Brake master cylinder w/front discs - valve or no?

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ianfotheringham

ianfotheringham

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Hey guys - doing some work on my '78 40, front discs (but i believe they were converted from drums at some point), drums in the rear....question is - with discs in the front - should the valve (#47280) still be there? I was under the impression that was a proportioning valve only for drums?...

I'm swapping in a new master and rear cylinders due to some sponginess and poor overall braking - i first put a rebuild kit in my existing Aisin master - but found the outside diameter of the new pistons/seals were much smaller than stock....so was completely useless - put it back together as was and while bench bleeding found the front circuit wasn't working at all....with or without the valve in place.....also, when installed back on the booster, i found that when i depressed the pedal, that the brake pressure was just venting air out the vacuum hose - is this normal??

4720160050dia.gif


brake-master-cylinder.webp
 
Find a parts fiche for your year vehicle. It will tell you a couple of things, whether it came with disc front or drum and if there is a valve on the front circuit. I believe that front disc started about 1976 but different parts of the world may have different implementation dates. Normally disc have a 2 lb valve while drums have a 10 lb valve if I remember correctly.
 
Assuming your vehicle is a non-US FJ40, it did not come with front disks. I have the same year and converted to disks.
Part of that job is removing the valve you are talking about. I fought with my master for a while before I figured out that I had almost no pressure at all in the rear brakes. I found an Aisin master and when I installed it (with that residual valve removed) that solved the problem.
 
Gents I am doing the same swap. A 1982 FJ45 Troopy with drums all around. Putting on a set of 82 FJ60 front discs. Do I also remove the rear drum brake valve as per @ianfotheringham is saying (47280)?

@Mcladin has done the same swap on his '82 FJ40 and is having issues with the brakes. We still haven't figured out what to do.

Also, do we use the Fj60 master and booster, which seems too large to fit on the 40/45 firewall or do we stick with the 40/45 master/booster and just remove the valve?

This is the last piece of the puzzle!

Cheers
 
The valve you are talking about is a residual valve. It's needed for drums but not for disks. So if you put front disks on, take the front residual valve out. I just used my j40 master/booster and it's fine.
 
I have a new, dual-diaphragm booster for the overseas FJ/BJ40 market that has identical diameter and stud patterns as the OEM booster, except it's thinner (about 4 inches deep). I don't think it's as powerful as the fat Tandem booster on the U.S. cars, but it's likely better than the original drum brake booster.

I can't guarantee it will work for your application, but if anyone wants to try it, PM me. I'll send it to you to try out if you cover the shipping cost. If you decide to keep it, you can buy it from me for $250. Otherwise, I'll need it back.

photo 1.webp
photo 2.webp
photo 3.webp
 
Racer65 said:
I have a new, dual-diaphragm booster for the overseas FJ/BJ40 market that has identical diameter and stud patterns as the OEM booster, except it's thinner (about 4 inches deep). I don't think it's as powerful as the fat Tandem booster on the U.S. cars, but it's likely better than the original drum brake booster.

I can't guarantee it will work for your application, but if anyone wants to try it, PM me. I'll send it to you to try out if you cover the shipping cost. If you decide to keep it, you can buy it from me for $250. Otherwise, I'll need it back.

View attachment 959105 View attachment 959106 View attachment 959107
Click to expand...

That's pretty close (in appearance) to the 7.5" single-type Aisin booster on my BJ40 (which is unobtanium):

BrakeMasterOrigAisin.webp


Do you have any details about it? (Where you got it from and/or the part number for it etc?)

:beer:
 
lostmarbles said:
That's pretty close (in appearance) to the 7.5" single-type Aisin booster on my BJ40 (which is unobtanium):

View attachment 959112

Do you have any details about it? (Where you got it from and/or the part number for it etc?)

:beer:
Click to expand...

Not to spill my own beans, I'm in the process of setting up a small shop to bring back some of the unobtanium products of the past. I'm bringing that booster in your photo back. Not almost, but exactly built to Aisin 44610-60030 spec, and brand new.

As a matter of fact, one is currently installed in a local Mudder's FJ40.

New Booster1.webp
 
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Thanks. That is indeed the part number of mine..:beer:
 
Racer65 said:
I'm bringing that booster in your photo back. Not almost, but exactly built to Aisin 44610-60030 spec, and brand new.
Click to expand...

