Rear disk conversion with changing the master cylinder

Not doing this just wonder what problems would occur. Would the rear brakes be biased to strongly?

 

No

 

How do I dislike your post? Very helpful

 

It answers your question. Plain and simple

 

Here you go: I did this to my Tacoma. I used the SOS performance kit. At the time there were only two kits I was aware of. Pedders and SOS. Pedders' kit was expensive and they wouldn't provide me pictures of the kit or give me any information about parts sourcing (as in, can I go to Auto Zone and get consumables).

Up front, I wouldn't ever do this again. It worked and it worked fine. For the most part, I was happy with it, but I had some self-induced incidents that made me realize it was a stupid modification. The master cylinder conversion was optional. I don't remember if it made much, if any difference. The appeal behind their kit was that the consumables were from Toyota vehicles. SOS actually only made the backing plate and e-brake cable adapter. And the master cylinder adapter if that was done. Toward the end of my life with the Tacoma, I was attempting to figure out if the brake booster from the Sequoia (where the master cylinder came from) would work in the Tacoma. I wanted a cleaner assembly.

Edit: There was also one or two questionable design decisions in the entire kit. They were easily fixable. At a cost.

 

It depends. The amount of torque generated for a given amount of brake pressure is a function of a long list of variables, most notably piston area, mu, and rotor diameter. If these main variables are balanced to match the braking torque vs pressure relationship of the stock drums there is no balance change. If they are engineered to not match then they can change the brake balance in a desired direction.

The OR/Pro models use electronic brake force distribution (EBD) which produces rear brake pressure "by-wire" based on the control system's design. It would be an involved solution to adjust brake pressure bias on these models.

I'm not sure how the non-OR/Pro models control brake pressure bias but they also have some form of the EBD system.

 

My truck is old school and i wanna keep it that way

 

My reading comprehension needs help. So I never experienced any braking issues that felt like the rear was biased. I never even felt anything for the short time I ran the stock master cylinder. Mine was a TRD Sport, so I can't speak to the Off-road version.

My goal wasn't to improve performance. I just do not like drum brakes for a variety of reasons.

 

I do not really notice any biased per se either. I have the SOS BBK front and rear on mine. Based on compounds of the setup brakes are a bit stiff at first but warm up nicely. There may be a bit of biased in the rear on a hard stop as I have felt the rear a bit squirrly but overall its has been a nice setup.

My main complaint is the e brake setup. So far its is useless. I have adjusted it, had others adjusted it and it just does not do anything for me. It could be that my truck weight is over capacity for this type of setup. Hard to say. Maybe its the pads and one side is not agressive enough like stock or that they are just undersized overall. I have been looking into electronic e brakes and may go down that route as the e brake has become a luxury item on my truck. Wilwood makes one among others and Tom over at SOS noted that Stoptech is coming out with one soon and that may be another solution coming out.

Overall the Master does not seem to be an issue. I am honestly not sure if the 4runner and OR electronic masters are any different. I swore one time i saw they used similar parts but I am sure there is some since piston and overall brakes are differnt.

I have had 5th gen 4runner, Wilwood Aero6 calipers (T4R pistons) and now Stoptech calipers. mostly its been good. The 5th gen setups had more softness but the Tacoma version is very firm.

 

Interesting. If anything, I always felt the conversion leveled out the braking a little. It definitely didn't seem to dive as much previous to the conversion.

The parking brake is not you. I had the same issue. Actually caused me to fail my state safety inspection twice. I adjusted under the center console and at the rotor hat and could never get a satisfactory hold. SOS used to supply a cable with their kits. I emailed them and they said they were custom made. I imagine they also worked better. We went back and forth for a while, and I finally gave up.

I had a trail mishap that destroyed my backing plate. I emailed for a replacement and almost fell out of my chair. I wish I could remember what it was, but it was beyond what I was expecting. I also had an issue where his supplied bearing hub bolts were frozen inside where they pass through the axle. That was fun. Reinstalled with a lot of anti-seize.

