pedal felt like before and after the master change.

Going from the 1" to the 1-1/8" will be a ~23%increase in fluid volume. The 1-1/4" will be a 56% increase over the 1".

I'd be careful about going too big or the brakes will be very sensitive.

if you still have issues. take a pair of vice grips and block the fluid on the rubber lines. I had to do this on my cherokee to find out that I had bad front calipers. it will tell you real quick if there is still air in the main lines. when I did it i clamped both sides of the rubber lines to make sure that the rubber was not expanding.

I call BS on the 1" M/C not working... I have the same setup as you.

what calipers are you using?
I have the 1" V6 M/C with 1985 monty carlo calipers, (sky brackets) and have awesome brakes.

I even still have the Prop valve (lever tied up) in-line.

Davez off-road parts are usually pull-off parts, not new I believe. Least not what he sent me.

My guess is you still have air in the lines, or your M/C is bad...

agreed!!!!!!!!!!