Replaced Master Cylinder

[Ezra]

I purchased my FJ40 a couple weeks ago. Of all the 40s I test dest driven in the past 6 months, most of them that did not have instrument issues had the brake light come on every time I hit the brakes. I actually thought this was normal until I read the manual.

So after purchasing my FJ40 I noticed the rear BMC reservoir was going down in level, while the front (larger) reservoir was over flowing. I was also occasionally get a left side swerve when I got on the brakes. I figured there was some middle seal separating the front and back systems within the BMC, checked here on the forum, and confirmed. I considered buying a rebuild kit for a moment, but then thought about it a little longer and decided a new replacement for a 40+ year old master cylinder might be a good option. found one here in California for a little over $200, which would get here in two days.

A quick back story about my experience with master cylinders: I also own a 1970 Porsche 914. Last time I tried to bleed the brakes I just couldnt get them firm. I pulled the carped and could easily see the brake fluid pooling in the pedal assembly. Obviously time to replace the BMC. So I ordered a 911 BMC (upgrades from 16mm to 19mm capacity) and set aside an afternoon to set it all up.

9 moths later, I have replaced all the hard lines (after tweaking them trying to remove the BMC), have the gas tank out, because I needed to to access the lines that run to and from the reservoir to reattach them to the BMC, sealed the gas tank while it was out, discovered problems with two of my 4 calipers, so have now rebuilt and painted all of them, etc, etc, etc. The car is still not done.

Last night i replaced the BMC in the FJ40, and bled all four drums in about an hour and a half with the assistance of my girlfriend. The truck will now lock up all four wheel almost instantly at 35mph if I really get on it, with no swerving to one side. Its night and day compared to where it began, and the brake pressure light stays off. What a pleasure to work on.

 

[toyotaspeed90]

Pushing the pedal in and having fluid come back into the cab is indicative that there is pitting inside of the BMC. This typically happens on older cast iron units as the water that ends up being absorbed into the brake fluid slowly pits/rusts the inside of the BMC - the seal pushes past leaving fluid in the pits, and when the seal is pulled back without pressure, it pulls the fluid into the car.

Toyota's have this issue as well with cast units - it's why they went with aluminum units later on. The nice thing about Toyota is they keep their bolt pattern constant. For instance - when I wanted to add a booster to my rig I wanted something thin, but I wanted to use the brake master that I had from the parts 76.... so the thinnest booster I could find (that normally runs 4 calipers) is from an early 90's MR2/SW20 - and the 4 bolt pattern is identical to the 76 FJ40 booster. Make sure what you're looking for is a 4 bolt, though... as not all of the Toyota's are a 4 bolt pattern.

Those needing to replace and wanting to be nostalgic and keep it stock- go with a rebuilt/honed factory BMC. Those wanting an upgrade, look to the newer landcruisers that use a 1" bore, they have the same bolt pattern (I had a 1" bore truck BMC in my 87 MR2 and I had a 15/16" bore SW20 BMC in my 86 MR2).

Note - those with drums may have a different bolt pattern as there is no booster....

 

[Alstruck]

I just did mine to. When everything is working, the brakes work real well.

 

[Ezra]

Couple questions about the brakes:

1) occasionally when I release the brake the brake light comes on for a split second. I assume this is just a result of the fluid having pressure released from it and normal but wanted to double check.

2) I drove about 40 miles today, maybe as much as 60, and when I got back into the city I noticed a knocking through the brake pedal when i was braking. It is very subtle when moving more quickly but coming to a slow stop it is more pronounced, to a point where maybe you could lightly hear it. Any ideas what this could be, it seems to have just popped up today.

Wondering if I should just make this a new topic.

Thanks.

 

[sggoat]

You may have a cylinder leak getting onto the pads/shoes. When braking, the slick spot will skid by, then the dry spot will catch--creating a thumping or chatter.

 

[Ezra]

I kind of figured this would result in my pulling some wheels off and investigating more. This 40 has had the bad cylinder for some time before I purchased it, so the extra stress may have pushed the piston over the edge. May try to pull the wheels off tomorrow. I am guessing I can infer weather the issue is with the front or the back by applying less pressure for a longer stop, and if the knock is there it is probably the back correct?

