3 Basic Master Cylinder Upgrade Questions for a 1976 FJ40?

Ackcruisers

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Working my way through my 1976 FJ40 imported from Colombia and mapping out the areas the restorer chose aftermarket parts. My latest discovery is this Sanyco (Taiwan) master cylinder here is link on eBay. What's strange is the reservoir numbers appear to be OEM with 47221-30010 and corresponds with this (link here) reservoir on eBay. Image 3 shows numbers 47221-30010 exact match to my reservoir numbers. Perhaps Sanyco sourced these from Toyota....


My 4/1976 truck has the three holes on firewall, single reservoir master and drum brakes. (yes, I know this is strange since US spec 76 trucks all have front disc, booster and 4 holes on firewall). My brake set-up is of an earlier truck. I'm not interested in the disc brake upgrade at this time.

My current master cylinder may have a small leak. The evidence - paint peeling off the firewall as shown in image #1 below plus slight fluid level drop.

IMAGE #1

Sanyco FJ40 Master Reservoir.jpeg


Three Questions:

1. Can a single reservoir master cylinder be boosted?
2. What master cylinder would you recommend I upgrade to with minimal brake line modifications? (see image #2 below for diameter of lines and Image #3 for space at firewall).

3. Is it worth attempting to repair the Taiwan $49 master?

IMAGE #2
Sanyco FJ40 Master.jpeg


IMAGE #3

Sanyco FJ40 Master Firewall.jpeg


Thanks for any assistance.
 
Last edited:

BeerM3

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One of the FJ40 experts on this site, @65swb45, will probably tell you something along the lines of #1) Fix the brakes first and make it safe. There are plenty of single circuit vehicles on the road and yours are probably functioning okay, I'd much prefer to drive something that has a 50% chance of stopping if a brake line goes.

1. Can a single reservoir master cylinder be boosted? The US drum models 69-75 have a compatible booster. Doublecheck for clearance issues at the carb though if the import locations are slightly different.
2. What master cylinder would you recommend I upgrade to with minimal brake line modifications? (see image #2 below for diameter of lines and Image #3 for space at firewall). I personally use a ~75 dual master cylinder I purchased from Cruiser Outfitters on my '76, but only because someone swapped out my original axle with a drum version. I plan to reverse that down the road.
3. Is it worth attempting to repair the Taiwan $49 master? I would dig into the expense and effort of adding a brake circuit to the back. @Rainman (makes brake lines specifically for these trucks), Mark listed above, and plenty of others can help you with the logistics of that. NiCopp and Stainless can be fabricated from scratch with some tube bending skills.

Be aware that if you purchase a '76 compatible master, it has a residual valve in the front that will prohibit enough psi to push the front drum cylinders. Ask me how I know!
 

65swb45

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I do indeed have firewall brackets to put a non-boosted tandem master cylinder onto the three hole firewall. I have been making them since 1992, and have them on all four of my Landcruisers. There is a picture of the bracket on the specials page of my website: www.marksoffroad.net. There are also many pictures of the bracket installed on this website.

I will be happy to sell you the bracket and updated master cylinder, and to help with installation logistics post-sale. I am out of the office until Monday.

Thanks for your interest.
 

Ackcruisers

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Thanks @BeerM3 for the insights and assistance. Statistically speaking, I prefer the odds of the dual circuit master/braking system. I never thought about it that way since my truck (and the two US spec 69 & 72 in my past) have single circuit. @65swb45 I will check out the spacer/bracket and dual circuit master. I very much would take you up on the post-sale support and logistics. What a generous offer...

After closer examination of the space on my firewall/clutch master/carb, it appears there is 12" of distance from firewall to carb diaphragm. The brake booster built for 7/70 - 9/75 FJ40's looks like it will fit if the spacer is large enough to clear the throttle linkage. Image below. Given the necessary work to install new brake lines for dual circuit, it may make sense to add booster at same time.

7E6CC120-F257-4D5E-BF1E-109225E1DFD5.jpeg
 
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When i installed a new master on my 64 it leaked everywhere from brand new and took off all the paint on the inside of the fire wall.
(NOT happy hadnt even driven it yet bare metal 2 pac respray)
Found the rod from the pedal was adjusted in too far allowing brake fluid to get behind the last seal and leak down my firewall
 

1911

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Any time (every time) you replace a master cylinder, you must always check the pushrod adjustment as per the factory service manual.
 

