Need some brake advice please (1 Viewer)

[GTSSportCoupe]

My pedal has been spongy and some days are worse than others. My calipers and brake lines are all in really good shape. But I did replace some flexible lines a while back, and have just not been able to bleed the spongy out no matter how much I try.

So, today, giving it another try, I notice huge 1/2" bubbles coming up in the reservoir as my son is pumping the pedal. Is it pretty safe to assume I have a worn out master cylinder and air is somehow being drawn in? There is no external brake fluid leaking visible anywhere around the master or inside the truck.

So, assuming it is a leaking master cylinder issue: the sub assembly is no longer available. Seems the best I can do is a 'cylinder kit'. Any of you bought one of these and done a DIY rebuild? Success?

 

[seapotato]

I've only tried it once and it wasn't really worth the effort.

Toyota MC's are all really similar, so I'd be surprised if one of the generic types didn't work for you. There's really only bolt pattern and bore size.

MC39996 is a raybestos number that crosses over to a bunch of trucks. 4runner or 80 depending.

TOYOTA	4RUNNER	1989-1993
TOYOTA	LAND CRUISER	1993-1994
TOYOTA	PICKUP	1989-1993
TOYOTA	T100	1993

New Master Cylinder by RAYBESTOS - MC39996

Buy RAYBESTOS MC39996 New Master Cylinder compatible with Toyota 4 Runner, Toyota Hi Lux

partsavatar.ca

I had to buy a different one because I didn't have a reservoir.

I think this is the one I bought this one for my 60. Details are a bit murky, I don't remember which I put in the 40 and which in the 60

Advics is Aisin I gather, so pretty much same as buying toyota. Nice firm pedal, stops as well as disc/drums can I guess.

More Information for ADVICS BMT090

www.rockauto.com

 

[cruiserpilot]

I replaced my master with one from 80 series on advice of JBarron. It's same bolt pattern and just bolts on.
Only thing is to make sure you get the rod length right so it's perfect tension. I think it would be a matter of
cost. What does the bore look like on the current master? If it's all good maybe a rebuild would be fine.
Just a matter of sealing I guess

 

[GTSSportCoupe]

I've only tried it once and it wasn't really worth the effort.

Toyota MC's are all really similar, so I'd be surprised if one of the generic types didn't work for you. There's really only bolt pattern and bore size.

MC39996 is a raybestos number that crosses over to a bunch of trucks. 4runner or 80 depending.

TOYOTA	4RUNNER	1989-1993
TOYOTA	LAND CRUISER	1993-1994
TOYOTA	PICKUP	1989-1993
TOYOTA	T100	1993

New Master Cylinder by RAYBESTOS - MC39996

Buy RAYBESTOS MC39996 New Master Cylinder compatible with Toyota 4 Runner, Toyota Hi Lux

partsavatar.ca

I had to buy a different one because I didn't have a reservoir.

I think this is the one I bought this one for my 60. Details are a bit murky, I don't remember which I put in the 40 and which in the 60

Advics is Aisin I gather, so pretty much same as buying toyota. Nice firm pedal, stops as well as disc/drums can I guess.

More Information for ADVICS BMT090

www.rockauto.com

Thanks so much man! I'm going to focus on finding a cross then. One of the brake lines comes out the side like the ones you suggested, but the other line comes out the top (at the end). After a bit more reading, apparently it crosses to some of the larger bore JDM 80 series ones; which would be a nice upgrade for the hassle.... Now to find the exact right number. Will keep digging.

 

[GTSSportCoupe]

I replaced my master with one from 80 series on advice of JBarron. It's same bolt pattern and just bolts on.
Only thing is to make sure you get the rod length right so it's perfect tension. I think it would be a matter of
cost. What does the bore look like on the current master? If it's all good maybe a rebuild would be fine.
Just a matter of sealing I guess

Yup, that's where I'm leaning now. But there are a number of 80 series variations. I'm going to need a RHD one I'm pretty sure.