 

[DSRTRDR]

Couple questions about the brakes:

1) occasionally when I release the brake the brake light comes on for a split second. I assume this is just a result of the fluid having pressure released from it and normal but wanted to double check.

2) I drove about 40 miles today, maybe as much as 60, and when I got back into the city I noticed a knocking through the brake pedal when i was braking. It is very subtle when moving more quickly but coming to a slow stop it is more pronounced, to a point where maybe you could lightly hear it. Any ideas what this could be, it seems to have just popped up today.

Wondering if I should just make this a new topic.

Thanks.

the intermittent brake light could be due to the rubber pad at the pedal worn out, or the brake switch needing adjustment

and to cite the "clack and clack": "if you feel it in the seat of your pants, it's from the rear of the car"

 

[Ezra]

Strangely it seems to have gone away today. we drove about 20 blocks to get coffee this morning, and initially there was a little squeaking coming from the front drivers side, but that pretty quickly went away.

All the same I am going to pull each of the wheels off today and have a look at the pistons, check the general condition of everything. I will take some pictures and share.

 

[Ezra]

I am thinking this issue is all in the front wheels. I feel like the rear wheels are stopping just fine, and locking up before the front wheels are really engaging. The thumping is intermittent but seems like it is happening when I really press in the pedal down hard (and thus kicking in the front brakes). Like when I go down hill and have to put some extra muscle in.

I took each of the wheels and drums off today and took some pictures. The drum retaining screw was absent from all 4 wheels, there was no obvious issue with either of the rear brakes (some spider webs, and lots of dirt, thats about it). I did not take off the dust covers because it seemed like I was going to have to remove the cylinders to get access to the dust covers. There was a little evidence of fluid in the drum on the rear passenger side drum (little paint corrosion) but that could easily have been an old issue. The rear wheels lock up, they are stopping evenly.

I have a plenty of experience with the disc brakes on my 914, and have worked on the drum brakes on my BMW R60, but I have no experience with the FJ40, this is my first time dealing with hydraulic drum brakes. So any advice would be greatly appreciated.

Front passenger side had a lot of bubbling paint, I did not see any immediate evidence of a fluid leaking from the cylinders, but would not be surprised if it was leaking.

The front drivers side was a BI**H to get off. Very tight agains the hub, and while they are all missing the retaining screws, this was the only drum that was not even aligned with the retaining screw hole. Once I got it off (i had to wedge a screwdriver into the holes to create a little leverage, and from the look of the drum this has been done before). It had two loose dust covers, and both were damp underneath. There was some evidence of fluid leaking on the dust covers themselves. The shoe had some damage, with about a 1/4" chip missing from one edge and damage that looks like it could be a result of the missing chunk?

I havent looked into em to see if they are pitted or not, but am thinking about buying rebuild kits for the front cylinders and a honing tool and giving it a go. Alternatively I could see if NAPA has rebuilds at a decent price and just replace them.

Before all of that I am going to dig through all the adjustments within the braking system this week and see if that makes anything more apparent.

Here are some photos, I am posting a lot in case anyone with a more experienced eye than my own can spot any issues:

(rear drivers side) Like I said, all four retaining screws were absent. Is this usual, is there any ill effects from not having them in place?

drum looks good, no signs of bad wear (that I am seeing at least)

Here some more images of the same wheel after a quick spray down with brake cleaner.

skipping the rear passenger side its basically the same as the drivers side.

Now, onto the front passenger side, while I do not see any damp areas, I am seeing evidence of fluid bouncing around in there as a lot of paint is bubbling / falling off. Here are the images:

So now the front drivers side, this was so hard to get off, almost gave up, you can were how it is not aligned with the retaining screw hole. both dust covers were popped off the ridge on one side (see the pics) etc.

and here is the damage I am seeing on the front drivers side brake pad (lower one mainly)

 

[TheHardWay]

Your cylinders seem clean, and not leaking. Leave your drums off and have someone push on the brake pedal while you watch how the cylinders push the shoes out to make sure they are working properly, especially the fronts. I would bet that front shoe was damaged when someone was prying against it with a big screwdriver, trying to install it with the springs keeping the shoes from going into place easily. I wouldn't risk leaving it on.