I also didn't like the adjustable piston rod between the pedal and master cylinder. A big PITA to adjust with the way he had it set-up. I was able to get custom made braided lines coming off the master cylinder to make it easier to remove and adjust the rod countless times.

 

ahh yah I had one backing plate where it threads in get stripped too unsure what it was but I got that replaced. Also had someone adjust the e-brake ones and put in the pad adjuster backward which ended up destroying my pads and cracking the rotor so I had to replace that.

Interesting on the hub bolts ill have to keep an eye out on that.

What adjustable piston rod? I do not think they include that anymore as I do not recall that as part of the kit. The different cable lengths would make a lot of sense. I tried the cable the pads right now I have it all just loose so I don't end up with another cracked rotor. I am going to give it another go as last time I think I ended up having it too tight and while on the go I just loosened it so it was not a factor for now. In general if you think bout it the drotor hub is a good size smaller and would make sense to have a different cable but adjusting the pads should work. I do not recall both pads having different compounds or roughness. The stock setups one side is more aggressive then the other to help with this. At least some recent info I was not aware of in the tacoma setup.

But honestly at this point if I can get an electronic setup to work ill go that route. I am now looking at a new axle and like the benefits of a full float axle and if I go that route it won't use the stock e-brake anymore anyway.

 

I just removed the rear brake shoes, and cut the parking break cables... who needs brakes anyway?

 

I've never seen the e-brake rotor assembly in person but it looks way smaller than stock so I'm not surprised. On a slightly different note, I was rotating the tires on my wife's model y a few weeks ago and noticed it used a 2nd electric actuated caliper. After spending so much on a BBK, it doesn't seem like it would be much more work to get a laser cut mount for a 2nd caliper on the rear.

 

I think you're joking about this but about 20 years ago I know someone who died trying to open a gate. They put their truck in park, tried to open a gate. The pin in the transmission broke and the truck rolled forward and crushed them between the gate. I've never trusted leaving a vehicle in park or in gear because of this.

 

Is the adapter plate flat? Could it be cut from a sheet or does it have depth to it that would require 3d machining or casting?

 

With all the traffic in the city nowadays i don't need brakes, i'll just use the brakes of the car in front of me.

 

It's usually a Prius, so I don't have any issue taking one off the road each time I need to stop in the city.

 

This is all from memory, and my memory isn't the greatest. The hub bolts are standard off the shelf bolts as supplied. What I remember the issue being is that the shoulder on them is a hair too big and they get wedged into the axle. I was able to get three out, but the third broke. There's not threads there so it wasn't a huge pain, but it wasn't fun. I believe I used an air hammer to punch it out.

For the e-brake, I had something. It just wasn't enough, so you may have an issue. The inside adjusters were as tight as they could be and so were the adjusters at the rotor hat. I looked into options such as a separate caliper, etc, but I was limited. I don't have access to the big-dollar fabrication tools. I'd be curious to see what Tom comes up with. The way the kit is currently is unacceptable.

When I got my kit, there was an adjustable rod that sits into the cup on the back of the master cylinder and into the booster. It was a button-head bolt threaded into a space of some sort, If I remember. It was a hit or miss affair trying to adjust it. The first time I did, I put it all together thinking I was fine. Then I went for a test drive. As the fluid heated up and expanded the calipers gripped and after a while I seriously couldn't move the truck. Sat on the side of the road for a few hours while everything cooled off. The next test drive I brought a 12mm wrench so I could back off the master cylinder mounting bolts and give myself some space.

Also, everytime I made an adjustment I would have to remove or break the lines free. That's why I ordered the braided lines. I could pull the master cylinder off and put it aside for the adjustment. No bleeding needed. It was actually pretty awesome.

So it's no longer like this??

 

Not completely. There were some additions for the parking brake shoes and a piece welded on for the brake cable to run into the rotor hat.

 

https://sosperformance.com/products...dot-ta5-dot-bpk-fits-2005-2018-tacoma-six-lug

And holy crap has the price gone up! I did everything for about $800!