SMKYTXN'S 2011 DCFBFTMFW Solid Axle Swap

Did you by chance try a land cruiser 1.125" master cylinder?

 

Why not go 1 ton master cylinder and full hydro boost? This is on my first gen

 

What does your pedal do? Lots of travel then it finally engages and stops?

Nope, that one wasn't on my list. So far I've tried the stock MC and the Tundra MC. The Tundra MC has a 0.94" diameter and the GM mc has a bore of 1.3".

At this point it's not a force issue it's a proportion issue. The hydro boost would push harder, but if there's not enough fluid to push it's not going to help. We'll see what the new master does for me and if the Tundra dual diaphragm booster is enough to push it.

 

Well if you do want to go full hydro I have about $250 into my master cylinder/booster. So it’s not super costly to swap.


Edit: now that I think about it idk if the set up I have will work since it is Alittle longer then the factory set up and you will loose certain electrical connections for your abs and such. So scratch that.

 

yup, lots of travel then stops. I mean, it will definitely lock them up but lots of travel.

 

We don't have abs at this point anyway so it doesn't sound bad.

 

I only suggest the Land Cruiser MC because it shares the common Toyota mount flange. I used it and a Early Tundra booster on my first gen toyota when I went to tons and 42" worked good for me but it was also not a daily driver. It would however lockup 42s on pavement.

 

Yeah, the ABS pump is long gone and the only other electrical component is the level sensor. One more light on the dash won't hurt.

You're still on the stock mc and booster, right?

The area of the LC mc isn't quite as large as I need it to be. At least not as big as I think, but we'll find out.

 

One step down. The mc is now bolted up to the booster. I’ll measure for and make the plunger on Sunday when I get out to the shop.

 

Still on stock mc and booster yes.

 

So here's my take on the problem I have with my current setup. Current being a Tundra master cylinder and booster.

The relatively small mc produces more pressure, but pushes a smaller volume of fluid. So that ends up with a much greater pedal travel to achieve that pressure.

The hydraulic ratio between the mc and caliper piston is what I'm basing the new mc choice on. The higher the ratio between the two the less pedal effort is required and the longer the pedal travel to achieve the clamping force.

The Tundra MC has a bore of 0.94" and an area of 0.69 sq. in. The chevy 3/4 ton calipers on the truck have 2-15/16" pistons. Each caliper is a single piston. The area of the caliper piston is 6.77 sq. in. So right now my hydraulic ratio is 6.77 / 0.94 = 9.81:1. In order to decrease that ratio I will need a larger bore master cylinder or smaller piston calipers. The smaller calipers aren't a good idea with the weight of the rig, so a new master cylinder is in order.

The GM MC has a 1.3125" diameter bore and an area of 1.35 sq. in. So my new ratio will be 6.77 / 1.35 = 5.01:1. That decrease in hydraulic ratio will mean a higher pedal with an increased effort in pedal force to achieve the same braking force. The next question will be does the Tundra dual diaphragm booster have enough balls to overcome that higher force or not. Time will tell on that one.

Obviously we're not going to get, nor do we want to get down to a 1:1 ratio. Meaning the master and caliper have the same size. We want that hydraulic advantage of a smaller piston pushing a larger one. We also don't want the hydraulic advantage to be too high causing the pedal to be too easy to push.

So that's where I'm headed with this. I'll report back when I have everything installed and test.

 

Success! The combination of the Tundra booster and the gm one ton master cylinder did the trick. I now have a pedal with stock travel length or a hair less.

I did discover a few things during the install. One being that I need to size the hole in my adapter to accommodate an oring on the master. I also need a gasket between the adapter and the booster.

For now I have temporary rubberized gaskets in place that are doing a decent job. I still have a slight vacuum leak, but it’s not horrible. I’ll revise my cut file and make another adapter.

I’ll get the pictures posted when I get back to the house.

 

I’ll take one if your selling

 

That’s the plan bud. Give me a bit to get the kit together.

 

Awesome! Normally I don't care much for flatbeds, but that thing is awesome.



I need more taco money....

 

well done sir!

 

Not sure if this is of any help at this point buuuutttttttt http://home.4x4wire.com/erik/4runner/brakes/

 

That's one of the pages I used to do my research on what booster size I needed.