 

[Weber Sarge]

Watch actuating the brakes without the drums in place - you can blow the cylinders out in some cases .
People remove the retaining screws when installing aftermarket wheels as they interfere with the wheel seating flat against the hub area .
Do the adjusters still work and were the brakes adjusted up tight enough to drag a bit on the drums ? If the rear is holding more pressure than the front I'd start looking a lot closer at the master cylinder .
Sarge

 

[Ezra]

I have not yet adjusted the brake adjusters, will do that this week. My parking brake is very soft so I am guessing they could use some adjustment. The tight drum was not stuck due to the shoes, it seemed more of getting stuck on the center hub or bolts.

Master cylinder is new, less than a week old.

 

[lostmarbles]

..... I noticed a knocking through the brake pedal when i was braking. It is very subtle when moving more quickly but coming to a slow stop it is more pronounced, to a point where maybe you could lightly hear it. ........

You may have a cylinder leak getting onto the pads/shoes. When braking, the slick spot will skid by, then the dry spot will catch--creating a thumping or chatter.

I've never heard of a fluid leak causing a bumpy-pedal before.. From my experience it is normally caused by an out-of-round brake drum (or one that is somehow not mounted concentrically with the hub).

Do you know what's caused this wear-groove here (arrowed) Ezra:

And you appear to have these installed incorrectly:

The shoe sits in a groove. The groove has a slope if you look carefully. (BTW - Only the grooves at the adjusters on the rear wheels have this slope though.) And the slope must always "slope down towards the nearby hub. (This pic shows the slope being opposite to how it should be orientated.)


Well .... I'm basing this advice on how it should be for my 1979 BJ40 anyway ... so I assume whatever you've got should be the same...



PS. And why are some of the dust boots not seated in their grooves in some of your photos? Edit later: Never mind... I posted this at 2am in the morning and no doubt I was tired.. I now see you noted that some of the boots had come off... (This is worrying to me as it suggests that possibly the piston travel may be too far or the boots may somehow be too short causing them to pop them off during brake applications. - But thinking about it further, it's more likely that it's just the results of a sloppy previous brake job.)

And are some of your boots supposed to have those steel spring-clips holding them in place? (I have none and Toyota specifically instruct me not to use them in their instructions with a new OEM wheel cylinder kit I just purchased last month.)

 

[John McVicker]

Lostmarbles,

That's interesting about what you say about Toyota instructing us to not use those springs in the rubber boots. Wonder why ? I purchased my 40 brand new, '75 US model and still have all my springs.

When I stop to think about it, other than redundancy, I can't see a reason to 'need' the springs, just trying to figure out why they are specifically instructing us to not use them.

And to the OP, I'd try to determine how that groove got there.

John

 

[pedwards]

Hi Ezra. I'm my experience, having properly adjusted brakes effects braking performance the most.

With your truck you will need to properly adjust your brakes often.

Have you considered a front disk conversion? If you're not picky about total originality its a significant safety upgrade.

 

[lostmarbles]

Lostmarbles,
That's interesting about what you say about Toyota instructing us to not use those springs in the rubber boots. Wonder why ? I purchased my 40 brand new, '75 US model and still have all my springs.
When I stop to think about it, other than redundancy, I can't see a reason to 'need' the springs, just trying to figure out why they are specifically instructing us to not use them.
And to the OP, I'd try to determine how that groove got there.
John

Hi John

Ezra doesn't have any vehicle details in any signature line so I have no idea what vehicle we're talking about.

My vehicle has never had boot spring-clips on its wheel cylinders and Toyota specifically advises against fitting them to MY vehicle... so that was the sole reason for my questioning seeing them there.

Soooooo. Taking note of what you've just said.....