Ackcruisers

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Thanks for the insights @1911 and @Marn0 . I’m now starting to plan for a brake booster/dual master upgrade for my 4 wheel drum brake truck. @65swb45 is there any concern about weight/stress on firewall when using a brake booster with your 3 to 4 hole converter adapter spacer? I’m not sure why my 1976 Colombian truck has the 3 hole firewall vs 4 (see image A below taken during resto) Also, my truck does not have a pedal bucket (55106-60020). image B below.

IMAGE A
CCB3A71E-F4B8-4CBF-8E84-93247BEC5980.jpeg


IMAGE B
81854AED-CD07-4D8B-8865-BD4DD02FFE8E.jpeg
 

Ackcruisers

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Because it is a South American-market truck. Toyota kept them much more simple, easy to repair in the bush, and less costly for the 3rd world/bush markets.
That makes sense. Was concerned the firewall was from an earlier truck. To upgrade with a booster, it appears it will require a pedal bucket, removal and replacement of welded nuts on firewall to do this right. Anyone know where I can source the welded nuts? Alternatively, will using rivnuts work?
 

Ackcruisers

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Thanks for the insights @1911 and @Marn0 . I’m now starting to plan for a brake booster/dual master upgrade for my 4 wheel drum brake truck. @65swb45 is there any concern about weight/stress on firewall when using a brake booster with your 3 to 4 hole converter adapter spacer? I’m not sure why my 1976 Colombian truck has the 3 hole firewall vs 4 (see image A below taken during resto) Also, my truck does not have a pedal bucket (55106-60020). image B below.

IMAGE A
View attachment 2222477

IMAGE B
View attachment 2222479
A quick correction. My truck does have a pedal bucket. However, it is welded to the firewall. To change this is a ton of work. Hoping the 3:4 spacer/adapter will work. If anyone has experience with this please let me know.

2C6BACA5-D02E-478B-AE11-98B4807BF6E4.jpeg
 

Living in the Past

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Because it is a South American-market truck. Toyota kept them much more simple, easy to repair in the bush, and less costly for the 3rd world/bush markets.

It was also because DOT and EPA requirements in the US market. Padded dash, three point seat belts, roll bar and front disc brakes were US safety requirements. Other markets got some of these later or earlier depending on the market. Emissions are a whole other story. Toyota didn't add them because they thought they could charge more. In the end it was all these and the big three pushing congress for higher import tax why Toyota dropped the FJ40 in 1983 and never imported the 70 series.
 

65swb45

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A non-boosted dual-reservoir cylinder would be the easiest solution. That is what I run in all 4 of my cruisers.

Clearance is the issue with the booster-firewall adapter pushing the master cylinder into the space required by the carburetor. Clearance is compounded with the extra distance the 2F intake sticks out from the engine block.

I build my adapters myself, so, since you don't have the rib to contend with, I could build you a shallower version of my adapter. I would be looking to have you source the booster and master from me as well to offset the extra time it would take to build the one-off adapter.
 

Ackcruisers

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Thanks @65swb45. If a straight dual master is what you run on all four of your trucks, it should work for me. My previous two FJ40’s were not boosted. I think I will just purchase your adapter/spacer and a non boosted dual reservoir master. How much shallower would the custom spacer be vs your standard version?
 

65swb45

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Thanks @65swb45. If a straight dual master is what you run on all four of your trucks, it should work for me. My previous two FJ40’s were not boosted. I think I will just purchase your adapter/spacer and a non boosted dual reservoir master. How much shallower would the custom spacer be vs your standard version?
We will talk...by telephone. ;)
 
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I do indeed have firewall brackets to put a non-boosted tandem master cylinder onto the three hole firewall. I have been making them since 1992, and have them on all four of my Landcruisers. There is a picture of the bracket on the specials page of my website: www.marksoffroad.net. There are also many pictures of the bracket installed on this website.

I will be happy to sell you the bracket and updated master cylinder, and to help with installation logistics post-sale. I am out of the office until Monday.

Thanks for your interest.
what are the dimensions of the master cylinder adapter.
 
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