Here's a picture of mine:

 

[cruiserpilot]

I found the Dorman version for an '95 80 series at about $138. Dorman is the brand name for Toyota parts now which
I learned through Tundra stuff.

Sorry, this went up at the same time. I dont' think LH or RH makes a pinch of difference. If the hoses line up should be good to go.

That ADVICS one that Seapotato posted looks identical to mine, sort of finished aluminum pot metal

 

[GTSSportCoupe]

I found the Dorman version for an '95 80 series at about $138. Dorman is the brand name for Toyota parts now which
I learned through Tundra stuff.

Sorry, this went up at the same time. I dont' think LH or RH makes a pinch of difference. If the hoses line up should be good to go.

That ADVICS one that Seapotato posted looks identical to mine, sort of finished aluminum pot metal

I'll have to bend my brake lines around to match some of these. Not recommended I'm thinking? Proper way would be to fab new lines?

 

[seapotato]

I'd be inclined to cut a slot in that firewall rib so you don't have to look for any rhd stuff.

I have a flaring kit and a bender if you need to make new lines.

It's really easy.

 

[GTSSportCoupe]

I'd be inclined to cut a slot in that firewall rib so you don't have to look for any rhd stuff.

I have a flaring kit and a bender if you need to make new lines.

It's really easy.

Thanks very much; I may very well take you up on that!

 

[stevebradford]

If you had this issue develop after putting new rubber lines on and bleeding your system, likely your master is rusty inside and when bleeding you sank the peddle lower than it usually travels during normal use forcing the cups into the rusty sections. Now it’s leaking past the pistons. New master or a at minimum hone the old master if you are to try a rebuild.

 

[cruiserpilot]

I'll have to bend my brake lines around to match some of these. Not recommended I'm thinking? Proper way would be to fab new lines?

If they bend without crimping bend away. I believe mine are a bit spastic looking.

 

[GTSSportCoupe]

I ended up buying this one. I've bought from this company before and they've been good. This is an 80 one that they seem to think crosses to my truck. Doesn't look right, but will deal with it if it's not (basically switch one line to other side). It'll be an upgrade as it's a larger bore.. Brake Master Cylinder (Right Hand Drive) With ABS for TOYOTA LAND CRUISER 2.4L Turbo Diesel - 5 door - 1/1990 to 5/1993 - https://www.milneroffroad.com/toyota-land-cruiser-5-door-2.4-diesel-from-1990-to-1993-lj78/product/brake-master-cylinders-load-sensing-valves-bsmh-br/brake-master-cylinder-right-hand-drive-with-abs-004430/004430

 

[stevebradford]

Dual diaphragm booster?

Larger bore master moves more fluid to the brakes with the same amount of through. Yes, but it takes more effort at the peddle end to impose the same pressure on the callipers.

If you have plenty of booster assist already though it should indeed be an upgrade with no noticeable extra force needed.

I tried the one inch 80 series master on my 60 with my upgraded booster it was too much. The peddle was like an on off switch and would lock up all four too easily due to my extra boost and small tires so I stuck with the 7/8 bore master. I can still lock up all the tires when I like but also have a safe braking range to the peddle. You with your large tires have much more mechanical disadvantage working against your brakes, guessing this new master will work better for you than it did for me.

 

[GTSSportCoupe]

Dual diaphragm booster?

Larger bore master moves more fluid to the brakes with the same amount of through. Yes, but it takes more effort at the peddle end to impose the same pressure on the callipers.

If you have plenty of booster assist already though it should indeed be an upgrade with no noticeable extra force needed.

I tried the one inch 80 series master on my 60 with my upgraded booster it was too much. The peddle was like an on off switch and would lock up all four too easily due to my extra boost and small tires so I stuck with the 7/8 bore master. I can still lock up all the tires when I like but also have a safe braking range to the peddle. You with your large tires have much more mechanical disadvantage working against your brakes, guessing this new master will work better for you than it did for me.

Well, I'm just confused so it seems. Noticed tonight mine says 15/16" on it, and the one I ordered is 24mm. Same thing? Just haven't had the time to really dig into these details today. The one I bought is listed for my vehicle, but has connections in different areas. Price was right either way, so will see how it goes.

