72 FJ40 master cylinder question (1 Viewer)

[Defcon989]

Going through my 72 FJ40 to get it ready for its first run and have a brake issue. It has the stock drums on all four, replaced all of the wheel cylinders and pads and turned the drums. After a couple days bleeding the system with my boy no dice. Pedal would go to floor each time on the first pump and would build and then hold pressure. Did this multiple times. Decided to bleed master cylinder and while doing so noticed that when the pedal was depressed all the way I would get bubbles from the bottom of the rear reservoir. This would only happen when the pedal was within the last couple inches of travel. Pulled the master cylinder off the and looks like it may be leaking in the rear.

Running low on time and in searching for solutions noticed a lot of references to using the Fj80 master cylinder from Marlin Crawler. Has anyone used this on their Fj40 running all drums? I only see reference to rear drums with front discs. Since time is an issue and Marlin Crawler is about an hour away this seems to be a good choice since eventually I will go with discs in the front.

 

[tornio]

hi defcon989, IMO , i would check the inner side of master cylinder and if it is not too much damaged i would polish it
and buy a MC rebuild kit..

bu sure to bleed correctly and VERY IMPORTANT adjust the shoes !!!

even better before adjust all the shoes and then check the brakes , you won't believe how important is .!
I LATELY discovered it here on the forum after months of poor brake... ( AS YOU THE FIRST PUMP NOT BRAKING)

TRY good luck

 

[Defcon989]

hi defcon989, IMO , i would check the inner side of master cylinder and if it is not too much damaged i would polish it
and buy a MC rebuild kit..

bu sure to bleed correctly and VERY IMPORTANT adjust the shoes !!!

even better before adjust all the shoes and then check the brakes , you won't believe how important is .!
I LATELY discovered it here on the forum after months of poor brake... ( AS YOU THE FIRST PUMP NOT BRAKING)

TRY good luck

I had thought about rebuild kit but the corrosion at the rear of the mc and when I looked down the rear reservoir it seemed to be pretty funky down in the port was concerned it wouldn't work. Time is also an issue so anything I have to ship would be a problem. I called napa and they have a reman with no reservoirs, no rebuild kits, and they said they also had one with a single reservoir. When I searched their website it looked like the only single reservoir mc they had was for the clutch.

I did adjust the brakes all the way to lock in the drum. The front I had to adjust about three different times. Once I quit using a screwdriver for adjustment and ground down my brake tool to fit through the slot it worked perfect.

 

[toyotaspeed90]

Understood that there could be variances internally in how much pressure is provided front/rear.... my setup is quite an odd duck but seems to work.

I have a 2nd Gen MR2 booster and a supercharged Previa 1" bore aluminum master, with the 76 FJ40 proportional valve and 76 front/rear axles. Now, understand that the lines may vary in location (had a 76 fj40 master on it before and it was quite a soft pedal).

In my MR2 days I would jump the stock cast 15/16 MC to a Toyota truck 1" aluminum for increased reliability and performance.

I believe there are 2 bolt hole variants of the Toyota 4 bolt master cylinders..... then look at line placement and proportional valves. I like the aluminum units since they can't rust.

 

[tornio]

I had thought about rebuild kit but the corrosion at the rear of the mc and when I looked down the rear reservoir it seemed to be pretty funky down in the port was concerned it wouldn't work. Time is also an issue so anything I have to ship would be a problem. I called napa and they have a reman with no reservoirs, no rebuild kits, and they said they also had one with a single reservoir. When I searched their website it looked like the only single reservoir mc they had was for the clutch.

I did adjust the brakes all the way to lock in the drum. The front I had to adjust about three different times. Once I quit using a screwdriver for adjustment and ground down my brake tool to fit through the slot it worked perfect.

he...i know... i adjusted my shoes (the first time) 5-6 or more times to solve my problem and finally i discovered that only one drum was not adjusted tight so only my think : take patience and check again before changing the mc.... maybe you save some money !

also because if the MC hold the pressure is strange that it is the culprit ...

i read you changed all the wheel cylinders , have you read about the problem that some members here had with after market cylinder ?
look here , great tread that helped me to solve my problem, hope it help you also...

Booster Issue?

cheers and good luck

 

[Cleg]

RockAuto has some choices for a new or rebuilt brake master cylinder without reservoirs for about $34, with reservoirs for $116.