Just now I looked in a 1976 98154 FSM (after searching through a few others and finding no clips) and sure enough .... I see clips on all the rear boots there.

And looking on the EPC it appears that perhaps they were used (for FJ4# and BJ4# at least) only on semi-floating rear axles after Sept 1975 ... but don't take this as gospel... I don't have enough spare time to check through everything now..

I have a full-floating rear axle ... so that now looks like having something to do with it.

I can crawl under the house and try and dig out that kit from my spares stash if you want proof of the written warning. (I'm pretty sure I really did see one because I looked at that kit only a few weeks ago and my memory's not that bad yet.)

 

[Alstruck]

The brake light going on when the parking brake is off means that one of the pressure sensors isn't turning off in time when you press your brake pedal

The circuit is wired through the parking brake switch and your foot pedal brake switch and your brake master cylinder sensors.
With the parking brake off, when you press the brake pedal and the brake light switch is activated, it wants the brake cylinder sensors sensing pressure, there by opening the circuit from ground so the brake light won't go on. It could be just a timing issue. I wouldn't worry about it if the brake light just blinks.
The idea behind the brake light is if one of the chambers in the master cylinder is empty of brake fluid or not creating pressure this system will
Light up the brake light every time you press the pedal and alerts you of a brake system problem.
I hope that makes sense.
Rick

 

[Ezra]

For everyone, My FJ40 is a 1973 (June). Will update my signature.

I've never heard of a fluid leak causing a bumpy-pedal before.. From my experience it is normally caused by an out-of-round brake drum (or one that is somehow not mounted concentrically with the hub).

My best (not really experienced guess) is that all wheels need to be adjusted, and the front drivers side brake drum is warped, and that is why it was so damn hard to pull off. This is the same one with the brake show that is missing a chunk. When I first started feeling the thumping my first thought was that it felt like warped disk...which obviously is not a possibility.

What is the best technique for establishing if your drum is warped?

Do you know what's caused this wear-groove here (arrowed) Ezra:

I went back and double checked my photos, and this groove exists on both rear drums. There is what seems like a dust groove right down the center of the pad on the shoe. It looks intentional, but i dont know why you would intentionally create an area of non ware in the center like that, and wonder if it is just a strange shoe?

And you appear to have these installed incorrectly:

Good catch, and good to know how to check, I am betting there is another one on the rear wheels that is also reversed.

And are some of your boots supposed to have those steel spring-clips holding them in place? (I have none and Toyota specifically instruct me not to use them in their instructions with a new OEM wheel cylinder kit I just purchased last month.)

Dont know, the rear wheel had them, the front wheel did not. Would be interested to find out what different their presence makes.

Hi Ezra. I'm my experience, having properly adjusted brakes effects braking performance the most.

With your truck you will need to properly adjust your brakes often.

Yes, I am going to go through each wheel and adjust them tonight. On question when adjusting, which direction is tightening and which direction is loosening? Am I pushing the wheel towards the center of the hub to tighten? (so starting with the top of the screw driver towards the inside of the hub, and finishing with the top of the screw driver towards the outside of the hub)? I checked the haynes manual but it did not make things much clearer.

As I understand it the process is: tighten one shoe until it rubs, then back off once, do that individually to each of the 8 shoes.

Have you considered a front disk conversion? If you're not picky about total originality its a significant safety upgrade.

Right now I am a little bit of a purist (except I am adding a later model oem roll bar, and my suspension is aftermarket so probably upgrading to an old man emu, provided it fits in my parking garage at work).

The circuit is wired through the parking brake switch and your foot pedal brake switch and your brake master cylinder sensors.
With the parking brake off, when you press the brake pedal and the brake light switch is activated, it wants the brake cylinder sensors sensing pressure, there by opening the circuit from ground so the brake light won't go on. It could be just a timing issue. I wouldn't worry about it if the brake light just blinks.
The idea behind the brake light is if one of the chambers in the master cylinder is empty of brake fluid or not creating pressure this system will
Light up the brake light every time you press the pedal and alerts you of a brake system problem.
I hope that makes sense.

