Brake booster master question. (1 Viewer)

[SSCR]

I'm running the following calipers with 14" rotors on all four corners of the truck I'm building.

http://www.wilwood.com/Calipers/CaliperProd.aspx?itemno=120-6818

Any suggestions for a good booster master combo to run to feed them? I'd prefer something that is readily available and can be had new off the shelf if possible. The calipers are on the smallish side but have 4 pistons, hopefully they will provide good stopping power for the rig.

Thanks

 

[SSCR]

It was suggested to run a FJ60 booster with a FJ80 master but its difficult to find a 60 booster and it's only going to get harder. Anyone run a combo from The Right Stuff? Something like this with a proportioning valve and brake light sensor?

http://www.getdiscbrakes.com/g84310572

 

[cruiser guy]

I'm in the same boat. Found this guy. I heard you wanna bolt it up to a fj80 booster but I don't know if the 60 one would work or if its the same bolt pattern

 

[SSCR]

Interesting, ill have to look into that. I read in another thread about using a 95 4runner booster
http://shop.advanceautoparts.com/p/...dium=ir&utm_campaign=27795&utm_content=120917

Good, price and maybe match that to an 80 master? I got to figure out the math of what I need to push the pistons in the calipers....

 

[J Mack]

I'm running the following calipers with 14" rotors on all four corners of the truck I'm building.

http://www.wilwood.com/Calipers/CaliperProd.aspx?itemno=120-6818

Any suggestions for a good booster master combo to run to feed them? I'd prefer something that is readily available and can be had new off the shelf if possible. The calipers are on the smallish side but have 4 pistons, hopefully they will provide good stopping power for the rig.

Thanks

I just went through this with my project and these are some things to take into consideration.

It’s very difficult to setup a braking system with the same size calipers front and rear, by the time you adjust the proportioning (Pressure Reducing) valve enough to prevent the rears form locking up you start to have fluid volume issues. I would call Wilwoods tech line and talk to them before I spent too much time looking for a master to run calipers that may not work for you.



Lots of internet information on what size master to run with four wheel disc conversions but unfortunately most of it is based on what is perceived to be working or not working and not based on any type of formula or proved science. Once you figure out what size pistons you’ll run in you calipers there are some online calculators to help determine the proper size master cylinder piston size and stroke to give the desired foot pedal force and travel, again the tech at Wilwood could give you this info.

FYI: I was having a hard time contacting a tech at Wilwood the day I was trying to get solid answers but the guys at Baer Brake’s where very helpful at getting me lined out with a master cylinder for my conversion.

 

[sadam_husain]

as above you'll have to work out what your fluid displacement is to determine what size master cylinder will work, when you choose a master cylinder the bigger the bore size the more pressure you'll have to apply to the foot pedal to clamp the callipers.

60 series boosters are single diaphragm and 80 series boosters are dual diaphragm so you'll get better braking assistance from an 80 series booster than a 60 series booster

 

[maxamillion2345]

The 4runner boosters are duals too, should bolt up the same as an 80 and easier to find, use a skys adapter to run a chevy master or a dodge master

 

[SSCR]

Good info thanks guys! I will check with Sky, Baer and try to get a hold of someone at Wilwood today. I went with those particular calipers because those are what were offered with the Spidertrax axle kits I bought. Maybe I should call them also. I was also looking at the kit offered by BTB.

 

[SSCR]

Just got off the phone with Wilwood. They suggested when using a booster if it has 18" or under total vacuum I should use a master with 1" bore, 21" or higher I should use a master with 1 1/8" bore. 18"-21" is a "grey" area. I will have to use a proportioning valve, which I figured. The vacuum of the booster is measured by the size of the diaphragm.

Anyone know the vacuum of a 4runner diaphragm?

 

[SSCR]

Im also looking at this..
http://www.btbprod.com/BRAKE-BOOSTER-MASTER-TOY-FJ40-45-55-DISC-BRAKE-CONVERSIONS.html

I called them and they said it has 17" vacuum at the booster. They weren't sure about the master bore size.

Just read their site and it says 1 1/8".... Wilwood tech says I should use a 1" bore...

 

[maxamillion2345]

Split the difference, skip the adapter and shoot for a 1 1/16 t100 master and a yota dual diaphragm booster. If you look around on rock auto you can find that different boosters had different diameters as well... I'd get biggest booster you can find.

Worth a shot, if not, step up to a 1 1/8 dodge w250 master with the skys adapter or step down to the 1" yota master off of an 80 or something.

When messing with my brake setup I was amazed how much difference a couple 16ths makes. I hate to admit it but I had to just keep trying different things until I got mine right.

You'll definitely need a proportioning valve, agreed.

 

[SSCR]

That sounds good, I also reached out to icon to see what they are using

 

[SSCR]

Heard back from icon, they also run an 8" dual booster with a 1 1/8" master just like btb.

 

[Fast Eddy]

Dual-diaphram 8" Toyota-pattern replacement booster coming in September from forum member @Racer65:

With 14" rotors you might want to consider hydraulic. (?)

 

[SSCR]

Icon is running 14" rotors and 4 piston calipers from stop tech with great success, so are most new "sporty cars". I just need to find the right balance for the master and booster combo. The calipers total piston area is 4.8 inch each (19.2) I need to find the formula car manufacturers use to determine what I need. Still thinking of running a 4runner and 80 combo to start with....

 

[J Mack]

I need to find the formula car manufacturers use to determine what I need.

Bottom of the page.

http://www.markwilliams.com/braketech.aspx

 

[SSCR]

Great, thanks!

 

[J Mack]

Great, thanks!

Another good read on brake bias and sizing your components to work as intended.


http://www.stoptech.com/technical-s...ias-and-performance-why-brake-balance-matters

 

[SSCR]

That marks William page suggest using a 1 1/8 master.

 

[SSCR]

Four 81100/82100 4-Piston Calipers
19.2 sq. in.
1-1/8" Bore
1.24 cubic in Master cylinder displacement