I just bled more tonight and am beginning to wonder if we ran the brake fluid too low and ingested some air earlier today. Barely any bubbles now and pedal feels much better (although not 100%). Ran out of fluid and my kid's patience though. At least I'm running for the time being. Busy week ahead.

 

[bikersmurf]

It should work out just fine. If I can install an ‘89 JDM 80 series booster and master in a ‘74 LHD Fj40, it should be fine. Over the years I’ve carefully reshaped the lines several times over… shouldn’t be a problem.

 

[cruiserpilot]

Hey, since you are all in on this. This guy installed a better booster. I hadn't thought of the one result is lighter pressure
required for use. It ticked my memory that was a difference on mine when I did the booster / master at the same time.
Less pressure required, superb performance at stopping. It won't take long its a short thread.

Dual diaphragm brake booster install

Hey Mud, this is a quick walk thru for installing the City Racer dual diaphragm brake booster in your FJ60. There's a posted installation guide for the FJ40, which serves as a general guide for the swap. OTRAMM also has a useful 80 series video on their channel. I'm doing this specific swap for...

forum.ih8mud.com

 

[seapotato]

Hey, since you are all in on this. This guy installed a better booster. I hadn't thought of the one result is lighter pressure
required for use. It ticked my memory that was a difference on mine when I did the booster / master at the same time.
Less pressure required, superb performance at stopping. It won't take long its a short thread.

Dual diaphragm brake booster install

Hey Mud, this is a quick walk thru for installing the City Racer dual diaphragm brake booster in your FJ60. There's a posted installation guide for the FJ40, which serves as a general guide for the swap. OTRAMM also has a useful 80 series video on their channel. I'm doing this specific swap for...

forum.ih8mud.com

Some cruisers already have it. My 61 did.

Look for the double step on the outside of the booster.

 

[bikersmurf]

Hey, since you are all in on this. This guy installed a better booster. I hadn't thought of the one result is lighter pressure
required for use. It ticked my memory that was a difference on mine when I did the booster / master at the same time.
Less pressure required, superb performance at stopping. It won't take long its a short thread.

Dual diaphragm brake booster install

Hey Mud, this is a quick walk thru for installing the City Racer dual diaphragm brake booster in your FJ60. There's a posted installation guide for the FJ40, which serves as a general guide for the swap. OTRAMM also has a useful 80 series video on their channel. I'm doing this specific swap for...

forum.ih8mud.com

The 80 series booster is way more powerful than a 40 one. At the worst, if front drums were a bit out of adjustment, it was two feet on the brake pedal and holding on the steering wheel while pushing down (at 210 lbs there was only so much downward force available).

Now, I can curl my big toe to stop the 40. If I Jab the pedal with two fingers it'll lock all four wheels on dry pavement at 30 mph. The brakes aren’t grabby but they sure work.

 

[stevebradford]

Since every thread must devolve into wild rambling at some point, do any of you also bleed each brake at the wheel once a year to flush the moisture rich brake fluid that’s settled to the bottom of the callipers and wheel cylinders?

I do mine once a year just a couple squirts from the bleeder at each wheel in hopes of preventing my callipers and cylinders from rusting internally and eventually ceasing.

 

[seapotato]

Since every thread must devolve into wild rambling at some point, do any of you also bleed each brake at the wheel once a year to flush the moisture rich brake fluid that’s settled to the bottom of the callipers and wheel cylinders?

I do mine once a year just a couple squirts from the bleeder at each wheel in hopes of preventing my callipers and cylinders from rusting internally and eventually ceasing.

I never used to, but having had that moisture boil off on me and create a zero brakes situation after 1/2 hour of driving with a sticky ebrake, I do now.

That was after only 2 years, but it was a jug of brake fluid that I'd had for a while, so it probably had sucked up a fair bit of moisture before I even put it in the truck.

Underwear are too expensive to keep loading them like that.