I am interested . . . please send a PM with info for purchasing . . .
 
DSRTRDR said:
I am interested . . . please send a PM with info for purchasing . . .
Click to expand...
My production batch should be ready in about a month. I'll PM you when I'm ready.
The only unit I have on hand is that dual diaphragm version, which is Aisin 44610-60050, but not the fat U.S. Tandem type.
I suggest you wait for my production spec 44610-60030 so that I can warranty it.
 
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Racer65 said:
I have a new, dual-diaphragm booster for the overseas FJ/BJ40 market that has identical diameter and stud patterns as the OEM booster, except it's thinner (about 4 inches deep). I don't think it's as powerful as the fat Tandem booster on the U.S. cars, but it's likely better than the original drum brake booster.
Click to expand...

I don't think the fat ones are particularly powerful, but they would have been more reliable. I went to a thinner one out of a 4runner and it works great. I'm guessing that would be a fine replacement, and it looks closer to the original than I've seen.

The 44610-60030 replacement above looks awfully small. I'd be waiting for a review before paying much for it. A $25 OEM Toyota one from a junkyard 4runner works really, really well.
 
Fast Eddy said:
I don't think the fat ones are particularly powerful, but they would have been more reliable. I went to a thinner one out of a 4runner and it works great. I'm guessing that would be a fine replacement, and it looks closer to the original than I've seen.

The 44610-60030 replacement above looks awfully small. I'd be waiting for a review before paying much for it. A $25 OEM Toyota one from a junkyard 4runner works really, really well.
Click to expand...

The size is identical to OEM. You can judge the size by the distance to the clutch MC. It does not cover up the clutch bolt like some of the junk yard solutions. My supplier is authorized by Toyota to manufacture 44610-60030, so there will be no difference in performance.
 
I didn't intend to disrespect the product. I'm just saying that's not the proper replacement for the '76 and later dual-diaphram booster, which was an improvement over that part number.

My opinion is that it is a better idea to use later parts as replacements, rather than earlier parts.
 
No worries. Healthy skepticism is welcomed. Perhaps I should summarize:
I will be introducing 44610-60030 as the brake booster for Cruisers on drum brakes. That's U.S. models 1971-1975, and overseas models on drum brakes. This booster isn't intended as replacement for '76 and later U.S. spec FJ40's with dual-diaphragm brake boosters.

Meanwhile, I am looking into the feasibility of re-introducing 44610-60050, but it will not be the one pictured above. It needs to be the Tandem model (or the "fat kind") for the U.S. market. The criteria I've set for myself are: Everything needs to be plug-and-play, match original spec, and cannot cost an arm and a leg.
 
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Gents….had a look today at my master and it seems different than the one in @ianfotheringham drawing.

Attached below is the master on my 45 troopy, along with the drawings. It doesn't seem like I can remove the front residual valve.

Can someone point me in the right direction?



 
Well why don't you inspect your front residual valve and see what it really does? (If it can't leave permanent residual pressure in your front brake circuit, then just leave it there for a front disc conversion.)

People told me my residual valves left permanent pressure in my brake circuits but I took a look to see if they could actually do that and I found they can't!

But then my brake master has different residual valves again to yours ....

Here's my master for my "drums all around" BJ40:
BrakeMasterOrigAisin.webp


Washer4.webp


And here is what sits in each of the outlets if this master (and what's referred to by Toyota as a "residual valve":

Residual4.webp

Residual3.webp

That hole right through the centre of the "cup" means that pressures must eventually equalise either side of my residual valves no matter what else happens....

So if the design of your front residual valve is similar ... just leave it in place (assuming you are doing a front disc conversion) because "how can it cause you any problems?"..

I was trying to work out what mine actually accomplish... and the best I could figure out is that they do maintain pressure in my wheel cylinders but only while there is a backflow of fluid occurring. And I believe this is done to help keep the "piston seal lips" (in the wheel cylinders) pushed against the cylinder walls (and thus to help prevent leakage during this leakage-prone event in every braking cycle).

Note: When you lift your foot off the brake pedal, the springs on drum brake shoes push the wheel-cylinder-pistons back into their cylinders ... and this of course creates a backflow of fluid from the cylinders to the brake reservoir(s) on top of the brake master..

(With discs, you also get a similar back-flow but it is very brief/short because piston-travel in callipers is minimal.)

:beer:

PS. Please post photos of what you find?
 
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