dual brake wheel cyl.'s- why?

[Brownd3max]

I'm wondering why, on a simple vehicle like my '77 fj40, did Toyota feel the need to put TWO wheel cylinders on the rear brakes? Rear brakes typically contribute a small amount of stopping power anyway, especially with front discs, so what's the deal?

 

[FishTacos]

For reverse......duh.

 

[Brownd3max]

For reverse......duh.

"duh"? wtf does that mean?

 

[Woodrow]

I was curious about this as well and found this link:

http://www.hemmings.com/magazine/hmn/2013/09/Duo-Servo-Brakes/3730001.html

 

[FishTacos]

"duh"? wtf does that mean?

I meant no offense.

The dual cylinders allow for more dynamic, and therefore more efficient, breaking. The curve in the break pad is applied at the trailing edge first and then as more hydraulic pressure is applied, more fully. If you have only one slave cylinder, one of the pads inevitably applies on the leading edge which makes it catch and apply completely....so.... less dynamic breaking.

 

[shawnfj40]

Not all of Toyotas ideas were better. They over engineered many things that turned out to be awesome. The two cylinder drums were not one of them.

 

[SW20]

For reverse......duh.

I had to admit, I laughed good on this one.

 

[ginmtb]

I had to admit, I laughed good on this one.

Me too!

 

[Frank Traverse]

Are the stock drums self-adjusting? years?

 

[western flyer]

Twin-leading-shoe drum brake - Wikipedia, the free encyclopedia

Twin leading shoe design = more braking power in the forward direction.

They typically do not work as well in reverse direction.

My Type 2 VW (bus) had them (2 cyl per wheel in front with 4-wheel drums; stolen pic at bottom). Some high performance vintage motorcycles had similar mechanical twin leading shoe drum brakes in front before front discs where made popular (stolen pic below).


Twin Leading Shoe Motorcycle Brakes Explained - Motopsyco's Asylum

Converting Single Leading Shoe Drum Brakes to Dual Leading Shoe Comments

 

[brian]

Are the stock drums self-adjusting? years?

no.
i dont think north americian cruisers every had self adjusting rear drums. the fronts were never self adjusting.

 

[JohnnyC]

Non self adjusting drums was a dumb design

Ebrake adjusted rear drums is a step up from non adjustable

As a DD I was adjusting every 3 months ... And that was pushing it ... Went to 4wheel disc ... That ended that

 

[Splangy]

"duh"? wtf does that mean?

Take it easy, cowboy. He was joking around with you.

 

[Brownd3max]

Take it easy, cowboy. He was joking around with you.

No problem Splangy, just wanted some clarification of his (unhelpful?) remark.

 

[brian]

"duh"? wtf does that mean?

duh - Wiktionary

 

[Brownd3max]

"Duh?" or "No Duh?" - that is the question?

 

[White Stripe]

The dual wheel cylinder design is far less efficient in reverse. I remember my dad when he and his shop was really into building 40s had just crossed a river in his soa 383v8 77 fj40, I think he was still refining a good traction bar for the rear to prevent axle rap back then. We climbed up a long Hill in woods about 50 yards-pretty steep, at the top was a even steeper rock face. We were on the verge of going over backwards when the rear driveshaft tube twisted in half. Front discs were pretty much useless at that angle going backwards. The rears did nothing either. It was a very scary and dangerous ride to the river. He used the front discs as a rear parking brake and we came to a stop sideways at the river. He has since lost the 40 bug, and only works on them at his shop when people ask if he does it. I remember in automotive class they told us that drum design has 50% less braking in reverse. I believe it. If your 40 is a driver, and not a nut n bolt restoration, discs is the way to go all around unless you have a 79 or newer with rear drums. They have a modern design that works fine. Im sure others will chime in, but when I put discs on the rear of mine, I can now brake confidently, as in Im still getting used to no drama at all stopping.

 

[JohnnyC]

@White Stripe

No drama now is right!!

one time i went 5 months... It was a double pump or no stop...a gang of blue-hairs raced out of a side road and my slamming on the drum brakes wasn't doing much... i swerved to avoid collision 2 wheels must have left the ground. I thank God I didn't roll or better yet plow thru them...thats when i went to 4 wheel disc (thanks again @stainless 40/45 )

I still dont know what hurt more ....my heart pounding, my white kuckles or the vinyl seat that sucked up my due to pucker factor 10.

 

[Poser]

Are the stock drums self-adjusting? years?

There is not a 40/45/55/60/62 Toyota Land Cruiser that had any form of "self-adjusting" front or rear drum brakes, unless you are considering yourself, THE SELF.

 

[White Stripe]

There is not a 40/45/55/60/62 Toyota Land Cruiser that had any form of "self-adjusting" front or rear drum brakes, unless you are considering yourself, THE SELF.

Didn't 79s to 83 have them? I can't remember really, I thought they did.