I never had much luck rebuilding cylinders.
It seemed no matter how carefully I polished the bores, they would eventually begin to leak again in 6 to 12 months.
Those were on British cars that had crummy hydraulics to start with.

On my 72 FJ40 I am currently using a brake master made for a 93 Landcruiser, NON-ABS unit.
I have a later disc brake front axle and did not need to add a separate proportioning valve.
The later Landcruiser master bolts right to the 72 booster.
Centric #13044720, about $64 for a brand new unit from Rockauto.
It is aluminum with one large reservoir feeding the 2 circuits.

Booster Dewey rebuilt my brake booster and did a wonderful job.

I'd be interested in knowing if that 2nd Generation MR2 booster can be used without cutting the rib on the firewall.

Good luck

 

[Defcon989]

Getting the reman from Napa today. Went there last night and the only one they had in stock had surface rust in multiple spots, mysterious liquid all over it (didn't seem like brake fluid for protection) and the bag it had been in was opened. Not going to trust that someone else had bought it then returned it to the store. Not willing to chance it. I can't seem to get my old pressure sensors off my original mc (they aren't wired in on my LC) so I am thinking of just getting some plugs from napa for those openings.

Tornio, I did read that thread once before and was concerned that I might need to purge each wheel cylinder as described. After the issues with the bench bleeding of my mc if figured I would eliminate that problem first and then see what the results will be.

Cleg, I have looked at the later mc's and like the idea of one reservoir and the aluminum bodies, only issue I have is the concern that the internal pressures from the front circuit would be too much for the drum setup and would blow out my wheel cylinders at some point. Front what I understand of disc brakes, they take a greater pressure to operate.

 

[65swb45]

Based on your description and your pic, I earnestly recommend you pull the booster and up end it to make sure there is no fluid in it. You will have to pull the check valve and grommet to be sure, but if fluid comes out, THERE IS NO POINT IN REINSTALLING IT.

It's the brakes; be safe.

Best

Mark

 

[Bshaunessy]

Defcon 989:
I am very interested in hearing how your saga finally gets solved.
I am having an almost identical, frustrating experience: ( see new posted thread "BRAKE ISSUES -1966 FJ45 all new components -SPONGY BRAKES"......synopsis of my story below:

1966 FJ45 body off restoration,recently reassembled but having serious brake gremlin issues ( just like you!)
HISTORY
- upgraded brakes from drum/drum and single hydraulic circuit to drum rear, disc front with USED BUT FUNCTIONING power booster (1976 FJ40) and new OEM dual circuit master ( note -sourced firewall spacer from JT Outfitters to make this work)
-all new brake cylinders rear ( SOR =non OEM.....wondering, per your thread, if these cylinders might be harbouring air???)
-new ( reman) front calipers
-new 10mm hard brake lines and all new SS hoses throughout ( NB original 1966 system was all 9mm fittings....now entire system is more modern 10mm fittings.....much better)
-in short.....entire brake system is NEW ( or reman)

-have manually ( very carefully, one man on peddal and 2nd man at cyclinder or caliber with hose into clear jar of brake fluid, being careful to close bleed screw after peddal push so as not to suck air in via bleed screw when peddal released) bled and bled and bled system . Lots of air initially, as you would expect with a new air filled system. Bled 9 litres through system ( even switched part way from a clear brake fluid to a blue tinge brake fluid so I could see at caliber or cylinder when I was getting new fluid).

NET EFFECT: have sort of brakes but peddal will go to floor for two strokes until I get some brake action. ( with engine running and booster functioning OR with engine off and booster not running. Very frustrating after amount of effort have put in. Sure sounds like air in system ( impossible....but likely?) OR failed MC ??

SUSPICIONS AND NEXT STEPS:
(1) think I may have overstroked MC ( new) when bench bleeding so have a rebuild kit coming ( even though it was new OEM MC)
(2) bought NAPA vacuum bleed tool and will try vacuum bleeding entire system with particular emphasis on rear cyclinders x 2 ( per earlier in this thread.....getting air out of both rear cylinders per wheel sounds very problematic....mention in your thread (?) of having to remove these and bench bleed /reinstall?? good grief!!)