I think I really need to go through and adjust not only the brakes at wheel level, but also the brake pedal and parking brake.

Thanks everyone for the tips, really glad to have found this forum. I will update more once I get under the truck again.

Here are all the photos, if anyone is interested in digging through all of them:
https://picasaweb.google.com/111036900856959742112/FJ40?authkey=Gv1sRgCInz3LXnqMmXTQ
There is some random stuff in there as well, but when the brake images start they go in this order (rear left, rear right, front right, front left), each set starts with a view of the wheel with the drum on, and then continues through the disassembly and cleaning, followed by some more detailed images.

 

[bikersmurf]

Drums can be a real pain to remove. Working right, drums can work very well. That said, I'd not recomend dumping a lot of money into drum brakes.

When my front drums needed to be entirely redone, I converted them to discs. That way I wasn't spending money on something I'd later replace. Discs cost roughly the same amount as replacing all the parts that were needed. The replacement disc brakes lasted 19 years and 95,000 miles... And never needed adjustment. (The had drums only lasted 20,000 miles.)

Work with what you've got... But at the end of the day, I'd not give up my four wheel discs for anything (just about... Because they could be done again).



I see you have stated you're a purist... Done right, front discs are 100% Toyota, and indistinguishable from stock. Unless you've got a trailer show queen, I'd highly recomend them for the increased safety. Front discs are a very worthwhile upgrade... Rears are good, but rear drums aren't as big a deal since the fronts do 80% of the work. Only a handful of people who've ever seen my truck can tell they weren't stock for annother year and a half later.

 

[lostmarbles]

For everyone, My FJ40 is a 1973 (June). Will update my signature...

Thanks. (It does make it MUCH easier to comment sensibly on someone's post.)

And now that I know this ... and that you're based in San Francisco ...... I look at the EPC for a 1973 FJ40 for the USA-market and lo and behold ....I discover those boot-clips ....

So that of course means I'm now very pleased to see them there on your cruiser..

... ... the front drivers side brake drum is warped, and that is why it was so damn hard to pull off. ...

If this is true... That would explain (to my satisfaction at least) a brake pedal that moves up and down with braking (to give a tapping sensation on the sole of your foot).

...What is the best technique for establishing if your drum is warped?..

Mounting it in a lathe (by gripping the internal circumference where the hub or axle-flange pokes through) and turning it around by hand with a scriber or whatever locked in the toolpost so you can immediately see any out-of-round characteristics.

...I went back and double checked my photos, and this groove exists on both rear drums. There is what seems like a dust groove right down the center of the pad on the shoe. It looks intentional, but i dont know why you would intentionally create an area of non ware in the center like that, and wonder if it is just a strange shoe? ..

I'm ignorant of 1973 models. Perhaps that groove is factory for this year?

...... Would be interested to find out what different their presence makes...

The slope where the shoe sits (and there are 2 of these sloping components per rear wheel) is just a design feature relating to the rear drums. For them to work best, the FSM instructions relating to the orientation of the slope must be followed.

The front shoes are designed to operate without these slopes.

That's all I know (relating to info I've studied for my 1979.)

.... On question when adjusting, which direction is tightening and which direction is loosening? Am I pushing the wheel towards the center of the hub to tighten? (so starting with the top of the screw driver towards the inside of the hub, and finishing with the top of the screw driver towards the outside of the hub)? I checked the haynes manual but it did not make things much clearer.
As I understand it the process is: tighten one shoe until it rubs, then back off once, do that individually to each of the 8 shoes. ..

I've posted this elsewhere and it's what I put together for my own benefit on my 1979.

I suspect (but don't know for sure) that it all applies to your 1973 (despite you not having full-floaters like you see here):

I'll edit in a link to a post in which I describe how I do my adjusting in a minute .. if I can find it.

Edit later.... Here it is in post #27:
https://forum.ih8mud.com/threads/br...-rubbers-coolant-reservoir-caps.831409/page-2

But one thing I didn't mention there is that it always pays to have the wheel itself in place (with tightened lugnuts) to make sure the drum is seated correctly during the adjustment work!!!!