master cylinder

[Rock Cruiser]

My brake master cylinder is going out and would like to upgrade the calipers in the future?

Which would be the best MC for the 4runner caliper mod but work with the stock calipers I have now?

Or should I just get OEM replacement from cruiser corps or cruiser outfitters?

I have an 88 fj62

Thanks

 

[NolanFJ60]

T100 MC. It bolts right up to your booster. You'll have to bend the brake lines just a little to get them lined up with the new MC ports.

 

[gregnash]

Until you move up to the 4runner calipers the higher bore of the T100/4runner/etc m/c will make the brakes feel spongy. There are numerous threads on this due to the increased bore size of the brake master.

Just an FYI.

 

[Rock Cruiser]

I thought it was a firmer less braking thing and not spongy?

yeah I've read probably every post on it but never got a definitive answer from anyone like best year and model?

Is going with the bigger MC that bad or is pretty scary or really not that bad?

Thanks!

 

[gregnash]

Well from what I have read the larger bore with the stock FJ6x caliper causes a spongy brake were you get some long travel before it really feels like it begins to engage. I have not read much about the change to the larger bore m/c with the increased braking of the 4Runner calipers.

There are both camps for and against doing the upgrade. Really it seems to be a pretty personal experience.

 

[Tapage]

bigger bore with the same " others " ( everything else ) should make your pedal rock solid, short travel and you will need more effort to lock your tires ..

that's what happened to me when I went to big in MC ... ( 1 1/4 )

 

[TurboDino]

Just reading through the posts about this upgrade, and I wonder if the spongy brake feel is with or without the residual valve mentioned in agent oranges's excellent thread on the brake and MC (titled: 4runner brake install) upgrade. I can see that without a residual valve to stop bleed off of the rear brake fluid back into the MC the pedal would get mushy with a long travel. No direct experience though, so you might want to read that thread for yourself...

 

[Trapper50cal]

Wow....that's what I'm experiencing right now....rock hard pedal feel and no lock up in site...mediocre braking. I got my BMC from rock auto. I've been going over everything but the MC because I thought it was good...could it be the bore size? Any help would be appreciated. Should I get a used LC BMC and see what happens?

Sorry...not trying to hijack

 

[dbleon]

Installed a t100 MC from napa... was my only quick option to get back on the road at the time. Dont like it. Going back to stock soon.

Used to be able to lock the brakes up, now got a real 'firm' pedal, but less overall braking power IMO.

I read replacing the booster (fj80 or 4runner?) is the ticket.. in terms of upgrading the system if thats what you are after. Otherwise leave well enough alone and make sure its all in good repair.

 

[Callahan Offroad]

That makes no sense from a scientific stand-point. Larger Master Cylinders force a higher pressure of fluid through the same volume of tubing, and should there-fore increase braking response. That's like saying a bigger turbo makes less power. Something must be incorrect in the install, bleeding, or in a different but related component. I wonder if the brake booster can't handle the extra pressure?

 

[dbleon]

That makes no sense from a scientific stand-point. Larger Master Cylinders force a higher pressure of fluid through the same volume of tubing, and should there-fore increase braking response. That's like saying a bigger turbo makes less power. Something must be incorrect in the install, bleeding, or in a different but related component. I wonder if the brake booster can't handle the extra pressure?

Nope, sorry.

Let NTSQ chime in on this to explain.

 

[Trapper50cal]

Not sure about that, Ryan...the way I see it bigger bore means larger volume to initially compress...equaling less efficient/less pressure.

I don't know much about turbos, but I imagine it's also one of the reasons why a smaller turbo spools up faster.

 

[tag3]

Larger bore=larger volume, smaller bore=smaller volume higher pressure.

 

[60Works]

What master cylinder to choose is based on two things. What is safe to operate now. And what is safe to operate when you've made all your brake upgrades.

To reiterate other wise posters; master size is counterintuitive. Bigger bore master with stock calipers = less braking pressure and a potentially dangerous increase in stopping distance.

Note: If you can apply enough pressure to lock up your tires, braking distance is the same no matter what mix of parts you have. Small components don't last as long because they can't handle the heat.

One my 60's has the 4 Runner caliper upgrade with a stock master and booster. I think the pedal travel is fine. Brakes apply smoothly and with authority when pressed hard. If all you're planning to change in the system is the front calipers, I'd recommend sticking with a stock master.

I haven't tried changing it yet, but I think upgrading the booster will result in the best gains of pedal pressure to caliper pressure. Two of my 62's are bone stock and both have better braking than either of my 60's. The booster and the LSPV are the only differences in the systems.

There is also a larger rotor mod using Tundy disks and calipers with IFS hubs. This widens the stance by 3.5" so it would need to be coupled with a rear axle mod as well as master and booster and wheels. It's pretty much changing the entire system with a newer Tundy's.

 

[Spike Strip]

The T100 MC is a 1" bore, and it's what I used with the 4R calipers I installed. Pedal pressure is on the hard side, but works fine. Dynosoar used a 15/16" MC (I don't remember out of what model/years) and it seems to have a more "stock" feel w/ 4R calipers.

If your cruiser is stock w/stock or under 33" tires, I'd stick with the stock setup.

Stock FJ60 MC is 7/8" IIRC - it's stamped on the side of the casting.

 

[GeologistFelix]

Hydraulic systems are kind of counter-intuitive.

Basically, the larger the bore, the wider the area you're spreading the force of your foot on the pedal (and the booster) over. So, the larger the MC, the smaller the pressure you generate from a given amount of force applied to the cylinder.

Meanwhile, the bigger the cylinders in the caliper, the more total force it can exert on the pads for a given pressure.

What you want is a booster with a bigger diaphragm (or just a rebuilt/new stock diameter booster), and then keep the caliper/MC bore ratio the same as the factory setup, so that you can apply more force to the brake pads for the same input from your leg.