 

[tornadoalleycruiser]

Use two hard brake lines bent into u's redirected into the reservoir to insure bleeding. Making your own sst you will use many times in the course of cruiser ownership. Your situation sounds like a bad master. Personally I wouldn't throw money at the drums. I would do your disk conversion on the front and use the master listed above and insure you have all 4 new soft lines . I also recommend rear disk for ease of maint and not trying to adjust. But for now you need a new 4w drum master. Your master 4wd can be used for a front disk conversion later by removing the residual spring in the front circuit

 

[Defcon989]

Update to my frustrating brake issue.......I HAVE BRAKES. After missing out on the run I was trying to get ready for last March I threw the towel in for awhile and had other priorities...life gets in the way sometimes. Here is the latest;

1. Originally have almost no brakes after replacing all of the wheel cylinders with new pads and turned drums as well

2. Replaced the master cylinder as it was in poor shape and appeared to be leaking. Ended up getting another after the first replacement seemed to have similar results.

3. Had originally tried bleeding with the pedal, then hand vac, then pneumatic bleeder and every combination I could with no change in the pedal or ability to stop.

4. After sitting for months I put the second master cylinder in it, replaced all of the rubber hoses and tried a new bleeding method my brother uses for his work on forklifts and such. We made a cover for the reservoir in the master cylinder, used cork gasket material from napa to help seal it and used quick clamps to fasten it to the mc. Drilled a small hole in the cover that allowed me to use the typical air nozzle that has a rubber tip to pressurize the reservoir (ended up at about 4psi on the regulator). My brother pressurized the reservoir while I operated the bleeders. We put a lid from a gear oil bottle on the brake fluid bottle to refill the reservoir without removing the cover we made. This method worked great and gave me the best pedal and braking I had achieved so far. Still couldn't obtain lock up from one pump of the pedal, but I could stop. After looking at the results and realizing that in pumping the brakes we were filling the wheel cylinders quicker than they can move fluid back to the mc, it was just all about adjustment of the pads at that point. I adjusted the pads as far as possible until I could adjust them out no further then backed off 5 clicks, or at least what I thought was 5 since the feel isn't great. Tested it and achieved lock up. Still need to back the rears down a little I think as they locked first and also seemed to be much warmer after just driving for a few miles than the front. Also still adjusting the play in the brake pedal by adjusting the rod on the front of the booster. Pedal height sucks but from what I have read that seems to be universal and in fact I am lower than what the manual calls for in a 72.

Hope this helps with someone else out there beating there head off a wall over these drums. Bleeding was the worst experience of any vehicle I have ever done. Adjusting just takes persistence and really isn't that bad.

 

[tornio]

HAPPY to ear you solved !!

 

[bikersmurf]

Backing off 5 clicks seems like a lot. It has been 20 years since my 40 last had drums... so my memory has faded. I've enjoyed not having to adjust the front brakes in 25 years... and having the front pads last 19 years vs 2 years for brake shoes.

Although, I've not used the method of adjusting till they won't go further. I'd have a look around, there is a thread that covers how to do it per FSM instructions.

 

[Defcon989]

Bikersmurf,

I thought 5 clicks would be a lot as well, but my rear brakes were still a little tight and I had to back off a little further. As far as adjusting till they won't go further this is what the FSM that I have states....

"4. Expand the brake shoe by turning the wheel cylinder adjusting nut.....until the shoe is tight against the drum. At this time, pump the brake pedal a few times to make sure that the shoes contact the drum onto the entire surface. If the wheel still turns after removing the foot from the brake pedal, turn the adjusting nut further until the wheel is locked completely.

5. Back off the adjusting nut 5 notches if the shoe still drags lightly on the drum, then back off the adjusting nut 1-2 additional notches. Check if the wheel rotates freely."

I have read in multiple posts on this forum that the brakes need to start off a little tight. All I know is that method did work for my stock 4-drum setup. I took it for a 5 mile test drive and the brakes were good, other than the rears being a little tight at the time. After reading MANY posts on these brakes and my own experience with my 72, I definitely think that each vehicle has its own solution. I just know that I tried every bleeding method I could without buying expensive equipment (including the gravity method) and nothing worked like pressurizing the master cylinder reservoirs. Thanks to all those that took the time to give their advice, very helpful in every way.