brake upgrades
I upgraded the Master Cylinder in preparation for my T100 caliper swap - the bigger pistons on the T100 calipers need a slightly bigger MC bore. The '90s T100 1 tons have a 1-1/16" MC bore vs the popular 1" bore found in many mid 90's 4runners and LandCruisers - bigger isn't necessarily better when it comes to the MC bore. A bigger bore moves more fluid, but produces less hydraulic pressure with the same amount of force on the pedal. In this case, I wanted to match what was available on the T100. I should have probably stayed with the 1” bore since I can't fit the dual diaphragm booster that the T100 uses and I've since installed the 1" bore MC
here's my $50 ebay master cylinder, brand new - note the 1-1/16" cast on the side
out with the old 7/8" bore MC
in with the new (and the aluminum looks much prettier than rust
)
EDIT:
I've recently installed a 15/16" master cylinder from a 91-95 MR2 turbo w/ ABS and while the pedal is slightly softer, I can now lock it up if I stand on the pedal. If I could have fit the dual diaphragm booster I probably wouldn't have had to take off the 1" master cylinder. I think I finally got the balance just right between master cylinder and everything else
it was a simple bolt on swap, no drama. The front brake line needed to be bent a bit to match up with the T100 MC port. I didn't bother to bench bleed it, prefering to do it on the vehicle with a rag under the lines. Initial driving impressions were good with pressure building and the pedal firm very near the top of it's travel, though when I got the T100 calipers on it softened up just a bit. I would not recommend this size MC with the stock 1st gen calipers as it could get tiring to drive with the extra firm pedal.
Here are the original calipers, note the S12+8 casting mark in the second pic. Toyota uses standard calipers on several different models, the cast mark identifies which ones are identical (no difference in the cast mark to indicate left or right side though)
Here's what happens if you try to use the T-100 (S13WB cast mark) calipers with the stock rotors.
BTW, when I was getting parts I told the parts guy it was a '95 T-100 4wd.
So I got a pair of T-100 rotors to go with the new calipers and pads - the only thing that needs to change for the rotors is to push the bottom of the backing plate away from the rotors about 1/8" to keep it from rubbing - otherwise everything just bolts on
Here are the '88 4runner rotor specs:
# of Bolt Holes:6
Bolt Circle Diameter:5"
Diameter:11.375"
Height:2.535"
Maximum Lateral Runout:.004"
Thickness When New:.79"
Discard Thickness:.709"
Vented / Solid:Vented
Center Hole Diameter:3.942"
here are the T-100 rotor specs:
# of Bolt Holes:6
Bolt Circle Diameter:5"
Diameter:11.41"
Height:2.59"
Maximum Lateral Runout:.004"
Thickness When New:.985"
Discard Thickness:.905"
Vented / Solid:Vented
Center Hole Diameter:3.942"
So the only real difference is thickness and overall diameter - if you saw the "height" is also different, that's only because the rotor is thicker and the height needed to change to keep the rotor centered in the caliper.
The calipers are a simple bolt on affair, the only thing necessary is little bit of trimming to the backing plate
Finished product (kinda finished, I didn't have the rotors on yet in these pics)
for some other caliper options
look here
The pedal feel with the bigger calipers was better, before with the stock S12+8 calipers and the 1 1/16" MC the pedal was rock solid. It still wasn't stopping the way I wanted it to and I had my doubts about the rear LSPV so I took it out of the picture.
Before we get to that, there's a lot of misinformation spread around regarding how this little piece of metal on the rear frame works. One of the most popular misconceptions is that the brake line going from the LSPV to the "T" near the passenger front wheel some how redirects pressure from the rear to the front brake circuit. How does the LSPV move fluid from the rear brakes to the front, to an area with higher pressure, without a mechanical pump? the line going to the front brakes is only used for "pressure sensing" in case of front brake failure -
here's some reading on how proportioning valves work, scroll down to pg 13
here are 2 screen shot from the link above
Here's the Field Service Manual for the
Brake System on a '93, but not much changed in over a decade - the system is essentially the same
Speedway Motors has manual valves for $33
here. Summit Racing or Jegs also carries them and you can probably find them in any respectable hotrod or racing equipment store. Just look for the knob style like I have in the link - they're all the same and brand name doesn't matter much with a simple part like this.
Here's the Wilwood manual brake proportioning valve that I used - the shiny fittings are SAE standard for 3/16" brake line, the only metric (Toyota) fittings are the rusty ones that I re-used on the master cylinder, the Toyota fittings worked perfectly with the 3/16" line and mixing them on the line made it easy to adapt between SAE and Metric
(note: all brake lines where bent with a tool, brake line doesn't bend very nicely by hand - it has a tendency to kink)
I took the LSPV off. The line that needs to get bent down to the flexible brake line is the one at the top of the LSPV - there is an -> next to the brake line on the LSPV. The line with an "F" next to it ties into the front brake line and can just be bent back or cut off . . . .
. . . . once you plug the front "T" I just took a fiting and put a big puddle of weld in the middle of it to make my own plug.
You might be able to get a plug, but I don't know where. I think the plug threads are 10mm - 1.0. Or you can forget about messing with the "T" and try to find a 90 degree brake line adapter from the same location on another toyota truck, like the one on the left in the pic below
Another option to get rid of the front "T" if you can flare a brake line:
- cut the original Toyota ends off at the "T"
- slide new 3/16" SAE sized nuts over the bare ends
- flare the line and use a male-male adapter like I had to do in on vertical part next to the brake booster to adapt the proportioning valve to the stock lines (but do this at the "T" in the pass. wheel well)